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OCR for page 49
Methods for Estimating and
Projecting Water Den~ancis
for Water-Resources Planning
I NTRO DU CTI O N
EVERARD M. LOFTING
University of California, Riverside
H. CRAIG DAVIS
University of British Columbia
Longrun solutions to problems associated with scarce
natural resources and raw materials are of critical impor-
tance to the economies of industrialized nations. Water is
undoubtedly one of the most critical of these scarce re-
sources, although recently attention has been focused
more upon various forms of energy. As both population
and economic growth continue, there is an increasing
need for the development of more effective planning
models and strategies to meet the problems associated
with expanding resource demands. In the market
economies, except in times of extreme exigency, such as
war, the allocation and distribution problems are solved
by rising prices. The demand for certain resources is
brought into balance with available supply at some new
(higher) price level.
In economic theory the concept of "demand" for a
particular commodity is the schedule of quantities of the
commodity consumers are willing to purchase at various
prices. While the concept can be precisely defined for any
good or service, the task of giving it operational and
49
empirical content with the same degree of exactness
has traditionally been considerably more difficult.
Economists have indicated on several occasions concern
about the continuing use of the terms "requirement,"
"use," and "need" when referring to the withdrawal or
intake of water as a natural resource." These terms are
called into question because they do not have an alloca-
tive connotation that is in keeping with the competitive
market framework.
Given the general problems associated with statistical
demand estimation and, in the case of water, present
conditions of"block pricing" and substitute goods such as
self-supplied, reclaimed, or recirculated water, the pros-
pect for determining demand functions relating to water
(particularly for water as a production input) for purposes
of policy formulation may remain tenuous for some time
to come.
In the sections that follow, the current state of the art of
forecasting water demands or requirements is reviewed
for the water-use categories of irrigation, minerals indus-
tries, manufacturing industries, thermoelectric power,
commercial, and municipal. Water-resource systems
OCR for page 50
50
planning and the role of water-use data in the develop-
ment of water-use forecasts are discussed, and the possi-
ble impact of climatic variability on water-use forecasting
is considered. The paper concludes with a graphical
comparison of existing water-use forecasts to the years
2000 and 2020 with the results of a simple forecasting
model constructed by the authors.
DEFINITION AND USE OF THE
TERM ''DEMAND''
The concept of a demand schedule in its strictest sense
applies only to consumer purchases. Purchases of re-
sources and materials inputs by producers to satisfy the
demands of consumers for specific products are more
properly termed "derived" demands. The terms "water
requirements" or "water use" have been historically as-
sociated with water development planning and do not
carry any precise or rigorous connotation of quantitative
measurement of water withdrawals in relation to price.
They are generally used in an engineering or technologi-
cal context to relate the quantity of water employed in the
production process per unit of output.
The use of the term "water demand," as opposed to
"water requirements" or "water use," carries with it the
implication that the impact of price on the amount of
water being withdrawn has explicitly been taken into
consideration and that the amount being withdrawn is the
smallest amount needed for whatever purpose to
minimize costs to the withdrawer.
This may be true if the withdrawer is an individual
consumer. If, as a matter of policy, prices of public
supplies are increased to agricultural and industrial pro-
ducers, there is no guarantee that they will in fact use less
water but in times of inflation may simply pass the in-
creased costs on to the purchasers of their products and
ultimately to consumers, adding further upward pressures
to market prices. This has been a vexing matter. In the
market economies, there has been a continuing search for
more precise policy instruments that have greater cer-
tainty of achieving a more efficient use of resources than
certain autonomous increases in commodity prices.
There is another aspect to the demand for water. Water
is demanded for productive uses. There are also over-
whelming demands for the waste-assimilation services of
water. Pricing policies concerning the latter in the form of
taxes and surcharges on pollutants and volume of outfalls
have been long recommended. In the United States,
events overtook these recommendations in 1972 in the
fop- of amendments to the Federal Water Pollution Con-
trol Act, known generally as Public Law 92-500. Under
Phase I of the law, federal regulations require industry to
install "best practicable control technology currently
available" (BPT); Phase II requirements are intended to
be more rigorous and more innovative. Industries are to
install best available technology economically achievable
(BAT) by July 1, 1983, and, ultimately, all point source
EVERARD M. LOFTING and H. CRAIG DAVIS
controls are directed toward achieving the national goal of
the elimination of the discharge of pollutants (EOD) by
1985. In the case of irrigation, the Act requires the use of
Irrigation Management Services (IMS), in which water
use and return water discharges are to be scientifically
managed to ensure minimal use and minimal discharge.
Under the provisions of Public Law 92-500, revolutionary
changes in water use in most sectors can be expected, and
the projection of water "demands" should ultimately be
subject to some minimal technological requirements in
most cases. If the provisions of the Act are enforced in the
agricultural and industrial sectors, water demands and
water requirements may become essentially equivalent
regardless of the withdrawal price of water.
STATE OF THE ART OF
FORECASTING DEMANDS
Projections of demands for water are usually made for the
major industry divisions and the household (residential)
sector of the economy. Traditionally, however, water-use
categories and economic-sector categories have not been
aligned. Specifically these categories can be listed as
shown in Table 3.1.
In order to bring the economic-sector categories into
agreement with the Gross National Product and its com-
ponents for analysis and projection purposes, the addi-
tions to the economic sectors shown in Table 3.2 are
necessary. This grouping provides an exhaustive, highly
aggregated classification scheme for all productive sec-
tors of the national economy or its geographic regions.
The Gross National Product (GNP) iS a scalar quantity
that is typically projected by federal agencies in constant
dollar terms to various target years.2~3 The projected scalar
values can then be decomposed into the sectoral compo-
nents that reflect the relative growth or decline of these
within Me overall control total. The resulting estimates
can be termed "consistent." That is, the interdependent
nature of the sectors of the economy is usually explicitly
(or implicitly) recognized. If the individual sectors were
projected on the basis of historical Rends or over criteria
and the values summed for the target years, results may
be inconsistent with more reasonable estimates of the
GNP based on the material requirements of the projected
population and resource availability. Moreover, since
water is regional in its occurrence, the national control
TABLE 3.1 Economic-Sector and Water-Use Categories
Economic Sector Water Supply-Demand Category
.
1. Irrigation
2. Mineral Industry Water Use
3. Industrial
4. Thermoelectric Power
5. Commercial
6. Municipal (Part)
1. Agriculture
2. Mining
3. Manufacturing
4. Utilities
5. Trade and Services
6. Households
OCR for page 51
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
TABLE 3.2 Additional Economic-Sector and Water-Use
Categories
Economic Sector
Water Supply-Demand Category
1. Agriculture
2. Forestry and Fisheries
3. Mining
4. Construction
5. Manufacturing
6. Utilities
7. Transportation and
Communication
8. Trade and Services
9. Households
1. Irrigation
2.
3. Mineral-Industry Water Use
4.
5. Industrial
6. Thermoelectric Power
7.
8. Commercial
9. Municipal (Part)
totals can be disaggregated spatially to yield a furler
consistency for the various sectoral components.
Before dealing with We specific sector demand analysis
and projections some further points should be made
regarding the alignment of water supply-demand cate-
gories with the economic-sector categories.
Consistent estimates in money terms can be made for
the GNP and its sector components as indicated above. It
is desirable that these be matched (aligned) as closely as
possible with water-demand estimates in physical terms,
i.e., gallons per day or acre-feet per year. This is not an
easy problem since the engineers and hydrologists gener-
ally charged with the responsibility for gathering or esti-
mating the water data do not choose their classifications to
fit precisely with the economic-sector specifications. Water
uses may be measured or gauged by the amount supplied
in a given time period. Further, water may be impounded
and supplied for certain joint uses, and it may not be
known except in the most aggregate way which end use
actually withdrew the water. For example, water may be
impounded and distributed by a public water supply
system. The water may be supplied to households, indus-
try, municipal buildings, and commercial enterprises. In
fact, multiple-unit dwellings are frequently considered a
commercial use of water and are so classified by many
water-supply agencies. Thus, commercial and multiple-
unit dwelling household uses may be inseparable in the
supplying agency's records, and other estimating tech-
niques must be found to separate these for analytical
purposes. The same type of end-use identification occurs
for commercial and industrial uses from time to time. The
overall alignment scheme suggested above is not entirely
precise but is probably the most satisfactory for establish-
ing aggregate control totals, given the nature of the basic
water-use data as presently compiled.
DEMAND ESTIMATING AND FORECASTING
TECHNIQUES FOR AGRICULTURAL
( IRRI GA TI O N ) WA TE R
The state of the art in estimating demand functions for
water used in agriculture appears to be progressing at
51
three levels: (1) the micro, or small area, approach; (2) the
macro interregional programming approach; and (3) the
dynamic multisector model approach.
Examples of We first approach are cited by Howe4:
For consumer goods~and many producer inputs, we have data
on prices, quantities sold, and other relevant variables sufficient
to permit estimation of the demand function. For irrigation
water, markets generally don't exist, prices are usually nominal
and highly subsidized and unrelated to costs or willingness to
pay. Transfers among uses are infrequent and sluggish. Thus,
often we simply don't have the data needed to estimate the
demand functions for irrigation water. It is then necessary to
estimate farmers' willingness to pay for water by modeling their
production operations and, upon the assumption that the farmer
consciously or unconsciously is attempting to maximize profits,
deducing how his applications of water would vary as the price of
water is varied. This is most frequently done through linear
programming models in which the activities represent different
crops and methods of cropping (including different amounts of
water). The same results can be deduced by placing a water
constraint on production, plotting the relationship between the
shadow price of water and the quantity available. Examples of
excellent studies following this approach to the estimation of
irrigation demands are Moore and Hedges,5 Young and Bre-
dehoeft,6 Cummings,78 Stults,9 and Gisser.~° The resultant de-
mand functions are either for individual farm or farms of different
types,5 for a farming area,6 7 or for an entire region.8-~0 . . . Other
methods are possible for estimating irrigation water demand
functions. Hartman and Anderson estimated the value of irriga-
tion water from farm sales data. Andersont2 has estimated ilTiga-
tion water values from data on seasonal water rental markets in
northeastern Colorado. Gardner et al.~3 have estimated irrigation
water values from time series data on water rental values before
and after consolidation to Utah irrigation districts.
The outstanding example of the second approach is the
interregional programming model developed by
Heady.~4 The Heady model is formulated as a linear
program, the solution of which yields the least-cost distri-
bution of agricultural production by crop type and geo-
graphic region, under various assumptions about resource
availabilities and their costs, farm support programs, and
consumer and export demand for agricultural products.
The model was developed to use the following data as
inputs. The 223 water-resource subregions defined by the
U.S. Water Resources Council are used to specify the
basic geographical production areas. In each production
area the quantities of land that are available for various
types of production are identified. These include crop
land, irrigated crop land, dry land for tame hay or crops,
irrigated land for tame hay or crops or land available only
for pasture or wild hay, and land diverted by certain
government programs. Consumptive uses of water for
municipal, industrial, and specific on-site purposes (such
as wet lands) and for fruit, vegetable, and rice growing are
forecast as requirements for each water-supply region.
The limitations of water and land serve as the major
constraints on agricultural production in each geo-
graphical area in the model. Additional constraints re-
flecting the need for crop rotation and the need for satisfy-
OCR for page 52
52
TABLE 3.3 Correlative Water-Use Factors
EVERARD M. LOFTING a nd H. CRAIG DAVIS
P.
X n—2 r r2 percent
By river basin
Total water Value of production 16 0.58 0.34 2
Total water (except natural gas processing) Quantity of crude material 16 0.66 0.44 1
New water (except natural gas processing) Do 16 0.68 0.46 1
Percent total water recirculated Average temperature 16 0.64 0.41 1
Consumed water Do 16 0.59 0.35 1
Do Humidity 16 -0.54 0.29 2
Do Recirculation 16 0.75 0.56 1
By commodity
Total water (except natural gas processing) Quantity of crude material 33 0.62 0.38 1
Percent new water consumed Percent total water used for 17 0.69 0.48 1
cooling and condensing
By states
Recirculated water Value of product 43 0.61 0.37 1
Consumed water Temperature (30-year average) 43 0.43 0.18 1
Do Temperature (l-year average for 1962) 43 0.43 0.18 1
New water (treated) Population 1960 48 0.46 0.21 1
TABLE 3.4 Noncorrelative Water-Use Factors
Y X n—2 r
By river basin
New water Average precipitation 17 0.04
Do Mean stream discharge 16 -0.01
Recirculated water Value of production 17 --0.14
Do Average precipitation 17 —O.1Q
Do Mean stream discharge 16 - 0.12
Do Days with O.Ol-in. precipitation or more 16 -0.23
Do Humidity 16 -0.21
Recirculated water (except natural gas Days with O.Ol-in. precipitation or more 16 -0.24
processing)
Percent total water recirculated Do 16 -0.42
Do Humidity 16 -0.33
Recirculation per ton crushed limestone Days with O.Ol-in. precipitation or more 16 0.52
Recirculation per ton sand and gravel Do 13 0.35
Consumed water Precipitation 17 -0.22
By commodity
Total water Value of production 33 0.14
Total wafer per ton Value per ton 7 0.21
Discharged water per ton Recirculated water per ton 32 0.21
Water consumed per ton Do 32 0.25
By States
New water Precipitation (30-year average) 43 0.11
Do Price of water 42 -0.11
Recirculated water Precipitation (30-year average) 43 -0.03
Do Price of water 42 - 0.04
Consumed water Precipitation 43 -0.11
New water treated Population density 48 -0.14
OCR for page 53
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
ing basic nutrient requirements in animal feeding are also
included. Given the constraints for each producing area,
the objective of the model is to find the geographical
distribution of agricultural production that satisfies the
forecast demand for food and fiber at the national level
while at the same time minimizing the cost of agricultural
production. By means of a given set of assumptions about
price support levels, quantities of land under diversion,
export levels, consumer demands, and water prices, the
various solutions of the model give the level of produc-
tion by each agricultural activity, the quantities of water
and land used productively, and the marginal values of
water and land in use, for each region. The results so
obtained have been primarily used to provide indications
of relative changes in demand that might be anticipated
under alternative futures. In order to evaluate the sen-
sitivity of water use in irrigated agriculture to the price
changes of water, the prices of water that are paid by
agricultural producers in the model were increased sys-
tematically above the prices charged by the Bureau of
Reclamation in different water-supply regions. Prices of
$15, $22.5D, and $40 per acre-foot were evaluated where
they were higher than prevailing prices. The findings
appear to indicate that the demands for water in the
water-short areas of the West could be relatively insensi-
tive to increases in water prices from the prevailing low
levels to prices of up to $15 per acre-foot in the water-
short areas in the Great Basin, Lower Colorado,
Missouri-Arkansas-White-Red, and Texas Gulf. The
higher water prices resulted in increased prices for each
commodity classification that was studied. If a $40 per
acre-foot price of water prevailed, it was estimated that
beefprices would be 9 percent higher than they are under
present water prices, and the price of wheat was esti-
mated to be 10 percent higher. The ultimate effects of
such higher farm product prices on retail food prices were
not studied. Given the present inflationary trends, this is
a crucial issue that cannot long be overlooked.
An example of the third approach is that of Duloy and
Norton,~5 whose efforts form part of a larger study of the
Mexican economy sponsored by the Basic Research Cen-
ter of the World Bank. The largest component of the
overall modeling effort is a programming model of the
Mexican agricultural sector. Possibly the single most
striking feature of the submodel is the detailed manner in
which the demand for agricultural products is specified.
Not only are demand functions for 33 short-cycle crops
included at the national level, but import and export
estimates are made for 21 of these crops. Prices for com-
modities that do not enter foreign trade are determined
endogenously, and prices for traded commodities are
bounded both above and below by Mexican FOB and CIF
prices. The model functions as a market-clearing
general-equilibrium system in respect to agricultural
commodity production. Duloy and Norton were able to
include within their linear programming format both a
competitive and noncompetitive market equilibrium. Ag-
ricultural markets have typically been competitive; how-
53
ever, the incomes accruing to agricultural enterprises
under major changes in output may respond like the
incomes that would be experienced by any monopolistic
producer. Thus, while agricultural markets are usually
characterized by competitive conditions, future national
policy may require that some constraints be imposed in
this area.
WATER DEMANDS IN THE MINERAL
INDUSTRIES
Water needs of the mineral industries constitute only
about 2 percent of water withdrawn by the industrial
sector as a whole.~6~7 The largest water-using mineral
industries are natural gas processing, phosphate rock,
sand and gravel, and iron ore.
Kaufman and Nadler carefully analyzed the results of a
comprehensive canvass of mineral-industry water use in
1963. This analysis was based on the product-moment
method of calculating correlation coefficients.
The results are presented as Tables 3.3 and 3.4; r2 is the
coefficient of determination, and P is the level of signifi-
cance. From Table 3.3 it can be seen that approximately
44 percent of the variation in total water use can be
explained by the amount of crude material that was pro-
cessed.
Kaufman and Nadler further stated:
Some 46 percent of the variations in new-water use can be
explained by variations in crude material. The remaining 54
percent is assumed to be the result of processing variations.
As total water use is the sum of new and recirculated water,
the bulk of the effort in the correlation analysis was devoted to
these components rather than to the total. This analysis indicated
that water availability, as measured by average precipitation or
mean stream discharge, is not a use factor insofar as new-water
use by the mineral industry is concerned. There does not appear
to be a relationship between new-water use and the price of
water, although the lack of relationship may result from the type
of price data used. The price of water was taken from charges
levied by water companies against large industrial users in
selected cities for 1955.~8 However, most mineral producers
obtain their water from self-operated systems, and therefore the
type of cost data used may be completely inapplicable. It is also
possible that in many cases the cost of water per ton of ore is such
a minor item that cost is not a factor in determining use. In other
instances the capital cost of developing a self-operated system is
so great, compared with the operating cost, that the total cost per
gallon will decline substantially the more water is used. The
relative low cost of self-supplied water, particularly in relation to
purchased water, is substantiated by data compiled by the Na-
tional Association of Manufacturers. ~9 The Association computed
that water derived from self-supplied systems would cost be-
tween one cent and fifteen cents per 1000 gallons. This would
include sources, pumping, treatment and distribution. Water
purchased from a utility company would cost between ten and
thirty cents per 1000 gallons, exclusive of distribution within the
plant.
The authors further point out that if it can be assumed
that mineral producers are paying $0.15 per 1000 gallons
OCR for page 54
54
of water, the cost of water as a percentage of the average
values per ton of ore would be as follows:
New Water Total Water
By) (%)
Bituminous coal
Copper ores
Iron ores
Phosphate rock
Sand and gravel
0.3
.3
1.2
3.9
4.3
1.8
3.0
2.7
3.0
6.7
The figures shown can be considered to be maximums,
since many mineral producers do not pay $0.15 per 1000
gallons. Except for the very large user such as the phos-
phate rock industry, or an extremely low-value product
such as sand and gravel, the cost of water cannot be seen
as a significant item. A general assumption can be made
that the cost of recirculated water is lower than the cost of
new water. Therefore the proportion of average value
contributed by total water costs is most likely to be less
than indicated by the foregoing data. This tends to bear
out Me lack of statistical correlation between water intake
and prices. From the foregoing it can be inferred that
statistical demand functions for water, as they are gen-
erally understood, essentially do not exist for the mineral
industry.
INDUSTRIAL WATER DEMANDS
The factors affecting industrial water demands for a
number of industries have been dealt with in some detail
by Bower.20 2~ Bower formulates conceptually a joint func-
tion governing industrial water demand as follows:
QIbQD6C t,QEt,WDt,WEt =
where
PP
L
OR
poqr
R
S
f(Q t,q t,T,PP,L,OR, poqr,R,S, E c,A ,, Q dt,q dt,~, C U,./C t
Qt and At are the quantity and quality and their cor-
responding time patterns of water available
at the intake;
is the water- and waste-treatment processes
within the production unit;
is the technology of the production process;
is the physical layout of the plant;
is the operating rate;
is the product output quality requirements;
is the degree of recirculation;
is the solid wastes from the production
process;
is the limitations on the final liquid effluent;
is the limitations on the final gaseous ef-
fluent;
Qua and qua are We quantity and quality and their
corresponding time patterns of water avail-
able for dilution at the effluent point;
is the availability of places for final disposal
of wastes; and
is the ratio of total water utilization costs
to total production costs.
EVERARD M. LOFTING and H. CRAIG DAVIS
Bower emphasizes that a forecast of industrial water
demand for a particular industry must include the amount
of water required for all uses explicitly process, boiler
feed, cooling and condensing, and sanitary uses. Because
of increasing concern over thermal pollution, a separate
consideration of cooling and condensing uses is stressed.
These include product cooling, equipment cooling, and
condensing in steam electric power generation.
Bower summarizes20:
Essential to any effort to forecast industrial water demand is an
economic base study which includes projections of demands for
the product outputs of Me various heavy water-using indus-
tries.... Given an economic base study, forecasting industrial
water demand involves the following five steps:
(1) Classifying existing plants by process, region, product mix,
and size;
'(2) Forecasting trends and production processes, product mix,
and regional location patterns, i.e., forecasting technology;
(3) Relating the production process-product mix combinations
to gross water applied and waste loads generated;
(4) Analyzing the alternative internal water utilization pat-
terns and costs thereof, considering the impacts of in-plant water
quality requirements in relation to product quality and the costs
of other factor inputs such as fuel and heat exchanges; and
(5) Forecasting political decisions relating to pricing policy for
water at the intakes and policies relating to waste discharges.
Given (3) and (4), and the water environment (5), water demand
can Men be forecast.
In view of the waste-assimilation properties of water,
the effect of waste-discharge control on water intake
should also be stressed in industrial water-demand fore-
casting.
Russell, using mathematical programming techniques,
developed a model of typical refinery operations that
could portray the withdrawal demand for water as a func-
tion of intake price and also effluent charges.22 The Na-
tional Water Commission staff summarized the results of
the Russell model as follows:
1. A petroleum refinery's water withdrawals are sensi-
tive to the price of withdrawals and may be reduced by as
much as 95 percent if the withdrawal charge goes above 2
cents per 1000 gallons. If the price is raised further, the
refinery will be able to reduce water withdrawal further
by in-plant recirculation.
2. Discharges of biological oxygen demand (BOD) ma-
terials by petroleum refineries are sensitive to effluent
charges. An effluent charge of about 2 cents per pound of
BOD material discharged may be approximately the tax
that would induce a BOD waste reduction of 5~65 per-
cent, depending on the technology of the plant.
3. The costs incurred by the petroleum refinery (and
presumably passed on to the consumer) for reducing
discharges of BOD material are comparable with the costs
of developing sufficient additional flow to dilute the
discharges.
4. The overall effect of BOD effluent standards on the
OCR for page 55
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
final gasoline price at the refinery might be about one
fiftieth of a cent per gallon.
5. Effluent charges or standards directed at curbing the
discharge of one type of residual, or pollutant, could have
important effects on the discharge of other wastes. In a
refinery of the type studied, the quantities of phenols
discharged would also be reduced as the discharge of BOD
wastes is reduced in response to a BOD discharge tax.
Although these results imply that petroleum refineries
are sensitive to intake water prices and effluent charges,
the 1972 Census of Manufactures (1973 data)23 shows that
refinery intake from all sources was 1278 billion gallons
with 635 billion being freshwater. Of this amount of
freshwater, 132 billion gallons, or 21 percent, was from
public supplies with the balance being self-supplied.
Data on effluents show that refineries discharged 1155
billion gallons of water during the year, of which 463
billion gallons, or 40 percent, were untreated.
Refineries are undoubtedly sensitive to the price of
withdrawals given the fact that they can and do supply
their own needs well below one cent per 1000 gallons as
estimated in the National Association of Manufacturers.24
As the price of publicly supplied water is increased they
may opt for developing their own systems. This helps to
explain the problem of "block pricing" as noted by
Bower25:
. . . it should be noted that in many cases rate structures for
industrial water users encourage high water intake per unit of
product. Generally, large consumers receive lower rates for
using more water~.e., the more water used, the lower the price
per 1000 gallons. In such situations it often becomes less expen-
sive for the industrial user to discharge once used water Man to
adopt recirculation.
As matters stand, there appears to be no clear-cut
method of empirically deriving and projecting demand
functions for industrial water use. In contrast to agricul-
ture, reliance on water prices and pricing policies for both
withdrawals and discharges seems to have been too tenu-
ous an instrument for achieving the desired goal of
dramatically reducing water demands and wastewater
discharges. Only 11 percent of industrial water in 1973
was publicly supplied and thus subject to price increases
as a matter of policy. This is in contrast to the 50 percent
of industrial water drawn from public supplies in 1950.26
Furthermore, only 60 percent of discharges were treated
in 1973. The requirement of Public Law 92-500 can be
expected to bring more dramatic changes to industrial
water demands than have been evident over the past few
decades.
Historical water intake data are given in Table 3.5.
The National Commission on Water Quality report
states27:
Several technological solutions for both 1977 and 1983 limita-
hor~s are founded upon reduction in water use or by-product
55
TABLE 3.5 Historical Gross and Intake Water Usage by
All Manufacturing Industriesa
Year
Gross Water Used
(billions of gallons)
Net Water Intake
(billions of gallons)
1959
1964
1968
1973
26,257
29,857
35,701
46,965
12,131
14,007
15,467
15,024
aSource Plater Use in Manufactunng,' Census of Manufactures, Bureau of the
Census, 1961, 1966, 1971, 1975.
recovery. These options are likely to have wider application for
BAT [best available technology] than for BPT [best practicable
technology]. The full potential for such approaches is unde-
veloped, but they will probably become more prevalent as limi-
tations become more stringent and technologies for treating large
wastewater volumes become more expensive.
In general, the Commission on Water Quality submits
the data in Figure 3.1 to show overall industry respon-
siveness to price changes in water and cost increases in
waste discharge.
The price elasticity of demand for industrial water
intake as given can be used as a guide for estimating
future withdrawal demands in limited instances.
THERMOELECTRIC POWER WATER DEMAND
Steam electric generating stations primarily use water for
cooling. The amount of cooling water withdrawn per
kilowatt-hour generated is governed by the type of plant,
the thermal efficiency, the number of degrees over which
the intake water is heated (this is termed the "range"),
and the method of cooling that is used. The amount of
water used in steam electric power generation in the
United States is now greater than irrigation water with-
drawals.28 It accounts for somewhat more Man 40
percent of all water withdrawn. Water used consump-
tively, that is evaporated or lost in the cooling process,
is only about 1 percent of total intake at the present
time.
A typical "range" for a plant using once-~rough cool-
ing is 15°F. This means that each gallon used absorbs 125
Btu of waste heat.29 On this basis, some 43 gallons of
cooling water are circulated per kilowatt-hour generated
in thermal plants, and about one half gallon (1 percent) of
this water is ultimately evaporated.30
Table 3.6 provides estimates of water withdrawals and
consumption for the years 198(}2020 for thermal electric
generating facilities.3~ These estimates assume minimal
increases in plant efficiency and once-through cooling
practice. The assumptions, although termed unrealistic
by the National Water Commission staff, afford an upper
bound for withdrawal and consumptive uses based on
projected growth of thermal generating facilities. The
values shown in the table indicate that the withdrawal
needs for condenser cooling will be approximately equal
OCR for page 56
56
IF:
Price of water I oh |
increases L
PRICE OF WATER
_ TH EN:
_ Water intake volume decreases
4:,.'~ 0.7% for chemicals
1.4% Paper
4 ,. :~,'.-.] 1.4% Petroleum
Am: .; A. . A; 4~ 1.6 as Stee I
COST OF WATER
cost of effluent discharge volume of effluent discharge
IF ,
. . .
combined water 1%
~ sewer f low charge
increases
Suspended solids ~ |
chargeincreases '%L
Biochemical I
oxygen demand I%
charge increases
SOD charge 1'~ |
increases L
THEN:
Flow decreases
4~1.4%
SS concentration decreases
_ ~0.7°70
BOO concentration decreases
40.2S1 %
BOO volume decreases
30.1%
FIGURE 3.1 Industry responsiveness to cost of intake water
and waste discharge.
to the average annual runoff of the United States by the
year 2000. The consumptive use is only slightly more
than 1 percent of withdrawals, however.
In order to place the projected thermal energy demands
in perspective and assess some overall means of bringing
the associated water needs into balance with available
supplies, two avenues have been investigated: (1) the
reduction in overall electrical energy demand and (2) the
means for the direct reduction in water withdrawals.
(1) An analysis of socioeconomic data for the period
1955-1969 indicates that electric power consumption
plus losses and in-plant uses can be statistically corre-
lated with population, Gross National Product, electricity
prices, and gas prices.32
The Bureau of Economic Analysis, United States De-
partment of Commerce, has made high, medium, and low
projections of Gross National Product to the target year
2020. These were based on the B. C, and D population
TABLE 3.6 Sample Projections of Total Water With-
drawals and Consumption for Thermal Electricity Gener-
ation (billion gallons per day)
1980 2000 2020
Withdrawn 330
Consumed 3.8
EVERARD M. LOFTING and H. CRAIG DAVIS
growth rates of the Bureau of the Census.33 These growth
rates were then used in a regression model to project
electric power needs. A fourth projection was based on a
low growth rate combined with a 50 percent increase in
electricity prices. The four resulting projections of cool-
ing water are presented in Figure 3.2. These projections
of freshwater withdrawals assume no technological
change and no recirculation.
The relation between the price of electricity and
cooling-water withdrawals has also been studied. The
analysis showed that a 50 percent increase in We price of
electricity would result in a 27 percent decline in
cooling-water withdrawals. There appears to be some
indication that We demand for electricity is related nega-
tively to increases in price. An analysis by Wilson34 shows
that regional power demands may have an elasticity
greater than 2, which would mean that a 10 percent
increase in price would cause a 20 percent fall in energy
use. It is felt that some of this decline would be due to We
relocation of energy-intensive industries to other areas
where energy rates may be lower. On such evidence, it
appears that pricing policies could be used to influence
electricity use and thus cooling-water use.
The analysis, however, does not distinguish between
We industry demands and consumer demands. In fact,
energy studies at the Center for Advanced Computation,
University of Illinois, have shown that approximately 65
percent of all energy demands are interindustry demands.
For electrical energy only, the proportion may be closer
to 55 percent in interindustry demands.35 If estimates of
4000
Or
1000 ~
1072 2297
12.5 26.7
3000
2000
HIG H
199 0
LOW GROWTH-
HIGH COST
2000
2010 2020
FIGURE 3.2 Projections of freshwater withdrawals for electric-
ity generation under different economic growth rates.
OCR for page 57
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
reductions in electricity demand are calculated in such an
aggregate manner, the possibilities for "self-supplied"
electrical energy are masked. An important problem
raised by the research staff of the Electric Power Re-
search Institute relates to the setting of power prices so
that large users will continue to purchase "blocks" from
utilities rather than develop their own generating
capacity an option available to a number of industries.
The foregoing analysis gives no indication which sector
(industrial or household) of the economy is affected and
the manner in which the reductions may occur.
(2) A potential way to reduce cooling-water withdraw-
als might be to raise the price of water itself. However, if
the price of cooling water is increased, utilities may recir-
culate the cooling water several times rather than use a
"once-through" cooling process. If this is done, then the
temperature ofthe cooling water is raised and evaporative
(consumptive) losses are substantially greater.36 Less
water is returned to the natural water course for other
downstream users, and thermal pollution problems are
increased. Thus, increasing the price of cooling water
may result in changing withdrawal demands into con-
sumptive demands and an overall depletion of available
. . . .
supp les In a given per~oc .
It is conceivable that different prices might be levied
for withdrawing freshwater and also for using it consump-
tively. Basically, in order to keep the consumptive use of
water at low levels, the only possible alternatives are to
use once-through cooling or, at higher water prices, to use
dry towers.36 However, the National Water Commission
staff estimated that water prices greater than $1400 per
million gallons consumed would have to be charged to
induce plants to limit their water consumption to the zero
level, given the capital cost of dry tower technology.
In the overall, freshwater withdrawals by steam-
electric generating stations might be influenced by set-
ting water prices at levels that could only be considered
unreasonable in the present economy. The consumptive
use of water by thermal plants appears to be insensitive to
price changes within what might be considered a reason-
able price range. It should be stressed, nevertheless, that
pricing withdrawals of freshwater for thermal plant cool-
ing has not yet been tried and may be limited in practice.
The response of regulated utility companies to increases
in costs is very different from the response of nonregu-
lated industries. Thus, changes in the price of water may
in fact have little or no effect on demand. The consump-
tive use of freshwater for cooling is virtually insensitive to
price changes for water within any realistic price range.
COMMERCIAL DEMANDS FOR WATER
The definition of commercial water use by water-supply
agencies is probably less rigorous than for any other
category. In the alignment scheme presented earlier in
this paper in Table 3.2, the commercial sector can be
accurately defined as Standard Industrial Classification
57
(sic) groups 50 through 89, excluding major group 88—
Private Households.37
Demand functions for water use in the trade and ser-
vice sectors of the economy are needed; however, only
rather fragmentary data appear to have been accumulated
and analyzed. Howe reported on these in 1968.38 One of
the points not dealt with by Howe, but mentioned in an
earlier section of the present paper, is the fact that many
water-supply agencies may classify multiple-unit dwell-
ings as commercial users. Thus, the water supply to
apartment houses that are clearly residential or household
in nature may be classified as a commercial end-use by
the agency. This may tend to skew badly the results of any
study. Moreover, many trade and service establishments
have the option of self-supplied water systems, which
may further tend to limit the validity of the results based
solely on an analysis of water-agency data, which reflect
supplies to a broad category of users termed "commer-
cial." For analytical purposes, overall water-agency data
from selected cities may need to be modified in order to
account for the total amount of household intake and the
possible misclassification of light industry or other man-
ufacturing establishments to the category of commercial
users.
At present, specific price elasticity of demand functions
for water used in the various trade and service sectors of
the U.S. economy have not been estimated.
HOUSEHOLD (RESIDENTIAL)
WATER DEMANDS
Water withdrawals for household use in 1975 amounted
to approximately 23.6 billion gallons per day, of which
about 91 percent, or 21.5 billion gallons per day, were
furnished by municipal water systems. }7 Household water
needs are typically divided into two categories: in-house
uses and lawn sprinkling. The major in-house uses are
drinking and cooking, 5 percent; dishwashing and laun-
dry, 20 percent; bathing and personal use, 30 percent;
toilet flushing, 45 percent.39 For single-family dwellings,
lawn-sprinkling uses amount to more than 50 percent of
the total yearly use. Howe and Linaweaver statistically
analyzed the effects of density, property value, geo-
graphical location, and water price on household de-
mands.40 Both in-house and lawn-sprinkling uses have
been found to be responsive to changes in water prices;
Table 3.7 shows average commercial water-use data in
metered and flat-rate areas.39
Howe and Linaweaver determined the important vari-
ables governing water use for sprinkling in areas that are
metered were water price, dwelling unit value, and pre-
cipitation. For flat-rate areas, the governing variable was
dwelling unit value. Demands for in-house uses were
determined to be less responsive to price and income
changes than those for sprinkling.
Using the Howe and Linaweaver data, a Resources for
the Future report for the National Water Commission
OCR for page 58
58
TABLE 3.7 Average Annual Water Use in Metered and
Flat-Rate Areas
Gal/day per Dwelling Unit
Metered Areas
Flat-Rate Areas
Leakage
In-house
Sprinkling
TOTAL
Maximum Day
Peak Hour
25
247
186
458
979
2481
36
236
420
692
2354
5170
projected household needs to 1990.4° Under different
assumptions of price and population growth, it was ar-
gued that the growth of population alone has a greater
impact on water use than the spatial expansion of urban
areas, and further, the price of water has a much greater
impact than either of the two preceding variables.
In summarizing, it can be noted that the theory of
consumer demand truly comes into its own in the analysis
of residential water use. The demand functions were well
behaved in all cases studied. The data indicate that lawn
sprinkling accounts for more than 50 percent of average
annual use for single-family dwellings. The amount of
sprinkling water used decreases with price increases.
This is less striking in the western United States than in
the East. The amount of water used for in-house purposes
is approximately the same regardless of the price charged
for the water.
USE OF DE MAND FUNCTIONS IN WATER-
RESOURCES SYSTEMS PLANNING
The term "water-resources systems" can be used to en-
compass the large-scale impoundments and conveyance
systems typical of the Tennessee Valley Authority and the
Bonneville Power Administration and the smaller pump-
ing, storage, and distribution systems of many metropoli-
tan areas. Historically, in the United States many of these
systems were developed on the basis of engineering
feasibility studies and certain multipurpose objectives,
such as hydra power generation, flood control, land rec-
lamation, and navigation, along with water supply. Many
of the nation's largest multipurpose water-resource sys-
tems were planned and developed after 1930 when the
federal government indirectly assumed an increased re-
sponsibility for the use of water resources. Most, if not all,
of these large projects were begun as part of the major
public works programs typical of the 1930's.4t Several
decades earlier, the Reclamation Act of 1902 had been
passed to stimulate and consolidate the westward expan-
sion that followed the development of the transcontinen-
tal rail lines. By 1929, about 19 million acres were irri-
EVERARD M. LOFTING and H. CRAIG DAVIS
gated,42 although only about 7.5 percent were directly
controlled by the Bureau of Reclamation.
At present, attention is focused on the rather striking
amounts of water that have been developed by means of
federal projects, the rather modest prices that are charged
for water, and what the past trend augurs for the future. It
is felt that if water prices are permitted to rise on the basis
of the value the water would have in alternative uses, or
are increased as a matter of public policy, then users
would presumably carefully monitor their withdrawals to
minimize costs and thus substantially reduce overall
water use in the economy. If this occurs, new projects can
be postponed or possibly deferred indefinitely. This
would permit substantial sums of money, tentatively allo-
cated to proposed projects, to be reallocated to other
pressing national needs. These considerations are obvi-
ously at the root of the demand versus requirements
Issue.
In the earlier sections of this paper, the potential for
developing statistical demand curves for each major cate-
gory of water use was explored. In light of the findings, it
seems feasible that water-demand functions for irrigation
water can be developed, using either statistical analysis
or mathematical programming techniques, and applied in
water-resources systems planning. For the mineral indus-
tries and certain industries that are heavy users of water,
the prospects for developing and using statistical demand
functions in systems planning appear to have been over-
shadowed by changes in the Water Pollution Control Act
passed by Congress in 1972. The stipulations of the Act
will bring to the fore some minimal technological level of
water use to meet discharge standards regardless of intake
price. The best achievable technology (BAT) should carry
with it some minimal level of in-plant use of water for all
industries. If the provisions of the Act are enforced, water
price should have little influence on demand in the future
for those classes of industries that have traditionally been
termed "water intensive."
For the trade and service sectors and those light indus-
tries where water use is limited to sanitary, air condition-
ing, and boiler feed uses, and certainly for residential and
household needs, the development and use of water-
demand functions should play a major role in water-
resource systems planning in the future. Such applica-
tions will probably find more immediate use in the
planning of metropolitan water-supply systems than in
any large multipurpose project in which water supply is
coupled with flood protection or other water-related
considerations.
THE ROLE OF WATER-USE INFORMATION
IN FORECASTING FUTURE WATER
DE MAND S
Official water-use data are compiled and published by
several federal agencies. Additionally, there are special
OCR for page 59
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
studies funded by federal, state, and local governments as
needs arise.
Official data sources:
1. United States Geological Survey, "Estimated Use
of Water in the United States," quinquennially since
1950.28,43-46
2. United States Water Resources Council. National
Water Assessment Studies, by decades beginning in
1965 ~7 47
3. Census of Agriculture, United States Bureau of the
Census. Irrigation and Drainage on Farms.48
4. Census of Mineral Industries, United States Bureau
of the Census. "Water Use in Mineral Industries," Eco-
nomic Census years 1954, 1963, 1967, i972.49-52
5. Census of Manufactures, United States Bureau of
the Census. Water Use in Manufacturing. Economic Cen-
sus years 1954, 1958, i964, 1968, 1973.53-57
6. United States Army Engineers Permit data, 1971,
unpublished.58
The United States Geological Survey (USGS) data pro-
vide water use by major categories for the United States,
the 50 states, and water-use regions. The data are related
to population and acreage. A bibliography of primary data
sources is given in the USGS publications.
The United States Water Resources Council provides
base-year data, principally following the USGS categories,
and furnishes projections at 10-, 15-, or 20-year intervals.
The data as presented are not related to measures of
production.
The Census of Agriculture includes data on drainage
basins, land irrigated, crop production on irrigated land,
water conveyed, users, and types of organizations.
The Census of Mineral Industries and Census of Man-
ufactures water data are furnished for detailed categories
of end-use and are related to establishment, employment,
value added, and value of shipments for the United
States, the 50 states, and regions. The Army Engineers
Permit data relate water use to employment and value of
product for specific dischargers.
At the state and regional levels, the Census data be-
come sketchy because of disclosure problems; however,
they can be made usable with some statistical effort.
As resource scarcities, particularly water, have become
increasingly evident in the United States, the need for
estimating future demands in some standardized manner
has been apparent. The sources of supply are regional in
nature, as are the elements of demand. If forecasting
techniques are not standard and uniformly applicable to
any of various geographical regions, estimates of supply
and demand may tend to embody broader interregional
political considerations rather than the objective realities
of regional resource availabilities. Water-resource de-
velopment, transfer, and distribution systems are usually
capital-intensive and may take as long as a quarter of a
century from conception to water delivery for major proj-
ects. Over the decades, this has led planners to perhaps
59
wish to err on the side of recommending excessive re-
finement in projection techniques rather than be guilty of
overbuilding. If, of course, it can be successfully argued
that the benefit-cost ratio of obtaining better data for
planning purposes at any level is not greater than one,
then the concern over detail is not a valid one. Nonethe-
less, the dilemma for planners is real. If they are conser-
vative in planning irrigation projects, the basic objective
of adequate food supplies is defeated by shortfalls in
production and high prices. If they are liberal in their
projections, unused facilities and surplus productive ca-
pacity bring on not only agriculture surplus problems but
also a loss of public confidence.
In order to project future water demands in a stan-
dardized fashion for a region, a series of regions, and
ultimately the nation, a multisector economic framework
should be established for some base year. Such a
framework permits region-by-region comparisons to be
made objectively. Economic activity projections can be
made by region in constant dollar terms to the specified
target years from the base year. The finer the industry
detail, and the water-use detail available by specific pur-
pose for the base year, the more comfortable one might
feel that errors might tend to be in a conservative direc-
tion. As the time span of the projection is increased, the
likelihood lessens for a detailed product mix or perhaps
even the industry mix to be maintained in any specified
proportions for a given economic region. Projections, of
necessity, have to be made in a more aggregate format as
the time span from the base year increases. Once the
given set of industry projections in constant dollars has
been made, the base-year water-use information can be
modified in the light of modeling techniques that include
demand elasticity considerations, where they are appli-
cable, and technological considerations for those sectors
where these seem to be the governing factor, i.e., where
thermoelectric cooling may be involved.
The base-year water-use information should also in-
clude data on self-supplied or publicly supplied water.
Consideration should be given in the economic projec-
tions to the practice the various industries in the region
will be expected to follow in regard to sources of supply
throughout the time span under consideration. When
dealing with economic variables, there tends to be a cer-
tain stability exhibited by aggregates and their projection
despite marked changes in their underlying components.
A relevant example that can be cited is the water-use fore-
casts made by the staff of the Paley Commission in 195226
shown in Table 3.8. Based on the water-use information
available in 1950, a forecast of requirements for 1975 was
made. The estimate for 1975 was some 4 percent lower
than the 1975 figures provided by the United States Water
Resources Council,~7 despite substantial changes in
product output beyond those forecast in detail by the
Commission.
Although the period 1975 to 1985 should bring major
changes in the pattern of water use, once new technology
is adopted, it is reasonable to speculate that longer-term
OCR for page 60
60
EVERARD M. LOFTING a net H. CRAIG DAVIS
TABLE 3.8 Estimated Total Withdrawals and Requirements for Water 1950 and 1975
Estimated with-
drawals, 1950
Billion
Gallons
per Day
Estimated Require-
ments, 1975
Billion
Gallons
per Day
Percent
of Total
Increase, 195~1975
Billion
Gallons
per Day
Percent
of Total
Percent
Increase
Municipal and rurala 17 9 25 7 8 50
Direct industrial 80b 43 215 62 135 170
Irrigation 88 48 110 31 22 25
TOTAL 185 100 350 100 165 ~5
aRoughly half of total municipal supplies are used industrially.
Includes an estimated 15 billion gallons per day of salt water used in industry for cooling.
projections of the rate of growth of withdrawal demand
may stabilize at some markedly lower intake value. Be-
cause of recirculation and reuse, consumptive demands
may rise substantially during the same period.
In earlier sections of this paper it has been noted that
demand functions can be estimated statistically for most
consumer goods. It has also been pointed out that large-
scale multisector programming models have been used in
certain instances to estimate demand functions for water
for the agricultural and industrial sectors of the economy.
Given the marked changes in water use that may occur in
various sectors under the stimulus of water-pollution con-
trol measures, it seems unlikely that a high degree of
reliability should be attached to demand functions for
water based on current data. For the agricultural and
industrial sectors of the economy, the forecasting of future
water demands may be greatly improved by implement-
ing a series of detailed process analysis studies to deter-
mine the required minimum amounts of water that will be
necessary for these sectors to function efficiently under
adverse conditions. Placing too great a reliance on the
concept of market supply and demand functions as op-
posed to gaining a comprehensive understanding of the
technological possibilities for reducing resource inputs
may be an error. The entire discussion of deriving market
supply and demand functions should be leavened with
the critical comments of some detractors. Leontief59 has
given some insight into the problems relating to the
derivation of demand functions:
As objects of empirical analysis the market supply and demand
functions [have] proved to be singularly elusive. They cannot be
observed directly and most attempts to derive them through
methods of indirect statistical inference have yielded with a
few notable exceptions- disappointing results. The principal
difficulty lies in the great instability of the observed price
quantity relationships and this instability can be shown to be
inherent in the internal logic of the general equilibrium system
itself. Within the framework of such a system each structural
relationship is by definition independent of all the (structural or
non-structural) relationships. Every price and every quantity
produced or consumed is on the contrary- by the theoretical
general equilibrium hypothesis expected to depend simulta-
neously on all the structural relationships. This means that, if the
hypothesis as applied to an observed system is correct, the
dependent variations of each price and quantity would necessar-
ily reflect the autonomous changes of all the basic structural
relationships and, what is more important, these variations will
be distributed in such a way that a statistical determination of the
unknown shapes of the corresponding Walrasian demand anal
supply equations would practically be impossible.
Boulding and Spivey have spoken to the same problem
within the broader framework of the theory of the firm60:
A theory which assumes knowledge of what cannot be known is
clearly defective as a guide to actual behavior. What must be
known, however, . . . is a whole set of functional relationships,
such as demand and supply functions, which are not given by
immediate experience, and often are not even given by Me most
refined analysis of past data.
Theoretical demand functions for the industrial sector
should thus be seen as useful heuristic devices. For
empirical research they provide an overall framework for
structuring the various components of water-use informa-
tion.
IMPACT OF CLIMATIC VARIABILITY AND
CHANGE TO FORECASTING DEMANDS
Currently there appears to be no firm consensus regard-
ing the magnitude or direction of fixture climatic change.
There is geological evidence that such changes could
occur relatively rapidly 50 to 100 years and that the
impacts might possibly have catastrophic consequences
in terms of human conditions.6i
Translating the impacts of climatic variability and
change into certain direct effects on regional and national
water demands can, at best, involve only the grossest
assumptions as matters stand.
A general warming trend in the United States climate
could translate into increases in evaporative losses, low-
ered efficiencies in cooling for all major purposes, in-
creased use of water for air conditioning, and presumably
some decreases in boiler feed water for heating. If a
OCR for page 61
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
general cooling trend were to be experienced, then
evaporative losses would be decreased, cooling efficien-
cies may be increased slightly, air-conditioning uses
would decline, and boiler feed-water use should increase.
Quantifying these changes in response to the expected
climatic changes would require a detailed modeling ef-
fort.
The impacts of climatic variability in terms of
worldwide and local droughts will have both direct and
indirect impacts on U.S. agriculture, which may over-
whelm the other aspects of water-demand changes.
Winstanley et al.,62 Winski,63 and Alexander64 summarize
predictions that indicate that by the year 2000 the preven-
tion of starvation may be the main global concern. This
view is not by any means entirely acceptable to many
agriculturalists or water planners. On balance, agricul-
turalists have acknowledged this possibility; however, in
the face of past agricultural surpluses in the United States
it has not been considered a fruitful avenue of research.
One can cite, for example, the typical comments in a text
by Barlowe65:
Winstanley et al. 62 state, nevertheless:
Probably the most serious problem facing the world concerns our
ability to meet the increasing demand for food. At least one and a
half billion people are chronically mar-nourished (Erlich and
Erlich 1972~66 and it has been estimated that 1~20 million
people die every year directly or indirectly from lack of food
(Dumont and Rosier 1969~.67 These figures are for an average
year, and do not reflect the situation in times of drought or other
calamities (U.N. 1974~.68 Last year some ten million people in the
Sahel Zone of Africa were on the brink of starvation, and 100,000
people in Ethiopia died from starvation. Hunger is closely corre-
lated with poverty and bow lead to social and political instabil-
ity: within the last twelve months there have been political
upheavals in the drought-affected countries of Ethiopia, Upper
Volta, and Niger, and serious food riots in India. Food production
must be doubled in about thirty years to meet the projected
demand—and it has taken at least ten thousand years to attain the
present level of production.
The U.N. (1974~68 has identified the effect of recent adverse
weather conditions on crop production as one of the major factors
in the present world food crisis. World grain reserves now
represent less than a month's food supply for the world and there
is no longer any idle agricultural land in the U. S. A. to act as a
reserve. There is a real threat that crop failures would lead to
widespread starvation.
Evidence is accumulating which shows that the climates of the
Earth are changing, and it has been suggested Mat they might be
changing in a direction which could have a net adverse effect on
world food production, and global economic and political stabil-
ity (I.F.I.A.S. 197469; Rockefeller Foundation 19747°).
Probably the main reason for irrigating and draining the land is
to increase food production and one of the main factors detennin-
ing the need for irrigation and drainage is climate.
If the Winstanley, Alexander, and Winski summary
prospects are borne out, then planners may possibly have
to reconsider the extent to which irrigable lands will play
a preponderant role in the future, and present projections
may have to be revised. Alexander cites Reid Bryson, who
61
contends that the monsoons may probably not return with
regularity to regions such as northern India during the
remainder of this century. If this is correct, the prospect
looms that even the present populations of the monsoon
belts could not be maintained even if all the arable. land
in the rest of the world were placed in full production for
this period. Because of the unusual and irregular way in
which the global weather changes are beginning to man-
ifest themselves, there is some evidence that a return of
heavier rainfall in the western plains and Rocky Moun-
tain states may not be unusual. Settlers who traveled to
California left accounts that one of the hazards of crossing
the plains was the possibility of losing sight of the main
party because of endless stretches of head-high grass that
grew in regions that are almost desert at the present time.
Bryson speculates that the change in climate might possi-
bly have played a greater role than hunters in the disap-
pearance of the huge herds of bison. If the heavier rain-
falls in the western United States were to occur, then
possibly certain proposed irrigation projects might have
major flood-control benefits.
On the other hand, Winstanley has noted that if the
weather patterns in Africa persist they may shift the
entire Sahara Desert southward; and efforts to halt such
climatological encroachments by, for example, planting
windbreaks or increasing irrigation would be in vain. In
the Soviet Union, for example, a third of the grain crop
comes from the drought-prone virgin lands of Siberia, and
consideration has been given to diverting some of the
great Siberian rivers into large irrigation projects. These
rivers empty into the Arctic Ocean, where the less-dense
freshwater spreads out on top of the salt water and thus
permits the Arctic Ocean to freeze over. According to
some experiments by a Russian scientist, O. A. Drozdov,
and a British meteorologist, R. L. Newson, who have
constructed a mathematical model of wind patterns in the
northern hemisphere, the consequence of inhibiting the
freezing of the Arctic Ocean may be to cause winters
to become colder and drier over many continental
areas at the middle latitudes. Some prominent Soviet
meteorologists have expressed concern over these propo-
sals. However, if disastrous, protracted droughts were to
occur in the Siberian wheatlands, Soviet planning au-
thorities might feel that there would be little to lose in
proceeding with these projects. In the United States and
Canada such proposals as the North American Water and
Power Alliance schemes called for diverting rivers like
the MacKenzie, which flows northward into the Arctic
Ocean and through large impoundment and conveyance
structures carrying these waters southward into the
United States for irrigation and power-generating pur-
poses. Such engineering schemes could possibly have
impacts similar to those of the proposed diversions in the
Soviet Union. If droughts were to persist, possibly these
schemes, or some variant, might be given consideration in
order to increase worldwide food supplies.
In order to place the question of increased irrigation
demands in perspective, assuming that increased food
OCR for page 62
62
EVERARD M. LOFTING and H. CRAIG DAVIS
TABLE 3.9 Land Utilization, Farm and Nonfarm: 194(}1969 (in millions of acres, except percents. Prior to 1950,
excludes Alaska and Hawaiia
1940
Major Use
1950
Land Percent
1959
Land Percent
1964
Land Percent
2271 100.0
Land Percent
1969
Land Percent
Total land area
100.0
2273 100.0
100.0
2264
100.0
In farms 1061 55.7 1162 51.1 1124 49.5 1110 49.0 1064 47.0
Croplandb 399 20.9 409 18.0 392 17.3 387 17.1 384 17.0
Grassland pastures 461 24.2 486 21.4 532 23.4 547 24.1 540 23.9
Woodland pastured 100 5.2 135 5.9 93 4.1 82 3.6 62 2.7,
Woodland not pastured 57 3.0 86 3.8 70 3.1 64 2.8 50 2.2
Farmsteads, roads, and other land 44 2.3 46 2.0 37 1.6 30 1.3 28 1.2
Not in farms
Grazing lands
Forest land not grazede
Other landf
844 44.3
504 26.4
203 10.7
137 7.2
1111 48.9 1
402 17.7
368 16.2.
341 15.0
147 50.5 1156 51.0 1200 53.0
319 14.0 293 12.9 288 12.7
438 19.3 443 19.5 475 21.0
390 17.2 420 18.5 437 19.3
aSource: U.S. Dept. of Agriculture, Economic Research Service. In Agricultural Statistics, annual.
DCompnses cropland used for crops, soil improvement crops, and idle cropland.
Includes cropland used only for pasture.
Includes grassland, and woodland, and shrub and other forested land grazed.
eExcludes forest areas in parks and most other special uses.
fCompnses urban, industrial, and residential areas; rural parks; wildlife refuges; highway, road, and railroad nghts-of-way; ungraded desert; rocky, barren, swamp, tundra, and
other land not otherwise counted.
production requires this, land-use patterns and trends are
given for the United States (Table 3.9~. Irrigated acreage
data are given in Table 3.10. It should be noted that these
data are provided for the 17 western states only. Federal
irrigation projects data are provided in Table 3.11.
In April 1974, the Water Resources Council released
the new Series E Population OBERS projections showing
an 18 percent decrease in cropland harvested by the year
2020 (Table 3.12~. In May 1975, a revised series of ag-
ricultural projections (Series E') was released, which
showed a 15 percent increase in cropland harvested by
the year 2020 (Table 3.131. The revisions have been
attributed to more recent assessments of the domestic and
foreign supply-demand relationships.
Figure 3.3 has been reproduced from Winstanley et.
al.62 If the United States should wish to assume a posture
in which the food deficits of the so-called "Baird World"
countries can be met by the agricultural production of the
United States and other developed countries, then further
revisions of the projections of irrigated cropland may be
in order.
1
WATER-USE FORECASTS FOR 2000 AND 2020
Projections of water withdrawals and consumptive use to
the years 2000 and 2020 were made by the United States
Water Resources Council in 196847 and by Wollman and
TABLE 3.10 Irrigation of Agricultural Land Summary: 192~1969 EData are for 17 Western States (Alaska and
Hawaii excluded) and Louisiana, except as notedia
Item 1920 1930 1940 1950 1959 1969 19690
Approximate land area milt acres 1190 119~) 1191 1191 1189 1187 2263
Farms, total 1,000 1684 1820 1681 1430 1044 854 2730
Irrigated 1,000 222 264 290 289 267 210 257
Land in farms, total milt acres 488 553 611 699 715 733 1063
In irrigated farms milt acres c 78 112 168 213 218 237
Land irrigated, total milt acres c 14 18 25 31 35 39
Irrigation organizations:
~ O _
Number 1,000 c 4 6 10 9 8 8
Area irrigated milt acres 12 13 14 15 18 21 21
Investment from prior census year milt dol. c 162 160 520 1040 1591 1607
aSource: U.S. Bureau of the Census, U.S. Census of Agriculture: 1930, 1940, 1950, 1959, and 1969, Irrigation of Agricultural Lands.
Data are for all states in the U.S.
CComparable data not available.
OCR for page 63
Methodsfor Estimating and Projecting Water Demands for Water-Resources Planning
TABLE 3.11 Federal Irrigation Projects: 195(}1971 (Acreage in thousands; value in $ millions
Supplemental and Temporary
Entire Area Full Irrigation Servicer Imgation Servicer
Gross Gross Gross
Irr~gable Irrigated Crop Irugable Irrigated Crop Irngable Irrigated Crop
Year Acreage Acreage Value Acreage Acreage Value Acreage Acreage Value
.
1950 6025 5071 578 3305 2716 311 2720 2361 267
1955 7368 6262 828 3826 3163 429 3542 3099 399
1960 8171 6900 1158 4326 3488 581 3845 3412 577
1965 9612 8012 1557 4540 3731 675 5072 4281 882
1968 9g04 8387 1840 4683 3940 813 5221 4447 1027
1969 10140 8576 1885 4839 4070 867 5301 4506 1018
1970 10198 8570 1882 4844 4037 847 5354 4533 1035
1971 10560 8834 2124 4853 4050 943 5707 4784 1182
63
aSource: U.S. Bureau of Reclamation, Federal Reclamation Projects, Water and Land Resource Accomplishments, annual.
Applies to irrigable land receiving its sole irrigation supply through Bureau of Reclamation-constructed facilities and to previously irrigated land in nonfederal projects where
a substantial part of the facilities was constructed, rehabilitated, or replaced by the Bureau.
CApplies to irrigable land receiving irrigation water through Bureau projects in addition to supply from nonproject sources and to land for which water is delivered under
temporary arrangements.
TABLE 3.12 Use of Land Resources, Selected Historical and Projected Years
Land in Farmsa
1959
1964 1980
, 195~2020 (in Thousands of Acres)
1985 2000 2020
Cropland Harvested 311,285.2 286,708.1 292,242.6 285,585.4 271,920.4 255,656.1
Feed crops
Grainsb 125,395.0 93,658.2 102,936.3 99,795.9 91,147.2 63,016.8
RoughageC 76,432.0 78,829.4 68,787.2 67,446.5 64,396.1 61,862.7
Food crops
Grains 52,376.0 51,413.6 43,976.3 42,786.1 40,306.1 37,297.2
Vegetables, fruits, and sugar 8,992.9 9,638.1 9,024.3 9,006.4 9,154.7 9,078.6
Others 3,176.0 2,923.1 3,105.9 3,087.8 2,982.9 2,908.1
Over crops
Oil' 26,261.0 33,841.6 53,044.2 52,773.5 52,801.1 51,277.7
Cotton, tobacco, and miscellaneous 22,765.5 21,230.1 14,843.0 14,841.1 14,335.5 13,222.0
- Total crops harvested 315,598.4 291,533.7 295,717.4 289,737.4 275,123.6 258,663.2
Cropland not Harvestedh 136,278.5 147,130.0 165,843.4 172,601.4 186,401.5 202,420.4
Total Cropland 447,563.7 433,838.1 458,086.0 458,186.8 458,321.9 458,076.5
Forest and woodland 163,684.3 145,711.5 105,231.8 102,759.6 95,339.7 86,404.5
Pasture, range, and other lanai 508,909.8 526,323.5 481,566.3 478,927.2 472,341.4 463,098.2
Total land in farms 1,120,157.8 1,105,873.1 1,044,884.1 1,839,873.6 1,025,003.0 1,007,579.2
Irrigated Cropland Harvestedj 27,436.8 29,902.8 36,919.1 36,446.6 36,218.8 36,003.5
Feed crops
Grains. 5,255.4 6,585.0 10,196.5 9,975.5 9,581.0 9,495.6
RoughageC 7,483.6 9,144.9 10,581.6 10,557.3 10,983.3 10,932.2
Food crops
Grains 2,961.9 3,785.5 4,208.9 4,086.9 3,869.2 3,772.2
Vegetables, fruits, and sugar 3,601.8 4,826.6 5,049.9 5,191.8 5,514.5 5,837.0
Others 1,158.0 1,007.1 1,263.9 1,276.4 1,319.4 1,358.7
Other crops
Oil' 395.0 479.8 1,264.1 1,292.4 1,380.3 1,443.5
Cotton, tobacco, and miscellaneous 3,465.0 4,281.2 4,743.6 4,454.6 3,961.8 3,565.8
Total irrigated crops harvestedk 24,320.7 30,110.1 37,308.4 36,835.0 36,609.6 36,405.0
Acreages are exclusive of Alaska and Hawaii.
6~fFootnotes b-f identify the 23 major crops for which acreages were projected; historical values for food
account for total acreages of crops harvested.
Includes corn, grain sorghum, oats, and barley.
qncludes hay and silage.
Includes wheat, rye, and rice.
CIncludes Irish and sweet potatoes, dry beans, and dry peas.
Includes soybeans, peanuts, and flaxseed.
Total crops harvested will not equal Cropland harvested because of double cropping.
Cropland used only for pasture or grazing, cover, crops, legumes and soil-improvement grasses, crop failure, cultivated summer fallow, and idle land.
Land occupied by houses or other buildings, lanes, roads, ditches, land in ponds, and wasteland.
Includes acreages for 17 western states, Arkansas, Mississippi, Louisiana, and Florida (1960 acreage reported under 1959 for Arkansas, Mississippi, and Florida).
Total irrigated crops harvested will not equal cropland harvested because of double cropping and/or nonreporting.
feed, and other crops include acreages of minor crops to
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64
EVERARD M. LOFTING a nd H. CRAIG DAVIS
TABLE 3.13 Use of Land Resources, Selected Historical and Projected Years, 1959-2020 (in Thousands of Acres)
Land in Farmsa
1959 1964 1980 1985 2000 2020
Cropland Harvested 311,285.2 286,708.1 307,624.4 317,000.6 354,270.2 356,423.3
Feed crops
Grainsb 125,395.0 93,658.2 96,127.4 98,778.5 113,774.4 111,738.7
Roughage C 76,432.~) 78,829.4 73,664.9 74,524.6 77,485.6 81,086.4
Food crops
Grains 52,576.0 51,413.4 51~956.1 50,069.1 49,909.1 49,104.0
Vegetables, fruits, and sugar 8,992.9 9,638.1 9,471.7 9,634.4 9,892.5 10,274.1
Othere 3,176.0 2,923.1 2,922.7 2,869.0 2,708.3 2,678.8
Over crops
Oily 26,261.0 33,841.4 61,488.4 69,483.9 88,486.0 88,908.2
Cotton, tobacco, and miscellaneous 22,765.5 21,230.1 16,355.0 16;,3()7.5 16,319.9 16,934.9
Total crops harvested 315,598.4 291,533.7 311,286.7 32l,66S.9 358,575.7 360,725.1
Cropland not Harvestedh 136,278.5 147,130.0 150,510.3 141,166.2 104,(~51.8 101,653.2
Toad Cropland 447,563.7 433,838.1 458,134.8 458,186.8 458,321.9 458,076.5
Forest and woodland 163,684.3 145,711.5 105,231.8 102,759.6 95,339.7 86,404.5
Pasture, range, and other lanai 5~)8 909.8 526,323.5 481,566.3 478,927.2 471,341.4 463,098.2
Total land in farms 1,120,157.8 1,105,873.1 1,044,932.9 1,039,873.6 1,025,003.0 1,007,579.2
Irrigated Cropland Harvested 27,436.8 29,902.8 37,463.6 36,935.8 37,042.6 37,184.3
Feed crops
Grainsb 5,255.4 6,585.0 10,079.8 9,799.3 9,567.3 9,516.2
RoughageC 7,483.6 9,144.~ 10,648.8 10,681.3 :11,221.8 11,072.5
Food crops
Grains 2,961.9 3,785.5 4,563.8 4,488.3 4,541.D 4,490.6
Vegetables, fruits, and sugar 3,601.8 4,826.6 5,396.4 5,514.8 5,866.5 6,463.8
Othere 1,158.0 1,007.1 1,265.0 1,278.2 1,289.5 1,328.6
Other crops
Oilf 395.0 479.8 1,113.5 1,090.4 1,054.1 1,090.3
Cotton, tobacco, and miscellaneous 3,465.0 4,281.2 4,789.1 4,471.9 3,892.5 3,623.8
Total irrigated crops harvestedk 24,320.7 30,110.1 37,856.3 37,324.2 37,433.4 37,585.7
Acreages are exclusive of Alaska and Hawaii.
Footnotes b-f identify die 23 major crops for which acreages were projected; historical values for food, feed, and other crops include acreages of minor crops to
account for total acreages of crops harvested.
Includes corn, grain sorghum, oats, and barley.
CIncludes hay and silage.
Includes wheat, rye, and rice.
Includes Irish and sweet potatoes, dry beans, and dry peas.
Includes soybeans, peanuts, and flaxseed.
Total crops harvested will not equal Cropland harvested because of double cropping.
Cropland used only for pasture or grazing, cover, crops, legumes and soil-improvement grasses, crop failure, cultivated summer fallow, and idle land.
Land occupied by houses or other buildings, lanes, roads, ditches, land in ponds, and wasteland.
Includes acreages for 17 western states, Arkansas, Mississippi, Louisiana, and Florida (1960 acreage reported under 1959 for Arkansas, Mississippi. and Florida).
Total irrigated crops harvested will not equal Cropland harvested because of double cropping and/or nonreporting.
Bonem in 1971.3~ Preliminary projections that are subject
to revision have been made to 1985 and 2000 under the
Water Resources Council's 1975 National Assessment
Program (Table 3.141.
To test the usefulness of a simplistic national "projec-
tion model," based on an extrapolation of past production
growth trends and fixed water requirements per unit of
output, the Series E OBERS growth rates were used with
1970 agricultural and steam-electric withdrawals data
and the 1973 Census of mineral industry and manufactur-
ing water-use data. Essentially the gross outputs of a
400-sector 1972 national interindustry table, updated
from 1967, were aggregated to conform to the OBERS
industry classification scheme. The OBERS growth rates of
earnings that had been projected by sector to 2000 and
2020 in constant dollars were calculated in index terms
and then applied to the 1972 gross domestic outputs by
sector to project these to the target years. Water-use
coefficients for the base year were calculated for the
industry classifications in the form of water use in billions
of gallons per day per million dollars of product output.
These coefficients were then multiplied into the pro-
jected levels of constant-dollar output to yield the esti-
mated values of water use by sector. These values have
been plotted along with the other projections in Figures
3.4 3.11. The results of the simplistic projection model
compare favorably with some of the middle-range projec-
tions developed by Wollman and Bonem. The values of
the water coefficients used in the simplistic model for the
mineral industry category may be low because of the fact
that the Census data, as presented, cover only 7 percent of
the total number of establishments. The 7 percent that are
OCR for page 65
Methods for Estimating and Projecting Water Demands for Water-Resources Planning
170—
lln _
FIGURE 3.3 Projections to 1985 of population, food demand,
food projection, and food valance in (a) the developed countries
(including eastern Europe and the Soviet Union) and (b) the
developing market economy countries. 196~1971=100. Data
source: Reference 68.
covered are nevertheless stated to represent some 98
percent of total water withdrawals.
If the climatic changes that portend are in fact realized,
then the irrigation demands may be substantially greater
than the preliminary Water Resources Council second
national assessment estimates as they are currently
shown. If increased irrigation demands are to be met both
in the traditionally semiarid areas of the West and in the
dry farming areas of the Midwest and East, then some-
thing approximating a fixed water input per unit of output
may ultimately be a more realistic assumption to be made.
The agricultural sector in the United States is basic to
the support of the large concentrations of population in
metropolitan and suburban areas. However, this sector is
extremely vulnerable to any adverse climatic change that
could lead to a series of crop failures. Additionally,
BGD
140
I20
100 r
80~
1 1 1
1 975 1985 2000
FIGURE 3.4 1975 Water Resources Council projections for
consumptive water use. Key: , constant-water-use coefficient
model; _ ; Water Resources Council preliminary
projection, 1975; , Water Resources Council, 1965;
Wollman and Bonem3t (high, medium, low projections). BGD,
billion gallons/day.
65
12 _
8 _
4 _
MANUFACTURING,
/ STEAM-
, ELECTRIC,
it' _ DOMESTIC
/
~ - - MINERALS
_ . _
u 1 1 1
1975 1985 2000
FIGURE 3.5 1975 Water Resources Council projections for
consumptive water use. Key: See Figure 3.4.
household water needs are similarly vulnerable in many
localities because of limited reservoir capacities. The
combined conditions of drought in agricultural areas and
insufficient capacity in public water supplies for met-
ropolitan areas could lead to unstable political and eco-
nomic conditions where populations are highly concen-
trated. Unforeseen shortages of water for any protracted
period of time may be difficult to contend with in terms of
public health and safety. While results of the simplistic
projection model of water demands constructed by the
authors for the years 2000 and 2020 based on current
water-use data and economic growth rates associated with
a series E population growth compare favorably with the
middle-range projections developed by Wollman and
Bonem, both sets of forecasts, as well as others such as
BGD
220
200
I80
160
140
I20
100
/
/
, 1 1 1 ~
19 60 1980 2000 2020
FIGURE 3.6 Agricultural water withdrawals. Key: See Figure
3.4.
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66
TABLE 3.14 Annual Water Requirements
EVERARD M. LOFTING and H. CRAIG DAVIS
Withdrawal Use Consumptive Use
Water Requirement (mad) (mad)
Categories 1975 1985 2000 1975 1985 2000
Domestic Central 21,520.4 24,698.0 29,086.0 5,003.4 5,744.8 6,756.0
Domestic Noncentral 2,072.7 2,296.0 2,371.7 1,288.5 1,392.1 1,417.5
Manufacturing Total 58,176.8 33,086.5 45,701.6 6,275.0 9,199.9 15,758.3
Food end kindred 2,500.6 1,440.3 1,137.6 310.3 465.7 770.5
Paper, pulp, and board 8,595.6 5,821.5 5,193.2 1,039.7 2,065.0 4,112.6
All other manufacturing 4,910.7 2,496.5 2,606.7 598.6 865.0 1,400.6
Textile mills 559.6 265.7 211.6 65.1 93,1 144.5
Chemicals 14,005.4 5,867.6 5,445.4 1,305.5 2,128.3 4,260.1
Primary metals 17,324.0 5,591.0 3,398.0 2,007.0 2,282.0 2,685.0
Transport, machinery 1,331.4 579.4 479.4 143.8 226.7 364.4
Petroleum refining 2,313.8 1,578.4 1,201.6 533.5 687.5 955.4
Minerals, Total 7,506.1 8,810.4 10,912.4 2,333.2 2,628.4 3,145.8
Metals 1,081.2 1,288.2 1,605.3 233.5 272.5 300.1
Nonmetals 3,518.7 4,385.7 5,745.6 470.8 599.1 785.0
Fuels 2,907.4 3,137.0 3,622.4 1,627.9 1,758.9 2,022.4
Crop Irrigation 179,053.4 184,984.5 163,652.9 92,024.5 98,153.5 93,742.2
Livestock 1,851.9 2,153.1 2,444.1 1,851.9 2,153.1 2,444.1
Steam Electric 92,602.0 86,801~0 70,047.0 2,103.0 3,647.0 9,147.0
National Parks 13.8 18.0 21.7 10.3 13.5 15.9
Fish Hatcheries 628.0 697.2 726.3 0.0 0.0 0.0
BLM Lands 1,050.7 1,129.9 1,232.8 1,050.7 1,129.9 1,232.8
National Forests 393.0 591.5 793.4 393.0 591.5 793.4
Total Requirements 364,868.8 345,266.6 326,990.0 112,333.5 124,653.5 134,453.1
Man-made Evaporation 13,114.0 13,556.2 13,779.8 13,114.0 13,556.2 13,779.8
Total Requirements plus Evaporation 377,982.7 358.822.8 340,769.8 125,447.5 138,209.7 148,232.9
Net Exports 450.7 651.7 862.2 450.7 651.7 862.2
Net Depletions 378,433.4 359,474.5 341,631.9 125,898.2 138,861.4 149,095.1
Groundwater Withdrawals 68,665.5 66,410.5 63,481.5
Net Imports 0.0 0.0 0.0
OCR for page 67
Methods for Estimating and Projecting Water Demands for Water-Reso?'rces Planning
BED
an
60
40
20 _
/
FIGURE 3.7 Mining water withdrawals. Key: See Figure 3.4.
BGD
200 _
160 _
120 _
80 _
40 _
-
/ /
/ /
/ _
it_
~ 1 1 1 1
1960 1980 2000 2020
FIGURE 3.8 Manufacturing water withdrawals. Key: See
Figure 3.4.
67
BGD
I 000
800
600
400 t
200;
100:
Rae ~
ma_
it' ~
1960 1980 2000 2020
FIGURE 3.9 Steam-electric water withdrawals. Key: See
Figure 3.4.
BGD
140
120 _
100 _
80 _
60 _
40 _
2n _
// :~<
:~
1960 1980 2000 2020
FIGURE 3.10 Municipal water withdrawals. Water Resources
Council data are for domestic use only. Key: See Figure 3.4.
OCR for page 68
68
BGD
1600:
1400:
1200:
1000:
800:
600:
400:
200 _
/
I I ~
1960 1980 2000 2020
O ~ _ . .
FIGURE 3.11 Total water withdrawals. Key: See Figure 3.4.
those developed by the United States Water Resources
Council for 1968 and 1975, may substantially understate
agricultural water demands if any unfavorable climatic
change is experienced during the coming 50-year plan-
. .
nlng perlo( ..
The authors are indebted to Nathaniel Wollman and
Warren Hall for helpful review comments given for an
earlier draft of this chapter.
BE F ERE N C E S
1.
3.
.S
EVERARD M. LOFTING and H. CRAIG DAVIS
R. G. Thompson and H. P. Young (1973~. Forecasting water
use for policy making: A review, Water Resources Res. 9,792.
2. C. T. Bowman and T. H. Mortar (1976~. Revised projections
of the U.S. economy to 1980 and 1985, Mon. Labor Rev.,
March.
R. E. Kutscher (1976~. Revised BES projections to 1980 and
1985: An overview, Mon. Labor Rev., March.
4. C. W. Howe (1972~. Economic modelling: Analysis of the
interrelationships between water and society, presented at
International Symposium on Mathematical Modelling Tech-
niques in Water Resources Systems, Ottawa, Ont., Canada,
May.
. C. V. Moore and T. R. Hedges (1963~. Economics of On-
Farm Irrigation Water Availability and Costs and Related
Farm Adjustments, Vol. 2, California Agricultural Experi-
ment Station, Giannini Foundation Research Rep. No. 263,
U. of California, Berkeley.
6. R. A. Young and J. D. Bredehoeft (1972~. Digital computer
simulation for solving management problems of conjunctive
groundwater and surface water systems, Water Resources
Res. 8, No. 3.
7. R. G. Cummings (1971). Optimum exploitation of ground-
water reserves with saltwater intrusion, Water Resources
Res. 7, No. 6.
8. R. G. Cummings (1971). Water resource management prob-
lems in northern Mexico, unpublished paper presented at
Workshop on Problems of Agricultural Development in
Latin America, Caracas, Venezuela, May 17-19.
9. H. M. Stults (19661. Predicting farmer response to a falling
water table: An Arizona case study, in Water Resources and
Economic Development of the West, Rep. No. 15, Confer-
ence Proceedings, Committee on the Economics of Water
Resources Development of the Western Agricultural Eco-
nomics Research Council, Las Vegas, Dec.
10. M. Gisser ( 1970~. Linear programming models for estimating
the agricultural demand for imported water in the Pecos
River Basin, Water Resources Res. 6, No. 4.
11. L. M. Hartman and R. L. Anderson (1962~. Estimating the
value of irrigation water from farm sales data in northeastern
Colorado, J. Farm Econ. 44, No. 1.
12. R. L. Anderson (1961). The irrigation water rental market: A
case study, Agri. Econ. Res. 13, No. 2.
13. B. D. Gardner and H. H. Fullerton (1968~. Transfer restric-
tions and the misallocation of irrigation water, Am. J. Agri.
Econ. 50, No. 3.
14. E. O. Heady, H. C. Madsen, K. J. Nichol, and S. H. Hargrove
(1971~. Agricultural Water Needs~uture Water and Land
Use: Effects of Selected Public Agricultural and Irrigation
Policies on Water Demand and Land Use, summary report
prepared for the National Water Commission by the Center
for Agricultural and Rural Development, Iowa State U., Nov.
(available from NTIS, Springfield, Vat..
15. J. H. Duloy and R. D. Norton (1972~. CHAC, a programming
model of Mexican agriculture, draft copy of a chapter in a
forthcoming book tentatively titled "Multi-Level Planning:
Case Studies in Mexico" (mimeo), IBRD, Feb. Cited by C. W.
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Representative terms from entire chapter:
water resources
