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Where do Decision-Makers Get Advice?
Sustainability and Groundwater Management Decisions
Stephen E. Ragone,
National Groundwater Association
A major issue facing global societies is water sustainability—having enough good-
quality, reasonably priced water to meet all future needs, region by region. In seeking the
goal of a sustainable future the decision maker must justify the cost to achieve this goal
against expenditures to resolve more immediate and pressing societal problems. To do
this, the decision maker must seek advice not only about the “controlling factors”—the
climatic variability and the complexity of the groundwater system that affect the quantity,
quality and distribution of water resources but also the “constraining forces”—the
prevailing socio-economic conditions that affect decision-making. The decision maker
must also seek advice about emerging technologies that may serve to conserve or
augment natural water resources. So, the short answer to the question, “Where do
decision makers get scientific advice?” is, “It depends”—on the mix of controlling
factors and constraining forces that affect water resources at the place of interest.
The Complexity and Interconnectedness of Groundwater Systems
A groundwater system (Figure 1) consists of a sequence of continuous and discontinuous
aquifers (saturated, permeable consolidated or unconsolidated geologic units that can
transmit “usable” quantities of water) and confining beds (geologic units that restrict the
movement of water into and out of adjacent aquifers). The water table defines the
boundary between the uppermost aquifer—the unconfined aquifer—with the overlying
unsaturated geologic unit (the unsaturated zone or vadose zone, not defined on Figure 1.
The lateral boundaries and vertical extent of a groundwater system can vary widely as
determined by the conditions under which the geologic units were formed. Heath (1984)
provides an excellent summary of the physical, chemical, and hydraulic characteristics
that delineate different types of regional groundwater systems. It is these characteristics
that determine, among other things, the volume of water in a groundwater system and
time of travel of water through the system—which can range from days to millennia.
Current distributions of water in regional groundwater systems generally developed since
the end of the last ice age some twenty thousand years ago. During this period glaciers
retreated and left behind reconfigured surface-water and shallow groundwater systems in
many parts of the world. A dynamic equilibrium was established among: the water
recharging the groundwater system, that which was held in storage and that which
discharged from the system (see “A” in Figure 2.) There was little exchange of water
between shallow groundwater and that in the deeper, confined parts of regional
groundwater systems prior to development. In humid areas the regional systems were,
“brim full; that is, most of the potential recharge was rejected….” (Johnson, 1999).
Likewise, in drier regions, “recharge to and flow through most regional aquifers were
small before development.” (Johnson, 1999) Thus, under pre-development conditions,
most of the annual recharge of water to regional systems entered and moved through the
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unconfined aquifers en route to surface water bodies. It is this part of the groundwater
system that is often used to estimate the part of global water resources that is available for
human use—the “mean annual river runoff and annually renewable groundwater
resources….” (Shiklomanov, 1993) The reality, however, is that pumpage from deeper
confined parts of groundwater systems is now routinely used to supply water in many
places throughout the world—but not without effect. Pumpage from confined regional
aquifers alters the dynamic equilibrium (see “B” in Figure 2) and, thus, the volumes of
water being recharged, held in storage or being discharged. The characteristics of the
system determine the specific response to pumpage. The Southern High Plains aquifer
(Figure 3), for instance, responded to pumpage predominantly with a decrease in storage,
and an increase in induced recharge and the infiltration of irrigation water. The Edwards
aquifer, on the other hand, responded to pumpage predominantly with a decrease in
discharge to streams and an increase in induced recharge. The other regional aquifers
included in Figure 3 show other combinations of responses to pumpage.
Figure 1 Simplified Groundwater system.
Response time to pumpage can vary widely as well. Alley and others (2002) demonstrate
that an aquifer’s response to some hydraulic perturbation can vary from hundreds of
minutes (for horizontal flow in a confined stream-aquifer system) to thousands of years
(for vertical flow in a thick regional low-permeability unit.) Water-quality changes can
take even longer as such changes depend on the physical movement of water. It would
take 82 years for water to move under natural conditions through the entire width of the
confined stream-aquifer system described above, for instance (Alley and others 2002.)
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However, water-quality change in fractured rock systems or in groundwater systems that
are being intensively pumped can be relatively rapid.
The interconnection between groundwater and surface waters can be significant. Winter
and others (1998) found, for instance, that groundwater contributes from 14 to 90 percent
(median of 55 percent) of the streamflow of 54 streams throughout the United States.
The interconnection between groundwater and surface water reinforces the “common-
good” valuation of groundwater (as compared with its value as a commodity) and that--
“many uses and environmental values depend on the depth to water—not the volumetric
amount of (groundwater) that is theoretically available.” (Sophocleous, 2003)
Figure 2 Groundwater balance before (A) and after (B) development.
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Figure 3 Hydrologic responses to pumpage of major aquifer systems in the United States
(from Alley and others, 2002).
Thus, when seeking scientific advice the decision maker must be aware of the complex
nature of groundwater systems and that their response to pumpage can vary in both space
and time. As most water-management actions take place at the local and regional scales,
the decision maker must also be aware of the different water supply and waste disposal
requirements of urban, rural and agricultural areas in his/her region, as well as the role of
planned and inadvertent point and nonpoint pollution in either diminishing the
availability of usable water reserves or increasing water-development costs. Finally, the
decision maker must recognize the role groundwater plays as part of the broader
ecological system, “the running streams, wetlands, and all the plants and animals that
depend on it,” (Sophocleous, 1997).
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Weighing the Tradeoffs
The recent droughts in the United States caused significant decreases in surface water
reserves and water table elevations thus reinforcing a growing concern that demand for
water is outstripping supply, and causing state agencies and water managers to take
unprecedented actions to prioritize and regulate water use even in parts of the country
that were once considered to be “water rich.” “The United States has had (many)
droughts since the 1930s (the time of the “Dust Bowl” that added to the economic travails
of the Depression years and undermined social structures.) With each drought the
concern was raised that water supplies were no longer adequate to meet demands.
However, the improved water-supply infrastructure (particularly the advent of large,
high-volume pumps used to tap into deep, confined aquifers) and federal support
programs made such concerns short-lived. So, what is it about the recent drought that
seems more foreboding? One reason is the large increase in population--from about 50
million people to more than 250 million--that occurred in the United States during the last
century and the consequent increase in water withdrawals (National Research Council,
2002). A disproportionately large part of the increase occurred in arid and semi-arid
regions, and urban centers, thus effectively increasing the net imbalance between local
supply and demand. Also, the pervasive nature of the drought--affecting water-rich and
arid regions, and people in agricultural, rural, and urban areas—and concerns about
global climate change--reinforced perceptions that more severe droughts would happen
more often and in more places....”(Ragone and Sophocleous, 2004).
In the United States the public’s growing disaffection with dams—a social phenomenon
arising out of ecological concerns--and the fact that virtually all surface waters are fully
allocated strongly suggests that groundwater will become a more important component of
water supplies in the future. However, two factors work against its efficient and, maybe,
appropriate development. The first is the bureaucratic/regulatory water resources
management framework that developed over time—one that separates the regulation and
management of surface waters and groundwaters--and the state regulations and interstate
compacts that often “lock in” inefficient land-use and water-use practices (see Maguire
this volume). The second factor is that the increasing value of groundwater as a
commodity (as opposed to water’s value as a common good as described above) can lead
to its exploitation. “Over the years the intense use of groundwater for irrigation in the
High Plains has caused major water-level declines and decreased the saturated thickness
of the aquifer significantly in some areas....”(Taylor and Alley, 2001). Intensive
pumpage of groundwater has resulted in instances of land subsidence and groundwater
contamination in the High Plains aquifer and in other groundwater systems. In the face of
such “negative outcomes” water purveyors often opt to tap into still pristine parts—
deeper, confined parts--of groundwater systems rather than paying the high costs to
renovate contaminated water and aquifers. As mentioned in the previous section such
extractions from confined systems can significantly alter regional groundwater flow
patterns. It can also accelerate groundwater contamination, thus further exacerbating
current water shortages and potentially worsening future shortages.
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But, do the benefits derived from “exploitive” pumpage—improved agriculture or
industrial productivity or domestic supplies--outweigh the negative effects? Freeze and
Cherry (1978) recognize, that “from the optimization viewpoint, groundwater has value
only by virtue of its use...that best meets a set of economic and/or social objectives....”
Abderrahman (2003) reports that Saudi Arabia chose to use about 19% of its non-
renewable groundwater resources between 1975 and 2000 to support socioeconomic
development in rural areas—to help rural populations and nomads “to be converted into
skilled agricultural communities...with effective public services (and to support) the
security of the country....” Likewise, it could be argued that the “exploitation” of
groundwater in parts of the High Plains aquifer to stabilize agricultural production and
community structure following the droughts of the 1930s also served the United States
well.
Thus, although the consequences of the “exploitation” of water resources to meet
immediate socio-economic needs may be viewed as undermining the long-term goal of
sustainable water resources the decision about the “best” use of groundwater reserves will
ultimately be decided by society as it ponders more pragmatic, present-day concerns. In
response the decision maker will be required to choose a pathway to a sustainable future
from the continuum of options that lie between “weak” and “strong” sustainability.
“Weak Sustainability requires one generation to hand over to the next a nondeclining
total capital stock (of water), which assumes that perfect substitution exists between
different types of capital, e.g. new technologies for water treatment or improved water
use efficiencies might be developed that somehow substitutes for the reduced capital
stock of aquifer water. Strong sustainability, on the other hand, assumes that some kinds
of natural capital have no substitutes.” (Alley and Leake, 2004) William Mills speaks to
the issue of weak sustainability in his talk (this volume) about the efforts of the Orange
County Water District to provide the technologies needed to ensure an adequate supply of
water for its citizens. Gonzalo Merediz Alonso speaks (this volume) to the desire for
strong sustainability in the Yucatan.
A danger is that society will make such decisions only in response to immediate concerns
and without necessary information about the longer-term outcomes of their decisions.
Thus, it is essential that those giving scientific advice act in good faith and with
objectively, and that the decision makers ask the right questions to ensure that this is so.
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References
Abderrahman, W.A. 2003. Should intensive use of non-renewable groundwater
resources always be rejected? in: Intensive Groundwater Use-Challenges and
Opportunities, E. Custodio and R. Llamas (eds.) A.A. Balkema Publishers, Lisse,
The Netherlands, 191-206.
Alley, William M., Richard W. Healy, James W. LaBaugh and Thomas E. Reilly. 2002.
Flow and Storage in Groundwater Systems, Science, volume 296.
Alley, William M., and Leake, Stanley A. 2004. The Journey from Safe Yield to
Sustainability; Groundwater, volume 42, number 1.
Freeze, R. Allen and Cherry, John A. 1978. Groundwater; Prentice-Hall International,
Inc. London.
Johnson, Richard H. revised 1999. Hydrologic Budgets of Regional Aquifer Systems of
the United States for Predevelopment and Development Conditions; U.S.
Professional Paper 1425.
Heath, Ralph C., 1984. Groundwater Regions of the United States; U.S. Geological
Survey Water-Supply Paper 2242.
National Research Council. 2002. Estimating Water Use in the United States: A New
Paradigm for the National Water-Use Information Program; National Academy
Press, Washington, D.C.
Ragone, Stephen E. and Sophocleous, M.A. (2004). Perceptions and Realities about
Groundwater and Future Water Availability; in New World Water (in press).
Shiklomanov, Igor A., 1993. World fresh water resources, in Water in Crisis: A Guide to
the World’s Fresh Water Resources, Peter H. Gleick editor; Oxford University
Press, Oxford, England.
Sophocleous, M.A., 1997. Managing water resources systems: Why safe yield is not
sustainable; Groundwater volume 35, number 4.
Sophocleous, M.A., 2003. Environmental implications of intensive groundwater use with
special regard to streams and wetlands, in: Intensive Groundwater Use-Challenges
and Opportunities, E. Custodio and R. Llamas (eds.) A.A. Balkema Publishers,
Lisse, The Netherlands, pp.93-112.
Taylor, C.J. and Alley, W.T. 2001. Groundwater-Level Monitoring and the Importance of
Long-Term Water-Level Data, U.S. Geological Survey Circular 1217.
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Winter, Thomas C., J. W. Harvey, O.L. Franke, and W. M. Alley. 1998. Groundwater
and Surface Water A Single Resource, U.S. Geological Survey Circular 1139.
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Representative terms from entire chapter:
decision maker
