Estimating Water Use in the United States A New Paradigm for the National Water-Use Information Program (2002) / Chapter Skim
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7. A Vision for the NWUIP
7. A Vision for the NWUIP
Pages 115-129
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From page 115... ...
To use water use information in investigations of water resources or ecosystems requires placing water use prominently within the hydrologic cycle. The NWUIP should, therefore, be viewed as much more than a data collection and database management program focused on county-level categorical water use.
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From page 116... ...
understanding hydrologic water use. Spatial water use refers to estimates of the total use of surface and
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From page 117... ...
Although consumptive use and return flows are essential for understanding the water budget, these water uses are often calculated as the residual in a hydrologic budget and are not routinely obtained from site-specific water withdrawal records. The NWUIP can and should characterize and quantify the importance of water as an essential commodity in the economy and the use of water as a critical hydrologic stress affecting the sustainability of the nation's water resources.
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From page 118... ...
water use on aquatic ecosystems, on the hydrologic cycle, and on the reliability and vulnerability of the nation's water resources. The goals of understanding spatial water use and hydrologic water use require a view of water use from the perspective of both the infrastructure water system and the natural water system.
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From page 119... ...
Links to the natural water system directly connect water use to surface and groundwater sources by withdrawals, discharges, recharge, instream flow, and ecosystem impacts. Links to the human environment connect water use to the infrastructure water system of pipes, canals, treatment plants, and other man-made structures that extract, convey, distribute, and collect water.
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From page 120... ...
(b) Legend —Streams Lake Watersh ed Surface Water I stake Giroundwater Well Wastewater Discharge ESTIMATING WATER USE IN THE UNITED STATES Natural Water System O ~ 0 :5 10 1 1 1 1 1 20 Miles FIGURE 7.2 (a)
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From page 121... ...
The linkages are shown by solid lines for the water supply and distribution systems and by dashed lines for the wastewater collection and disposal systems. Although there are many points of water withdrawal, the local concern about wastewater discharge to lakes led to the construction of a regional wastewater treatment plant near the most downstream town, Franklin, from which the treated wastewater is discharged to the Merrimack River.
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From page 122... ...
TABLE 7.1 Characteristics of Spatial and Hydrologic Water Use Spatial Water Use Hydrologic Water Use Estimates the quantity and type of water use in an arbitrarily defined area Reflects water use as a material flow or as a commodity input to human activities Takes place principally within the infrastructure water system, but is connected to the hydrologic system through withdrawal, discharge, recharge, and return flows NWUIP products describe quantity, trends, and the spatial and temporal distribution of water use, by water use category Estimates spatial and temporal impacts of water use in the hydrologic cycle Reflects water use as a hydrologic flux resulting from human activities Takes place principally within the natural water system, but is connected to the infrastructure water system through withdrawal, discharge, recharge, and return flows NWUIP products describe impacts on vulnerability and sustainability of the resource, aquatic ecosystems, and riparian vegetation, by hydroclimatic category
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From page 123... ...
At the third level in the hierarchy, information is added describing the water infrastructure: the jurisdictional boundaries of the institutions that manage water use, and the locations of their water and wastewater treatment plants and water distribution and collection systems. The quantity and quality of water flowing Link-node water use data structure Natural and infrastructure water systems Water withdrawal and discharge points ~ ~ 1 K3'$''' ~ :<'~ 1 1 1 1 ~ ~ ~1~~ .
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From page 124... ...
Many of these databases, including the Arkansas database with nearly 45,000 permitted water withdrawal points used throughout this report, are easily accessed and manipulated with over-the-counter GIS programs. Thus, it is now practical and efficient for the USGS to manage site-specific water use data (which would consist of literally millions of water withdrawal points and their associated attributes)
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From page 125... ...
This error may be negligible if the data are used to estimate total water use in a state, but may be unacceptably large for assessing drought vulnerability, sourcewater protection, or ecosystem impacts (see Box 7.1~.
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From page 126... ...
They used publicly available spatial data to estimate global water use for 0.5-degree grid cells, and linked these estimates to the natural hydrologic drainage network extracted from digital elevation model data. To estimate urban water use without site-specific data, urban population was distributed between 1-km-resolution city polygons and 1-km grid cells classified as "city lights" from nighttime remote sensing images.
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From page 127... ...
Chapter 5 illustrated the advantages of statistical sampling of site-specific water use for estimating spatial water use and its uncertainty, while Chapter 6 demonstrated how statistical inference based on statewide categorical water use data can help reveal the structure of water use on a national scale. As part of the NWUIP, there is a strong need for the USGS to systematically compare these and other water use estimation methods in order to identify the techniques (or combination of techniques)
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From page 128... ...
utilize statistical sampling and inference within the context of an unambiguous and statistically meaningful definition of the populations of water users to be estimated, (5) incorporate error analysis designed to give relative standard errors, (6)
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From page 129... ...
These considerations suggest a conceptual framework for the NWUIP that links the infrastructure water system, described by locations of water withdrawals, water discharges, and the principal water facilities, with the natural water system of streams, rivers, lakes, aquifers, and watersheds. The increasingly common availability of site-specific water use databases and GIS technology among the states is a key enabling factor for this approach.
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