Investigating Groundwater Systems on Regional and National Scales (2000) / Chapter Skim
Currently Skimming:
Approaches to Synthesis of Groundwater Issues at the Regional Scale
Approaches to Synthesis of Groundwater Issues at the Regional Scale
Pages 25-47
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From page 25... ...
The customary description of groundwater as a resource is contrasted with a process-based approach to regional groundwater science and regional assessments. Finally, a new approach to regional studies is proposed, based on parallel and synthesized regional groundwater assessments (i.e., evaluation of the quantity and quality of available groundwater, recharge, extraction rates, etc.)
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From page 26... ...
During the first half of the twentieth century, the public needed reliable water supplies to serve a growing and westward-expanding population, with much of this water being consumed for irrigation. These early pressures on groundwater resources revealed many of the issues, including subsidence, groundwater depletion, groundwater contamination, and salt-water intrusion, that continue to define issue-based groundwater investigations conducted by the Survey today.
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From page 27... ...
-pumping tests; analytical solutions for groundwa ter flow (Theis, 1935; Hubbert, 1940) 1940-1960 -use of electrical resistance analog models -World War II -experiments with scaled physical model of ground water flow -advances in well hydraulics 1960-1970 -mainframe computers available -first digital flow models (Pinder and Bredehoeft, 1 968)
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From page 28... ...
The close structural association between the occurrence of mineral deposits and groundwater, combined with the USGS expertise in mapping and geophysical characterization of resource availability and abundance, provided a natural framework for groundwater investigations. The need for better predictions of basinwide groundwater flow in turn led to the development of mathematical models.
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From page 29... ...
In the past 30 years, the USGS made more quantitative assessments of the extent, availability, and quality of groundwater resources. The most comprehensive of these was the Regional Aquifer-System Analysis (RASA)
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From page 30... ...
The quality of both surface water and groundwater is inventoried for standard parameters, including dissolved solids, nutrients, trace elements, radionuclides, pesticides, organic chemicals, and bacteria.
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From page 31... ...
Groundwater Monitoring Networks Understanding the environmental effects of groundwater development on land and surface water resources, and evaluating the overall sustainability of pumping rates, requires long-term monitoring and assessments. The extended time periods are necessary to distinguish transient responses of regional groundwater systems to groundwater withdrawals from other factors such as interannual- to decadal-scaTe variability in climate and changing land use.
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From page 32... ...
, and the Death Valley Regional Ground-Water Flow System Project is one example of a large, regionally integrated study largely supported by DOE funds (see Box 2.1~. Ground-Water Resources Program Current USGS groundwater assessment is greatly reduced in magnitude from the peak of the RASA program (Figure 2.4~.
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From page 33... ...
Approaches to Synthesis of Groundwater 33
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From page 34... ...
34 Investigating Groundwater Systems
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From page 35... ...
Approaches to Synthesis of Groundwater 35
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From page 37... ...
In many areas, there is extensive groundwater overdraft, leading to declining groundwater levels, increased recovery costs, decreasing water quality with depth, migration of contaminated water into production areas, subsidence with permanent damage to aquifers, earth fissures, and degradation of rip arian habitats. The water budgets associated with overdraft
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From page 38... ...
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From page 39... ...
New research approaches will need to be introduced to provide the information on the complex underlying processes that will be necessary to resolve such questions. -- ~ -- -o rThe Middle Rio Grande Basin Study (Bartolino, 1997b)
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From page 40... ...
An Emphasis on Sustainability New issues are driving a change in priorities in groundwater science and information needs. Whereas regional groundwater assessments traditionally focused on water availability and extraction, new concerns emphasize a complex of issues related to sustainable uses and management.
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From page 41... ...
Collaboration may be facilitated by partnerships with other federal or state science agencies and with universities. This approach to regional investigations requires the integration of regional process-based science and requires regional groundwater assessments oriented to issues of sustainability of current and projected uses, as is discussed later in this chapter.
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From page 42... ...
Beyond the historically static, descriptive assessment of characteristics such as depth to water table, regional potentiometric maps, and the concentrations of water quality parameters, regional groundwater assessments must integrate process-oriented science to evaluate the sustainability of current and projected trends for hydrogeologically and geographically distinct regional groundwater systems. Of necessity, these regional assessments must be inclusive, incorporating regional
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From page 43... ...
Improved process-based groundwater science on regional scales, in turn, supports improved management and policy-making on regional scales. Thus, regional groundwater assessments and regional process-based science form the foundation supporting the synthesis of groundwater investigations on regional and national scales.
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From page 44... ...
For the Middle Rio Grande-Santa Fe Group aquifer system, the information needed to formulate sustainable policies requires a reliable quantitative description of the regional groundwater flow system, including the hydrogeologic framework as well as patterns and trends in extraction and recharge. The demand for this understanding, in turn, clefines critical issues in regional groundwater science that have become the focus of process-oriented groundwater research of regional and national significance.
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From page 45... ...
Middle Rio Grande Regional Science. The regional assessment of the Middle Rio Grande basin system motivates the need to reliably quantify the recharge, flow paths, surface water interconnections, residence times, and hydrostratigraphic uncertainties in the regional groundwater flow system.
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From page 46... ...
For example, the detailed investigations of recharge to alluvial aquifers and streambed fluxes in the Middle Rio Grande basin study require scientific understanding of the dominant processes governing the flow between fluvial and groundwater systems. Regional groundwater science focused on common dominant processes, studied across different hydrocTimatic and hydrogeologic settings, will expand the scientific understanding of recharge processes common to alluvial aquifers.
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From page 47... ...
The elements to support these investigations include policy-relevant regional assessments of the sustainability of current and projected patterns of resource use. And finally, the management and policy questions that drive regional groundwater assessments will, in turn, drive the need for regional scientific investigations in fundamental process-oriented groundwater science common to regions with similar dominant processes.
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