Analysis of infrequent large groundwater recharge events: Their importance for long-term groundwater availability, use, and management
Project ID: 5424
Principal Investigator: Subhrendu Gangopadhyay
Research Topic: Managing Hydrologic Events
Funded Fiscal Years: 2014
Keywords: groundwater, infrequent, recharge, management, adaptation, climate change
Hypothesis: Infrequent large groundwater recharge events provide much of the recharge to aquifers in arid and semi-arid regions of the western U.S. and changes in the magnitude and frequency of these events may affect long-term groundwater availability, use, and management.
1) What are the characteristics of large recharge events? Specifically what are the antecedent conditions, and climatic conditions that constitute a large recharge event?
2) What methods are most useful in identifying and classifying large recharge events in the time series data?
3) How much does groundwater storage change with large recharge events and what are the implications for groundwater availability and management and connected streamflow should the magnitude and frequency large recharge events change?
Need and Benefit
As identified in the Long-Term User Needs document, Reclamation would like to address the information gap on climate change effects on groundwater and the resultant impacts to surface-water supply over the next several decades. At the same time, Reclamation would like to develop a methodology that could be applied drainage-basin by drainage-basin across the western US. The ideal assessment method should consistently provide information about the relative importance of groundwater in support of basin-specific surface-water flow and illustrate how changing climate conditions (i.e. changes in groundwater recharge) might impact future stream-flow volumes in these drainage basins.
Complicating this assessment are two important factors: (1) each drainage basin is unique – the climatic conditions, the hydrogeologic framework, and the development of the groundwater and surface-water resources vary basin by basin; and (2) most basins are data limited – the amount of data available on groundwater resources, water-use and manipulation, and hydro-climatic variables are limited or dispersed. Given these limitations, it is proposed that the first step to an analytical framework would be to understand how large groundwater recharge events, which are episodic occur. In essence answer the question, what combination of events triggers actual recharge?
This study will help to make progress to that end using a documented large recharge event in northern Utah. This specific case study will help Reclamation to understand the underlying climatic and hydrogeologic construct that drive infrequent large groundwater recharge events. As a next step, this proof-of-concept can be extended to other Reclamation Regions.
This information was last updated on September 23, 2014
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