Importance of Temporal and Spatial Scale on Basin-Scale Groundwater Recharge Estimates in Historical and Projected Climate Change Conditions

Project ID: 9037
Principal Investigator: Subhrendu Gangopadhyay
Research Topic: Water Resource Data Analysis
Funded Fiscal Years: 2016
Keywords: groundwater, recharge, climate change, cmip-5, scale

Research Question

Hypothesis

Groundwater supplies baseflow to streams and rivers, maintaining flow during time periods after snowmelt and peak runoff have been routed through the system. Reductions in groundwater recharge will result in reduced streamflow during baseflow-dominant times of the year and could negatively affect riparian vegetation and associated ecosystems. Simulating groundwater recharge using the Soil Water Balance (SWB) model requires spatial information on land cover, available water capacity, hydrologic soil group, and overland flow direction, and temporal and spatial climate data including temperature and precipitation.

Contemporary climate forcing datasets are available at multiple space-time resolutions. It is important to understand the error structures introduced from spatial and temporal aggregation and disaggregation of climate forcing datasets, and in interpreting results from impacts models.

Research Questions

1. Will historical and projected estimates of groundwater recharge in the Upper Colorado River Basin differ substantially between simulations using daily climate data and monthly climate data for a range of spatial resolutions varying from finer (~ 1-km) to coarser (~10-km)?

2. What are the implications of space-time aggregation-disaggregation error structures in climate forcing datasets in interpreting the groundwater recharge estimates?

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, and information on the required scale of input data is important. 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.

This research will provide important insights into the appropriate scale for input datasets in groundwater recharge simulations for both historical and potential changing climate in the UCRB, and impacts on streamflow for the basins. The impact of the loss of information from coarser spatial and temporal scale datasets on recharge estimates will be summarized and lessons learned on the cost-benefit of dataset scale will be documented.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Importance of Temporal and Spatial Scale on Basin-Scale Groundwater Recharge Estimates in Historical and Projected Climate Change Conditions (final, PDF, 7.6MB)
By Fred D Tillman, Tom Pruitt, Subhrendu Gangopadhyay
Research Product completed on September 30, 2017

This research product summarizes the research results and potential application to Reclamation's mission.

Importance of Temporal and Spatial Scale on Basin-Scale Groundwater Recharge Estimates in Historical and Projected Climate Change Conditions (final, PDF, 369KB)
By Subhrendu Gangopadhyay
R&D Bulletin completed on September 30, 2018

This research product summarizes the research results and potential application to Reclamation's mission.


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Last Updated: 4/4/17