Water availability in the upper Rio Grande Basin is dependent on winter and monsoon season precipitation. Consecutive years of drought and above average temperatures have diminished water supply and increased demand for water in this region. The increasing gap between water supply and demand is cause for concern. Climate projections for the southwestern and south central United States suggest that temperatures will continue to increase, affecting seasonal precipitation and water availability. To better manage current water supply and prepare for possible future changes, water managers need projections of future streamflow and landscape conditions that may affect future water supply. The project researchers are currently calibrating [...]
Summary
Water availability in the upper Rio Grande Basin is dependent on winter and monsoon season precipitation. Consecutive years of drought and above average temperatures have diminished water supply and increased demand for water in this region. The increasing gap between water supply and demand is cause for concern. Climate projections for the southwestern and south central United States suggest that temperatures will continue to increase, affecting seasonal precipitation and water availability. To better manage current water supply and prepare for possible future changes, water managers need projections of future streamflow and landscape conditions that may affect future water supply.
The project researchers are currently calibrating the U.S Geological Survey’s Precipitation-Runoff Modeling System (PRMS) to represent the natural state of the basin without managed water operations such as reservoirs or diversions. The calibrated PRMS model will be used to estimate how water flow will respond to projected future temperature and precipitation. Several model outputs, including streamflow, evapotranspiration, and soil moisture, will also be used to help provide a clear picture of how hydrologic changes affect the water resources we use for farming, municipal water supply, healthy ecological streamflow, and other uses. Also, because the future is uncertain, the project researchers will integrate multiple future climate conditions to project a range of likely future hydrologic conditions. The team will use stakeholder meetings and an interactive web page to disseminate results and provide water managers with useable information about the magnitude, uncertainty, and implications of hydrologic response to climate change in the future.
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RioGrandeRiver_AlanCressler.jpg “Rio Grande River, Alan Cressler - Credit”
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Objectives. The project goal is to assess and communicate how future climate may change water availability in the Upper Rio Grande Basin (URGB). Future climate and uncertainty will be defined by 81 downscaled climate projections. Water availability will be defined by Precipitation-Runoff Modeling System (PRMS) simulations and calculation of hydrologic indices that are relevant to stakeholders. Communication will be stakeholder-focused and multi-faceted. Background. Concern is growing over the increasing gap between water supply and demand in the URGB. Future climate may exacerbate this gap. A PRMS model has been developed and calibrated for the URGB that can simulate daily streamflow and landscape-level hydrologic response to climate. Instead of just summarizing response using simple annual average responses, hydrologic indices calculated from daily variables go further by focusing on ecologically and socially relevant responses with meaning to stakeholders, such as number of bank-full floods, magnitude and variability of seasonal flows, number of zero-flow days, days and timing of soil-moisture stress, or drought severity index. Procedures/Methods. An existing collection of 81 downscaled climate projections of daily precipitation, and minimum and maximum temperatures will be spatially disaggregated to provide climate input files for a PRMS model of the URGB with 1,021 subbasins (hydrologic response units [HRUs]). Daily hydrologic response will be simulated and used to calculate hydrologic indices at the landscape (HRU) and watershed outlet (streamflow) scales across the URGB. Importantly, sources of climate-projection uncertainty will be tracked through the collective modeling framework and used to better define future hydrologic responses. Uncertainty envelopes of hydrologic response will provide realistic hydrologic index ranges for future conditions. Expected Products and Information. Results will be communicated by a web-based story map and visualization tools, research publications, and stakeholder presentations. Results are planned for immediate use by the USBR and stakeholders to assist water-management decisions.