PRMS Flow Model Output - Southeast - Difference from Historic

<span style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'>Summary</span><br /><span style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'>A study by the U.S. Geological Survey (USGS), in cooperation with the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (GCPO LCC) and the Department of Interior Southeast Climate Adaptation Science Center, evaluated the hydrologic response of a daily time step hydrologic model to historical observations and projections of potential climate and land cover change for the period 1952-2099. An application of the Precipitation Runoff Modeling System (PRMS) was used to develop the hydrologic simulations.  The model simulations were used to compute the potential changes in hydrologic response across the southeastern U.S. using historical observations of climate and streamflow, and 13 downscaled general circulation models with four representative concentration pathways representing a range of potential future changes in climate.</span><br /><span style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'> </span><br /><span style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'>The PRMS simulated hydrologic response within the entire geographic study area – the model domain.  The model domain was subset into small local watersheds delineating areas expected to have a similar hydrologic response due to changes in the model inputs.  These local watersheds are called “hydrologic response units” or HRUs.  </span><div style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'><span style='font-family:inherit; font-size:12.0012px;'><br /></span>The PRMS computes flow generated locally on each HRU for each time step. These flow components then are directed to stream segments (SEGs) for flow aggregation.  These segments connect the network of HRUs to simulate accumulated streamflow from the upstream watershed. Each HRU and SEG has a unique ID.  For each HRU and SEG, 52 summary streamflow metrics (Index of Hydrologic Alteration or IHA metrics) were calculated based on the daily flow outputs.  A description of each IHA metric may be found here (streamflow_description_table.xlsx). <br /><br /></div><div style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'>The summary information presented here shows geospatial results from three main components:  <br /><br /></div><div style='font-family:&quot;Avenir Next W01&quot;, &quot;Avenir Next W00&quot;, &quot;Avenir Next&quot;, Avenir, &quot;Helvetica Neue&quot;, sans-serif; font-size:16px;'>1)    The future percent difference from historical conditions for each HRU and SEG and for each of 50 IHA metrics (two metrics excluded due to a predominance of missing values).  The results are based on the difference between future conditions in 2045-2075 and historical conditions from 1952-2005.   Values are expressed as the percent difference based on a median of 45 future scenarios.  https://www.sciencebase.gov/catalog/item/597b37bbe4b0a38ca27563d4<br /> <br />Data source - HRU: “Summary of percent change in statistics by GCM/RCP scenario by HRU”<br />stats_difference_hru_gcm_v2_csv<br />Data source - SEG: “Summary of percent change in statistics by GCM/RCP scenario by SEG”<br />stats_difference_seg_gcm_v2_csv<br /> <br />Purpose<br />The streamflow statistics were selected to describe streamflow conditions that may be most useful in defining the suitability for each river or stream to support sustaining populations of priority aquatic species across the GCPO LCC. The data presented here are intended to provide more easily accessible landscape scale summary information in support of the USGS flow modeling project.</div>