Hydrological impacts of climate change over the contiguous United States: Project overview

Objectives Improve depiction of impacts of climate change on water resources –Improve downscaling methods (better statistical downscaling, high- resolution dynamical downscaling, simple weather model) –Improve hydrologic scenarios of climate change (shift from single- model to multi-model approaches; implement state-of-the-art hydrologic modeling approaches and parameter estimation methods –Develop a routing tool to transform gridded hydrologic projections into daily time series of streamflow at any point in the river network within any river basin within the contiguous U.S. –Document the relative impact of different sources of uncertainty in hydrologic projections in different hydroclimatic regions throughout the contiguous U.S.

100 VIC-modeled runoff time-series from CMIP5 simulations –Monthly runoff at 1/8 th degree in mm –CMIP5 BCSD Forcing USACE Requirement –Runoff & Routed runoff for HUC4 basins in CFS –Forcing data aggregated to HUC4 basins Surface air temperature Precipitation Runoff Aggregation

GIS Methods applied –Derive HUC4 basin-to-grid correspondence –Aggregation (zonal statistics) and unit conversion –Output time-series to custom NC format Runoff Aggregation

Routed runoff for non-headwater basins. Routed runoff time-series for HUC 0809 – Lower Mississippi Runoff Aggregation

Hydrologic modeling: USGS Geospatial Fabric Infrastructure for Nat’l Hydro Modeling (NHM) GIS dataset of hydrologic modeling features Sets of parameter tables Simplify simulation of streamflow at (almost) any point in US Pre-process feature delineation & parameterization Support PRMS, NWBM, SPARROW, WaterSmart Census, ??? Method for indexing & sharing of results Use hydrography to organize information resources related to hydrologic modeling

Aggregate NHDPlus catchments based on Points of Interest (POIs) to make Hydrologic Response Units (HRUs) Geospatial Fabric Methodology

Geospatial Fabric feature dataset: Points of Interest (POI) Aggregate NHDPlus features based on POIs to define segments & HRUs POIs : Gages II USGS Reference/non Ref. Gages SPARROW National Weather Service River Forecast Centers Major confluences and waterbody inlets/outlets Travel time points (< 1 day) Elevation bands (500m) Aggregate NHDPlus features based on POIs to define segments & HRUs POIs : Gages II USGS Reference/non Ref. Gages SPARROW National Weather Service River Forecast Centers Major confluences and waterbody inlets/outlets Travel time points (< 1 day) Elevation bands (500m)

NHDPlus Region 1a and 2b

NHDPlus Region 1a and 2b HRUs from aggregated NHDPlus

Using high-resolution NED elevation data & PRMS stream segments Establishing flow connectivity of runoff through the river network Building routing table for entire CONUS region Routing (collaboration with the USGS)

Objectives Improve depiction of impacts of climate change on water resources –Improve downscaling methods (better statistical downscaling, high- resolution dynamical downscaling, simple weather model) –Improve hydrologic scenarios of climate change (shift from single- model to multi-model approaches; implement state-of-the-art hydrologic modeling approaches and parameter estimation methods –Develop a routing tool to transform gridded hydrologic projections into daily time series of streamflow at any point in the river network within any river basin within the contiguous U.S. –Document the relative impact of different sources of uncertainty in hydrologic projections in different hydroclimatic regions throughout the contiguous U.S.