Potential Water Resource Monitoring Indices Kwabena Asante

Potential Water Resource Monitoring Indices Kwabena Asante & Gabriel Senay USGS EROS / FEWS NET Sioux Falls, SD 57198 U.S. Department of the Interior U.S. Geological Survey

GeoSFM Challenges Conversion between raster GIS grids and text files makes data management more difficult, particularly as number of basins get larger Display of interactive hydrographs requires a live IMS connection which has been difficult to maintain Getting absolute flow values correct without local calibration has been difficult

Flow Routing using River Network Catchment delineated around the river network Flow routed within catchments to catchment outlet Flow goes along river network to from outlet to outlet

Impacts on Routing Flow must be routed through even tiny river reaches A new record is generated for each river reach each time step Results in a large time series matrix which is difficult to manipulate

Flow Time to Basin Outlet Time for water to travel from a given location to the basin outlet Computed from elevation derived flow length and velocity

Bands of Daily Travel Time Travel time to the basin outlet discretized into daily intervals Flow time between two areas along same river can also be estimated

Identify River Exit Points for Time Zones Identify points at which river exits daily travel time zones Delineate catchments associated with these exit point

Travel Time Based Catchments Water takes exactly one day to travel between the travel time-based catchments Hence we can directly propagate daily runoff generated in a catchment to the next downstream catchment Travel Time Based Catchments Sample Daily Runoff Grid

Daily Runoff Grids An existing operational product

Event Monitoring with Daily Runoff Doesn’t track what happens to the excess runoff

Flow Event Monitoring with Proposed Grid-based Routing

Comparison of Grid-based Model with GeoSFM

Comparison of Grid-based Model with GeoSFM

Annual Maximum Flows 1998 2000 2002

Median of Annual Max Flows

Sample Daily Flood Hazard Indices Flow in absolute terms Flood Hazard Index as a % of median annual flow

Sample Output: Daily Flows or Storage A climatology is being computed. It will enable anomalies to be presented relative to median of peak flows (1998 – 2005).

Conclusions A new daily flood hazard index (FHI) product is being created to simulate the movement of flow from daily runoff grids. Flood Hazard Index (FHI) is will be presented as a percentage of median annual flood peak, and will be useful for identifying the location and relative magnitude of flood hazards. Low daily flows do not necessarily indicate hydrologic drought as subsurface runoff yield is not being simulated. The product could be operational within the next couple of weeks if it meets with your approval.