Rainfall-Runoff Modeling

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Required Data

• Watershed Delineation

“For most hydrologic studies, it is essential that good topographic maps be used. It is important that the maps contain contours of ground-surface elevation, so that drainage basins can be delineated and important features such as slopes, exposure, and stream patterns can be measured”.

• Precipitation

“In areas of relatively uniform terrain and little spatial variability or precipitation, classical textbook procedures, such as Thiessen polygons or the isohyetal method, can be used and are generally adequate. These procedures are simple methods of developing spatial averages from point measurements but are inadequate to describe the orthographic or other spatially variable behavior of any appreciable complexity. In these cases, such as in mountainous areas, more comprehensive algorithms are needed to develop spatial averages from point measurements that describe the elevational (vertical) and horizontal variability. For time series at the watershed scale, the algorithm based on detrended kriging developed by Garen, Johnson, and Hanson (1994) is an example. (Further information on this procedure is available from the NRCS National Water and Climate Center in Portland, Oregon.) For annual or monthly averages or monthly time series at somewhat larger spatial scales (watershed to regional), the best method is to use the PRISM maps and GIS layers, as mentioned previously. This would be the recommended procedure in most watershed yield analyses”.

• Rainfall Losses

• Unit Hydrograph

• Reach Routing

Examples

Best Practices Resources

Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420)

National Engineering Handbook 210 Part 630 Hydrology: Chapter 20 Watershed Yield

Trainings

Citations:

Revision ID: 2624
Revision Date: 09/08/2022