Regression
“In some areas, special studies have been conducted to develop multiple regression equations to predict water yield from precipitation and watershed characteristics... The equations from these studies, however, are location specific and should not be used in any other areas. Local experts should be consulted for information on the existence and applicability of regional equations”.[1]
The U.S. Geological Survey has developed streamflow regression equations that can be applied to ungaged watersheds across the country. "The regression equations included in NSS are used to transfer streamflow statistics from gaged to ungaged sites through the use of watershed and climatic characteristics as explanatory or predictor variables. Generally, the equations were developed on a statewide or metropolitan-area basis as part of cooperative study programs. Equations are available for estimating rural and urban flood-frequency statistics, such as the 100-year flood, for every state, for Puerto Rico, and for the island of Tutuila, American Samoa. Equations are available for estimating other statistics, such as the mean annual flow, monthly mean flows, flow-duration percentiles, and low-flow frequencies (such as the 7-day, 10-year low flow) for less than half of the states. All equations available for estimating streamflow statistics other than flood-frequency statistics assume rural (non-regulated, non-urbanized) conditions.[2]
Best Practices Resources
StreamStats: Streamflow Statistics and Spatial Analysis Tools for Water-Resources Applications, USGS
Guidelines for Determining Flood Flow Frequency (Bulletin 17C), USGS
Citations:
Revision ID: 7353
Revision Date: 07/21/2023