Estimating Runoff from Precipitation and Temperature

by George H. Hargreaves, Utah State Univ, Logan, United States,

Document Type: Proceeding Paper

Part of: Management of Irrigation and Drainage Systems: Integrated Perspectives


Increasing demands for water and the global climate change resulting from the CO2 buildup in the atmosphere require an improved evaluation of surface-water resources. Available data on precipitation, temperature, and surface-water runoff are used to develop a procedure for estimating runoff from the monthly surplus values of precipitation minus reference evapotranspiration. Twenty seven regions or portions from 22 states were used to regress runoff (R) as a function of the sum of monthly surplus values (S). The resulting equation predicts 96% of the variance in the runoff values. For a watershed in Honduras annual values of S were regressed against annual R and the resulting equation predicted 96 percent of the variance in R. This procedure is recommended for evaluating the influence of climate change on water supply and water demand, for extending short runoff records, for estimating the variability of surface-water runoff, and for evaluating the areal distribution of precipitation surplusses in excess of reference evapotranspiration.

Subject Headings: Runoff | Precipitation | Surface water | Climate change | Water supply | Temperature effects | Evapotranspiration | Honduras | Central America

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