Relation Between Evapotranspiration and Seasonal Variation of the Recession Curve

Abstract

　Hydrograph recession analysis, which is a commonly used method for elucidating the dynamics of water (especially groundwater) in a watershed after rainfall, is extremely important for the separation of runoff components, modeling and parameter estimation of all runoff components, and long-term low-water management. However, various factors are involved in hydrograph recession. The high degree of uncertainty in the recession curves or equations is attributable to hydrograph recession analysis. For this study, we derived new recession equations while considering the effects of evapotranspiration, which have long been pointed out. We also elucidated the effects of evapotranspiration on the recession constants and their seasonal variation. The seasonal variation of the constants of recession equations is determined by the basin-specific recession constants, which are determined by basin characteristics such as geology and evapotranspiration, which have strong seasonality.