Dynamics of depression storage during sprinkler irrigation and precipitation events

Depression storage plays a key role in retaining excess precipitation. When modeling irrigation systems and surface hydrology, depression storage is often treated as static storage, meaning that the maximum storage volume must be filled before overland runoff occurs. However, several researchers have documented that runoff can begin before all depressions fill. The objectives of this study were to (1) analyze the process of dynamic filling of surface depressions and (2) determine the effect of slope and microrelief on maximum depression storage. Plaster of Paris molds of 12 soil surfaces were collected from plots that are part of a tillage study which includes plow, disk, and no-till treatments. The molded surfaces were subjected to a 100mm/hr simulated rain on a bed with adjustable slopes. Dynamic filling of surface depressions was analyzed by measuring depressional storage at points before maximum depressional storage was achieved. An empirical relationship relating depressional storage to precipitation excess is proposed, and suggests that the dynamic nature of depressional storage may be predicted if the maximum depressional storage and excess precipitation hyetograph are known.