In situ Field Study of Ephemeral Gully Propagation in a Cultivated Cropland

Abstract

<abstract> <bold>Abstract.</bold> Ephemeral gullies are ephemeral channels in cultivated croplands occurring due to water runoff during intensive rainfall events, and which can be removed by tillage operation. Ephemeral gully erosion carries out the essential part of topsoil from agricultural fields and pollutes downstream creeks and lakes. The goal of this study was to estimate the impact of precipitation runoff on ephemeral gully propagation by measuring the development of an ephemeral gully headcut in an actual cultivated cropland. A field experiment was conducted during Summer and Fall of 2013 on a no-till field near the city of McPherson in Central Kansas. Precipitation data were collected, and 11 channel cross sections 10 cm apart around a gully headcut were measured every 3 to 4 weeks during the monitoring period. The rainfall excess was calculated for each storm event resulting in estimation of headcut migration rates. Cross sectional profiles at different times showed that no gully development was detected for most of the rainfall events. The headcut propagation was detected only for rainfalls happened in saturated soil conditions. The conducted study helps to understand the mechanics of the ephemeral gully development. Further measurements of precipitation and gully morphology will provide additional data for regression analysis of gully erosion and the associated soil losses as a result of intense rainfall events.