Submitted to: International Journal of Sediment Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 9, 1999
Publication Date: N/A
Interpretive Summary: Computer simulation models are helpful for predicting the effects of various management practices. Soil erosion models developed to predict rain-induced erosion cannot be used directly for irrigated fields because of unique differences between erosion from rain and irrigation. Erosion mechanisms are similar between rain and irrigation. Soil is detached, transported and deposited. However, there are systematic differences in the way these mechanisms occur during irrigation and rain. Water initially flows onto dry soil during furrow irrigation, but rain wets the soil before runoff begins during a rain storm. Irrigation water quality varies tremendously compared to rain water quality. These differences, and others, affect erosion and must be considered before computer models can accurately simulate irrigation-induced soil erosion.
Technical Abstract: The mechanics of soil erosion from irrigated and rainfed lands are similar. Soil particles are detached, transported and deposited. However, there are some systematic differences between irrigation and rainfall erosion. Electrolyte concentrations in irrigation water, for example, are almost always greater than in rain water. Differences between rainfall and irrigation are more prominent for surface irrigation than for sprinkler irrigation. For instance, rainfall wets the soil before runoff begins, but water initially flows onto dry soil in irrigation furrows. Furthermore, furrow flow rate decreases with distance and increases with time, while the opposite tends to occur with rainfall. For sprinkler systems, travel direction and slope aspect interact, so runoff can flow within the irrigated area or from the irrigated area onto dry or wet soil. Thus, a sprinkler-irrigation erosion model must consider both the rainfall-runoff situation and the furrow flow situation. These differences in soil and water interactions must be considered before computer models can accurately simulate irrigation-induced soil erosion.