Modeling infiltration in surface irrigation with minimum measurement (study of USDA–NRCS intake families)

Abstract

The US Department of Agriculture–Natural Resources and Conservation Service (USDA–NRCS) intake families, in spite of lacking localized field data, often provide sufficient information for the initial design, evaluation, or management of surface irrigation systems. Scaling as a tool to characterize soil water dynamics and obviates need for the measurements. The present research aims to scale nineteen equations of intake families presented in SIRMOD. To doing so, one of the intake families’ equations was selected as the reference curve and the scaling factor for each intake family equals to the depth of water infiltrated after the given time (ts) (e.g., the depth of water infiltration after 2 h) in the reference infiltration equation to depth of infiltrated water after the specified time intake families equation. The results showed that the selection of the reference infiltration curve is optional and each of the cumulative intake families might be selected as the reference curve. According to the results of surface irrigation evaluation in terms of application efficiency, deep percolation and runoff percentage, there is no difference between the use of the cumulative intake families’ equation and intake families curve obtained from the scaling process.