Hydrologic Modeling of a Canal-Irrigated Agricultural Watershed with Irrigation Best Management Practices: Case Study

Simulating irrigation systems by accounting for various water loss rates is necessary while modeling the hydrology of cultivated canal-irrigated watersheds. The existing approaches to modeling canal irrigation use situation-specific optimization procedures. In addition, they are focused on a water management perspective rather than a hydrologic perspective. In this study, an approach is developed to model canal irrigation systems and irrigation best management practices (BMPs) to adequately simulate the water balance of irrigated watersheds. The approach is based on the water requirement of crops, number and frequency of irrigation, and critical crop water requirement stages. Two irrigation BMPs are modeled as water savers rather than physical changes in irrigation appurtenances. Land leveling is modeled by changing model parameters and water management by changes in frequency, timing, and magnitude of irrigation with respect to cumulative precipitation. The developed approach was tested with a 1,692 km(2) intensively cultivated, canal-irrigated watershed using the Soil and Water Assessment Tool (SWAT). Test results suggest that the approach captures water balance and observed runoff hydrograph of the study area adequately. DOI: 10.1061/(ASCE)HE.1943-5584.0000364. (C) 2011 American Society of Civil Engineers.