Estimation of Groundwater Recharge Originating From Agricultural Irrigation and Rainfall in Shyramyn Plain, Iran

Groundwater recharge from rainfall and return flow of irrigation are essential for sustainable water resources management. There are many ways to estimate groundwater recharge. Most of them require a lot of field data, which limits their application in practice. To overcome this limitation, the rainfall infiltration breakthrough (RIB) model has been applied, which has the potential for estimating recharge using only rainfall, pumping rate, specific yield and groundwater level data in a semi‐arid region, the Shyramyn area, Iran. The groundwater recharge from rainfall (r) and the return flow of irrigation (λ) were estimated using the RIB model. Results of this effort indicated that the value of r varied around a ratio of 24.6% across the site, with a minimum and maximum of 1.1 and 27.0%, respectively, while λ varied with a minimum and maximum value of 0.0 and 33.0%, respectively. For the estimation of groundwater recharge most emphasis was usually put on recharge from rainfall. However, the findings of this study indicate that recharge from the return flow of irrigation played a major role in groundwater recharge and was 66.3% more than the recharge from rainfall. We hypothesize that this is a common process in similar areas where surface irrigation is applied.