Evaluation of effect of increased irrigation efficiency over groundwater table evapotranspiration rate, Case Study: Zarrineh-Rood Plain

For optimum use of water resources in irrigation and drainage networks, creation of simulation models by available data for the identification of effective parameters in groundwater resource system is useful. In this study, due to the existing high levels of groundwater table in Zarrineh-Rood plain at West Azerbaijan province, the impact of Zarrineh-Rood irrigation and drainage network on underlying groundwater resources is investigated. Groundwater surface variation under existing active irrigation and drainage network area as a recharge zone on the body of the plain was simulated through MODFLOW and the effect of increment in irrigation efficiency was investigated. The results of model calibration and verification indicate the reliability of the proposed model for the depiction of groundwater resources behavior under Zarrineh-Rood plain. The involved error in simulation of groundwater depth is less than 1.69 percent. After obtaining validated model water balance, the scenarios of increased irrigation efficiency as 10, 30 and 50 percents, were imposed over irrigation and drainage network area. Model results show that the groundwater table drawdown with increased irrigation efficiencies is about 0.5, 1.20 and 2 meter respectively. Moreover, due to the imposed increased irrigation efficiency scenarios, evapotranspiration is reduced about 12, 30 and 39 per-cent respectively.