Effect of Irrigation Methods on Groundwater Recharge in Alluvial Fan Area

Abstract

Estimation of water table and recharge is a key component in the control of groundwater level in arid and semiarid regions such as northwestern China. This study compared groundwater recharge in land subject to flood-irrigation and water-saving irrigation within the Manasi Basin, China, with the aim of analyzing the influence of irrigation method on the response characteristics of groundwater. A simulation of the two irrigation methods was conducted over four years, using a coupled MIKESHE/MIKE 11 model, from which the average water balance was calculated. Moran’s I was used to explain the spatial variability of recharge response associated with each irrigation method. ArcGIS 9.0 geostatistical and spatial analysis applications were used to interpolate/extrapolate and create grids for specific yield, bedrock elevation, and raw groundwater data. The results of the simulations are generally consistent with observed data, indicating that the method is capable of recognizing detailed characteristics of the groundwater response. The groundwater recharge intensity was found to become weaker in water-saving irrigation than in floodirrigation, but groundwater discharge is greater for water-saving irrigation than for flood-irrigation, making the reduction in depth more obvious. Furthermore, the reduction in depth of the groundwater level increases with site elevation. The results indicate that the proposed methodology are applicable to the management of groundwater resources in arid regions. The study quantified the processes affecting groundwater levels and provided an insight into their implications for the management and control of groundwater level.