The potential and actual urban aquifer recharge and site selection for artificial recharge using GIS and AHP methods(Case Study: Urmia urban aquifer)

Development of urban areas has a significant impact on the natural water cycle. Expansion of impermeable surfaces caused reduce infiltration, increase runoff volume and changes in the amount and source of aquifer recharge. The purpose of this study was to present the aquifer recharge model to determine suitable areas for urban runoff dispersal with artificial aquifer recharge approach in Urmia city. To this purpose, first groundwater recharge model was implemented. Afterwards, the potential and actual recharge map was estimated. Also, the suitable areas map for urban storm water spreading for groundwater recharge was proposed. The result shows that due to the expansion of urban areas and the increment of impermeable surfaces, the potential of direct aquifer recharge has decreased. The most aquifer recharge is through leakage from urban drinking water network, sewage wells and irrigated water returns. The actual recharge has changed according to different land use and it was between 0-28 mm/y. The greatest potential recharge was related to, bare land, open spaces, parks and agricultural land and various between 4-262 mm/y. The results indicated that in the study area, land use, impact of aeration zone and drainage net are the most important factors that affects site selection for flood spreading. Barren and agricultural land with a slop of less than 5%, areas with high thickness of aeration zone, coarse sediment and high permeable in suburban area are suitable site for groundwater artificial recharge.