Floodwater recharge to improve sustainable water supply in arid Iran
Summary, in English
Groundwater depletion in arid areas is of increasing concern in the Middle East. Small precipitation and high evaporation losses during the dry season lead to water shortage in arid areas. The optimum development of groundwater resources is generally associated with abstractions from the aquifer balancing the recharge to it. When abstractions exceed recharge, many undesirable effects may result. Due to scarce water resources in the Gareh-Bygone Plain, located in arid southern part of Iran, a Floodwater Spreading System was established in1983. The floodwater spreading system has an extent of 2000 ha to improve the groundwater quantity, which involves surface spreading of floodwater. The present study had as aim to study the long term sustainability of the floodwater spreading system by applying a water balance methodology. The main idea of the water balance approach is to ensure that water resources in a certain area are used in a sustainable manner and optimally used with respect to water consumption, demand management, and water conservation. The methodology for this study was a combination of modeling to estimate inflow, outflow, and recharged groundwater and water balance approach. The study period was 14 years between 1993 and 2007. The results showed that the fluctuation of groundwater level is strongly controlled by both precipitation and groundwater recharge by floodwater spreading system. However, the general groundwater trend depends on the number of pumping wells and water abstraction established in the area. A 5-year drought period was the main cause of groundwater depletion. In the drought period, less precipitation accompanied with increasing farm land areas and pumping wells have created declining groundwater level. The recharge volume was seen to depend heavily on timing, duration, and magnitude of floods.