The impacts of irrigation and groundwater drainage induced salinity and overflooding of evaporation ponds in Khuzestan, Iran

Di Mao ^1* Frank Riesbeck ¹ Hamid Reza Khodabakhshi ² Arash Mahjoobi ²

• ¹ Humboldt University of Berlin, Berlin, Germany
• ² Khuzestan Water and Power Authority, Ahwaz, Iran

In the low-elevation plain above sea level, the south of Khuzestan province, Iran, productive activities and life of humans cause the water resource suffering from salinity issues, which can neither be recycled for agricultural production nor discharged into the Great Karun River. To protect the fresh surface water resource from salinization, a lagoon, also known as an evaporation pond, was formed to store and dispose of the drainage water. An investigation was carried out to assess the scale of water governance based on evaluating the effectiveness and efficiency of drainage water management, particularly in the discharge and salinity control of the lagoon. The result revealed that saline groundwater stays at a shallow level above the ground in the agricultural production area and is brought to the lagoon by the inappropriate layout of the drainage system, resulting in the phenomenon of overflooding in the study area. The overall discharge flows at a rate of 84.63 m 3 /s compared to the inflow threshold of 21.17 m 3 /s, and the disequilibrium is mainly caused by unexcepted saline groundwater and frequent exchanges of pond water in fish farms. The intensified level of salinity consecutively decreases the evaporation rate of the lagoon, potentially affecting the hydrological balance and altering the inflow threshold. The scale of water governance turns inefficient because of the reduced inflow threshold of the lagoon. In summary, cutting down the discharge and controlling the salinity of the lagoon should be jointly implemented to maintain the long-term sustainable development of water governance.