Inter-basin water governance by transfer rules based on system dynamics

Inter-basin water transfers are implemented to counter the uneven geographical distribution of natural water sources. This paper's novelty consists of providing a system-dynamics framework to evaluate inter-basin water transfers based on integrated water governance. The Big Karun Basin, Iran, has long been of interest to water managers due to its discharge potential. It houses several water-transfer projects that are under operation or under study for possible future implementation. This study implements system dynamics modeling (SDM) in the Big Karun Basin considering existing inter-basin water transfers. This study's results estimate an average annual 8 to 10 billion cubic meters of water are transfered from the Karun River to the Persian Gulf. Part of this flow can be used to meet some of the water demands in Iran's central and eastern basins subject to social and environmental assessment of impacts. SDM modeling was also implemented accounting for the existing water transfers plus the under-study water transfers. This study's results indicate the firm energy from hydropower produced by the Big Karun Basin system would decrease by 28% relative to existing water transfer conditions. This issue raises concerns given the Big Karun Basin contribution to electricity production Iran. The water supply to several sectors would be marginally impacted by future water tranfers, yet water quality would be compromised in some instances. Therefore, the Big Karun Basin water system was simulated considering inter-basin water governance based on hedging rules for the under-study water transfers. Results indicate the minimum drinking and industrial demands could be met. In addition, the firm energy from hydropower produced by the Big Karun Basin system would decline by 12% relative to existing water-transfer conditions and the vulnerability of the water system would decline in terms of required quality for downstream demands and water users in comparison with the full-transfer water condition.