Integration of hydrologic and water allocation models in basin- scale water resources management considering crop pattern and climate change: Karkheh River Basin in Iran

The paradigm of integrated water resources management requires coupled analysis of hydrology and water resources in a river basin. Population growth and uncertainties due to climate change make historic data not a reliable source of information for future planning of water resources, hence necessitating climate and landuse change impact studies. This work presents an integrated modeling approach by linking Soil and Water Assessment Tool (SWAT) and MODSIM. While SWAT produces hydrologic and water resources information, MODSIM provides a decision support system for water allocation. We used the coupled SWAT–MODSIM to analyze the effects of climate and cropping pattern changes on agricultural and hydroenergy production in the Karkheh River Basin, a semiarid region in south-west of Iran. Cropping patterns were considered by limiting the cereal production to 50 % (S1, near to historic), 17 % (S2), and 83 % (S3) of total agricultural areas. The future climate was provided by the Canadian Global Coupled Model (CGCM 3.1 version T63) for A1B, A2, and B1 scenarios. The results showed that based on future climate changes and landuse scenarios, wheat production had a large variation in five economically important agricultural regions ranging from 33,000 ton year (S2-A1B) to 74,000 ton year (S3-A2). Similarly, energy production, while increasing from 614 to 1,100 GWH in A2, decreased from 614 to 464 GWH in B1 climate scenario. Our analyses indicate that cropping pattern change can be used as an effective tool to adapt to the negative impacts of climate change.