Non-priority and priority allocation policies in water resources management concerning water resources scarcity using the WEAP model in the catchment area of Fars province

Water shortage in dry regions include the region of this study urge the needs for management of water supply in different parts such as drinking and agriculture sectors, the effects and climate changes of the region should be evaluated in order to anticipate the necessary measures to deal with these effects. In the present study, based on the fifth IPCC reports, these changes were predicted using scenarios of RCP2.6, RCP4.5, RCP8.5. The results showed that by the end of this century, the annual temperature will increase by 4.7%, but in the case of precipitation, according to different scenarios, 4.5RCP scenario considered as optimistic scenario and 2.6RCP as pessimistic and finally 8.5RCP considered as the median. Two general policies of allocation without prioritizing consumption and prioritizing urban consumption found to be ineffective regarding the allocation of water resources until the end of the present century. Many problems were observed in the drinking water sector in the policy without prioritization in the allocation of water resources in the months of June to October and in the allocation with prioritization of consumption in the months of August, September and October. Therefore, the rationing policy should be used to supply drinking water to the cities of Shiraz and Marvdasht. This policy showed the best efficiency by reducing the area under cultivation and changing the crop. Thus it is possible to avoid problems in both drinking water and agriculture by substituting rice product to wheat and reducing rice product to 50% as well as reducing the area under agricultural cultivation by 58.4%. in this paper the volume of water entering the reservoir in different months of the year in the region was modeled and calculated in the years to come in addition SDSM software used to collect and forecast data and inputs of the study area and in the following WEAP software used to study the management and allocation of water resources and subsequently by using the WEAP water resources allocation model, the amount of water resources shortage for drinking and agriculture for each month during the study period (2019-2099) has been estimated.