برآورد تقاضای آبی محصولات زراعی با استفاده ازداده‌های اقلیمی و مدل Cropwat

Extended Abstract

Background and Objective

The agricultural sector is the largest consumer of water in worldwide. Therefore, estimating the water consumption plays a very important role in future long-term policies. This will become much more important, especially in the future years, under the climate change effect.

Methodology

In the present study, Cropwat model has been used to estimate the irrigation water demand of various agricultural crops in Marun basin which is located in Khuzestan province under the 2.6 Representative Concentration Pathway (RCP) scenario in the future time interval (2016-2040). Cropwat model developed by the Food and Agriculture Organization of the United Nations was used to estimate the irrigation water requirements of agricultural crops in the Marun Basin. The inputs of this model include climate data and information on each agricultural crop. First, different climate models were evaluated under the International Panel on Climate Change (IPCC) Fifth Assessment Report. The results showed that based on the error criteria, the two climate models GFDL-CM3 and MIROC5 were proper for simulating temperature and precipitation variables in the future time interval, respectively. In the next step, Cropwat model has been used to estimate agricultural water irrigation demand. In the present study, for the first time, the trends in changes in reference plant evapotranspiration, effective rainfall, irrigation water requirements for agricultural crops, and agricultural water demand for each agricultural crop in the Marun basin were calculated using the Cropwat model under the RCP 2.6 climate scenario in the time interval (2016-2040). Final water demand for agricultural crops will increase in the future compared to the baseline. Agricultural water demand for vegetables, forage crops, grain maize, oilseeds, wheat, barley, and pulses will increase by 38%, 47%, 33%, 17%, 19%, 20% and 33% , respectively, under the RCP 2.6 scenario compared to the baseline interval. Overall, for all agricultural crops, agricultural water demand will be increased by 39% in the future time interval compared to the baseline period under the 2.6 RCP scenario.

Findings

The results show that the climatic variable of temperature will increase by 19% and the rainfall variable will decrease by 5% compared to the baseline time interval (1977-2001). The Cropwat model showed the total long-term average monthly ET0 will increase by 30% under the RCP 2.6 scenario compared to the baseline period and the effective precipitation in the future time interval will be increased by 7% compared to the base period under the 2.6 RCP scenario. Among all agricultural crops, forage crops by 47% increase and oilseeds by 17% increasing compared to the baseline time interval have the largest and lowest increase in water demand compared to other agricultural crops, respectively.

Conclusion

The results of the present study provide important information to planners and policymakers of water and food resources so that, by identifying water-intensive agricultural products in the Marun basin in future years under climate change impact, present sustainable strategies such as changing the cultivation pattern based on water and food security and prevent more severe stresses in the Marun River basin.