computing efficiency of water in the main products of zabol district using data envelopment analysis

water is one of the most important and limited inputs in agricultural productions. the aim of water resources management in agriculture is increasing production performance and raising water use efficiency. to achieve this, in the present research, the water use efficiency of the main agricultural products and farmers of zabol district was studied using data envelopment analysis (dea) in 2011. the results showed that the average of farms efficiency in the constant and variable return to scale was 0.77 and 0.98, respectively. the average of efficiency of scale was 0.78, which shows inefficiency of scale. the average efficiency of irrigation water in the constant return to scale was 0.52 and 0.86, respectively. also, , under the constant return to scale, to achieve perfect efficiency in wheat, barley, and corn silage, reduction of water use levels to 3269, 2377, and 7539 m3/ha, respectively, is recommended. according to the results, it seems that with the implementation of modern irrigation systems the amount of water use can be reduced.