Evaluation and Sensitivity Analysis of the Effective Parameters on the Relative Economic Water Productivity Index

It is necessary to be aware of water productivity indicators for decision-making and management in agriculture. A fast way to increase water productivity is to be known its sensitivity to its components. This issue, which is known as sensitivity analysis, can be in the water productivity index causes more focus and accuracy in measuring or estimating the effective parameters and ignoring the error of the parameter/parameters that have a small effect on the water productivity index. Among the conventional indicators, the Relative Water Economic Productivity Index (KWPe) considers many factors affecting on production and is more accurate. Therefore, in the first step, sensitivity analysis of the KWPe index to its components was made and in the second step to investigate the difference in sensitivity between the water productivity indicators, sensitivity analysis of the economic water productivity gap index (GWPe) whose components are similar to the KWPe index, was carried out for three crops: sugar beet, wheat and olive. The results showed that the KWPe index was the most sensitive to yield potential in studied crops. So that with a 30% underestimation error in the yield potential in wheat, sugarbeet and olive crops, 55%, 69% and 54%, respectively, and with the same amount of error in the applied irrigation water, 43% change in the KWPe index was occurred. Also, the results showed a difference in the sensitivity of KWPe and GWPe index to similar components, except production potential. Unlike the KWPe index, the sensitivity of the GWPe index to all index components was dependent on the plant, and the sensitivity to the actual yield and irrigation water volume was even lower than the product price..