A multi-criteria approach for selection of the best water quality improvement scenarios (Case Study: Gorganrud-River Basin, Golestan Province)

Water management and best use are among the topical issues and therefore the negative trends of water quality should be reduced. We have tested various water quality improvement scenarios in this research. We selected nine water quality factors and generated an initial set of 41 independent variables relating to landform, physical and biological plus landscape metrics of the surrounding environment of the rivers. Regression and correlation analyses helped narrow down the independent variables and define equations between dependent and independent variables. Five management items were devised based on the regression relationships and expert opinions including: decreasing fractal dimension of remnant tree patches, pasture extension onto bare land, decreasing area under agriculture based on a special multi-criteria analysis (MCE), decreasing road density based on a pattern suggested through least cost algorithm and increasing area under pasture management and the number of tree patches. To balance the results of the scenarios and select the optimum one, a multi-criteria approach was adopted during which the analytical hierarchy process was applied and the 32 scenarios were analyzed through technique for order preference by similarity to ideal solution (TOPSIS). The best scenario was found to be the one including road density decrease plus range extension onto bare land and decrease of fractal dimension of the remnant tree patches. These were the best in terms of the selected criteria for water quality improvement.