Water resources assessment of zayandeh-rood river basin using integrated surface water and groundwater footprints and K-means clustering method

Abstract

The lack of an integrated approach to assess the quantity and quality of surface water and groundwater resources undesirably affects their sustainability and errors in users' decisions in the optimal development of basins. Therefore, to help to solve the problem of water resources sustainability assessment in various parts of the basin, for the first time, this article has presented a practical approach for the temporal-spatial evaluation of surface water and groundwater resources. The method presented in this study is based on investigating the behavior of sustainability indicators for surface water and groundwater in different years and separately for the sub-basins and aquifers. Evaluation of water quality and quantity criteria provides the main components of the proposed approach using spatial clustering. Water quality and quantity evaluations were implemented, focusing on drinking water and irrigation water uses in all sub-basins of the Zayandeh-Rood river basin in Iran for the years 2006 and 2016 using groundwater footprint (GF) and integrated groundwater footprint (iGF). The GF to area ratios (GF/A) in the first and last years of the study period were 1.1 and 0.8, respectively, while the iGF/A values were 8.9 and 7.3 in the drinking water use, and 1.3 and 1.1 in the irrigation water use, respectively. In order to apply a perspective in investigating the sustainability of the basin, surface water footprint (SF) and integrated surface water footprint (iSF) indices are introduced in this study for the first time. The SF/A values ​​in the study period were 2.2 and 1.8, respectively. The iSF/A values ​​were 3.8 and 3.3 in the drinking water use, and 2.4 and 2 in the irrigation water use for 2006 and 2016, respectively. Values greater than or equal to one in the above indicators indicate water resources' critical and unsustainable state. The comparison of groundwater and surface water indices shows that despite the slight improvement of the average values of the indices in the whole basin, some sub-basins are still in critical condition. Therefore, by using the K-means algorithm, the sub-basins were clustered into three categories favorable, unfavorable, and critical in the mentioned years. Finally, this research provides spatial planning based on water resources, which provides a comprehensive approach to maintaining the sustainability of basin water resources proportional to each sub-basin's capacity and baseline status. In this way, the factors affecting the status of the basin, the effect of the plans implemented in previous years, and the main priority of each sub-basin to solve its problems are identified. This information leads to the best planning for the sustainability of water resources and increasing social welfare based on the water resource capacity of the river basin.