Assessment of water resources carrying capacity of watersheds using a combined approach of simulation and indicator-based assessment (Case study: Maharlo catchment)

Abstract

One of the methods is "water resources carrying capacity", which was created by developing the concept of "carrying capacity" in the science of water resources management. This research has used this concept to evaluate water resources management; and by developing previous methods and combining the simulation method, the indicator-based assessment method and the pressure-support determinant have created a new framework for assessing the carrying capacity of water resources. Also, an approach has been adopted to estimate the carrying capacity that overcomes some of the existing challenges in this field, such as the lack of attention to the state of environmental health and the possibility of interchangeability between indicators. The approach adopted and the framework created were used to assess the carrying capacity of water resources in the Maharlo catchment during the period (2003-2023). Considering the trend of changes in the evaluation indicators and providing better analyses, the period under review was divided into three periods: the first period (2003-2009), the second period (2010-2017), and the third period (2018-2023). The evaluations and analyses were conducted both annually and periodically. The results obtained indicate that the loading on water resources was within the carrying capacity of water resources only in the first period, and in the second and third periods, water resources were overloaded. Based on the evaluation standards, the carrying capacity of water resources and the state of environmental health fell by one level in the second and third periods, and reached the lowest possible level in the third period. The study of pressure-support of water resources indicates that in each period, the pressure on water resources has increased compared to the previous period, and the support capacity of water resources has decreased. These indications indicate that the policies implemented in the basin have pursued rapid economic development and have not paid any attention to the support capacity of water resources. Since the results obtained have a very good agreement and consistency with the realities of the region and express the effectiveness of the applied policies, they can be used to examine policies in other similar cases.