Analysis of the Cooperative Carrying Capacity of Ulan Suhai Lake Based on the Coupled Water Resources–Water Environment–Water Ecology System

In order to maximize the carrying benefits of Ulan Suhai Lake and utilize the important role of the Inner Mongolia plateau lake basin in restoring its ecology and conserving water, the carrying capacity of the water resources, water environment, and water ecology of Ulan Suhai Lake was determined using system theory and synergy theory, and a 17-item evaluation index system of the three levels of the water resources, water environment, and water ecology (including the ice-covered period) was established using hierarchical analysis. In addition, a system dynamics model of the synergistic carrying capacity of the water resources–water environment–water ecology of Ulan Suhai Lake was constructed. A principal component analysis was conducted on the indicators of the Ulan Suhai Lake survey; six main sensitive factors were selected, and five simulation scenarios (status continuation mode, development continuation mode, conservation continuation mode, comprehensive mode I, and comprehensive mode II) were designed to regulate the configuration, taking into account the actual local development needs. Using 2014 as the base year and 2014–2020 as the validation period, a dynamic simulation analysis of the carrying capacity of the Ulan Suhai Lake from 2014 to 2050 was carried out. The results show that Ulan Suhai Lake has a poor carrying capacity level and a fragile carrying state. Three of the five simulated scenarios lead to severe water shortages, while the others affect economic growth. Considering these aspects, it was found that comprehensive mode I performed better, and for the configuration of this scheme, the following countermeasures, and suggestions to enhance the carrying capacity of the Ulan Suhai Lake are proposed. The rate of change in the industrial water use should be reduced by 20%, the discharge coefficients of the domestic and industrial wastewater should be reduced by 10% and 50%, respectively, the effective utilization coefficient of agricultural irrigation should be increased to 0.71, and the wastewater treatment rate should be increased by 30%. These measures can ensure the protection of the water resources while ensuring economic development