Cell Reports Sustainability (Mar 2024)
Non-deterministic multi-level model for planning water-ecology nexus system under climate change
Abstract
Summary: Water scarcity and ecological degradation impede sustainable development in Central Asia, which urgently calls for synergistic planning of water-ecology (WE) nexus system. However, existing management models may have large uncertainties, restricting their effectiveness. Here, we develop a copula-based flexible fuzzy multi-level programming (CFMP) method, which tackles uncertainties, such as water demands, and balances trade-offs among competing managers in top-down decision-making processes. Next, we formulate a CFMP-WE model for Central Asia (2021–2050), considering objectives of economic development, food security, and ecological restoration, and design 243 planning scenarios. We found that ecological water allocation would account for 5.9%–12.2% to support sustainable development; however, policymakers need to reduce agricultural water allocation, forgoing 7.8%–20.1% of the system benefit (i.e., economic benefit for WE nexus system). Agricultural water use would still be the largest (with 25.6%–29.4% for cereal crops to ensure food security), but its share would decline to conserve water for users like industry. Science for society: Water resources play a vital role in maintaining ecosystem health, and they are influenced and restricted by each other to form a water-ecology (WE) nexus system. Central Asia is one of the regions with the most severe imbalances in the management of WE nexus system. In those regions, water resources are often scarce and unevenly distributed. Competition for water is intense among countries and users, leading to the drying up of the Aral Sea. Climate change threatens to exacerbate this situation. To address these issues, WE management models are required to plan the sustainability of water resources in the long term. However, existing management models may have large uncertainties restricting their effectiveness. We develop a copula-based flexible fuzzy multi-level programming-WE (CFMP-WE) model using non-deterministic programming for Central Asia (2021–2050) and find that the share of ecological water allocation needs to be increased, while that for agriculture needs to be reduced to achieve a more balanced WE nexus system.
