Analysis of water resources carrying capacity and spatiotemporal variation impacts in North Central Province of Sri Lanka based on combined weighting—TOPSIS model

Abstract

[Objective] Under the dual pressures of climate change and human activities, water resources carrying capacity has become a critical constraint on regional sustainable development. Water transfer projects, as a vital means to reconstruct the spatial equilibrium of water resources, require carrying capacity assessment that is crucial for project benefits and ecological safety. [Methods] To address the uneven spatiotemporal distribution and scarcity of water resources in Sri Lanka, a focus was placed on the local “South-North Water Transfer” project. The TOPSIS model based on entropy weight-CRITIC combined weighting was employed, and the potential fluctuating impacts of climate change were considered during the assessment. The effects of the water transfer project on the spatiotemporal evolution of water resource patterns across 11 regions in the North Central Province were systematically analyzed. [Results] The result showed that the project significantly optimized water resource allocation. Domestic water demand increased by 37. 9%, and agricultural water demand rose by 26%(partially offset by improved irrigation efficiency). Ecological water demand experienced a modest increase. Spatially, water resources carrying capacity exhibited a distribution pattern characterized by lower values in the central region and higher values in the northeast and southwest, with disparities gradually diminishing. After the implementation of the water transfer project, the evaluation indicators tended toward equilibrium, and agricultural water conservation became the key focus for long-term regulation. [Conclusion] The water transfer project elevates the water resources carrying capacity of most regions in North Central Province from “Weaker”(Grade Ⅱ) to “Moderate”(Grade Ⅲ), but disparities among regions still exist. Future efforts should focus on establishing a priority regulation mechanism for water transfer based on dynamic assessments of water supply and demand. The findings provide a scientific basis for coordinated inter-basin water resource management within the Belt and Road framework.

Keywords

water resources carrying capacity / water transfer project / combined weighting / TOPSIS model / spatiotemporal variation / Sri Lanka / climate change / influencing factors