Understanding and mitigating water resource decline in the deli watershed: a comprehensive analysis

The Deli watershed, located in the North Sumatra Province, is part of the Belawan–Ular–Padang River Area, which has the potential to supply raw water to three cities/regencies: Medan City, Deli Serdang Regency, and Karo Regency. According to the Regulation of the Minister of Public Works and Public Housing Number 04/PRT/M/2015, the Deli watershed area is classified as a National Strategic River Area. Despite its potential, the rapid economic growth and population increase have led to changes in land use, which have negatively impacted the carrying capacity of water resources in the Deli watershed. In this study, we used a dynamic system approach and the analytical hierarchy process (AHP) to assess the condition of the Deli watershed's water resource carrying capacity. The integration of dynamic systems and AHP yielded a water resource carrying capacity index, which describes the condition of the Deli watershed's water resources. Under current conditions, the value of the water resource carrying capacity index of the Deli watershed is expected to decline annually from 2019 to 2028. To increase the carrying capacity of water resources, it is recommended to decrease birth and migration rates, reduce water use, and restore land functions.