Distributed human-water relationship model based on the “four processes” of the human-water system

The human-water relationship has emerged as an interdisciplinary field, in which developing basic equations and models forms a core research area. Based on a systematic review, the “four processes” of the human-water system are proposed—the water cycle process, material cycle process, biological process, and humanistic process. The basic equations, coupling mechanisms, and computational methods of these processes are summarized to support construction of a distributed human-water relationship (DHWR) model. Application of the DHWR model to the Qinhe River Basin in China demonstrates high accuracy, with R² values for runoff ranging from 0.62 to 0.81 and NSE values between 0.67 and 0.82. For water quality, the model achieved NSE values from 0.64 to 0.91 and R² values between 0.76 and 0.95 for ammonia nitrogen and total phosphorus, with ecological pressure indices and water diversion data capturing impacts of biological and human activities. These findings provide a foundation for advancing human-water research.