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.