Exploring spatial heterogeneity and temporal dynamics of human-hydrological interactions in large river basins with intensive agriculture: A tightly coupled, fully integrated modeling approach

Analyzing river basins as coupled human and hydrological systems is important to advance our understanding of hydrological processes, and to provide insights into policy design for water resources management. However, assessing spatially heterogeneous and temporally dynamic characteristics of human-hydrological interactions remains a challenge, and relevant research has been limited by the lack of computationally tractable models that can integrate water management policies, human activities, and hydrological conditions with sufficient temporal and spatial details. In this study, we propose a modeling framework that tightly couples (1) an agent-based model for farmers’ decision-making on water use influenced by collective water management policies, and (2) a distributed hydrological model for simulating integrated groundwater-surface water processes with high spatial and temporal resolutions. We apply the modeling framework to the Heihe River Basin, a large semi-arid river basin with intensive agriculture in China. Through various policy portfolio analyses, the model has identified several unique spatial–temporal characteristics of human-hydrological interactions. These include (1) nonlinear relationships between water policies, farmers’ decisions on water use, and hydrological conditions, (2) spatially heterogeneous impacts of water policies on farmers’ conjunctive groundwater and surface water use, and (3) location-dependent temporal patterns regarding water policies’ influences on hydrological processes. It is found that regional hydrogeological conditions (e.g., depth to water table, distance to rivers) are key factors to influence human-hydrological interactions. The modeling results could advance our understanding of the role of human activities in hydrological cycles, and yield insights into the design of location-based policies for river basin management.