Integrative hydrological and ecological modeling for regional water resources management in the Yellow River Basin, China

An integrative Hydrological and Ecological modeling system at regional scale was developed to assess water resources use and ecosystem production in arid and semi-arid areas. Hydrological model in the integrative modeling system was adapted from Soil and Water Assessment Tool (SWAT), to simulate the water balance in terms of soil moisture, evapotranspiration, streamflow, and groundwater table change. An ecological model was integrated into the hydrological model to compute the ecosystem production of biomass and yield for different land use types. An indicator was estimated to quantify gross benefit of water management in terms of monetary value of ecosystem production and water productivity. The modeling system was implemented in a holistic approach, and able to produce simulation results at daily time steps with a spatial resolution of hydrological response unit (HRU). After identifying the sensitive parameters, the modeling system was calibrated using an automatic calibration procedure based on conventional Monte Carlo sampling method together with a multi-objective criterion for calibration over multi-site and multi-output. ^ The modeling system was tested in the upper and middle parts of the Yellow River basin, China. The simulated results revealed that water use in the study area had largely reduced the streamflow in many parts of the area except for that in the riverhead. Spatial distribution of water yield, crop yield, and water productivity showed a strong impact of irrigation on agricultural production. Water management scenario analyses suggested that a sustainable water supply requires a mixed management that consists of improving irrigation efficiency, allocating water for ecosystems, and balancing human water demand and basin water availability. In general, the simulation results from this study indicated that the model was capable of tracking the temporal and spatial variability of pertinent water balance variables, ecosystem dynamics, and regional economy, and provided a useful simulation tool in evaluating long-term water resources management strategies at the basin scale. The information and results provided by the study will contribute to knowledge of interdisciplinary modeling for water resources management in the study area, and be helpful to watershed modelers and model users in calibrating complex watershed models. ^ Keywords: Automatic calibration; Integrative modeling system; Sensitivity analysis; SWAT, Upper and middle parts of the Yellow River basin, Water resources management.