Zuhao Zhou

Development of Soil and Water Assessment Tool Model on Human Water Use and Application in the Area of High Human Activities, Tianjin, China

The basin water cycle affected by human activities presents the duality of natural and human characteristics. The effect of human activities to hydrology is becoming point of focus in the world with the development of society. As a physically based distributed parameter model, soil and water assessment tool is deficient when applied to the area with more human activities. In areas of increased activities, monthly changes in irrigation and consumptive water use has been observed over the years. In the past, this module was applied to a system with very little human influence. In this study we revised the theory and made appropriate improvement on irrigation module and consumptive water use module in order to apply it to the water system in Tianjin City, China, where water cycle is strongly affected by the human activities. The watershed model has been calibrated and validated using measured data available for the main river. By comparing the simulation results between initial model and improved model, the Nash-Sutcliffe efficiency is adjusted from 0.62 to 0.89 and correlation coefficient is improved from 0.79 to 0.91. The resulting validated model improves the simulation precision, especially amends the peak value of runoff, and adequately describes the impact of consumptive water use and irrigation on the natural water cycle. The model developed in this paper can be used to study water resource and water environment management in area of high human activities.

An Integrated Model for Simulating Regional Water Resources Based on Total Evapotranspiration Control Approach

Total evapotranspiration and water consumption (ET) control is considered an efficient method for water management. In this study, we developed a water allocation and simulation (WAS) model, which can simulate the water cycle and output different ET values for natural and artificial water use, such as crop evapotranspiration, grass evapotranspiration, forest evapotranspiration, living water consumption, and industry water consumption. In the calibration and validation periods, a “piece-by-piece” approach was used to evaluate the model from runoff to ET data, including the remote sensing ET data and regional measured ET data, which differ from the data from the traditional hydrology method. We applied the model to Tianjin City, China. The Nash-Sutcliffe efficiency (Ens) of the runoff simulation was 0.82, and its regression coefficient was 0.92. The Nash-Sutcliffe Efficiency (Ens) of regional total ET simulation was 0.93, and its regression coefficient was 0.98. These results demonstrate that ET of irrigation lands is the dominant part, which accounts for 53% of the total ET. The latter is also a priority in ET control for water management.

Development of Dualistic Model for Integrated Water Resources Management in the Haihe River Basin

The dualistic model which reflects “natural — artificial” dualistic characteristics of water cycle is developed to support integrated management of water and environment in the Haihe river basin (320000 km2) in North China. The dualistic model is established by coupling a distributed hydrological and water quality model (WEP-L), a water resources allocation model (ROWAS) and a multi-objective decision-making analysis model (DAMOS). Approach of two-hierarchy coupling is adopted for the three models. Hydrological simulation units and planning and management units are subdivided by taking full consideration of two kinds of factors, i.e., natural precipitation-runoff relation and river hydraulics, and human activities of land use and water resources utilization. The Haihe river basin is subdivided into 11752 hydrological simulation units and 125 planning and management units, and simulations of 50 years from 1956 to 2005 are carried out. The result shows that the simulation accuracy of established dualistic model is acceptable. Finally, a preliminary application of the model as a scenario analysis tool is introduced.

Water replenishment for ecological flow with an improved water resources allocation model

With rapid urbanization, there will be more conflict between human systems and the river ecological system, and therefore, ecological operations, practices and research must involve the ecological water replenishment of entire river basins with new modeling tools. In this study, based on a water resource allocation and simulation model (WAS), we establish an ecological flow-oriented water resource allocation and simulation framework (E-WAS) by comprehensively considering both ecological flow constraints and ecological flow targets. To control multiple types of water sources and dynamically allocate water resources to replenish ecological water in the river, virtual reservoirs and ecological units are added to the model network. With new water balance equations for virtual reservoirs and ecological units, the E-WAS can simulate the ecological replenishment process in a river basin and can provide a recommended water replenishment scheme that considers optimization principles. The E-WAS was applied in the Pingshan River Basin, Shenzhen, China. Fourteen ecological units and 38 water supply nodes are considered in the model. A water replenishment scheme that used water from 6 reservoirs and reclaimed water from 5 water sewage plants was selected. This scheme significantly increased the satisfactory degree of ecological water demand and efficiently supported the formulation of a control scheme for the water environment of a basin. The E-WAS framework is similar to model plug-ins but helps to avoid the large workload that is required for model redevelopment and can expand the functions of core models relatively quickly.