Dayong Qin

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.

Investigations into the Effects of Human Activities on the Hydrological Cycle in the Yellow River Basin

Abstract The Yellow River is the origin of Chinese Nation. The water shortage problem has become so serious in recent years that the social and economy development of the basin has been greatly affected. Investigation into and study of the effects of human activities on hydrological cycle in the Yellow River Basin has very important value to rational allocation, optimized regulation, and effective protection of water resources in the basin. The research principle and method is the natural-artificial dual evolution mode of hydrological cycle. A quantitative analysis was conducted starting from a typical sub-basin in the middle reach of the Yellow River Basin: the Wuding River Basin. Empirical hydrological cycle formulae for the Wuding River are tested to reflect dynamic variation of basin vegetation/land cover. A trend of non-linearity of hydrological cycle in the Wuding River is observed. The principle of the natural-artificial dual evolution mode of hydrological cycle was then applied in the whole Yellow River Basin. The reason for the variation of the hydrological cycle is investigated under natural-artificial driving forces. Results show that natural force takes a main role in evolution of hydro-logical cycle in the source region of the Yellow River Basin. Then as the Yellow River flows downstream, artificial driving forces by human activities such as reservoirs, water and soil conservation measures, and water withdrawal and diversion become more and more important in the evolution of hydrological cycle. The method of nonlinear correction to hydrological cycle is introduced and applied in the Yellow River Basin.

Coupling effect between thermal and dynamic factors on water surface evaporation and in-situ observation

Water surface evaporation is an important indicator of atmospheric circulation and hydrological cycle. This paper, after selecting representative alluvial plain in north of Haihe River Basin as the experimental point, designs in-situ observation experiment to explore the influence of wind speed on water surface evaporation and puts forward the coupling effect between thermal and air dynamic factors on evaporation, which refers to that actual evaporation is not only depended on the values of thermal factor and dynamic factor, but also on the correlation of the two factors. The observed data show that, the main factors influencing actual evaporation in experimental area are daily average air temperature and wind speed and the two variables are separately the main representation of thermal factor and air dynamic factor. It is proved that there is significant coupling effect between daily average temperature and wind speed on observed evaporation. At last, Penman Formula is analyzed to explore the theoretical evidence of the coupling effect, it is concluded that the structure of Penman Formula should be revised later to further characterize the coupling effect between thermal and air dynamic factors on evaporation. As a whole, coupling effect is a basic principle in evaporation, which could be the reference to explain “Evaporation Paradox”.