| Among the environmental factors, water is the most active one. Nowadays, water shortage is a serious global concern. It's very difficult to solve this problem, because water resource is very limited in many places, but what we can do is try our best to use water rationally and efficiently. Therefore, we need to understand the water cycle mechanism firstly. Hydrogen and oxygen stable isotopes are natural tracers, and have been widely used in hydrology research by stable isotope techniques for studying atmospheric precipitation, watershed hydrology, water resources, water runoff response and the origin of water in plant and other aspects, providing the information that traditional hydro-geological methods can't achieve, thus could reveal water cycle process and its characteristics.This study selected Hasi Mountain, located in the arid and semi-arid regions of the northwestern China, which has a complex hydro-geological conditions and serious water shortage problem, but has an important regional ecological effects. From June 2013 to April 2014, the atmospheric precipitation, soil and spring water samples were collected. The hydrogen and oxygen stable isotope of water samples were analyzed with LGR DLT-100 Liquid Water Stable Isotope Analyzer. The purpose of this study are as follows: 1) study the isotopic characteristics of atmospheric precipitation, combining with meteorological data, obtain the atmospheric precipitation equation and the relationship between temperature, rainfall and isotope values of this basin; 2) analyse the causes of spring water and the variations of spring flow, and then confirm the main factors of spring flow; 3) analyse the hydrogen and oxygen stable isotope of spring water of Hasi Mountain to obtain the main factors that affect isotopic values and the main resources of spring water, and to understand the water cycle characteristics even further.Through analyzing the hydrogen and oxygen stable isotope of precipitation in Hasi Mountain, we got the local atmospheric precipitation lines, that is ?D = 7.42767?18O +17.0345. The temperature and rainfall have effects on the isotope value of precipitation. The isotope values decrease with the temperature increasing, and increase with the rainfall increasing, then with the conclusion that Hasi Mountain is influenced by monsoon climate. According to the value of d(deuterium excess), the rain formation process is strongly affected by evaporation.The investigation demonstrated that Hasi Mountain is rocky mountain and the spring water is bedrock fissure water, mostly belong to artesian water, and is less affected by human exploitation. The spring flow of 9 sampling points were measured monthly with a flow meter to study the changing patterns of spring water flows and their influencing factors. Our results showed that although there were seasonal changes in local rainfall, there was no significant seasonal change in spring flow. In addition, spring water flow had a negative correlation with altitudes, and may affect by the aeration zone, water hold capacity of soil, catchment area and other factors.This study analysed hydrogen and oxygen stable isotope of spring water to determine the main factors of isotopic values and the supply of spring sources. The spring hydrogen and oxygen stable isotopes presented a linear relationship(?D= 5.7439?18O-10.6535), have no significant seasonal variations. This result suggested that spring is supplied mainly by precipitation, and is affected by the strong evaporation. There was a significantly linear relationship between the altitude of the spring and the ?18O. Similarly, ?D values showed a linear relationship with the altitude, while the correlation was not statistically significant.Overall, Hasi Mountain is a small watershed area, with complex water recycling, there are many factors that have effect on the springs. The runoff and distribution of springs needs further study, so we can clarify the forest eco-hydrological processes of Hasi Mountain. |
PDF Full Text Request