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Chang’an University (2006)

The Ordos Basin desert plateau District lakes and diving surface evaporation capacity

He Yuan

Titre : The Ordos Basin desert plateau District lakes and diving surface evaporation capacity

Auteur : He Yuan

Grade : Master’s Theses 2006

Université : Chang’an University

Résumé
Ardos desert plateau, with vast territory and abundant resource, lies in the northern of Ardos basin ,which is energy and chemical industry base of West Development of 21st century. Recently, the need of water is increasing rapidly with the development of economy. However, because of the scare rainfall with heavy evaporation, serious desertification and soil erosion and vulnerable ecological environment in the area. The preliminary research shows that vertical exchange is the chief way of water cycle in the area. The evaporation of lakes and groundwater occupied most of discharge of groundwater. Therefore, as one of the vital factors of groundwater balance, it is very important to study space-time distribution of evaporation intensity of lakes and groundwater in the area and discuss on the rules and influential factors of water surface evaporation, which played an important role to evaluate the quantity of water resource and protect the groundwater reasonably.The paper, relied on National Item, of the experiment study on intensity of influent seepage and evaporation of cretaceous ground water surface in Ardos basin ,which was charged by Environmental Engineering institute of Chang An University .I had participate in the works of The evaporation experiment of different salinity contained lakes and the observation of the vadose water pressure head, through investigated of the lithologies and analyzed the weather property of this area the paper was composed , the article mainly studied about the lake evaporation and phreatic evaporation those two sides :(1)With different salty-contained level water samples, water surface evaporation experiments is done by E601. During experiment, the evaporation intensity of different salinity - contained level lakes were monitored, the evaporation rules and influential factors were analyzed. The convert coefficient between two different evaporating dishes was calculated through evaporation data collected at weather station by 200mm evaporating dishes.The results show that the evaporation have no obvious differences between fresh water and different salty-contained level water. Lake evaporation is mainly influenced by temperature, air press, wind speed, humidity and solar radiation, however, the salt account played almost no impact on it. The convert coefficient between the different two evaporating dishes was 0.43 which has reduced about 22% than the former value.(2)The study on phreatic evaporation was based on monitoring aeration zone in-situ test in study area, the water movement of numerical simulation model in Ardos desert plateau was established , the evaporation intensity under different conditions were calculated by the model, the evaporation mechanism was discussed, the model was applied to the area through analyzing the precipitation and space-time distribution of evaporation intensity and investigating the lithologic structure and water table of aeration zone, the phreatic intensity of different districts of the study area were simulated.The study showed that The soil surface evaporation in non-freezing period was mainly influenced by precipitation and the lithologic structure of aeration zone, the evaporative intensity increased when rainfall increased and lithology thinned.

Mots clés : water surface evaporation phreatic evaporation aeration zone field test numerical simulation Ardos desert plateau

Présentation (Dissertationtopic )

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