Karst Drainage Basin Dry And Its Low Water Resource Carrying Capacity

Karst drainage is a regional synthetical whole which is made up of spatial drainage boundary, unique geomorphy-river net structure and hydrologic dynamic process and has its own special drainage structure . Thus, there are complicated and diversified factors which influence the amount of low flow in karst drainage. Therefore, based on the research of low flow at home and abroad, my paper researched the changing law of low flow and preliminily analyzed the carrying capacity of low water resources in karst draindge by means of GIS and SPSS software.Three main contents were researched about low flow in karst drainage. Firstly, my paper analysized the main factors which influence the amount of low flow in karst drainage such as the area of drainage, lithology, the type of landforms and its special assembly, forest etc from the point view of drainage structure and the relationship between the different type of landforms and the amount of low flow in particular. For example, the ratio of low flow to its area is higher in Fengcong region than that in Fenglin region. Further more, the same type of landforms also influences the amount of low flow if the spatial assembly is different. Secondly, my paper researched low flow frequency analysis in karst drainage and selected four types of the theoretic frequency distributions. Log-normal distribution and P-III distribution are applicable to low flow frequency analysis in karst region by caculating and comparing. Furthermore, the low flow frequency distrbutions are almost same in these drainages of different types of landforms. Thirdly, The mathematics model of forecasting low flow was established in Fengcong and Fenglin regions according to these factors influencing the amount of low flow in karst drainage (the area of drainage, lithology, the type of landforms and its special assembly and forest)The conception of low water resources carrying capacity was firstput forward according to the changing law of low water resources in space and the situation of exploitation and utilization in karst drainage (ie, under the condition of the virtuous ecological environment and the available technology, the explorable amount of water resources in certain areas is capacity and limitation which is able to coordinate the development of population, enviroment and economy during the period of low flow seasons) and preliminarily analyzed its connotation, characteristic and established the index system of low flow in karst drainage. Because the water resources are affect by enforcing element and constraining elelment together in the exploration and utilization logistic curve is used similarly to relate the increasing process of low flow carrying capacity and describe expressional forms of low flow in diffrernt stages.At last, taking the example of MaoTiao River the amount of low water resources carrying capacity was calculated. The result shows that the water resources carrying capacity is much higher according to the amount of year-runoff than that according to the low flow . This indicates that the carrying capacity of low water resources is lower and the amount of water resources has hindered the development of society and economy in karst region in dry seasons.