The Analysis Of The Driving Factors Of Zhangbei Lakes

Recently, researchers pay more attention to the study on the impact of lakes on the environment. At present, the development of the current science of lakes believed that lakes and drainage area should be regarded as a whole to research. It also pointed out that the evolution law of lakes and drainage area which is effected by human activity is the study orientation of lakes of geography. With economic development and population growth, human interfered with drainage areas violently. Human activity greatly influenced on the evolution of lakes and especially on the variation of water, while exploition of soil and covering of soil is the direct manifestation which is effected by human activity.Because of the influence of climate and human activity, the quantity of water, the area of lakes even the number of lakes in Zhangbei are decreasing. All these factors have bad effect on the industrial and agricultural production and ecosystem, while human's exploition of soil and social activity are the major driving factors of this phenomenon.This study is based on digital elevation model and SWAT hydrology distribution model of study area is applied in this study in order to produce digital drainage area and show the hydrology units in Zhangbei drainage area. TM image of the same period which are regarded as the basic information source, together with the relevant special maps, in support of GIS and RS, explains the information of explition of soil of Zhangbei lakes at different stages and works out the current charts of exploition of soil in this two periods. Through SWAT model, the variation of water is worked out according to different underlying surface and different weather condition. Use of water balance principle to derivate the quantitative relationship between the changes of lake water and lake area. Changes affecting the amount of water through the natural and socio-economic factors analysis, filter out the driving factor which lead to changes in lake water. On this basis, use the neural network model reflect the establishment of the driving factors and changes in the lake water area,predict the trend of lake evolution in the next five years. The followings are the major research conclusions:(1) Application of SWAT Hydrological Model simulated two different times of the runoff for the study area. The simulation results better reflect the actual situation of runoff. The results show that: The same weather conditions, different land use pattern change have significant impact on lake water, assuming the same weather conditions in the study area, lakes water changes of 2008 is 2.27 times in 1998. The same land use pattern, different meteorological weather conditions, lakes water changes of 2008 is 1.06 times in 1998. Different land use patterns and weather conditions, water simulation of 2008 lakes variation is 1.04 times in 1998. Reduce the area for lakes, water level variation is 5.82 times of the 1998. These results reflect the pattern of land use changes, changes in weather conditions can affect changes in water lakes.(2) Analysis land use and landscape pattern of the study area. The results show that: the transformation is obvious in different time scales change between landscapes, especially those from the dry land to irrigated land, woodland, grass land and lakes inland beach replacement. Pattern throughout the landscape, the dry land always take advantage of the status. However, since 1998 ~ 2008, the dry land connectivity decline, and increase the piece of the fragmentation. The irrigated land increased connectivity, increased the aggregation. Description of the study area over the past decade, eco-construction has a certain effect in returning farmland to forest and grassland. The main reason which leading to decreasing water is water project construction and have a big increase in irrigated area.(3) Using regression analysis, study the relationship between regions factors socio-economic factors and the lake area, to determine the leading group driving of lakes water. The regression equation: Y=0.01395X1+0.09382X2-0.30281X3-0.20308X4-0.13027X5+0.39392X6In a = 0.0001 level, the correlation coefficient R = 0.998834, reached a significant level. Through analysis the weight of the number of motor-pumped well, vegetable production, irrigated area, which reflect the socio-economic conditions, affected the lakes of water as the dominant driving factor.(4) Using neural networks to nonlinear model of the relationship between lakes area and the number of motor-pumped well, vegetable production, irrigated area, to predict the future trend of lake water group. Through the model calculation,2015 lakes area will be reduced to 1599.907 ha. The results compared to 1998 decreased nearly 9512 hectares, compared to 2008 decreased nearly 2422 hectares. Decreasing rate of the area lakes is 709 ha/year from 1998 to 2008. Decreasing rate of lake area is 346 ha/year from 2008 to 2015. Whole lakes area reduced year by year, trend of changes in lake water for the negative group, reservoir water have gradually declined.(5) The current situation of Zhangbei lakes is that the decreasing area of big lakes and the drying up of small lakes. Human activity is the major driving factor that results in the drying up of lakes. Climate change also has some influence. With the socio-economic development and population increase, the interference of human activities on further enhancing the natural, lakes deterioration of ecological environment would be more intensive.The following measures are effective to solve the problems such as the area decreasing of the lake, the quantity of water and the number of lakes. Saving water, limitation of the power-operated wells, adjusting the planting structure and appropriate irrigation are beneficial to alleviate current ecological problems of Study area.