Analysis On The Desiccation Of Xihu Lake In Naiman Banner, Inner Mongolia

Lakes are important water resources in Inner Mongolia, and also the sensitive indicator of climate and environmental change there. In recent years, with the regional climate change and increased human disturbance, the number, morphology, water quantity, water quality of lakes in Inner Mongolia have changed significantly. The desiccation of lake not only leads to serious desertification of lake beaches and the dried lakebed sediments could be transformed into direct material source for sandstorms, and thus impact on the sustainable development of the socio-economic and living in surrounding areas.From July to August in2013,four drillings of10m,numbered Xh01, Xh02, Xh03, Xh04were played in Naiman Banner, based on fieldwork on the use of GPS positioning. It collected a total of37lake sediment samples and analysis the sediment grain size, pollen and other aspects of the parameters. It also collected the precipitation, temperature, wind speed and other modern information. Microtrac S3500laser particle size analyzer was used to analyze the commonly used indicators about mean soil particle size, sorting coefficient, skewness and kurtosis;Sediment pollen extract by hydrofluoric acid and heavy liquid extraction method of combining quantitative counting method using volume obtained pollen species, the number of particles of pollen, pollen concentration and pollen percentages and other parameters; Using Excel software analyzed precipitation, temperature, wind speed characteristics of Naiman Banner.The use of SPSS18.0software using Pearson correlation coefficient analysis of the water level of Xihu Lake and the population precipitation of Naiman Banner. By comparing the characteristics of the stratigraphic data of Xihu Lake analysis the evolution of the historical period, using the climate, culture and other modern data analysis the reason of desiccation, The following conclusions will be achieved through the research:(1)Core Xh01and Xh04, Xh02and Xh03size parameters with a certain similarity, there are some rules to follow, but there are some differences in the specific parameter changes. The mean sediment grain size becomes smaller from near the lakeshore to the heart values, the minimum appeared in0-200cm and the maximum at280-350cm near the lakeshore; the minimum appeared in75-250cm, maximum at600-1030cm near the heart values. Sorting coefficient Overall poor performance, relative to the lower part of the upper part of the lake is better; migraine mostly coarse particle size distribution of the east side, west of the particle size distribution and more partial nearly symmetrical or thin side, may be associated with hydrodynamic complex, multi-source supply relevant. Through the analysis shows that the average particle layers Core Xh01experienced a change from drought periods-wet period-drought periods.(2) Xh01-01layers consist of most of the pollen,dominated by Chenopodiaceae andArtemisia.Xh01-05layer of the total pollen content Secondly, Chenopodiaceae, Pinus dominated;Xh01-09floor general less pollen content to Chenopodiaceae, Artemisia, cattail pollen-based; Xh01-12was the lowest layer of the total pollen to Chenopodiaceae, Artemisia, cattail pollen-based. Xh01borehole bottom pollen record indicates a higher level through the lake level-falling water-the water level rise-the evolution of the lake dried up.(3) For40years from1971to2010, the average annual precipitation is353.43mm, annual precipitation has decreased in a linear trend, the peak in1986, the lowest value in2000. Precipitation anomaly percentage between-39.7%and60.5%,the bias was-0.026mm/10a. Precipitation from1971to1983, mostly with partial teenager, shrinking lakes; precipitation from1984to1994, mostly with partial years, lakes expansion;1995to2010to partial precipitation mainly teenagers, shrinking lakes dried up.(4) The average temperature from1971to2010, the overall trend is gradually increased by0.067℃every year.40a mean temperature anomaly in1994as a watershed, mostly before1994was negative in1974for the coldest year (-1.59℃);1994after mostly positive, in2007as the warmest year (+1.26℃). Precipitation shows combined dry Lake from2000to2001as the year of drought, higher temperatures and precipitation decrease joint action intensified Lake atrophy.(5)From1971to2010the annual average wind speed is3.27ms’1.For40years,the annual average wind speed has a step change.It showed a slight decreasing linear trend, reducing the average per decade0.015ms-1; from four Seasons, the monthly average wind speed up to the maximum in April, August reached the minimum, arid windy spring, strong evaporation, accelerated the lake dried up, dried up in the West final in May, with the wind speed may be related.(6) Since the1970s, the Xihu Lake changing in area from time to time, showed that80years ago, due to the climate gradually becomes drought, shrinking Lake, West Lake, the water level at this time is mainly affected by natural factors such as rainfall; since the1980s due to the population, the increasing of the surrounding arable land, leads to increased domestic water and agricultural irrigation water, resulting in the local ecosystem imbalance, causing the Lake dried up. So that human activities mainly caused the Lake dried up.