Characteristics of Climate Change in the Lake Basin Area of Gangcha County

This paper mainly was based on the average temperature,precipitation,humidity,and wind direction of Gangcha county from 1960 to 2013.By using wavelet analysis and Mann-Kendall(M-K)mutation analysis,specifically analyzed the climate change characteristics in the lake basin area of Gangcha county.The result showed that the climatic change in the lake basin area of Gangcha county is noticeable.The average temperature,average minimum temperature,average maximum temperature,and evaporation showed an increasing trend.But the evaporation in the study area was higher than precipitation.The average relative humidity showed a decreasing trend.And the sunshine and the average wind speed percentage showed a significant decreasing trend.Utilizing the Morelet wavelet,The time series of annual mean temperature,annual evaporation and annual sunshine percentage all have quasi3a and quasi4A periods,and the annual mean precipitation has quasi2–3A,quasi2–5A and quasi2–6A periods,which appear in 1996–2005,1962–1978 and 1978–1996 respectively.The mean annual relative humidity has obvious quasi2–7A and quasi3A time series,which appear from 1960 to 1996,1997 to 2005 and after 2008,respectively.The annual mean wind speed has quasi3–4A and quasi5A time series characteristics,which appear in 1964–1967,1984–1995,after 2009 and 1971–1983,respectively.Through Mann-Kendall(M-K)mutation analysis,it is found that the mutations of evaporation and the average speed of wind are significant.The mutation of evaporation started in 2004,and the mutation of average started in 2003.

Characteristics of Desertification Change in Lake Basin Area in Gangcha County

Qinghai Lake Basin area in Gangcha county is selected as the study area in terms of desertification change features in this paper.Based on the remote sensing(RS)and global positioning system(GPS)technologies,the desertification information range from 1989 to 2014 in the study area is extracted.Using the method of the decision tree,the desertification in the research area is been divided into four grades including mild desertification,moderate desertification,severe desertification and serious desertification.The change characteristics of desertification in the study area were analyzed in detail,which showed that the desertification in the study area experienced a process of first development and then a reversal.The rapid development of desertification appears in the 1990s,where about 1101.22 kilometers of desertification area was increased in this stage.Since the twenty-first Century,the desertification is gradually significant recovered and local area exist intensified desertification.There are tendencies of interactive transform in different types of desertification.The tendencies of different degrees of desertification land are rising,and there’re some differences in rising rates,where the expansion rate of moderate desertification is the biggest,increasing by 7.27 kilometers per year.