Study On Climate Change In Laihe River Basin

Climate change takes an important influence on natural ecosystem and socio-economic development, and has become a hot issue with universal concern to the international community. Under the background of global warming, the climate change along, but in different regions the characteristics of climate change are inconsistent. The region of Qilian Mountains and Hexi corridor is across about 10 longitudes, the eastern is controlled by summer monsoon, whereas the western is influenced by the westerly circulation, and the central is located on the intersection of two circulation systems. With the Qinghai-Tibet Plateau monsoon coupling, the local climate change is more complicated. By the global warming, the characteristics of climate change in this region have some difference in time and space certainly. It is essential to study the integrity of climate change and regional differences based on a long series of meteorological data. Under global warming, it is a popular concern that increase of extreme weather’s frequency and resulted in adverse effects on the global social and economic development. Because Qilian Mountains and Hexi Corridor have unique geographic position and subject to the impact of different climate system, it is sensitive to climate change and is a vulnerable area, and extreme weather and climate have a major impact on the regional socio-economic so that to carry out extreme weather and climate change research is also necessary. In Hexi region, the surface water and groundwater come from snow melt water and mountain precipitation in the Qilian Mountains, so Qilian Mountains is an important water source for Hexi region. And what’s more, the agriculture, industry, cities and towns of Hexi oasis is mainly distributed in Hexi corridors, the number and changes of water resources in Hexi area is directly related to its socio-economic development, and the future trend of water resources is of most concern to policy makers. Researching the features of climate change on temporal and spatial distribution, it will provide the background of climate change for variation of surface runoff in Hexi region, moreover, provide scientific decision-making for the sustainable use of water resources. In this thesis, using meteorological data of 2 stations during from 1957 to 2012 in the Qilian Mountains and Hexi Corridor, we analyzed the inter-decadal and inter-annual change of climate trends by linear trends and the 5-year trend of sliding, regional differences in climate change was also discussed under the arcgis spatial interpolation by spline spatial measure, tested climate mutations on Mann-Kedall method, studied the cycle to climate change in wavelet analysis and predicted the trend of future climate change, the preliminary conclusions are following:(1) Based on the data of temperature and precipitation in Taolai River basin from 1957 to 2012, the extreme climate indices were employed to analyze the climatic changing trend and spatial differences. Results indicated that extreme temperature revealed statistically significant increases in the temperature of the warmest and coldest nights. The regionally averaged occurrence of extreme cold days and nights has significantly decreased with the increasing of growing season length. Decreases of the diurnal temperature range and the number of frost days were statistically significant, but a decreasing trend of ice days was not significant and increased after 2000. The greater increasing trend mainly occurred in higher altitudes in autumn and winter. It is also larger for regional trends for night index than in day index. There was also a statistically increase trend for precipitation extremes. At the same time, there is a significant increase in consecutive wet days, number of heavy precipitation days and maximum annual amount for 5-day precipitation and the rain day precipitation, but it not showed the significant increase for the regionally averaged daily rainfall intensity. The distribution of the number of rainy days in summer and autumn is more uniform, and the increasing precipitation mainly contributed by the increase of moderate-rain days and the lengthening of rainfall time for single precipitation event. Extreme precipitation events mainly also occured at high altitude areas in study region.(2) In this paper, using meteorological data of 2 stations during 1957-2012 in the Taolaihe river basin, we analyzed the inter-decadal and inter-annual change of climate trends by linear trends and the 5-year trend of sliding, tested climate mutations on Mann-Kedall method, studied the cycle to climate change in wavelet analysis, the conclusions are following:autumn precipitation is relatively less in 1960s,1980s and 1990s, but it is abundant in 1970s and after 2000, whiles precipitation in other seasons is also less during 1970s and 1990s, and summer precipitation showed the larger increasing after 2000; spring precipitation decreased during 1957-2012, whiles winter precipitation had no trend, but precipitation in other seasons displayed an obvious increase, especially after the mid-1980s;seasonal and annual precipitation variation but not including winter, there were about 8 years,15 years and above 26 years of cycle;spring and autumn rainfall had’t mutation, whiles summer, autumn and winter precipitation lied on an increase in the year of 1972,2003 and 1970, respectively, and what’s more, annual precipitation also increased after the mid-1980s, and these characteristics indicated the climate change for "warm-dry" to "warm-wet" in Taolaihe river basin.(3) In this paper, using meteorological data of 2 stations during 1957-2012 in the Taolaihe River Basin, we analyzed the inter-decadal and inter-annual change of potential evaporation by linear trends and the 5-year trend of sliding, tested climate mutations on Mann-Kedall method, studied the cycle to climate change in wavelet analysis, the conclusions are following:autumn and winter potential evaporation are relatively lower in 1960s and 1970s, but abundant in 1980s,1990s and after 2000, while potential evaporation in spring and summer are also abundant during 1960s and 1980s, and lower in 1990s and after 2000. In addition, variation for annual and wet season potential evaporation are relatively lower in 1960s,1970s and 1980s, but abundant in 1990s and after 2000; variation in annual and wet season potential evaporation tended to increase, which each season potential evaporation also has an obvious increase trend, and the largest increase occurred in summer, autumn followed;seasonal and annual potential evaporation variation, there are about 10-years,15-years and above 26-28-years of cycle during 1957-2012;mutation increase of the potential evaporation happened in the years of 1995,2000,1984,1980,1997,1992 for spring, summer, autumn, winter, annual and wet seasons, and what’s more, only the dry season potential evaporation experienced two mutation increase, respectively, in 1980 and 1995.