Using the 1970-2005 annual precipitation and evaporation data at 80 gauge stations across Hunan province, this work analyzes the spatial distribution and variation tendency of the local droughts and floods using linear regression, wavelet analysis, abrupt change, clusters, Empirical Orthogonal Function (EOF) and rotated EOF (REOF). Results show that there are four dry areas and three wet areas in Hunan. The whole province exhibits a moistening trend except some small areas in western, eastern and southern Hunan. The most prominent feature of annual precipitation is that the whole province basically displays a consistent variation tendency, as far as the dominant EOF mode is concerned. In addition, the spatial features of the other EOF modes include dry-wet differences, e. g. wet (or dry) in the north versus dry (or wet) in the south, wet (or dry) in the center and dry (or wet) in the surrounding areas. The distribution of the ratios of evaporation to precipitation exhibits both common features as well as spatial differences, which can be classified into four types: South Hunan, North Hunan, Northeast Hunan, and Central Hunan. There is an abrupt change from dry to wet patterns in the early 1990s. Generally, the drought-flood distribution presents variations of three periods. In the late 2000s, Hunan province will be in a period of drought, followed by a period of flood.

Drought is one of the severest agricultural natural disasters in Hunan Province. The disaster almost takes place every year and often causes great economic losses. The variation of anomalous indices of light and heavy agri- cultural drought reveals that： during the past 58 years, droughts took on fluctuant and staggered characteristics and reappeared in a cycle of about 5 years, light and heavy agricultural droughts appeared alternatively ; affected area ratio and suffering area ratio were coincident, that was obvious especially in the great disaster periods ; the situation of disasters have become severer since 1980, with the greater affected area ratio, sufering area ratio and heavy drought ratio. A grey system prediction model was established according to the changes of anomalous indices of drought affected area ratio and drought--suffering area ratio. The results show that there would be four periods of heavy drought in the coming 20 years, they would be during 2010 -2011,2013 -2014,2016 -2018 ,2021 -2022 and 2025 - 2027 respectively.

The change of temperature and characteristics of urban heat island effect were analyzed with climatology statistic methods called linear regression,Mann-Kendall and Wavelet Analysis based on meteorological data from 1960 to 2006 at 20 stations in Beijing area.The Mann-Kendall was applied to annual and seasonal temperature and UHI time series.The Mann-Kendall statistic test is a rank-based,nonparametric approach and has been widely used to estimate significance of long-term tends in hydro meteorological time series such as water quality,stream flow,temperature,precipitation.The results indicate that was an increasing trend of temperature in Beijing in the 47 years.Abrupt change analysis showed that: the temperature has the rising tend and the abrupt change happen in 1991.The difference is significantly in seasonal temperature,especially in spring and winter not in summer and autumn.Abrupt change analysis showed that: the temperature of winter has the rising tend and the abrupt change happen in 1980s.The other was happened in 1990s.The urban heat island effect in Beijing is typical.The UHI has the rising tend in recent 47 years in Beijing area.The rising tend over the significant level since early 1980s.The seasonal UHI is different too.UHI in winter is the highest,spring and autumn took the second place,summer is the lowest.However,the UHI has different hot center in summer.This is due to fast development of urbanization in recent years.However,the 7-year running mean curve showed that the UHI will decrease in the future.Abrupt change analysis showed that: the UHI rising tend is significant in spring,summer and autumn,weaker in winter.Wavelet Analysis showed that: UHI periodic variation is about 3 years.On the time scale of 25 years,the UHI in spring and winter relatively weak since 21st century,stronger in summer and autumn.

Using the 1960—2005 data of annual precipitation and evaporation,the spatial distribution of regional drought in Hu’nan Province is analyzed by linear regression,analyses of wavelet,abrupt change,clusters,and EOF and REOF.The results of an analysis of evaporation precipitation ratio data shows that there are four high-value areas and three low-value areas in Hu’nan Province.The spatial variations of Hunan Province are showing a wetness trend in all but its western and eastern areas.The most typical pattern of annual precipitation is a dry-wet consistency across the province.Other typical patterns include dry-wet differences,e.g.wet(or dry) in the north versus dry(or wet) in the south,wet(or dry) in the center and dry(or wet) in surrounding areas.The distribution of evaporation and precipitation ratio exhibits both common features as well as spatial differences,which can be classified into four types of South Hu’nan,North Hu’nan,Northeast Hu’nan and Central Hu’nan.There is an abrupt change from dry to wet in the early 1990s.Generally,the drought-flood distribution presents variations of three periods.In the late 2000s,Hu’nan Province will be in a period of drought,followed by a period of flood.

China's water issues are mainly manifested in threats of floods and drought disasters,shortage of water resources and deterioration of the eco-environment of the 21st century.Among the three problems,the shortage of water resources has become the important restrict factor for the sustainable development of society and economy.Therefore,it is essential to evaluate the degree of the drought of a district and work out the drought preparedness plans.Using data of annual precipitation and evaporation,river runoff and drought disaster affected cropping areas,the temporal distribution of regional drought in Hunan Province during 1960 -2005 is analyzed by fuzzy comprehensive evaluation,M -K test,wavelet analysis,abrupt change analysis,cluster analysis,EOF and REOF.In addition,the responses between regional drought-flood in Hunan Province and global change are studied.(1)Using an appropriate evaluation system,the fuzzy comprehensive evaluation model was established,and the level of regional drought-flood was identified.(2)The results showed that the composite indicator in Hunan Province has a weak increasing trend in the past 36 years,of which the 1970s and 1990s were in flood periods,the 1980s were in drought period.There was a decreasing trend upon entering the 21st century,and there was an abrupt change from dry to wet in the early 1990s.Generally,the composite indicator presented variations of three periods.In the late 2000s,Hunan Province will be in a period of drought,after that it will be in a period of flood.

The change of drought and flood in Xiangjiang River Basin in recent 48 years is discussed by using abrupt change analysis,wavelet analysis,coefficient of variance,EOF and REOF.The results show that the 1990s is in flood periods,and the 1960s and the 1980s is in drought period.There is a decreasing trend since the 21st century,and there is an abrupt change from dry climate to wet climate in 1980s.Generally,the Z Index presents variations of four periods.In the late 2000s,Xiangjiang River Basin would be in a period of drought,and would be in a period of flood afterwards.The most typical pattern of Z Index is the drought-flood consistence.The Z Index abnormal area can be divided into four as the southern,central,northern and southwestern regions.

The change of drought and flood in Dongting Lake Basin since recent 47years is analyzed using abrupt change analysis,wavelet analysis,coefficient of variance,EOF and REOF.The results showed that the 1990s were in flood periods,the 1960s and the 1980s were in drought period.There is a decreasing trend entering the 21st century,and there is an abrupt change from dry to wet 1980s.Generally,the Z Index presented variations of four periods.In the late 2000's,Dongting Lake Basin will be in a period of drought,after then will be in a period of flood.The most typical pattern of Z Index is the drought-flood consistence.The Z Index abnormal area can be divided into four:northern,the central,southern,northwestern.

The change of precipitation in Hunan Province since recent 46 years was analyzed by using linear regression,abrupt change analysis and wavelet analysis.The results showed that the annual precipitation increased at a climatic tendency of 21.8 mm/10a.However,the 11-year running mean curve showed that it will decrease in the future.Precipitations in spring and autumn were decreasing in most of the areas,while summer and winter precipitations both had increasing trends.There existed a wetter trend in summer and winter in Hunan Province in the last 46 years.The abrupt change occurred in summer and in winter during the early 1990s.Generally,both annual precipitation and seasonal precipitation presented four kinds of periodic change.

Using 1960～2005 annual precipitation data over 86 stations of Hu′nan Province,temporal and spatial variability features are studied by applying the methods of REOF,wavelet analysis and M-K methods. The result indicates: (1) The most typical pattern of annual precipitation is the dry-wet consistency. Other typical patterns show the dry-wet difference. For example,it is wet(or dry)in the north and dry(or wet)in the south,wet(or dry)in the center and dry(or wet) in the surrounding area,wet(or dry)in the northeast and dry(or wet)in the southwest. (2) The annual precipitation distribution exhibits common features as well as spatial differences,which can be classified into six types as Southeast Hu′nan,Northwest Hu′nan,North Hu′nan,central part of Hu′nan,West Hu′nan,and Southwest Hu′nan. (3) There is an wetter trend over Hu′nan Province in the past 46 years. Generally,annual precipitation presents an upward tendency and the periods of 4a,7a,10～12a and 24a. The abrupt change occurred about in the 1990s.

This paper analyzed the monthly precipitation data of Changsha from 1956 to 2005,by using the methods of linear regression,abrupt change analysis and wavelet analysis.The results show that the annual precipitation has been increasing by 59.8mm/10a.The precipitation in summer,autumn and winter has an increasing trend,but the precipitation in spring has a decreasing trend.The contours of the real part of Morlet wavelet coefficients of Changsha's precipitation of show that both annual and seasonal precipitation is decreasing except winter's precipitation during this century.The abrupt change analysis displayed that there existed an abrupt increase of annual and summer precipitation of which the abrupt change respectively occurred in 1988 and 1992.However,there was no abrupt change in spring,autumn and winter.

利用线性回归、突变分析及小波分析方法分析了湖南省86个地面台站降水量近46年的变化。结果表明：湖南省46年来年降水量呈增加的趋势，其中春秋两季降水量呈减少趋势，夏冬两季降水量呈显著增加的趋势，7年滑动平均曲线表明今后湖南省降水量有减少趋势。湖南省年降水量在1990年代初降水增多是一突变现象，降水量在春秋两季无突变现象，夏冬降水量在1990年代左右存在降水突变期。（3）湖南省年降水量和四季降水量均存在四个周期变化