| With the strengthening of the impact for climate change,the drought events are showing frequency trend on a global scale and China drought events corresponding rise,exhibiting from northern area gradually spread southwest.Guizhou is an important agriculture areas located in the southwest of China with maize and rice as its main food crops.However,droughts have frequently taken place recently,and resulted in a big reduction in its crop yield.So we collected the daily meteorological date of 19 stations within Guizhou province between 1960 and 2013.The precipitation concentration index,climate tendency coefficient,Mann-kendall test,moving t-text,Morlet wavelet analysis and the standard Precipitation-Evaporation index were applied to analyze the spatial and temporal distribution characteristics of precipitation,Extreme Precipitation,drought and regional response to climate change in Guizhou province in recent 54 years(from 1960 to 2013)under global climate change.These results are fundamental to the decision of drought mitigation measures in the local sites.Based on the actual needs,combined with the actual situation of Guizhou Province,carrying out detailed research and analysis,the main results are as follows:1)The research progress of situation climate change and theoretical Analysis of drought at home and abroad is summarized.The research progress of situation climate change,drought definition,classification arid,drought evaluation index and evolution of the drought in Southwest China are summarized and pointed out the significance of this paper from two aspects of theory and reality.Then,the main research contents and technical route are outlined.2)Temporal-spatial Distribution and Variation Characteristics of Rainfall in Guizhou ProvinceThe spatial distribution of rainfall is uneven,which has a decreasing gradient from east to west,and the formation of three clusters and three dry rainy concentrated area;The precipitation shows downward trend in the last 50 years and presents seasonal dynamics during the whole year.In addition,precipitation in spring and autumn is decreased trend and the decreasing trend is anomaly significant,however,there is no significant upward trend for precipitation in summer and winter.There are periodic oscillation of 22 a for the annual rainfalls variation and mutation phenomenon in 1984,1991,2001 years,there are abrupt changes and periods on seasonal precipitation.3)Temporal-spatial Distribution and Variation Characteristics of Extreme Precipitation in Guizhou ProvinceContinuous wet days(CWD)exhibit significant decreasing trend during the 52 years,so does the maximum 5-day precipitation(RX5day),very wet day precipitation(R95)and very heavy precipitation days(R20mm),but the variation trend of them is not significant.In contrast,there is not an obvious increasing trend in maximum 1-day precipitation(RX1day)and simple daily intensity index(SD?).Abrupt change points of RX1 day,RX5day,SDII and R20 mm are at 1973,1972,1981 and 1992,respectively,and no abrupt change occurred for R95 and CWD.Almost all extreme precipitation indexes exist two common oscillation cycles,namely,10~12(minor cycle)and 6~7 years(major cycle).The high value center of extreme precipitation is southwest and southeast areas in Guizhou province,while low value center is northeast areas in Guizhou province.There were significant positive correlation between precipitation indexes and total precipitation.Extreme precipitation indexes would keep long-term memory in the future.4)Spatial and temporal distribution characteristics of annual and season scales droughtThe drought stations proportions and drought intensities at the annual,spring,summer and autumn scales exhibit upward trend over the past 54 years with a better continuity in the future;The drought stations proportions appeare as the features of the local and all regional drought,and the drought intensity showe a moderate level at seasonal and annual scales.Drought occur in high frequency at stage of spring and summer.Spring drought happen frequently in northwest of Guizhou,in contrast,while summer drought happen frequently in the northeast and southeast parts.Precipitation and the accumulative sunshine are the main factors affecting the meteorological annual and season scales drought in Guizhou Province.5)Spatial and temporal distribution characteristics of drought during autumn crop growth period in Guizhou ProvinceIn consideration of the accumulate drought effect and autumn crop water requirement,the standard Precipitation-Evaporation index of six-month time scale between April and September(Sep-SPEI-6)was calculated.The correlation analysis between Sep-SPEI-6 and the crop yield reduction is tested.Some results are obtained as bellow.Sep-SPEI-6 in Guizhou province and the 9 cities showe a significant negative correlation with the annual crop yield reduction.The climate mutation occur two times around year 1991 and year 2001.Compare with the first phase between 1960 and 1991,the occurring frequency and drought extent in the second stage falling in 1992 and 2001 is decreased by 10.59%.Compare with the second stage,the occurring frequency and drought extent is increased by 23.67% and 24.74%,respectively in the third phase between year 2002 and 2013.In contrast to the former two stages,the drought duration and drought intensity in the third one increase significantly.There is an obvious periodic oscillation in Sep-SPEI 6 time series,and 22 years is the first primary period.The Hurst values by the index of Sep-SPEI-6 in different stations are all greater than 0.5,suggesting a better continuity in the Sep-SPEI-6 variation.The high frequency of drought region tend to move to the west.The precipitation and the accumulative sunshine during the crop growth were both found as main factors affecting the meteorological drought in Guizhou Province.6)Drought Coping Strategies and Measures of Guizhou Province are proposedCombining the Effects of drought disasters on society and economy and the challenges and difficulties faced in Guizhou Province.The paper initially propose some drought coping strategies from four aspects for Guizhou Province. |
PDF Full Text Request