洞庭湖流域降雨和降雨極值時(shí)空分布及風(fēng)險(xiǎn)變化研究

張曉艷 劉梅先

摘 要 洞庭湖流域是我國洪澇災(zāi)害最嚴(yán)重的地區(qū)之一，對(duì)當(dāng)?shù)剞r(nóng)業(yè)生產(chǎn)、經(jīng)濟(jì)建設(shè)和生態(tài)環(huán)境造成了巨大的影響.研究降雨極值的規(guī)律和風(fēng)險(xiǎn)，對(duì)當(dāng)?shù)胤篮榭篂?zāi)具有重要指導(dǎo)意義.本文結(jié)合MK檢驗(yàn)、概率模型和移動(dòng)窗口法，基于降雨量（R）、平均降雨強(qiáng)度（Ri）、暴雨天數(shù)（R50）和年最大日降雨量（Rx1）為指標(biāo)，研究了1960—2013年期間洞庭湖流域降雨變化規(guī)律及極值的風(fēng)險(xiǎn)特征.結(jié)果顯示，洞庭湖流域平均年降雨量以-5.6 mm/decade的速率下降，且其中夏季和冬季降雨量上升，春季和秋季下降.然而，Ri、R50、Rx1均呈現(xiàn)總體上升的趨勢(shì)（P>0.05）.概率（風(fēng)險(xiǎn)）分析結(jié)果表明，Ri、R50和Rx1的五年一遇值（Ri5、R505和Rx15）均呈現(xiàn)東北高西南低的規(guī)律，說明流域東北部洪水風(fēng)險(xiǎn)較高，另外，Ri5、R505和Rx15在總體上呈現(xiàn)顯著的上升趨勢(shì)（P<0.05）.這些結(jié)果表明，即使流域內(nèi)降雨量無顯著變化（P>0.05），但降雨有集中的趨勢(shì)（Ri上升），極端降雨事件逐漸增強(qiáng)（R50、Rx1上升），洪災(zāi)風(fēng)險(xiǎn)顯著上升（P<0.05）.

關(guān)鍵詞 降雨極值； 降雨； 風(fēng)險(xiǎn)； 洞庭湖

中圖分類號(hào) P333文獻(xiàn)標(biāo)識(shí)碼 A文章編號(hào) 10002537（2016）02001006

SpatialTemperal Variation and Risks of Precipitation

Extremes in Dongting Lake Catchment

ZHANG Xiaoyan1， LIU Meixian2，3*

（1. School of Education Science， Hunan First Normal University， Changsha 410205， China；

2. Key Laboratory for Agroecological Processes in Subtropical Region， Institute of Subtropical Agriculture， Chinese Academy of Sciences， Changsha 410125， China；

3. Huanjiang Observation and Research Station for Karst Ecosystem， Chinese Academy of Sciences， Huanjiang 547100， China）

Abstract The Dongting Lake catchment is a flood prone region in China. Heavy floods have brought out huge detrimental impacts on agriculture， economy and ecosystem in this region. Knowledges of the spatial and temporal characteristics and occurrence risks of precipitation extremes are essential for disaster management and hazards mitigation. Based on the daily precipitation dataset of 1960 to the year of 2013， in this study， we investigated spatialtemporal patterns and the occurrence risks of precipitation and precipitation extremes in Dongting Lake catchment， by using statistical analysis of MK test， probability distribution and 30year moving windows. Four indices， such as the annual precipitation amount （R）， the annual mean precipitation intensity （Ri）， the torrential rain days （R50） and the max 1day precipitation amount （Rx1） were employed in this study. Our results showed that the total amount of precipitation has significantly increased in summer and winter， but decreased in spring and autumn. The regional annual mean precipitation has been decreasing at the rate of -5.6 mm/decade in the past decades. Our results indicated that Ri， R50 and Rx1 exhibited an overall increasing trend， though the trends were generally not significant. Our probability results showed that， the 5year return levels of Ri， R50 and Rx1 （Ri5， R505 and Rx15） had demonstrated a clear tendency of increment from southwestern part to northeastern part in the catchment， indicating that the northeastern part has been suffered from high risks of floods. Moreover， our results also find that the values of Ri5， R505 and Rx15 have significantly increased at most of the stations. These results imply that the chance of precipitation extremes is being in the proces of enhancement， and the risks of floods will increase significantly. These tendencies are likely to result in additional pressures on the local government to flood disasters mitigation in this region.

Key words precipitation extreme； precipitation； risk； Dongting Lake catchment

在全球變暖的背景下，極端氣候事件的強(qiáng)度和頻率都發(fā)生了相應(yīng)變化[1].極端氣候事件的發(fā)生往往具有巨大的破壞性，如干旱、洪水、低溫等，對(duì)經(jīng)濟(jì)建設(shè)、生態(tài)環(huán)境、農(nóng)業(yè)生產(chǎn)和人類健康都會(huì)帶來重要的影響.因此，近些年來，極端氣候事件倍受關(guān)注，也受到國內(nèi)外學(xué)者的重視[12].

洞庭湖區(qū)是我國洪澇災(zāi)害發(fā)生頻率高且災(zāi)情嚴(yán)重的地區(qū).然而，該地區(qū)也是長江流域氣候變化極為顯著的區(qū)域[34].隨著全球氣候變化，洞庭湖流域洪澇災(zāi)害有明顯增多的趨勢(shì)[5]，如在1……