我国农田水利工程建设抵御水旱灾害效果评估

2011年中央一号文件提出“大兴农田水利建设”,之后伴随着高标准农田建设的发展,农田水利工程建设进入快速发展阶段,年均投资超过800亿元。【目的】评估我国过去农田水利工程建设减轻水旱灾害的效果。【方法】以2011年为时间节点,将各省级行政区降水量和水、旱灾受灾率和成灾率数据分成2组,建立模型,考察2个时段内水、旱灾受灾率随降水量的变化,分析2个时段水旱灾受灾率和成灾率的差异显著性。【结果】1994—2010年水灾受灾率随降水量的增加呈极显著增加趋势,而2011—2018年水灾受灾率则与降水量无显著关系,说明大力建设农田水利工程的减灾效果;1994—2010年和2011—2018年旱灾受灾率随降水量的增加显著降低,但2011—2018年比1994—2010年旱灾受灾率受降雨量影响的程度减小。2011—2018年旱灾受灾率和成灾率比1994—2010年分别降低了5.14~22.52百分点和2.21~16.79百分点,水灾受灾率和成灾率则分别降低了3.26~8.00百分点和1.95~4.54百分点。结合各省区的多年平均降水量数据分析表明,农田水利工程建设对于大多数干旱、半干旱和半湿润地区,如河北、山西、内蒙古、辽宁、吉林、黑龙江、西藏、甘肃、青海和新疆的抗旱效果较明显;对于湿润地区,如福建、江西、湖北和湖南则抗涝效果较明显;在某些半湿润地区,如山东、河南和某些湿润地区,如江苏、广东、重庆兼具抗旱和抗涝效果。【结论】统计意义上,农田水利工程建设抗旱效果显著高于抗涝效果;旱灾受灾率和成灾率比水灾的受灾率和成灾率分别降低很多。该研究可为未来农田水利设施建设区域规划提供参考。

Water vapor transport over China and its relationship with drought and flood in Yangtze River Basin

The characteristics of water vapor transport(WVT) over China and its relationship with precipitation anomalies in the Yangtze River Basin(YRB) are analyzed by using the upper-air station data in China and ECMWF reanalysis data in summer from 1981 to 2002.The results indicate that the first mode of the vertically integrated WVT is significant whose spatial distribution presents water vapor convergence or divergence in the YRB.When the Western Pacific Subtropical High(WPSH) is strong and shifts southward and westward, the Indian Monsoon Low Pressure(IMLP) is weak, and the northern part of China stands behind the middle and high latitude trough, a large amount of water vapor from the Bay of Bengal(BOB), the South China Sea(SCS) and the western Pacific forms a strong and steady southwest WVT band and meets the strong cold water vapor from northern China in the YRB, thus it is likely to cause flood in the YRB.When WPSH is weak and shifts northward and eastward, IMLP is strong, and there is nearly straight west wind over the middle and high latitude, it is unfavorable for oceanic vapor extending to China and no steady and strong southwest WVT exists in the region south of the YRB.Meanwhile, the cold air from northern China is weak and can hardly be transported to the YRB.This brings on no obvious water vapor convergence, and then less precipitation in the YRB.

Spatio-temporal evolution of drought and flood disaster chains in Baoji area from 1368 to 1911

Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of drought and flood disaster chains in this area during the Ming and Qing dynasties using the methods of moving average, cumulative anomaly and wavelet analysis. The results are as follows:(1) We found a total of 297 drought and flood events from 1368 to 1911 in Baoji. Among these events, droughts and floods occurred separately 191 and 106 times, which accounted for 64.31% and 35.69% of the total events, respectively.(2) We observed distinct characteristics of flood and drought events in Baoji in different phases. The climate was relatively dry from 1368 to 1644. A fluctuant climate phase with both floods and droughts occurred from 1645 to 1804. The climate was relatively wet from 1805 to 1911. Moreover, we observed a pattern of alternating dry and wet periods from 1368 to 1911. In addition, 3 oscillation periods of drought and flood events occurred around 70 a, 110 a and 170 a, which corresponded to sunspot cycles.(3) We also observed an obvious spatial difference in drought and flood events in Baoji. The northern and eastern parts of Weihe River basin were regions with both frequent droughts and floods.(4) The sequential appearance of drought and flood disaster chains in Baoji from 1368 to 1911 was in response to global climate change. Since the 1760s, global climatic deterioration has frequently led to extreme drought and flood events.