西南和华南干旱灾害链特征分析

Characteristic Analysis of Drought Disaster Chain in Southwest and South China

利用历史资料记录,考虑西南(云贵川渝)和华南(粤桂)各自不同的孕灾环境(包括气候背景、下垫面状况、地貌类型、土壤类型、河网分布)、人口密度、经济条件等,分别构建了西南和华南地区的干旱灾害链模式,分析各自灾害链链条上的灾害传递特点。结果表明,尽管西南和华南干旱灾害链的链条结构有相似的地方,但各自链条上灾害的传递过程不同。干旱灾害链上灾害传递具有明显的区域性特征,西南在轻度气象干旱时就会引起作物干旱,而华南则要在中度气象干旱时才会下传到作物干旱;西南在中度气象干旱就会引起诸如人畜饮水困难和牲畜饲草料不足等问题,而华南则要在重度气象干旱时才会引起相应的问题;由于孕灾环境的差异,西南在重度气象干旱时可引起部分区域的石漠化现象,而华南则除了桂北外,其他大部分地区出现石漠化的概率小。在同一区域,对不同承灾体而言,干旱等级的下传阈值不同,如干旱达中旱等级就可下传影响航运,达到重旱等级时可下传引发森林火灾和病虫害,而达到特旱等级时才可下传导致土壤退化。

Considering the different disaster - pregnant environment, population density and economic condition, the drought disaster chain models in southwest and south China were constructed respectively by using history data and record of references. Here, the disaster- pregnant environment includes climate background, underlying surface, landforms, soil and river network. And on this basis that the transmission characteristics of disaster on separate disaster chains were analyzed. The results show that the drought disaster chain structure is similar in southwest and south China, but their transfer process of disaster on the two chain is different. There are ob- vious regional characteristics of disaster transfer on their chain. The incipient drought can cause crop drought in southwest China, while moderate drought can cause crop drought in south China. In southwest China, the moderate drought can lead to some problems such as people and livestock drinking water difficult and livestock forage shortage, but these corresponding problems can be generated by the severe drought in south China. Being the difference in disaster - pregnant environment, the rock desertification phenomenon appears in southwest China under the severe drought condition, but the probability of rock desertifieation is small in south China except for north Guangxi. In the same region, as far as the various disaster - affected bodies are concerned, the threshold of drought degree transmitting is different. For example, shipping problems usually result from the moderate drought, and forest fire and pest disaster are often led by the severe drought, while soil degradations appear in the extreme drought.