关键词: 紫鹊界梯田, 自流灌溉系统, 降水条件, 集中度, 标准化降水指数

Abstract: In order to deeply understand the water cycle mechanism of Ziquejie Terrace in Hunan Province, a comparative study between the Ziquejie region and the surrounding areas was carried out to reveal the superior precipitation condition behind the terraces with the help of the concentration degree (DC) and rainfall standard index (ISP) methods, based on the precipitation data of 11 meteorological stations in the Ziquejie region and the surrounding areas from 1986 to 2015. The results show that the annual average rainfall in the Ziquejie region is 1 638.7 mm, which is 177.4 mm higher than that of the eight outer stations. The average rainfall in summer (from June to August) is 675.1 mm, which is 122.4 mm higher than the eight outer stations. The average DC of ten-day rainfall sequence of the three stations in Ziquejie is 0.373, which is significantly higher than the average value of 0.354 of the eight outside stations. Summer is the main predominant period of rainfall for the Ziquejie Terrace region. The average rainfall peak period in the Ziquejie Terrace region is in mid-June, later than the eight outside stations in early June or late May. The drought frequency of the three-month time scale shows the characteristics of “small first and then large”  from May to August in the Ziquejie region： The values of drought frequency in May and June are markedly less than the average value of the whole region, while the values in July and August are just the opposite. The main irrigation period of rice in the Ziquejie region lasts from mid-June to mid-August. The seasonal distributions of rainfall and drought frequency form a good match with the rice growth-period in the Ziquejie Terrace region, which is one of the important supporting conditions of the artesian irrigation system.

Key words:  Ziquejie Terrace, artesian irrigation system, rainfall condition, concentration, standard rainfall index