Spatial variability of irrigation factors and their relationships with “corridor-barrier” functions in the Longitudinal Range-Gorge Region

Abstract

Based on the monthly meteorological data at 58 meteorological stations from 1971 to 2000 in the Longitudinal Range-Gorge Region (LRGR) and the surrounding areas, six factors including yearly ET0, maximum monthly ET0 (May), minimum monthly ET0 (December), paddy irrigation quota and total agricultural irrigation quota (yearly and main irrigation period from April to June) were selected to examine their spatial variability using a geostatistical approach. The results indicated that the coefficients of Moran’s I, describing the intensity of spatial autocorrelation, were greater in longitudinal direction than in other directions; the spatial variabilities of the six parameters were mainly caused by structural factor accounting for 60.2%–87.9%; the largest variabilities of ET0 (yearly, in May and December) appeared in the northwest-southeast and northeast-southwest directions. Due to the summer monsoon atmospheric circumfluence from the Indian Ocean and the Pacific Ocean, and continental warm-dry current in winter, the minimum fractal dimension and the maximum spatial variability of ET0 (yearly, in May and December) occurred in southwest-northeast and southeast-northwest directions. The highest variabilities of paddy and total agricultural irrigation requirements occurred in the south-north direction due to the vapor and energy diffusion caused by corridor function of the longitudinal rivers. The minimum spatial autocorrelation was in east-west direction, which proves that the six parameters of agricultural irrigation requirement were influenced by the “corridor-barrier” function in the LRGR and its surrounding areas.