Abstract
In this study, the ecological effects of intermittent water allocation with emphasis on spatiotemporal responses of the corresponding vegetation were analyzed using remote sensing data and GIS-based buffer technology considering the period from 1st July 2000 to 31st December 2009. Three sampling sites (Angzh, Wangk, and Xidayang) with different water flow paths and three buffer distances were distinguished in the research. The Seasonal-Trend decomposition procedure based on Regression (STR) trend extraction and its corresponding linear regression and anomaly detection were executed to determine temporal variations of vegetation under the effects of water allocation. ANOVA and PCA methods were employed to identify the spatial responses of vegetation to different water flow paths and buffer distances. The results were as follows: (1) NDVI except NDVImin displayed higher values during the period without water allocation; (2) extremely significant decline trends (p<0.001) of all NDVI categories were observed in all sites at all buffer distance levels, except for NDVImin at buffer distances of 2 km and 4 km in Angzh, showing stronger fluctuations of frequency after 2008 as well as the decline gradient with the extent of buffer distance to river. The anomaly detection results provided similar evidence of stronger NDVI fluctuations after 2008; (3) water allocation had extremely significant effects on regional vegetation coverage (p<0.01) with a decline gradient of statistical p values along enlarged buffer distances. Our results provide evidence of spatial and temporal differences in vegetation response to water availability due to the intermittent frequency water allocation implemented via different river channels. The findings of this study will deepen our understanding of the effects of water division on regional vegetation restoration and can be used to develop a practical strategy for effective implementation of water allocation.