Precipitation Forecast And Its Application In Drought Study Of Guanzhong Basin

This article is intended to forecast precipitation in the future for Guanzhong basin, and then to use the results achived before to identify and evaluate drought there, thus the foundation can be layed for drought early warning and rational allocation of water resources in Guanzhong basin. The main research contents and conclusions of this paper are as follows:(1)Combined with some factors such as geological landform conditions of study area, geographical distribution of meteorological stations and the length of precipitation sequence as well as its continuity, after analyzing the temporal distribution characteristics of precipitation and drought, Guanzhong basin was divided as four partitions, namely the southern plain, the western plain, the eastern plain and Weibei dryland.(2)Predicted and tested the results of yearly rainfall and monthly rainfall from 2007 to 2013 for each district, which were obtained through the four techniques, namely nearest neighbor bootstrap regression(NNBR), BP neural network, cloud reasoning and coupling model based on information entropy theory. As can be seen from the results, the four kinds of rainfall predictive methods were feasible to Guanzhong basin, but by the contrast, the predictive effect of coupling model was superior to the other three single models, which forecasted results could reflect the changing process of precipitation by a more realistic way.(3)Took the coupling model based on information entropy theory to forecast yearly rainfall and monthly rainfall from 2014 to 2020 of each partition for Guanzhong basin. The results showed that the interannual variability of rainfall was large and its seasonal wet and dry change in a year was distinct, further more, the amount of rainfall was concentrated on the three months to September, while it presented decreasing changeable rules from the west to the east in spatial distribution, which were basically in line with historical temporal distribution of precipitation in the basin.(4)The obtained predictive values were used to the identification and evaluation of drought for Guanzhong basin, and by the way of TOPSIS, the relatively prone to drought area and drought degree were analyzed as well. The results showed that, Weibei was much easier to dry than the other three regions in the year scale, while in the month scale, the eastern plain(Jan., Feb., Apr., May., June, Nov., Dec.), Weibei dryland(Mar., July, Aug.) and the west plain(Sep. and Oct.) were relatively easy to break out drought; the drought degree of Guanzhong basin in 2020 would be the most serious, its type performed severe drought, of which the summer drought and autumn drought were the main, and the most severe drought occurred in August.(5)According to the results of comprehensive evaluation for drought in the future, the causes of drought in Guanzhong basin resulted from a function of nature and human were analyzed. Thus it was proposed that reasonable explotation and utilization of water resources should be strengthened, construction of water engineering needed to be reinforced, and the systems of drought monitor and early warning had to be improved, as well as promote the construction and management of water function zones with the developing trend of drought near the future.