新疆和田河流域河川径流时序特征分析

根据新疆和田河流域3个测站的多年实测径流资料,从径流的年内分配和年际变化2个方面分析了和田河流域河川径流的变化特征。计算结果表明,在年内分配方面,由于径流补给来源的作用,流域径流绝大部分集中在夏季,这就使得径流年内分配不均匀系数和集中度普遍较高,而计算所得的集中期也与实测最大月径流出现的情况相吻合。在径流的年际变化方面,尽管和田河流域的年降雨量存在递增的趋势,但是由于源区高山的雪线高程上升、冰川退缩,再加上人类活动的影响越来越显著,从而导致流域的河川径流呈现微弱的下降趋势。经过周期图法分析得到,和田河流域的年径流量不存在明显的周期成分。

Analysis on the Characteristics of Annual Runoff in Hotan Catchment

The runoff of a catchment is affected comprehensively by human activities and natural conditions such as soil,vegetation,climate,etc.Therefore streamflow represents the characteristics of determinacy as well as stochasticism.Researches on runoff characteristics are beneficial for the sustainable utilization of water resources,water conservancy planning and agricultural develop-ment. The study area of this paper is Hotan catchment,which is located in the Tarim River Basin in southern Xinjiang,with an area of 48 870km2.The Hotan River is of great importance to ecosystem and society in Taklimakan Desert,because it is the only river that traverses the desert.The paper analyzed the intra-annual distribution and annual variation of runoff in the catchment according to observed data.Some indexes,including the coefficient of nonuniformity,the degree of concentration and the time of concentration,were used to analyze the intra-annual distribution of runoff;the methods of Kendall rank test and periodgram were used to analyze the trend and period of multi-annual runoff. The results show that due to the impacts of runoff-supplying sources,the intra-annual nonuniformity is very high,being more than 75% of the annual total runoff in summer.The coefficient of nonuniformity and the degree of concentration are much bigger than the normal,and the computed time of concentration is in accordance with the time of the observed maximum monthly runoff.The streamflow concentrated in some period of time could possibly arise the conflicts between water usage and supply,which will restrict the sustainable development of agricultural production and the socioeconomy.The Hotan River Basin is supplied by the glaciers and snow mountains,so the statistic of annual runoff Cv is small which indicates that the variation of annual runoff is weak.The annual precipitation,temperature and human activities exert impacts on the variation of runoff.The precipitation influences the runoff directly,in the past 40 years,the precipitation in the Hotan catchment presented an increasing trend.Under the background of global warming,the snow line on the mountains is hoisting and the glacier is shrinking.And with the development of agriculture,the irrigation water requirement is increasing constantly.Owning to the effect of these factors,the runoff in Hotan catchment presents a weak declining trend.The result of periodical analysis is that the annual runoff has no obvious periodicity.