宁波市白溪水库水文特征演变规律分析

基于宁波市白溪水库长系列水文气象资料,采用不均匀系数、完全调节系数衡量入库流量的年内分配情况,通过极值比、变差系数、滑动平均法、累积距平法探究白溪水库降雨量、入库流量/年径流量的年际变化趋势,运用Mann-Kendall检验、滑动T检验和有序聚类检验探究径流量的可能突变年份,根据Morlet小波函数分析径流量的周期性。研究结果表明:受梅汛、台汛影响,白溪水库月入库流量呈双峰型曲线;降雨量的极值比、变差系数比入库流量的小,各阶段降雨量和入库流量的变化趋势并不完全一致;白溪水库年径流量呈略微增长趋势,其变化率为0.0 035亿m~3/a;多年平均径流量为2.54亿m~3,近10 a平均径流量为2.68亿m~3;白溪水库年径流量的突变年份为1971年,且存在着21,10,4 a的变化周期。

Analysis of hydrologic characteristics evolution law in Baixi Reservoir,Ningbo city

According to the long-term series of climate and hydrological data of the Baixi reservoir in Ningbo City, we estimated the annual runoff distribution by the nonuniformity coefficient method and the fully regulated coefficient method. The interannual variation trend of precipitation and runoff in the Baixi reservoir were forecast by the extreme values ratio method, variation coefficient method, moving average method and cumulative anomaly method. Also, we detected the abrupt changes in the runoff by the Mann-Kendall test, sliding t-test and sequential clustering analysis, and analyzed the periodic change in the runoff by Morlet wavelet. The results show that as a result of Plum rains and typhoon events, the distribution of monthly runoff in the Baixi Reservoir displays a bimodal curve. The extremes ratio and variation coefficient of precipitation are smaller than that of the runoff. Therefore, the trend of precipitation is not identical to that of runoff at different spatial scales. In addition, annual runoff of the Baixi reservoir shows a slight upward trend with a change rate of 0.35 million m3/a. The average annual runoff is 254 million m3 and the average runoff during the past 10 years is 268 million m3. The abrupt change in the runoff occurs in 1971, and runoff shows changes in periodicity of 21,10 and 4 years.