陕北年径流序列的谱分析研究

径流周期识别是径流模拟预测的依据。基于功率谱和极大熵谱分析原理,进行了陕北地区12个测站的年径流序列的周期识别。结果表明：最大熵谱分析具有高分辨率的周期识别的特点,陕北地区的年径流一般具有2－4年、11年左右和18－24年的水文周期。对于年径流序列长度大于35年的测站,功率谱分析和最大熵谱分析的分析结果一致,但是对于序列长度小于35年的序列,功率谱分析表现出分辨率低的不足;最大熵谱分析具有分辨率高的特点,提取的主要周期符合实际。     

溅水问题的试验研究与随机模拟

通过水力学试验,对于水舌撞击尾水形成的溅水分布进行研究,并运用随机溅水数值模型进行计算验证.研究结果表明,下游溅水区在水舌风的拖曳作用下,在平面上呈三角形分布,而降雨强度的纵向分布则符合伽玛函数形式.运用随机溅水模型得到的降雨强度分布与试验数据甚为吻合,证明该数值方法可以较好地模拟溅水雾化现象,具有较好的应用前景.     

招徕河水电工程规划设计中的几个问题

着重探讨了招徕河水电站工程规划设计中,在资料短缺的情况下径流和设计洪水的计算方法,以及受回水影响情况下水位流量关系的推求和处理方法,同时讨论了装机容量选择分析计算中应注意的问题。     

Monthly Joint Operations for the Nakdong Multi-reservoir System in Korea

Abstract

This study applies a state-of-art optimization technique, SSDP/ESP (Sampling Stochastic Dynamic Programming with Ensemble Streamflow Prediction), to derive a monthly joint operating policy for the Nakdong multi-reservoir system in Korea. A rainfall-runoff model, SSARR (Streamflow Synthesis And Reservoir Regulation), is linked to the SSDP/ESP model to provide ESP scenarios for runoff during the next month in the Nakdong River basin. The primary advantage of the SSDP/ESP is that it updates the derived operating policy as new ESP forecasts become available. Another SSDP model that employs historical runoff scenarios (SSDP/Hist) is also developed. The main difference between the two SSDP models is that SSDP/Hist is an off-line model whereas the SSDP/ESP is on-line. The developed operating policies are tested with a simulation model using an object-oriented simulation software, STELLA. The simulation results show that SSDP/ESP is superior to SSDP/Hist with respect to the water supply criterion, although both models perform similarly with respect to the hydroelectric energy production criterion.     

Modeling and analysis of effects of precipitation and vegetation coverage on runoff and sediment yield in Jinsha River Basin

This paper focuses on the effects of precipitation and vegetation coverage on runoff and sediment yield in the Jinsha River Basin. Results of regression analysis were taken as input variables to investigate the applicability of the adaptive network-based fuzzy inference system (ANFIS) to simulating annual runoff and sediment yield. Correlation analysis indicates that runoff and sediment yield are positively correlated with the precipitation indices, while negatively correlated with the vegetation indices. Furthermore, the results of stepwise regression show that annual precipitation is the most important factor influencing the variation of runoff, followed by forest coverage, and their contributions to the variation of runoff are 69.8% and 17.3%, respectively. For sediment yield, rainfall erosivity is the most important factor, followed by forest coverage, and their contributions to the variation of sediment yield are 49.3% and 24.2%, respectively. The ANFIS model is of high precision in runoff forecasting, with a relative error of less than 5%, but of poor precision in sediment yield forecasting, indicating that precipitation and vegetation coverage can explain only part of the variation of sediment yield, and that other impact factors, such as human activities, should be sufficiently considered as well.     

泾河年径流量BP神经网络模型研究

以1957—2000年的实测降水序列和泾河年径流量序列为研究对象,利用EMD法和GA建立了泾河年径流量的BP神经网络模型。分析结果表明:泾河流域年降水量变化可能存在准2～3、5～7、10～13、18～22 a的周期;基于EMD的年径流量BP神经网络模型预测值的相对误差为-4.71%～8.21%,基于GA的年径流量BP神经网络模型预测值的相对误差为2.25%～12.22%。     

桂林市青狮潭水库入库径流变化分析

采用极值比和变差系数分析桂林市青狮潭水库1958—1995年入库径流量的年际变化特征,采用距平百分率法和Kendall秩次相关法分析入库径流变化趋势。分析表明,洪水期径流年际变化最剧烈,枯水期径流年际变化最小;年径流、雨期径流、洪水期径流和枯水期径流均呈增加趋势,但趋势不显著。     

坡面植被分布对降雨侵蚀的影响研究

在黄土高原约15°的自然荒草坡面上,对两个坡面小区进行野外模拟降雨实验,其中一个从坡顶向坡底逐渐破坏地表植被和结皮,另一个从坡底向坡顶逐渐破坏地表植被和结皮,分别对破坏过程中各种植被面积下的降雨产流产沙量进行比较,结果认为:在相同面积条件下,位于坡底的植被比位于坡顶的植被保水作用高2.4倍,保土作用高2.8倍;随着植被面积的减少,坡面产流量和产沙量呈不均匀的增加趋势,在不同的植被面积变化范围,坡面产流量和产沙量的增幅不同。     

三峡库区水环境对库岸斜坡失稳的作用机理探讨

针对斜坡的稳定性与水的关系极为密切,阐述了水环境对三峡库区库岸斜坡稳定性的影响途径,从下滑力及抗剪强度等方面具体讨论了水对斜坡稳定性的影响机理,并以千将坪滑坡与石榴树包滑坡为例,论证了库区水的作用与滑坡形成的关系。     

南江县浅层土质滑坡降雨人渗规律与成因机理

为揭示土质滑坡中降雨入渗规律和滑坡成因机理,通过对四川南江县100多个滑坡进行现场调查、统计,选取二潢坪滑坡深入剖析典型滑坡成因机理,对降雨量、GPS累积位移、土体孔隙水压力、土体含水率等综合因素分析后,采用有限元数值法对滑坡的降雨人渗过程进行模拟.结果表明:浅层土质滑坡中孔隙水压力及含水率变化有明显滞后现象,降雨初期以垂直坡面入渗为主,一段时间后则以坡向渗流为主;斜坡中前缘孔隙水压力变化比后缘对降雨更敏感,其原因为前缘黏性堆积体、侧壁陡崖及基岩面共同构成斜坡储水边界;因滑体结构的各向异性,降雨过程中土体中局部孔隙水压力及渗流力瞬时剧增,土体饱水使得软黏土层发生软化,最终导致斜坡整体失稳.