基于SOM神经网络的年径流划分 ——以密云水库为例

传统的年径流划分往往通过年径流量的数量指标划分丰水年、平水年与枯水年.但仅仅通过该方法难以反映年内径流分布的情况.引入SOM神经网络,根据径流序列的月径流量、集中度与集中期,年内不均匀系数等指标,进行年径流序列的划分,得出具有年内特征的年径流划分成果.并以密云水库为例,对密云水库年径流进行了应用研究,将密云水库年径流序...     

邯郸市屋面雨水径流污染物变化规律研究

通过对邯郸市城区屋面雨水径流水质进行分析测定,发现城区雨水径流水质污染严重.一般规律为:初期径流污染最为严重,随降雨历时的延长,污染物浓度逐渐下降并最终趋于一个稳定值.影响雨水径流水质的主要因素有屋面材料、气温、降雨量、降雨强度和降雨时间等,其中屋面汇水面性质对雨水径流水质影响较大,水质污染状况主要取决于屋面材质.根据实验结果结合邯郸市的实际情况提出了改善雨水径流水质的建议,为城区屋面雨水利用提供参考.     

加权马尔可夫链在新疆阿克苏河年径流量预测中的应用

径流预测在水资源规划中发挥着重要作用.基于径流过程不确定性、不精确性的特点,利用资料系列的均方差方法把径流序列分为不同的状态.在此基础上,采用统计方法,建立转移概率矩阵,以规范化的各阶自相关系数为权重.用加权马尔可夫模型预测径流状态,并根据模糊集理论中的级别特征值预测径流量,最后把加权马尔可夫预测模型应用于新疆阿克苏河径流丰枯状态及年径流量的预测中,结果令人满意.     

辽河流域径流序列特性分析

以辽河干流、浑河、太子河3个子流域为研究区域,依据地域代表性选取辽河干流石佛寺水文站、浑河沈阳水文站、太子河辽阳水文站为分析测站,依据各测站1956-2000年月径流资料,分析辽河流域径流年内、年际变化规律.结果表明:辽河流域径流年内分配极不均匀,月径流变化幅度比较大,其中辽河干流最大月径流可占年总径流的60%以上;径流年际变化趋势不显著,约存在10a、12a、19a、21a的周期.     

基于小波分析-PSO优化ANFIS的径流组合预测模型研究

径流序列由于多种因素的影响,存在十分复杂的变化特性,如果利用常规方法直接进行预测,其预测精度一般不高.如果将径流序列分解成比较简单的序列,再利用非线性预测方法进行预测,其精度将会得到提高.利用小波分析的多分辨率分解功能对径流序列进行分解,降低了径流序列的复杂程度.利用PSO对自适应神经模糊推理系统的网络参数进行优化,提高模型结构参数的确定精度.将小波分析与PSO优化的ANFIS进行组合对径流序列进行预测,经实例验证:该模型能够提高径流预测的精度,预测效果较好.     

屋面集雨径流水质及初期弃流雨量研究

对屋面初期雨水径流水质进行了现场试验,对雨水径流的悬浮物和COD污染物指标进行了取样分析.结果表明,屋面雨水径流的初期冲刷效果明显,且雨水径流中的污染物浓度的变化符合指数形式的变化规律.在此基础上,提出屋面雨水利用的初期雨水弃流量,为雨水集蓄的实际应用提供参考依据.     

北部湾经济区径流、降雨分配特点及其变化分析

基于1970-2008年南流江常乐水文站、钦江陆屋水文站月均实测径流、降雨资料,采用年内分配不均匀系数、变差系数、绝对变化比率、年际不均匀系数、距平百分率等指标分析北部湾经济区径流、降雨的年内分配、年际变化特点,采用线性趋势线法、双累积曲线法分析径流、降雨的变化趋势.结果表明,南流江、钦江实测径流量与降雨量年内分配呈单峰型,径流、降雨年内分配不均系数呈上升趋势,径流的多年变化大于降雨,径流量的年际变化均匀度较差.降雨旱涝等级变化波动小,而径流丰枯等级变化波动频繁.实测径流系数呈下降趋势,降雨径流关系存在减小的规律.     

基于改进模糊支持向量机方法的车尔臣河径流预报

针对径流时间序列固有的非线性和随机性特点,本文提出了基于灰色关联分析的模糊支持向量机预报方法.该方法在传统支持向量机任意逼近的非线性映射能力上,引入模糊隶属函数来考虑气候和流域下垫面变化下径流样本对预报结果的影响.此外,预报因子选取是中长期径流预报的一大难点,考虑到相关系数法只能衡量因子间线性相关程度的不足,本文采用灰色关联分析来量化预报因子与预报对象的关联程度,并按关联度大小挑选出对径流过程影响显著的预报因子.将该方法应用于新疆车尔臣河的月径流预报中,与GRNN神经网络模型和A-FSVM模型的预报结果比较表明:该方法能提高径流中长期预报精度,是一种有效的径流时间序列预测模型.     

土壤中Cr(Ⅵ)的地表径流迁移试验研究

为了探讨农田土壤中重金属的地表径流污染,以含有吸附性溶质重铬酸钾Cr(Ⅵ)的土壤为试验材料,开展了室内模拟降雨试验,以研究土壤中Cr(Ⅵ)的地表径流迁移规律.通过对比分析不同试验条件下地表径流中溶解性溶质Cr(Ⅵ)的质量浓度变化过程,及其在地表径流和地下排水溶液中流失的质量速率过程后发现,溶解性溶质Cr(Ⅵ)流失到地表径流溶液中的质量浓度随时间以乘幂函数形式减小.当试验中地下排水条件越差、土壤初始体积含水率越大、地表最大积水深度越浅时,土壤溶质流失到地表径流中的溶解性Cr(Ⅵ)质量浓度越高,相应的土壤溶质流失到地表径流中的质量速率越大.当试验中同时有地下排水和地表径流产生时,土壤中溶解性Cr(Ⅵ)流失到地下排水中的质量速率远远大于地表径流,表明土壤中溶解性Cr(Ⅵ)大部分流失在地下排水中.     

基于DEM的华南森林小流域月径流模拟研究

森林小流域土壤的降雨入渗率大,地表产流量小,壤中流对径流的贡献相对较大,且对径流贡献较大的产流面积主要分布在河道毗邻的区域,目前针对森林小流域的月径流模拟尚不多见.根据上述森林小流域降雨入渗及产流的特点,以东莞市水濂山小流域为研究对象,利用DEM数据推导出小流域月径流的计算公式,建立了森林小流域的月径流模拟模型,取得了良好的效果.     

涪江流域径流量变化及对武引灌区引水的影响

研究运用涪江武都引水枢纽段1984-2010年的年径流量和月径流量资料分析流域径流量变化规律,并结合2005-2010年武引灌区实际引水情况分析流域径流量变化对灌区引水的影响。根据研究,涪江武都引水枢纽段具有年径流量线性下降、年代际平均径流量下降、年径流量丰枯波动等特征,而未来灌区需水总量将大幅增加,将对灌区引水总量产生影响;涪江发生枯水的月份与灌区灌溉用水时间的吻合,加剧了灌区供用水的矛盾,将对灌区引水时间产生影响。因此,应采取积极的措施应对径流量的变化,使武都引水工程更好地为灌区工农业生产服务。     

自然降雨对紫色土坡耕地氮磷流失的影响

在三峡库区主要土壤类型(紫色土)、不同坡度(15°、25°)、不同种植模式(柑桔-牧草、蔬菜-马铃薯、玉米-小麦)上建立径流池,研究自然降雨条件下土壤氮磷流失特点。结果表明,土壤氮、磷流失量和流失率在降雨量增加到一定程度时即达最大值,继续增加降雨量,氮、磷流失量和流失率呈下降趋势。氮、磷流失量和流失率同72h内降雨量呈S曲线关系。径流水中总氮(磷)量和浓度同坡度和种植模式无显著性差异。径流水中总氮(磷)浓度随降雨量增加无明显增加趋势,径流水中总氮流失量随降雨量的增加也无明显增加趋势,但径流水中总磷流失量随降雨量的增加呈直线增加。     

Polymer effects on runoff and soil erosion from sodic soils

High levels of soil sodicity, resulting from intensive irrigation with saline-sodic waters, lead to an increased soil susceptibility to seal formation and to severe problems of runoff and soil erosion. The objective of this study was to investigate the efficacy of the addition of small amounts of an anionic polyacrylamide (PAM) to the irrigation water in controlling seal formation, runoff and soil erosion. Two predominantly montmorillonitic soils were studied, a grumusol (Typic Haploxerert) and a loess (Calcic Haploxeralf), having naturally occurring exchangeable sodium percentage (ESP)>12. The soils were exposed to 60 mm of simulated irrigation with commonly used tap water (TW, electrical conductivity=0.8 dS m^–1; sodium adsorption ratio (SAR)=2), or saline water (SW, electrical conductivity=5.0 dS m^–1; SAR>12). PAM effectiveness in controlling runoff and erosion from the sodic soils was compared with runoff and erosion levels obtained from untreated soils having low ESPs (<4). For both soils and for both water qualities and polymer concentrations in the irrigation water, PAM was efficient in controlling runoff at low ESP levels and inefficient at high ESP levels. At moderate ESP levels, PAM's efficacy in controlling runoff was inconsistent and varied with water quality and polymer concentration. Conversely, in general, soil loss originating from rill erosion, was significantly and effectively reduced in moderate and high ESP soils by addition of PAM to the irrigation water, irrespective of water quality and polymer concentration. PAM was more effective in reducing rill erosion than in reducing runoff in the moderate and high ESP samples, because the energy involved in generating runoff is much higher than that involved in rill erosion. PAM treated surface aggregates were not stable against the distructive forces leading to seal formation and runoff production; but they were stable enough to resist the hydraulic shear exerted by the runoff flow.     

基于自动监测径流场的秸秆覆盖坡耕地产流产沙过程

设计了一个可用于坡面侵蚀过程研究的自动监测径流场,该径流场主要由6个径流小区和1套模拟降雨装置组成。采用德国UGT径流测量装置,实现地表径流的自动采样和记录。用设计的径流场对秸秆覆盖坡耕地的产流产沙过程进行了研究,结果表明相对于裸露地表,秸秆覆盖能明显降低各径流小区的产流率和产沙率,延缓产流增加趋势,减少产沙总量达54.5%~63.8%。因此,增加坡耕地土壤表面的秸秆覆盖量可有效避免产流在短时间内急剧增加,并能减少对土表的冲刷作用。     

气候变化对多年冻土区径流组成的影响分析——以长江源区为例

以多年冻土为主要下垫面的寒区流域水资源对气候变化敏感,以长江源区为例,根据数字滤波法对直门达水文站1966-2015年月径流的基流分析结果,明确了长江源区径流及其不同成分的变化规律;进一步利用格兰杰因果检验和累积斜率法分别定性和定量地分析了降水和温度对径流组成的影响。结果表明:近50年来,长江源区总径流呈现增加趋势,2004年发生突变后年平均径流量增长36.49亿m~3,基流和地表径流各贡献了50%;近50年持续地增温是引起径流变化的格兰杰原因,更有助于对河道径流成分变化的预测分析;对比径流突变前后,增温不仅改变降水形式,影响了地表产流,同时也改变了下渗后土壤水的冻融过程,对基流和地表径流改变的贡献率分别为90%和76%、高于降水变化68%和57%的贡献率。气候变化背景下,持续的增温对降水产流和下渗过程的影响,是多年冻土区流域径流成分变化的主要原因。     

Micro-catchment water harvesting potential of an arid environment

Micro-catchment water harvesting (MCWH) requires development of small structures across mild land slopes, which capture overland flow and store it in soil profile for subsequent plant uses. Water availability to plants depends on the micro-catchment runoff yield and water storage capacity of both the plant basin and the soil profile in the plant root zone. This study assessed the MCWH potential of a Mediterranean arid environment by using runoff micro-catchment and soil water balance approaches. Average annual rainfall and evapotranspiration of the studied environment were estimated as 111 and 1671 mm, respectively. This environment hardly supports vegetation without supplementary water. During the study period, the annual rain was 158 mm in year 2004/2005, 45 mm in year 2005/2006 and 127 mm in year 2006/2007. About 5000 MCWH basins were developed for shrub raising on a land slope between 2 and 5% by using three different techniques. Runoff at the outlets of 26 micro-catchments with catchment areas between 13 and 50 m² was measured. Also the runoff was indirectly assessed for another 40 micro-catchments by using soil water balance in the micro-catchments and the plant basins. Results show that runoff yield varied between 5 and 187 m³ ha⁻¹ for various rainfall events. It was between 5 and 85% of the incidental rainfall with an average value of 30%. The rainfall threshold for runoff generation was estimated about 4 mm. Overall; the soil water balance approach predicted 38-57% less water than micro-catchment runoff approach. This difference was due to the reason that the micro-catchment runoff approach accounted for entire event runoff in the tanks; thus showed a maximum water harvesting potential of the micro-catchments. Soil water balance approach estimated water storage in soil profile and did not incorporate water losses through spillage from plant basins and deep percolation. Therefore, this method depicted water storage capacity of the plant basins and the root zone soil profile. The different between maximum water harvesting potential and soil-water storage capacity is surplus runoff that can be better utilized through appropriate MCWH planning.     

基于SWAT模型的沂蒙山水土流失治理区地表水与地下水转化规律研究

为研究沂蒙山水土流失治理区,气候及植被覆盖变化影响下,水资源转化规律,以蒙阴县岸堤水库控制流域为研究对象,采用归一化植被指数(NDVI)为指标,分析植被覆盖的时空变化规律,采用分布式水文模型SWAT研究流域水文要素的时空演变规律,定量分析地表水与地下水转化量。计算结果表明:2000-2016年,流域NDVI呈增大趋势,其中2007-2009年,NDVI显著增大;空间上,84%的流域面积NDVI都呈现增加趋势。SWAT模型模拟效果较好,1990-2016年,流域平均降水量611.96 mm,径流量225.96 mm,地表径流量126.07 mm,基流量72.07 mm,潜水补给量119.52 mm。径流量中,地表径流占55%,基流量占27%,壤中流占18%。潜水的补给中,地表水量仅占5%左右,主要补给水源为降水。在气候条件与地表植被覆盖条件的综合影响下,2006年前后地表径流减少22%,地表水向地下水转化量减少,地下水向地表水转化量增多。研究成果可为沂蒙山区水资源的合理开发利用、水土流失治理提供理论依据和技术支撑。     

挠力河流域径流变化特征与影响因素分析

挠力河作为三江平原最大的流域,其径流变化过程对三江平原的社会经济发展、生态环境变化起着至关重要的作用。为获取该流域的径流量变化特征,首先采用线性趋势分析法和Mann-Kendall趋势检验法对流域4个代表性水文站径流序列进行趋势分析,然后采用滑动移除近似熵法(MC-Ap En法)和Mann-Kendall突变检验法分别对径流进行突变检验,并对径流发生变化的原因进行了探讨。结果表明:挠力河流域上、中、下游径流量分布不均匀,且同一水文站径流年际变化较大,不利于挠力河流域水资源的开发利用;挠力河流域近50 a来径流量呈明显的减少趋势,其中宝清站、保安站、菜咀子站径流下降趋势明显;挠力河径流量在1966年发生突变,突变后径流呈明显的减少趋势,发生突变的主要原因是降雨量减少、农业开垦的扩张以及水利工程建设的日益增多;滑动移除近似熵法在进行径流突变分析的过程中,表现出精确度高、抗干扰能力强等特点,是一种适于径流序列突变检测的方法。     

Water balance and water use efficiency of different land uses in western Himalayan valley region

Various land uses, including sole plantations of leucaena and eucalyptus, maize–wheat, chrysopogon grass or turmeric and their tree crop mixtures were compared for period of nine years in two sequences for runoff, water use and water use efficiency on nine large erosion plots on 4% slope. Availability of water during summers and climatic evaporative (EP) demand during winters appear to be the governing factors for seasonal water use. About 70% of annual water consumption occurs during the four months (July to October) of rainy season. During this season water use was about 3–4 times to EP for trees and grass and 2.5 times for maize. The water use equals EP regardless the land use during winter season, while it reduced to about one-third to half of EP in the summer season. Annual water use is found to be closely linked with runoff reduction efficiency of the land use. Sole plantations of leucaena and eucalyptus showed negligible runoff losses and their water use approximated annual rainfall. Agroforestry land uses also reduced runoff and increased water use and water use efficiency. Seasonal crops exploited 1.5 m depth of profile more exhaustively than trees, whereas trees used soil water down to 3.0 m depth. Therefore, in tree crop mixtures more efficient soil water use was observed as compared to monocropping systems. Results of this study indicate that water conserved under sole tree plantations and due to tree intervention in agroforestry land uses through runoff reduction, is utilised to meet increased evapotranspiration demand, and hence ground water recharge in appreciable quantities is unlikely.