丹江口水库水沙淤积特性分析

丹江口水库是由汉江库区和丹江库区组成的并联水库.根据多年平均入库水沙资料,分析了水库的水沙特性和淤积变化.结果表明,丹江口水库入库水沙地区分布极不均匀,汉江库区来水量和来沙量占绝大多数.入库水沙年内分布也极不均匀,来水来沙量均集中于汛期.水库十流库区淤积量占全库的85%左右,支流库区淤积量在15%左右.在于流库区中,汉江库区淤积量占全库的70%左右,淤积主要发生在汉江库区.汉江库区泥沙颗粒组成常年回水区以泥土为主,占81.9%～100%;变动回水区以泥沙为主,占46.8%～98%.汉江干流库区纵向淤积特点是常年回水区淤积多,变动回水区少;从库容变化上来看,中间库段库容损失大;两头库段库容损失小.横断面淤积特点主要分布在两岸边滩.最后,对丹江口水库泥沙淤积变化进行了预测分析.     

解决陕北库坝群泥沙淤积的根本途径

在对陕北黄土高原库坝群泥沙淤积治理模式研究的基础上,从该区地貌特征、水土流失成因出发,提出了解决库坝群泥沙淤积的途径。通过采用沟头、支毛沟、干沟及坡面的综合治理,实现相对就地拦截泥沙,从而达到控制库坝淤积的目的。     

基于探地雷达的水库坝前淤积土沉积规律研究

宁夏南部黄土丘陵山区水库除险加固工程中普遍采用"坝前淤积面加坝"工法进行施工,而淤积层的分布规律对评价坝基稳定性至关重要。为勘察淤积土剖面分层情况和空间分布特征,利用探地雷达(GPR)对固原市西吉县大沙河水库坝前淤积土进行探测试验。在选定的坝前淤积土探测区域内,布设了10条测线,首先确定了雷达探测最佳图像效果的叠加次数,然后在所有测线上每隔0.5 m (共计794个测点)进行了探测。同时开挖深度为1.5 m的探槽观察淤积层剖面状况,并在不同深度剖面上取土样进行室内基本物理性质试验。结果表明:雷达探测的最佳叠加次数为512次;雷达波谱图显示在深度为0～2.5 m范围内,坝前淤积土有6层明显的沉积层理;在深度为4～9 m范围内,有清晰连续的河道河床轮廓,各测线上淤泥的沉积厚度范围为3.7～8.2 m;在探槽深度约50 cm处可以观察到明显的砂质粉土—黏质粉土的层理,与探地雷达在该位置的图像解析一致。探测试验为坝前淤积层沉降计算及工程处理措施提供了基础数据。     

岔巴沟流域不同淤积状态下淤地坝淤积深度研究

为了进一步明确次暴雨条件下淤地坝的拦沙作用,利用岔巴沟流域不同淤积状态淤地坝泥沙沉积信息,结合线性回归和相关分析等方法,研究了不同淤积状态下淤地坝淤积深度关系。结果表明:(1)不同淤积状态淤地坝的最大淤积深度和平均淤积深度由高到低为堵塞坝(1.07 m,0.62 m)>水毁坝(0.72 m,0.53 m)>完好坝(0.70 m,0.45 m)>淤满坝(0.19 m,0.15 m)。(2)不同淤积状态下坝地淤积深度与降雨强度相关性拟合不明显; 堵塞坝和水毁坝坝地淤积深度与B值(坝地面积与坝控流域面积之比)呈指数负相关,相关指数分别为0.73,0.71。(3)不同淤积状态淤地坝平均拦沙模数由大到小依次为:堵塞坝(14 274 t/km²)>完好坝(12 480 t/km²)>水毁坝(11 725 t/km²)>淤满坝(3 350 t/km²)。综上所述,暴雨条件下,堵塞坝具有高效的拦沙作用,但小库容坝地极易产生较大的淤积深度,从而对坝体产生威胁; 堵塞坝和完好坝的合理配置是流域高效滞洪拦沙的关键。     

长江上游云贵高原区泥沙来源的^137Cs法研究

通过云贵高原区龙川江流域不同源地表层土壤和坝库淤积泥沙＾１３７Ｃｓ含量的对比,结合流域土地利用现状,分析了４个不同土地利用类型小流域相对来沙量,结果表明,侵蚀裸坡和沟道重力侵蚀是坝库淤积泥沙的主要来源,随着流域面积增大,相对产少量为５４％－８５％。     

神府─东胜煤田开发对乌兰木伦河河道淤积与输沙的影响

神府─东胜煤田自1987-1993年开发以来,河道露天采煤、矿区建设排弃的大量土石碴堆积于河道或岸坡,导致河床淤积严重,输沙量骤增.乌兰木伦河下游50km净淤积1310.5×10⁴m³,平均年增加187.2×10⁴m³,输沙量比采矿前增加70%,平均年增加735×10⁴t.文中对河道淤积的泥沙来源和采矿排弃物流失量进行了深入分析,并提出该流域治理的建议与对策.     

荆江与洞庭湖区近50年水沙变化的研究

在前人研究成果的基础上，对荆江与洞庭湖区的分流分沙变化、泥沙淤积变化、水位变化三个方面进行了总结。自20世纪50年代以来，荆江三口分流分沙减小，荆江分流加大；洞庭湖的泥沙淤积减缓，湖盆内的淤积部位主要是受湖盆形状和水流来向的影响；荆江河段冲刷，城陵矶-汉口河段淤积；荆江与洞庭湖汛期水位相对抬高。泥沙淤积是水沙变化的主要因素，江湖流量的分配在水沙变化中起着重要作用，人类活动也扮演着重要的角色。     

陕北子洲县典型淤地坝淤积过程和降雨关系的研究

淤地坝作为黄土丘陵沟壑区水土流失治理的重要工程措施之一，其坝系优化布局、相对稳定性及坝地效益等受到广泛关注，但对其淤积过程研究甚少。该文通过对黄土高原淤地坝进行调查，典型坝淤积过程剖面的观测及取样分析，结合库容曲线和每个淤积层的淤积厚度求出分层淤积量。根据暴雨产沙过程原理及淤积过程降雨资料，反演淤地坝各淤积层所对应的次侵蚀性降雨，建立层淤积量与相应次侵蚀性降雨指标的相关方程。研究结果表明：坝地淤积物中层淤积量和次侵蚀性降雨的降雨侵蚀力呈幂函数关系，层淤积量和次侵蚀性降雨的最大30 min降雨强度呈指数函数关系，经检验结果良好。     

白石水库运行初期泥沙淤积观测与分析

白石水库为辽西多泥沙河流大凌河干流的控制性水利枢纽工程,水库于2000年底建成并投入运行。白石水库的初期运行近10 a,水库泥沙淤积十分严重,防沙减淤已成为水库日常运行管理的重中之重。通过对2008年底水库监控断面的淤积测量与水库来水输沙率监测值计算的对比分析,确定水库当前的淤积总量,根据断面监测数据判断泥沙淤积形态;分析水库淤积现状,提出控制或减少水库淤积的措施,从而延长水库的有效使用寿命。     

泥石流与主河交汇的试验研究

泥石流入汇主河属于复杂的非牛顿流体与牛顿流体汇流问题,由于其机理的复杂性,一直缺少这方面的研究。本文在试验的基础上,分析了泥石流入汇主河后,汇口附近各水力参数的变化规律。探讨了泥石流入汇后下游水位相对壅高与流量比以及交汇角的关系,得出相对壅水高度随流量比及交汇角的增大而增大的结论。分析了交汇口附近淤积量及淤积率与流量及流量比的关系。30°,60°和120°交汇角情况下,淤积量总体趋势是随支流流量及流量比的增大而增大,淤积率随总流量增大而减小,在主支流量相当时出现最大值;90°交汇时,淤积量随支流流量及流量比的增大而减小,淤积率随总流量增大而增大,在主支流量相当时出现最小值。     

Excess River Sedimentation at Bridges in the Raya Graben (Northern Ethiopia)

This study investigates the temporal variability and effects of bio‐climatic factors and bridges on local hydro‐geomorphic conditions that cause excess sedimentation and flood hazard in ephemeral rivers of the Raya graben (northern Ethiopia). Normalized difference vegetation index (NDVI) was analyzed using Landsat imageries of 1972, 1986, 2000, 2005, 2010, and 2014. Daily rainfall data of three meteorological stations were considered to analyze the temporal trends and return time intervals of rainfall intensity in 24 h. Stream‐bed gradient and bed material grain size were measured in 20 river reaches. Results show that the maximum NDVI values were recorded in the time interval from 2000 to 2014. Nevertheless, during this decade, the study bridges experienced the largest excess sedimentation, in some bridges up to 1·6 m. Different factors to account for it are discussed as no evidence of rainfall pattern, accountable for an increase in sediment delivery from the headwaters, is found. The field data show that channel narrowing at bridges is the main cause of thick upstream sedimentation and of increasing frequency of overbank flows during the last 15 years. A simple hydraulic approach is presented to explain the variability of sediment deposition at bridges and change in bed material grain size between the main stem and the reach right upstream of the bridge. Copyright © 2016 John Wiley & Sons, Ltd.     

三门峡水库对黄河河流地貌的影响

三门峡水库建成后,先后采用了蓄水拦沙、滞洪排沙和蓄清排浑调水调沙三种运用方式,水库在运用过程中也相应的分为三个阶段.第一阶段水库淤积严重,主要在潼关到上游大坝;第二阶段为滞洪排沙,排沙量增加幅度较大,淤积主要在潼关以下;第三阶段为蓄清排浑,使潼关以下淤积得以改善.在分析了三门峡水库运用后库区的冲淤、潼关高程的变化及库区下游河流地貌的变化情况,总结了不同运用方式下下游黄河河流地貌的变化规律.     

2003年渭河下游洪灾分析及防洪对策

 2003年渭河下游洪灾是渭河上中游地区生态恶化、水土流失严重,入渭泥沙增多、泥沙大量淤积在下游河道,抬高下游河床,南山支流堤防质量差和排洪通道不畅等因素所致。渭河下游防洪存在着泥沙大量淤积、河势不稳多变、南山支流堤防标准低、水患威胁日益严重等问题,渭河防洪对策是在渭河全流域开展水土流失综合治理和加高加固防洪大堤和南山支流堤防、加强河道整治工程等措施。     

降雨量对洱海流域稻季氮磷湿沉降通量及浓度的影响

为了探究洱海流域稻季氮磷湿沉降规律,于2016及2017年稻季在大理洱海流域收集湿沉降样品,分析样品中总磷(total phosphorus,TP)、总氮(total nitrogen,TN)、NO_3~--N、NH_4~+-N等指标及其变化规律。结果表明,TN、TP湿沉降通量主要受降雨量支配,2016与2017年稻季单次降水TN、TP湿沉降通量与降雨量均呈极显著的线性正相关关系。TN、TP湿沉降浓度总体上随降雨量的增大而减小,同时与是否发生连续降雨及是否大规模施肥有关。以2017稻季氮素湿沉降为例,2017年稻季NH_4~+-N和NO_3~--N湿沉降对TN的占比分别为53.1%和20.6%,湿沉降以NH_4~+-N为主。可溶性无机氮(dissolved inorganic nitrogen,DIN)对TN的占比随着降雨量的增大而减小,随着连续降雨的延续而增大。2016及2017年稻季湿沉降TN质量浓度分别为0.87~4.03和0.90~6.85 mg/L,均远大于湖泊富营养化阀值,对洱海水生生态系统产生不利影响。     

Relationship between large rivers and granite-cored anticlines in the Lower Pearl River System,Southeast China: An example of a long-lived drainage pattern

The larger rivers in the lower Pearl River system of SE China typically avoid outcrops of late Mesozoic granite while most of the smaller rivers transect or originate in granite. It is difficult to explain this phenomenon in terms of probability, lithology, fault control or present day topography. Analyses of sediments, planation surfaces and topography in the lower Pearl River system, indicates that distribution of most of the larger rivers is pre-Oligocene. Late Mesozoic granite exposures are typically located in cores of anticlines implying that both were coeval. These structures were developed at shallow depths and resulted in the formation of topographic highs that controlled the ancient drainage pattern of the present Lower Pearl River system. Despite exhumation of the upper part of the deformed granite, the rivers mostly retained their initial courses, i.e. skirting the granite-cored anticlinal highs and traversing adjacent areas of red bed deposition. Uplift of the SE China mainland during the Oligocene caused incision of much of the river system preserving the late Cretaceous drainage pattern.     

长江滨江城市环境保护工程之一——汉口边滩防洪及环境综合治理效益浅析

从定、动床试验及环境保护进行分析研究。定床试验:研究工程实施后,本河段的水位,流速、流态及天兴洲左右汊分流比的变化;动床试验:研究在不同典型水文年条件下的河势、河道冲淤变化及疏浚区的回淤问题,为治理方案的比选优化及工程决策提供科学依据。这是长江干流滨江城市河道整治的先声,是城市规划建设中环境保护工程实施的首例,意义重大。其环境、社会及经济等效益也将十分显著。     

Acidification in Norway — Status and trends biological monitoring — Improvements in the invertebrate fauna

The Norwegian monitoring programme of acidification include studies of invertebrates, which started in 1981. The invertebrate programme is based on kick samples from a fixed station net in 8 river systems. The stations include tributaries as well as stations in the main river. This paper deals with three rivers located in a gradient covering the range of acidic deposition in West Norway. The invertebrates are identified to species level and sorted with respect to acid sensitive and acid tolerant species, used for stating an acidification index. The spring samples generally show the highest acidification due to release of acids during snow smelt. In fall the acidity was lower and the index was less variable. A significant increase in the acidification index (reduced acidity) was recorded during fall in the period 1989 – 94 in two of the watersheds. In the third watershed no significant trend was recorded. During the years 1982 – 1988 a significant increase in the index occurred in spring in the watershed with lowest acidic deposition. The increases observed in the index is probably a result of the reductions in acid deposition in Norway.     

A study of anthropogenic seasonal rivers in China

Natural rivers may be classified into two flow durations, perennial and seasonal. However, due to strong human activities, some perennial rivers in north China have been changed into seasonal rivers, among which the most striking examples are the lower Yellow River, the lower Yongdinghe River and the lower Hutuohe River in North China Plain. These rivers can be regarded as a new category of rivers, and termed anthropogenic seasonal river (ASR) in the present study. The transformation from perennial rivers to ASRs occurs under the influence of both natural factors and human activities. In the zones with some specific combination of environmental settings, the transformation from perennial to ASRs is most likely to occur. These zones can be regarded as sensitive or susceptible zones of ASRs. In the present study, three sensitive zones of ASRs have been identified, i.e., the transitional zone from arid to semiarid climates, the zone of “superelevated river” (i.e., a river whose bed is higher than the floodplain behind the artificial levees) development, and the zone with unbalanced land–water coupling. To a great degree, the formation of ASRs in these susceptible zones is the result of the excessive water diversion by human beings for irrigation and other water demands during low-water seasons. This study shows that the major anthropogenic seasonal rivers in China such as the lower Yellow River and Haihe River, and some of their tributaries are all located in these susceptible zones.     

寿昌江河流泥沙来源研究

人类活动是影响河流泥沙淤积的重要因素,为探讨道路建设和河道破坏对河流产沙的影响,以浙江省寿昌江流域为研究对象,采用复合指纹识别示踪技术,得到了不同潜在泥沙来源区对河流产沙的贡献。结果表明:采用Kruskal-Wallis H-test(KW-H)与多元判别分析(DFA)组合、主成分分析(PCA)与DFA组合得到的指纹示踪因子,结合复合指纹示踪模型,均能够很好地区分泥沙来源,但PCA和DFA统计法得到的4个指纹示踪因子组合能更好地区分泥沙来源。在河流出口处,来自河道的泥沙最多,占河流总产沙的34.7%,其次是建设用地,其产沙贡献为总产沙的28.1%,来自林地和水田的泥沙贡献分别为24.1%,12.7%,旱地产沙贡献最小,仅为0.3%。降水、土地利用、造桥、挖沙及道路建设等是引起产沙贡献差异的重要原因。因此,寿昌江流域降雨量大,植被覆盖度高,河流泥沙主要来自人类生产建设对地表的破坏。