Lake bank filtration at Nainital,India: water-quality evaluation

There are different water-supply schemes in Uttarakhand, India to tap the water from streams, rivers and lakes. At Nainital, seven tube-wells (depths 22.6–36.7 m), located at a distance of <100 m from the lake, are being used to abstract (1) lake water after passage through the soil and (2) subsurface water/groundwater flowing towards the lake. Water samples from the lake and tube-wells were analyzed in monsoon and non-monsoon periods from 1997 to 2006. Total dissolved solids, EC, alkalinity and hardness were found to be marginally greater in tube-well waters. The difference in hydrochemistry of tube-well water was mainly due to variation in flow regimes during monsoon and non-monsoon periods. Results clearly indicate that lake water as such is not potable as it contains unacceptable levels of organic matter in terms of COD (~44 mg/L), coliforms (~15.6 × 10⁴ MPN/100 mL) and nutrients. Coliform bacteria and COD have not been detected in any of the tube-well water samples over the years. Lake water, treated by sand filters did not conform to drinking water standards. These investigations have led to the closure of the treatment facility and installation of two tube-wells in addition to the existing five tube-wells.

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Résumé  Il existe divers projets d’alimentation en eau dans l’état d’Uttarakhand, Inde, afin de capter l’eau de ruisseaux, de rivières et de lacs. A Nainital, sept puits tubés (profondeur de 22.6–36.7 m), situés à une distance < à 100 m du lac, sont utilisés pour prélever (1) de l’eau du lac après transit à travers le sol et (2) de l’eau de sub-surface/eau souterraine s’écoulant vers le lac. Des échantillons d’eau du lac et des puits tubés ont été analysés en périodes de mousson et de celles sans mousson 1997 à 2006. Résidu sec, C.E., alcalinité et dureté ont été trouvés marginalement supérieurs dans l’eau des puits tubés. La différence d’hydrochimie de l’eau des puits tubés était surtout due à la variation des régimes d’écoulement pendant les périodes de mousson et de celles sans mousson. Les résultats indiquent clairement que l’eau du lac en tant que telle n’est pas potable car elle contient des teneurs inacceptables de matière organique en termes de COD (~44 mg/L), de coliformes (~15.6 × 10⁴ MPN/100 mL) et d’éléments nutritifs. Des bactéries coliformes et du COD n’ont été détectés dans aucun des échantillons d’eau de puits tubés au fil des années. L’eau du lac traitée par des filtres à sable ne se conformait pas aux normes de l’eau potable. Ces recherches ont conduit à la fermeture de l’installation de traitement et à l’implantation de deux puits tubés en plus des cinq puits existants.

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Resumen  En el estado de Uttarakhand, India, existen diferentes esquemas de abastecimiento de agua que explotan agua de arroyos, ríos y lagos. En Nainital, siete pozos (profundidades entre 22.6–36.7 m), ubicados a una distancia de <100 m del lago, se usan para extraer (1) agua del lago luego de su pasaje a través del suelo y (2) agua superficial y subterránea que fluye hacia el lago. En períodos de monzón y de no monzón de 1997 a 2006 se han analizado muestras de agua del lago y de las captaciones. Se halló que el agua de los pozos es ligeramente mayor en términos del total de sólidos disueltos, la conductividad eléctrica, la alcalinidad y la dureza. La diferencia en la hidroquímica del agua de las perforaciones se debe principalmente a la variación de los regímenes de flujo durante los períodos de monzón y de no monzón. Los resultados claramente indican que el agua del lago no es potable por su contenido inaceptable de materia orgánica medida como demanda de carbono orgánico/oxígeno –DCO- (~44 mg/L), coliformes (~15.6 × 10⁴ NMP/100 mL) y nutrientes. En el período, no se han detectado bacterias coliformes ni DCO en las muestras de agua de las captaciones. El agua del lago, tratada con filtros de arena, no conformó los estándares de agua para bebida. Estas investigaciones han demostrado la necesidad de clausurar las instalaciones de tratamiento y la adición de dos captaciones a las cinco ya existentes.

     

柳伊河水电站大坝右岸坝区研究

In the paper in order to ascertain the condition of the right-bank of the dam at the Vilyui hydroelectric power plant measurements are applied to obtain experimental date such as drilling borehole,hydrolocation and so forth. By finding out the distribution of the temperature field some corresponding measures are taken to improve the stability of the dam during the change of the ground temperature. And finally some conclusions are draw to the study.     

三峡库区巫山县城新址岩质库岸再造预测

巫山县城新址位于西坪和大宁河两岸.组成该库段的基岩主要为泥岩、粉砂岩、泥灰岩等,岩性较软弱,且地质构造变动强烈,褶皱、断裂发育,岩层破碎,崩塌、滑坡分布较多,库岸再造问题严重;同时,岸坡再造又严重影响着新县城的规划和库岸的防护.因此把稳态坡形类比法应用于巫山县城新址基岩岸坡的再造预测,定量预测库岸的最终再造宽度,以指导新城的规划与建设.     

桥基岸坡变形破坏机制物理模拟研究

结合某大桥桥基岸坡地质条件,采用相似原理为基础的底摩擦试验方法,定性模拟分析了在天然状态和加载条件下岸坡岩体的变形破坏过程和模式。试验结果表明：在天然状态下,左右岸岸坡岩体处于稳定状态;在加载条件下,左岸岸坡岩体稳定,右岸发育的错落体失稳,而导致整个岸坡不稳定,建议对其进行预加固或改变桥墩位置     

基于模糊数学综合评判的库岸稳定性分段——以新疆某水电站近坝库岸为例

从影响库岸稳定性的诸因素中筛选出六个主要因素：坡度、坡体形态、坡体完整性程度、库水面宽度、主风向与库岸夹角及坡体结构,根据其影响程度确定了它们的权重,将库岸稳定性分为良好、较好、较差和差四级。按照各个影响因素对斜坡和各级稳定性的影响不同,对各单因素进行离散化处理,得到各影响因素的隶属度矩阵。通过对各单因素矩阵与影响因素权重运算,得到各个单元分区的稳定性评价结果。运用该方法对新疆某水电站近坝库岸段20km的稳定性进行了评价,认为稳定性较差库岸段总长约4.1km,占20.3%,主要为地质灾害分布处及工程地质条件较差的地段。该综合评判成果与现场勘察及遥感解译结果较为一致。     

支盘灌注桩单桩承载力试验研究

通过对支盘灌注桩受力机理的分析 ,结合郑州某工程支盘灌注桩试桩资料 ,利用不同的估算方法 ,对支盘灌注桩单桩承载力进行了进一步的研究。     

南水北调中线水源工程丹江口水库坍岸问题浅析

南水北调中线水源工程大坝加高后,丹江口库区内的部分库段在库水作用下易发生坍岸问题.为了预测水库坍岸范围和发生坍岸的难易程度,对丹江口水库的地形、地质条件和坍岸的影响因素和型式进行了分析.在此基础上,通过大量的调查,采取工程地质类比法预测了坍岸范围和难易程度,为对坍岸范围内的对象采取针对性的处理措施提供了地质依据.     

塔里木河下游退化荒漠河岸林地上植被与土壤种子库关系初探

以塔里木河下游为研究区,选择退化程度不同的4个典型断面19个样地,利用种子萌发法进行了两年的种子库土壤萌发实验,试图就生态严重退化区的土壤种子库与地上植被的关系以及退化程度的差异对种子库特征的影响开展针对性的研究。结果显示: ①塔里木河下游土壤种子库的基本特征是:种子库密度小、物种种类组成较单一、物种的多样性低和地上植被与种子库的相似性较低;②随退化程度的加剧,土壤种子库密度明显下降、表层种子库比例升高、一年生草本占优势逐渐向多年生草本和灌木转变、地上植被与土壤种子库物种组成上差异显著;③退化过程中种子库多样性的变化比地上植被变化要迟缓,但是在植被退化演替的末期,土壤种子库的物种多样性指数衰减的幅度又明显快于地上植被的衰减幅度;④受干旱环境和严重退化的双重影响塔里木河下游土壤种子库与地上植被的关系表现出退化演替末期共有物种数的减少和相似性明显递减的特点。     

Hydraulic properties of concentrated flow of a bank gully in the dry‐hot valley region of southwest China

To quantify spatiotemporal variation in hydraulic properties of bank gully concentrated flow, a series of scour experiments were run under water discharge rates ranging from 30 to 120 l min^?1. Concentrated flows were found to be turbulent and supercritical in the upstream catchment area and downstream gully beds. As discharge increased, values of the soil erosion rate, Reynolds number (Re), shear stress, stream power, and flow energy consumption (ΔE) increased while values of the Froude number (Fr) and the Darcy–Weisbach friction factor (resistance f ) did not. With the exception of gully headcut collapse under discharge rates of 60, 90, and 120 l min^?1, a declining power function trend (P < 0.05) in the soil erosion rate developed in the upstream catchment area, headcuts, and downstream gully beds. However, increasing trends were observed in temporal variations of hydraulic properties for downstream gully beds and the upstream catchment area. Despite significant differences in temporal variation between the soil erosion rate and hydraulic property values, relative steady state conditions of the soil erosion rate and ΔE were attained following an initial period of adjustment in the upstream catchment area, headcuts, and downstream gully beds under different discharge rates. A logarithmic growth of flow energy consumption per unit soil loss (ΔE_u) was observed in bank gullies and the upstream catchment area as the experiment progressed, further illustrating the actual reason behind the discrepancy in temporal variation between soil erosion rates and ΔE. Results demonstrate that ΔE can be used to estimate headcut erosion soil loss, but further quantitative studies are required to quantify coupling effects between hydraulic properties and vertical variation in soil mechanical properties on temporal variation for bank gully soil erosion rates. Copyright © 2015 John Wiley & Sons, Ltd.     

Predicting gravel bed river response to environmental change: the strengths and limitations of a regime‐based approach

Rivers respond to environmental changes such as climate shifts, land use changes and the construction of hydro‐power dams in a variety of ways. Often there are multiple potential responses to any given change. Traditionally, potential stream channel response has been assessed using simple, qualitative frameworks based largely on professional judgement and field experience, or using some form of regime theory. Regime theory represents an attempt to use a physically based approach to predict the configuration of stable channels that can transport the imposed sediment supply with the available discharge. We review the development of regime theory, and then present a specific regime model that we have created as a stand‐alone computer program, called the UBC Regime Model (UBCRM). UBCRM differs from other regime models in that it constrains its predictions using a bank stability criterion, as well as a pattern stability criterion; it predicts both the stable channel cross‐sectional dimensions as well as the number of anabranches that the stream must have in order to establish a stable channel pattern. UBCRM also differs from other models in that it can be used in a stochastic modelling mode that translates uncertainty in the input variables into uncertainty in the predicted channel characteristics. However, since regime models are fundamentally based on the concept of grade, there are circumstances in which the model does not perform well. We explore the strengths and weaknesses of the UBCRM in this paper, and we attempt to illustrate how the UBCRM can be used to augment the existing qualitative frameworks, and to help guide professionals in their assessments. Copyright © 2016 John Wiley & Sons, Ltd.