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1.
Birsingh Dhami Sushil Kumar Himanshu Ashish Pandey Amar Kant Gautam 《Environmental Earth Sciences》2018,77(1):21
In this study, a semi-distributed hydrologic model Soil and Water Assessment Tool (SWAT) has been employed for the Karnali River basin, Nepal to test its applicability for hydrological simulation. Further, model was evaluated to carry out the water balance study of the basin and to determine the snowmelt contribution in the river flow. Snowmelt Runoff Model (SRM) was also used to compare the snowmelt runoff simulated from the SWAT model. The statistical results show that performance of the SWAT model in the Karnali River basin is quite good (p-factor = 0.88 and 0.88, for daily calibration and validation, respectively; r-factor = 0.76 and 0.71, for daily calibration and validation, respectively). Baseflow alpha factor (ALPHA_BF) was found most sensitive parameter for the flow simulation. The study revealed that the average annual runoff volume available at the basin outlet is about 47.16 billion cubic metre out of which about 12% of runoff volume is contributed by the snowmelt runoff. About 25% of annual precipitation seems to be lost as evapotranspiration. The results revealed that both the models, SWAT and SRM, can be efficiently applied in the mountainous river basins of Nepal for planning and management of water resources. 相似文献
2.
Basin hydrogeological characterization using remote sensing,hydrogeochemical and isotope methods (the case of Baro-Akobo,Eastern Nile,Ethiopia) 总被引：1，自引：0，他引：1
Hydrogeochemical and isotopic signatures of the waters of the Baro-Akobo River Basin show deviation from signatures in other Ethiopian river basins. In this study, hydrogeochemical and isotope methods were employed to determine regional and local hydrogeology and characteristics of the basin. Optical, thermal and radar remote sensing products were used to update geological and structural maps of the basin and determine sampling points using the judgment sampling method. A total of 363 samples from wells, springs, rivers, lakes, swamps and rain were collected for this study, and an additional 270 water quality data sets were added from previous studies. These data were analyzed for their hydrogeochemical characteristics and isotope signatures. Analysis of the oxygen, deuterium and tritium isotopes shows the groundwater of the basin is modern water. Among all basins in Ethiopia, the Baro-Akobo Basin shows the highest enrichment. This indicates the proximity of the rainfall sources, which presumably are the Sudd and other wetlands in South Sudan. The hydrochemical properties of the waters show evapotranspiration is the dominant hydrologic process in the basin and explains the large amount of water that is lost in the lowland plain. Analysis of radon-222 shows no significant groundwater flux over the wetlands, which are part of Machar Marshes. This shows evaporation to be dominant hydrologic process in this zone. Results from all analyses help explain the limited holding capacity of the aquifers in the recharge zone and their vulnerability to anthropogenic impacts and climate variability. There is a trend of decreasing surface flow and rainfall and increasing water soil erosion. 相似文献
3.
板块俯冲碰撞拼合带是盆山相互作用最为强烈的地区,发育有弧前、弧间及弧后多种类型的盆地,沉积物的剥蚀搬运作用极为活跃。证据显示,沉积物搬运充填过程在构造—古地理控制型盆地中具有一定的演变规律,伴随盆地演化,沉积物轴向搬运与横向搬运呈此消彼长的互动关系。南海南北两侧均发育了大型板块俯冲拼合带及相关的沉积盆地,在盆地发育早期沉积物沿盆地长轴方向分别形成昆莺琼古河和巽他古河,以轴向搬运的方式分别把越南中部及马来半岛沉积物由西向东输送到南海,形成大型三角洲及前三角洲深水扇沉积,河流发育位置均在板块拼合转折地段。在盆地发育的成熟阶段,沉积物以横向搬运的方式进入盆地,与轴向搬运沉积物形成混合堆积。轴向搬运是洋陆碰撞拼合盆地中一种重要的沉积物搬运途径,主要受盆地形成时的构造古地理控制。 相似文献
4.
板块俯冲碰撞拼合带是盆山相互作用最为强烈的地区,发育有弧前、弧间及弧后多种类型的盆地,沉积物的剥蚀搬运作用极为活跃。证据显示,沉积物搬运充填过程在构造—古地理控制型盆地中具有一定的演变规律,伴随盆地演化,沉积物轴向搬运与横向搬运呈此消彼长的互动关系。南海南北两侧均发育了大型板块俯冲拼合带及相关的沉积盆地,在盆地发育早期沉积物沿盆地长轴方向分别形成昆莺琼古河和巽他古河,以轴向搬运的方式分别把越南中部及马来半岛沉积物由西向东输送到南海,形成大型三角洲及前三角洲深水扇沉积,河流发育位置均在板块拼合转折地段。在盆地发育的成熟阶段,沉积物以横向搬运的方式进入盆地,与轴向搬运沉积物形成混合堆积。轴向搬运是洋陆碰撞拼合盆地中一种重要的沉积物搬运途径,主要受盆地形成时的构造古地理控制。 相似文献
5.
在气候变化和人类活动日趋增强的影响下,同一流域往往面临着水资源、水环境、水生态和水沙等多种水问题,且干旱和洪涝等极端事件发生的频率日渐增强;系统治理及减缓极值化,成为流域综合治理关键任务,而提升流域对水循环多过程的调节能力则是其关键。在对中国水问题发展形势进行研判的基础上,系统剖析了传统治水模式中强调“状态改变”、“末端治理”、“过程分离”等的不足;明晰了变化环境下水问题系统治理的总体需求和生态海绵智慧流域建设的总体思路;提出了生态海绵智慧流域建设的总体技术框架和若干关键问题。生态海绵智慧流域建设将充分遵循水循环多过程的演变规律,规范人类水土资源开发活动,实现地表-土壤-地下多过程、水量-水质-泥沙-水生态的联合调控,最大限度实现“去极值化”,建设健全流域的综合服务功能,保育“山水林田湖”生命体功能。 相似文献
6.
Urbanisation and climate change can have adverse effects on the streamflow and water balance components in river basins. This study focuses on the understanding of different hydrologic responses to climate change between urban and rural basins. The comprehensive semi-distributed hydrologic model, SWAT (Soil and Water Assessment Tool), is used to evaluate how the streamflow and water balance components vary under future climate change on Bharalu (urban basin) and Basistha (rural basin) River basins near the Brahmaputra River in India based on precipitation, temperature and geospatial data. Based on data collected in 1990–2012, it is found that 98.78% of the water yield generated for the urban Bharalu River basin is by surface runoff, comparing to 75% of that for the rural Basistha basin. Comparison of various hydrologic processes (e.g. precipitation, discharge, water yield, surface runoff, actual evapotranspiration and potential evapotranspiration) based on predicted climate change scenarios is evaluated. The urban Bharalu basin shows a decrease in streamflow, water yield, surface runoff, actual evapotranspiration in contrast to the rural Basistha basin, for the 2050s and 2090s decades. The average annual discharge will increase a maximum 1.43 and 2.20 m3/s from the base period for representative concentration pathways (RCPs) such as 2.6 and 8.5 pathways in Basistha River and it will decrease a maximum 0.67 and 0.46 m3/s for Bharalu River, respectively. This paper also discusses the influence of sensitive parameters on hydrologic processes, future issues and challenges in the rural and urban basins. 相似文献
7.
<正>The Huang Shui River,a main tributary of the Yellow River,crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation.The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping.Three terraces in the Haiyan Basin,four terraces in the Huangyuan Basin,19 terraces in the Xi'ning Basin(the four high terraces may belong to another river),nine terraces in the Ping'an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized.Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River,which is located at the margin of Tibet,are different from that of the rivers at other regions.The formation process of the terrace is more complicated at the Huang Shui catchment:both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins,indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins.A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper.First,the equilibrium state of the river is broken because of climatic change and/or tectonic movement,and the river incises in all basins in the whole catchment until reaching a new equilibrium state.Then,the downstream basin subsides quickly and the equilibrium state is broken again,and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again.Finally,the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins.The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment.These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin.Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau. 相似文献
8.
Annual dissolved fluxes from Central Nepal rivers: budget of chemical erosion in the Himalayas 总被引：2，自引：0，他引：2
Christian France-Lanord Matthew Evans Jean-Emmanuel Hurtrez Jean Riotte 《Comptes Rendus Geoscience》2003,335(16):1131-1140
Annual dissolved element fluxes of Himalayan rivers from Central Nepal are calculated using published river discharge and a new set chemical data of rivers, including monsoon sampling. These are used to study the control on chemical erosion of carbonate and silicate over the whole basin. Chemical erosion of carbonate is mainly controlled by the river runoff but it can be limited by the availability of carbonate in limestone-free basin. Chemical erosion of silicate is well correlated to the runoff. However differences between High Himalayan and Lesser Himalayan basins suggest that physical erosion may also play an important control on silicate weathering. To cite this article: C. France-Lanord et al., C. R. Geoscience 335 (2003). 相似文献
9.
流域侵蚀速率的时空变化对于理解活动造山带的地貌演化具有重要意义。以阿尔泰山8个山地流域为研究对象,利用1964—2011年的水文数据,采用河流输沙量法估算了年代际山地流域侵蚀速率。首先确定悬移质、推移质和溶解质对河流输沙量的贡献,然后计算各流域的年代际侵蚀速率,并结合已有研究结果,探讨了阿尔泰山流域侵蚀速率的时空特征及其控制因素。结果表明：阿尔泰山8个山地流域的平均侵蚀速率为0.03 mm·a-1,其中乌伦古河山地流域侵蚀速率最小（0.01 mm·a-1）,额尔齐斯河支流克兰河山地流域侵蚀速率最大（0.05 mm·a-1）。进一步对侵蚀速率与气候、地形、岩性、构造和植被等因素进行相关分析,发现流域侵蚀速率与地形因子（流域面积、地形起伏度）和气候因子（径流深度、平均温度）的相关性较强,表明这些因素可能对阿尔泰山山地流域侵蚀起主要影响。与阿尔泰山百万年尺度的剥蚀速率（0.07~0.3 mm·a-1）相比,研究时段内的流域侵蚀速率偏低,这表明中亚地区晚新生代持续的干旱气候可能制约了阿尔泰山地表侵蚀。 相似文献
10.
LOUISE HANSEN ACHIM BEYLICH VALENTIN BURKI† RAYMOND S. EILERTSEN‡ OLA FREDIN EILIV LARSEN ASTRID LYSÅ ATLE NESJE† KNUT STALSBERG JAN F. TØNNESEN Associate Editor – Nick Eyles 《Sedimentology》2009,56(6):1751-1773
The sediment fill of a silled bedrock valley in Western Norway has been investigated with respect to stratigraphy and infill history using a combination of mapping, georadar, seismic profiling and drilling. A small outlet glacier occupies the head of the valley that displays a stepwise down-valley profile and terminates in a lake at 29 m above sea-level. The valley is surrounded by high, steep bedrock slopes and is characterized by a series of filled basins each limited by sills of bedrock or moraine accumulations. Till, glacial outwash and/or rockslide deposits fill in the lower half of the two larger basins. (Fan) delta deposits fringed by the deposits of alluvial fans and colluvial cones dominate the upper fill of most basins. (Fan) delta deposits interfinger downstream with lake sediments in the larger basins and fluvial deposits comprise the top fill. The overall infill pattern was controlled by deglaciation as well as basin size and shape. An overall decreasing sediment supply following deglaciation is shown in the fill of a larger basin down-valley, whereas a recently increasing sediment supply during glacier growth is reflected primarily in an upstream basin. Only the lowermost basin was exposed to a sea-level drop from 75 m above sea-level to the present lake level associated with incision and river migration. This observation is in contrast to the basins above marine influence where incision has been limited due to fixed downstream sills resulting in insignificant erosion except for some fan-head entrenchment. It follows that the fills of these small valley basins display progradational and aggradational trends of deposition and paraglacial reworking has been limited. Additionally, the study demonstrates that georadar profiling, combined with other methods, is very useful for comprehensive investigation of valley basins. 相似文献
11.
Estuaries receive large quantities of suspended sediments following the first major storm of the water year. The first-flush events transport the majority of suspended sediments in any given year, and because of their relative freshness in the hydrologic system, these sediments may carry a significant amount of the sediment-associated pesticide load transported into estuaries. To characterize sediment-associated pesticides during a first-flush event, water and suspended sediment samples were collected at the head of the San Francisco Bay during the peak in suspended sediment concentration that followed the first major storm of the 1996 hydrologic year. Samples were analyzed for a variety of parameters as well as 19 pesticides and degradation products that span a wide range of hydrophobicity. Tidal mixing at the head of the estuary mixed relatively fresh suspended sediment transported down the rivers with suspended sediments in estuary waters. Segregation of the samples into groups with similar degrees of mixing between river and estuary water revealed that transport of suspended sediments from the Sacramento-San Joaquin drainage basin strongly influenced the concentration and distribution of sediment-associated pesticides entering the San Francisco Bay. The less-mixed suspended sediment contained a different distribution of pesticides than the sediments exposed to greater mixing. Temporal trends were evident in pesticide content after samples were segregated according to mixing history. These results indicate sampling strategies that collect at a low frequency or do not compare samples with similar mixing histories will not elucidate basin processes. Despite the considerable influence of mixing, a large number of pesticides were found associated with the suspended sediments. Few pesticides were found in the concurrent water samples and in concentrations much lower than predicted from equilibrium partitioning between the aqueous and sedimentary phases. The observed sediment-associated pesticide concentrations may reflect disequilibria between sedimentary and aqueous phases resulting from long equilibration times at locations where pesticides were applied, and relatively short transit times over which re-equilibration may occur. 相似文献
12.
地球化学异常靶区优选一直是勘查地球化学所面临的核心问题。目前地球化学异常靶区优选所采取的方法,主要是基于不同地质构造单元的地球化学异常评价方法和基于多元统计而发展的多元素定量化评价指标方法,然而这些异常评价方法缺少对水系中沉积物的物质来源区域进行限定。由于在一级水系中沉积的水系沉积物主要由一级水系流域内的岩石经过风化、剥蚀、搬运,最后在水系内沉积而成,因此一级水系中的水系沉积物的物源区域可近似与水系流域等同。本文通过水系流域的提取,以水系流域作为分析单元,对1∶50000丫他幅水系沉积物进行地球化学分析评价,通过与地质矿产资料对比,证明了本方法的有效性,并且缩小了地球化学异常区域,更精确地进行靶区定位。根据本文提出的方法,通过分析区内已知矿点所处流域的地球化学元素特征,将丫他幅内已有金矿划分为两种类型,对后期找矿工作有一定的指导意义。 相似文献
13.
Assessment of soil erosion in a tropical mountain river basin of the southern Western Ghats,India using RUSLE and GIS 总被引：1，自引：0，他引：1
Revised Universal Soil Loss Equation(RUSLE) model coupled with transport limited sediment delivery(TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposition-prone areas in a tropical mountain river basin, viz., Muthirapuzha River Basin(MRB; area=271.75 km~2), in the southern Western Ghats, India. Mean gross soil erosion in MRB is 14.36 t ha~(-1) yr~(-1), whereas mean net soil erosion(i.e., gross erosion-deposition) is only 3.60 t ha~(-1) yr~(-1)(i.e., roughly 25% of the gross erosion). Majority of the basin area(~86%) experiences only slight erosion(5 t ha~(-1) yr~(-1)), and nearly 3% of the area functions as depositional environment for the eroded sediments(e.g., the terraces of stream reaches, the gentle plains as well as the foot slopes of the plateau scarps and the terrain with concordant summits). Although mean gross soil erosion rates in the natural vegetation belts are relatively higher, compared to agriculture, settlement/built-up areas and tea plantation, the sediment transport efficiency in agricultural areas and tea plantation is significantly high,reflecting the role of human activities on accelerated soil erosion. In MRB, on a mean basis, 0.42 t of soil organic carbon(SOC) content is being eroded per hectare annually, and SOC loss from the 4th order subbasins shows considerable differences, mainly due to the spatial variability in the gross soil erosion rates among the sub-basins. The quantitative results, on soil erosion and deposition, modelled using RUSLE and TLSD, are expected to be beneficial while formulating comprehensive land management strategies for reducing the extent of soil degradation in tropical mountain river basins. 相似文献
14.
Suspended sediment concentration is a major variable influencing soil erosion and loss, study on which at different spatial
scales is of great meaning to understand soil erosion mechanism and sediment transport process. Based on data from 4 sloping
surfaces and 7 basins ranging from 0.0003 to 187 km2 in area, the suspended sediment concentration in flood season (SSC) with drainage area is studied. With increasing drainage
area on the slope surfaces, the mean suspended sediment concentration in flood season (MSSC) enhances continuously until a
peak value of 685 kg m−3 occurs at the whole slope surface No. 7 runoff plot resulting from harder and harder erosion forms downslope. Entering basin
systems, the diluted action of subsurface water on the toeslope on MSSC and small water flow power Ω make a minimum MSSC value
of 568 kg m−3 occur in the first-order basin system Tuanshangou basin at an area of 0.18 km2, and then from Tuanshangou basin to larger basins, the positive feedback function among drainage density, water flow energy,
and hyperconcentrated flow as well as its reduction of settling velocity of coarser particles generates continuously increasing
MSSC with drainage area. 相似文献
15.
The salinity crisis of the Mediterranean during Messinian time was one of the most dramatic episodes of oceanic change of the past 20 or so million years, resulting in the deposition of kilometer thick evaporitic sequences. A large and rapid drawdown of the Mediterranean water level caused erosion and deposition of non-marine sediments in a large ‘Lago Mare’ basin. Both the surface loading by the Lower Messinian evaporites, and the removal of the water load resulted in isostatic/flexural rebound that significantly affected river canyons and topographic slopes. We use flexure models to quantitatively predict possible signatures of these events, and verify these expectations at well-studied margins. The highly irregular shape of the reconstructed basin calls for a three-dimensional model. Near basin margins, plate-bending effects are most pronounced which is why flexure is particularly important for a relatively narrow basin like the Mediterranean. We focus on one specific sea level scenario for the Messinian Salinity Crisis, where most of the evaporite load was deposited during a sea level highstand, followed by a rapid desiccation. Evaporite loading at current sea level is expected to cause subsidence of the deep basins by hundreds of meters and simultaneous uplift of continental parts of the margins. Differential uplift may lead to significant slope angle changes and thus gravity flows. The relative scarcity of Lower Evaporite sequences along the margins may be a result of these phenomena. Normal faulting of Lower Evaporite and older sediments and rocks is expected on the margins. Desiccation enhances erosion of the freshly exposed continental shelf and slope. Subsidence and riverbed sedimentation occurs on the continental margins, and significant uplift towards the basin center. Reverse faulting is predicted at the margins. Finally, regional isostatic uplift following Zanclean flooding is predicted to destabilize margin slope deposits, and to cause marginal uplift, river down-cutting, and normal faulting. 相似文献
16.
三峡如何贯通并实现东流的问题历来是学术界关注和争议的问题。笔者认为,三峡的连通不是简单的江汉平原水系与四川盆地水系的连通,而是包括三峡库区段众多中小盆地及其水系的纵横交织性连通,连通过程中有地表水的溯源侵蚀作用,也有地下水的溶蚀、风化和侵蚀作用。地表水的流路与地下水的流路不尽相同,地下水的作用形成地下河,许多峡谷是地下河经进一步溶蚀垮塌形成的。地表河与地下河相连接构成长江主河道。虽然当时的水流有东西分流,但没有明显的分水岭,许多地段水流的方向因各盆地降雨量的变化而频繁改变。由于河流下切和新构造运动造成地表西升东降,最后流向四川盆地的水改向东流,形成统一的长江。三峡库区段是年轻的河段,成为完全地表河和东流的时间不长。这些认识对深化大江大河的成因理论具有重要的意义。 相似文献
17.
Müsteyde Baduna Koçyiğit Hüseyin Akay Ali Melih Yanmaz 《Arabian Journal of Geosciences》2017,10(15):331
The main goal of this study is to investigate the effect of the size of the subbasins of a watershed on the hydrologic parameters and their spatial variability in an estimation of the hydrologic parameters and hydrograph of a neighbouring ungauged basin. In this paper, Hydrologic Engineering Center-Hydrologic Modelling System (HEC-HMS), a semi-distributed hydrologic model, is used to calibrate and cross-validate two flood events occurred in 1998 and then validate four other flood events occurred in 1991, 1994, 2002, and 2009 in Gokirmak Basin in Western Black Sea Region, Turkey. The basin is divided into seven different subbasins to investigate the effect of watershed partitioning on calibrated hydrologic parameters of each subbasin using the peak-weighted root mean square error method as an objective function and the hydrograph at the outlet of the whole basin. It is found out that as the geometric magnitudes of the subbasins changed, the calibrated values of the hydrologic parameters of those subbasins changed as well. Then, a neighbouring basin, Kocanaz, is considered as an assumed neighbouring ungauged basin to investigate the effect of watershed partitioning of a gauged basin on the estimation of hydrograph of a neighbouring ungauged basin. Hydrologic parameters and direct runoff hydrograph of assumed ungauged neighbouring basin are estimated from the hydrologic parameters of the HEC-HMS calibration results of Gokirmak. Statistical indicators of the simulation results for each basin partitioning were graded with respect to the boundary values of the simulation outputs to find the best alternative. The grading results show that the simulation results with a single basin gave better representation among all other partitioning except two flood events. 相似文献
18.
通过对克里雅河、毛布拉格孔兑以及西拉木伦河三流域的河流-沙漠过渡带地表沉积物的7种常量氧化物以及15种微量元素进行因子分析,结果显示:三个流域之间或不同河段因子分析提取的公因子均可以概括为较稳定的铁锰矿物、较不稳定的长石类和方解石（白云石）类等硅酸盐矿物以及稳定的稀土元素和重矿物等类别;河流间因子分析结果表明,自西向东三个流域沿河地表沉积物的化学元素富集与迁移程度呈递增趋势,化学风化程度增强;流域内因子分析结果表明,自上游至下游,样点化学组成均愈变复杂,不同河段或不同河岸沉积物化学元素空间分布规律与其物源、地貌格局以及水分条件等因素有关;自河床至阶地,不同地貌单元地表沉积物化学元素呈相异的递变规律,这与在距离河道远近不同,物源、动力因素的分配不同有关。 相似文献
19.
陆相盆地充填层序的类型--以辽西地区中生代盆地为例 总被引：6，自引：1，他引：6
辽西地区在中生代发育了各种类型的陆相盆地，形成各种类型的地层。在按层序定义识别出不同盆地、不同时间的层序基础上，根据地质作用营力（如水、风和火成作用）、沉积介质与地质环境的特点将该区盆地充填的层序划分为湖盆层序、冲积层序、沙漠层序和火山层序等类型。对于不同类型的层序不仅其层序内部组成各异而且其层序控制因素也不尽相同。湖盆层序是指在湖盆地内由沉积作用形成的一类层序，表现为随湖水面的升降变化沉积体系或体系域在时空上的变化。一个完整发育的层序可以反映出一个水侵-水退的湖水变化周期。冲积层序是指在流域盆地中以冲积沉积作用为主而形成的一类层序，其不明显地受蓄水面的控制，但受潜水面的影响和地形及侵蚀基准面的控制。沙漠层序是指在风介质的条件下以沙漠沉积为主体的一类层序。火山层序是指由于火山作用导致的火山物质（包括沉积物）在盆地内的充填所形成的层序，通常发育在断陷盆地的早期阶段，由火山岩、火山碎屑岩、凝灰岩和沉积岩所构成。在辽西地区中生代盆地和各类型层序的控制因素中，构造因素是第一位的，表现在层序界因多为构造界面，如区域角度不整合面、平行不整合面以及构造转换面等。但各类型层序的具体控制因素是有差异的。 相似文献