Temporal and spatial variations in water discharge and sediment load in the Alaknanda and Bhagirathi Rivers in Himalaya, India

The Alaknanda and Bhagirathi Rivers originate in the mountainous regions of the Himalayas (Garhwal) and result in high sediment yields causing flood hazards downstream of the Ganga River and high sediment flux to the Bay of Bengal. The rivers are perennial, since runoff in these rivers is controlled by both precipitation and glacial melt. In the present study, three locations in the upper reaches of the Ganga River were monitored for 1 yr (daily observations of, more than >1000 samples) for suspended sediment concentrations. In addition, more than one hundred samples were collected from various locations of the Alaknanda and Bhagirathi Rivers at different periods to observe spatial and temporal variations in river suspensions. Further, multi-annual data (up to 40 yrs) of water flow and sediment concentrations were used for inferring the variations in water flow and sediment loads on longer time scales. In most previous studies of Himalayan Rivers, there has been a general lack of long term water flow and sediment load data. In the present study, we carried out high frequency sampling, considered long term discharge data and based on these information, discussed the temporal and spatial variations in water discharge and sediment loads in the rivers in the Himalayan region. The results show that, >75% of annual sediment loads are transported during the monsoon season (June through September). The annual physical weathering rates in the Alaknanda and Bhagirathi River basins at Devprayag are estimated to be 863 tons km⁻² yr⁻¹ (3.25 mm yr⁻¹) and 907 tons km⁻² yr⁻¹ (3.42 mm yr⁻¹) respectively, which are far in excess of the global average of 156 tons km⁻² yr⁻¹ (0.58 mm yr⁻¹).     

Sediment records as archives of the Late Pleistocene-Holocene hydrological change in the alluvial Narmada River basin, western India

The rivers of western India are monsoon dominated and have been so throughout the late Quaternary. Sediment accumulation in these river basins has been controlled by climatic and tectonic changes over a time span from the Late Pleistocene to the recent. The lithofacies assemblages associated with the various sediment archives in the Narmada basin range from the boulders of the alluvial fans to overbank fines on the alluvial plains. Estimates, based on clast size, of stream power and competence, bed shear stress and discharge reveal that hydrological conditions during the Late Pleistocene (∼90 ka) were comparable to the present day. The size of the transported clasts and the thickness of the accumulated sediment indicate the influence of basin subsidence rather than an increase in discharge. Discharge estimates based on sedimentary structures preserved in the alluvial-plain facies suggest that the channel had a persistent flow, with a low width-depth ratio and large meander wavelength. The hydrological changes during the Holocene are more pronounced where the early Holocene is marked by a high-intensity hydrological regime that induced erosion and incision of the earlier sediments. The mid-Holocene stream channel was less sinuous and had a higher width-depth ratio and a higher meander amplitude in comparison with the present-day channel. Palaeo-fluvial reconstructions based on the sediment archives in the alluvial reach of the river basin are important tools in understanding the long-term hydrological changes and the intricate fluvial architecture preserved in the Narmada River basin ensures scope for detailed studies to identify phases of weak and enhanced hydrological regimes.     

Occurrence of volcanic ash in the Quaternary alluvial deposits,lower Narmada basin,western India

This communication reports the occurrence of an ash layer intercalated within the late Quaternary alluvial succession of the Madhumati River, a tributary of the lower Narmada River. Petrographic, morphological and chemical details of glass shards and pumice fragments have formed the basis of this study. The ash has been correlated with the Youngest Toba Tuff. The finding of ash layer interbedded in Quaternary alluvial sequences of western Indian continental margin is significant, as ash being datable material, a near precise time-controlled stratigraphy can be interpreted for the Quaternary sediments of western India. The distant volcanic source of this ash requires a fresh re-assessment of ash volume and palaeoclimatic interpretations.     

Geochemical factors controlling the chemical nature of water and sediments in the Gomti River, India

 R-mode factor analysis of the recently acquired data on water and sediment chemistry has been performed. Basic chemical parameters have been merged together which aid in interpreting a few empirical geochemical factors controlling the chemical nature of water and sediments of the Gomti River, a major Himalayan tributary of the Ganges drainage basin. Water chemistry seems to be controlled by three factors: bicarbonate, rainfall and silicate and phosphate factors. Sediment chemistry is largely controlled by the following four factors: clay, adsorption/desorption, Fe-Mn hydroxide and mercury factors. These factors show spatial and temporal variability in terms of their R-scores. Received: 8 September 1997 · Accepted: 15 December 1997     

Hydrochemistry of reservoirs of Damodar River basin, India: weathering processes and water quality assessment

Water samples collected from the six reservoirs of Damodar River basin in pre- and post-monsoon, have been analysed, to study the major ion chemistry and the weathering and geochemical processes controlling the water composition. Ca, Na and HCO₃ dominate the chemical composition of the reservoir water. The seasonal data shows a minimum concentration of most of the ions in post-monsoon and a maximum concentration in pre-monsoon seasons, reflecting the concentrating effects due to elevated temperature and increased evaporation during the low water level period of the pre-monsoon season. Water chemistry of the reservoirs strongly reflects the dominance of continental weathering aided by atmospheric and anthropogenic activities in the catchment area. Higher concentration of SO₄ and TDS in Panchet, Durgapur and Tenughat reservoirs indicate mining and anthropogenic impact on water quality. The high contribution of (Ca+Mg) to the total cations, high concentration of dissolved silica, relatively high (Na+K)/TZ⁺ ratio (0.3) and low equivalent ratio of (Ca+Mg)/(Na+K) suggests combined influence of carbonate and silicate weathering. Kaolinite is the possible mineral that is in equilibrium with the water, implying that the chemistry of reservoir water favours kaolinite formation. The calculated values of SAR, RSC and sodium percentage indicate the ‘excellent to good quality’ of water for irrigation uses.     

Assessment of spatial variations in water quality of Garra River at Shahjahanpur,Ganga Basin,India

Arabian Journal of Geosciences - A comprehensive study on the chemical considerations of thermal waters (springs and geothermal wells) on the performance of solute geothermometers in predicting the...     

Scale effects of eroded sediment transport in Wujiang River Basin,Guizhou Province,China

In recent years, research on spatial scale and scale transformation of eroded sediment transport has become a forefront field in current soil erosion research, but there are very few studies on the scale effect problem in Karst regions of China. Here we quantitatively extracted five main factors influencing soil erosion, namely rainfall erosivity, soil erodibility, vegetative cover and management, soil and water conservation, and slope length and steepness. Regression relations were built between these factors and also the sediment transport modulus and drainage area, so as to initially analyze and discuss scale effects on sediment transport in the Wujiang River Basin (WRB). The size and extent of soil erosion influencing factors in the WRB were gauged from: Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM), precipitation data, land use, soil type and Normalized Difference Vegetation Index (NDVI) data from Global Inventory Modeling and Mapping Studies (GIMMS) or Advanced Very High Resolution Radiometer (AVHRR), and observed data from hydrometric stations. We find that scaling effects exist between the sediment transport modulus and the drainage area. Scaling effects are expressed after logarithmic transformation by a quadratic function regression relationship where the sediment transport modulus increases before decreasing, alongside changes in the drainage area. Among the five factors influencing soil erosion, slope length and steepness increases first and then decreases, alongside changes in the drainage area, and are the main factors determining the relationship between sediment transport modulus and drainage area. To eliminate the influence of scale effects on our results, we mapped the sediment yield modulus of the entire WRB, adopting a 1 000 km2 standard area with a smaller fitting error for all sub-basins, and using the common Kriging interpolation method.     

Major ion chemistry,weathering processes and water quality assessment in upper catchment of Damodar River basin,India

The chemical characteristics of surface, groundwater and mine water of the upper catchment of the Damodar River basin were studied to evaluate the major ion chemistry, geochemical processes controlling water composition and suitability of water for domestic, industrial and irrigation uses. Water samples from ponds, lakes, rivers, reservoirs and groundwater were collected and analysed for pH, EC, TDS, F, Cl, HCO₃, SO₄, NO_3, Ca, Mg, Na and K. In general, Ca, Na, Mg, HCO₃ and Cl dominate, except in samples from mining areas which have higher concentration of SO₄. Water chemistry of the area reflects continental weathering, aided by mining and other anthropogenic impacts. Limiting groundwater use for domestic purposes are contents of TDS, F, Cl, SO₄, NO₃ and TH that exceed the desirable limits in water collected from mining and urban areas. The calculated values of SAR, RSC and %Na indicate good to permissible use of water for irrigation. High salinity, %Na, Mg-hazard and RSC values at some sites limit use for agricultural purposes.     

基于EVI和MNDWI指数的石羊河流域水体、植被时空变化特征

水体和植被是生态环境的重要自然要素,水体和植被的动态研究对认识干旱区生态环境的变化过程及保护和恢复具有重要的理论和实践意义。基于2001-2016年96期MODIS遥感数据和1992、1998、2004、2010、2016年5年Landsat遥感数据,提取EVI植被指数和改进的归一化水体指数（MNDWI）,结合一元线性回归趋势分析方法对石羊河流域的水体和植被的时空变化特征进行了分析。结果表明,近16年来,流域植被EVI整体呈增加趋势,植被覆盖度上升,但随着季节变化,上、中、下游植被覆盖度变化分异明显;EVI植被指数年际变化倾向率与之一致。植被覆盖小幅增加地区占21.5%（春）、14.9%（夏）、8.8%（秋）,保持不变区域占流域总面积的52.5%（春）、40.2%（夏）、35.0%（秋）;此外,仍有轻度退化区和严重退化区。近25年来,研究区水域面积总体呈增大-减小-增大的波动变化趋势,1998年水域面积增大至725.92 km²,此后水域面积2010年减小至710.11 km²;但2010年以后水域面积又呈稳定增加趋势,水域面积2016年增加至723.00 km²。自然因素和人为因素是研究区水体和植被时空变化的驱动因素。     

Neoliberalism and water reforms in western India: Commercialization, self-sufficiency, and regulatory bodies

This paper deals with the changes brought about by the ‘reforms’ in water currently under way in many parts of the world. Three particular reforms in the state of Maharashtra in western India are discussed - the commercialization of a parastatal body, the concept of self-sufficiency as it plays out in the context of urban local bodies, and the working of the regulatory body in water. The analysis of these reforms shows how, in common with neoliberal projects elsewhere, changes in institutional practices are resulting in changes in subjectivities, foreclosing alternatives, and leading to attempts to ‘depoliticize’ the water arena. At the same time, there are differences between the regulatory experience of Maharashtra and regulation in other locales, which offers insights into how neoliberalism works in a context where water reforms have emerged relatively late.     

基于GRACE的黄河流域陆地水储量时空变化研究

黄河流域是我国目前主要的煤炭经济可采量和产能聚集地。了解和掌握黄河流域水资源及其变化不仅是推进黄河流域水资源节约集约利用的前提,更是开展黄河流域煤炭矿区生态保护与高质量发展的基础。相较于传统地面水资源监测手段受限于监测点分布和数目的影响,GRACE重力卫星为中长尺度陆地水储量时空变化研究提供一种新的途径。利用GRACE重力卫星数据,开展2002年4月到2017年6月黄河流域水储量的时空变化规律研究。利用纬圈长度加权平均,计算黄河上中下游水储量变化均值,发现黄河不同流段表现不同的变化趋势,且反映出2003年黄河流域水资源变化受到洪水等因素影响。进一步通过箱形图分析黄河流域上中下游水储量的月平均变化规律,反映出该流域“冬干春旱,夏秋多雨”的气候特点与水储量变化的密切关系。采用时间序列分解方法分析整个黄河流域水储量变化的趋势、年周期及半年周期等特征。结果表明,黄河流域水储量变化存在随经度由西向东递减趋势越来越明显的现象,其中黄河上游源头附近区域的水储量变化呈微弱的增长趋势;黄河流域水储量变化年周期和半年周期振幅存在明显区域差异,这与高山融雪、降水量的季节性差别及区域气候环境密切相关。了解和掌握上述黄河流域水储量时空变化,可为流域矿区的生态保护与可持续发展提供基础数据与参考。      

黄河泥沙百年演变特征与近期波动变化成因解析

黄河泥沙未来变化趋势关系到新时期治黄策略制定，科学认知入黄沙量变化特征，特别是一些典型或极端情况下的沙量变化原因，对于科学研判黄河泥沙未来情势具有重要指导意义。本文在分析百年黄河沙量演变特征基础上，重点解析了2013年和2018年典型"大沙"年份以及2017年典型"极端降雨"年份潼关沙量波动变化原因。结果表明：1919—2018年百年尺度上黄河潼关站输沙量呈"台阶式"减少特征且减少趋势极显著（P<0.001），尤其2000年以后年均输沙量降至2.44亿t左右；随着黄土高原下垫面土壤侵蚀环境大幅改善，黄河上游相似来水年头道拐—潼关区间流域输沙量减少82%，相似极端降雨情景下流域次洪输沙量平均减少50%~85%，2017极端降雨年并未导致大沙年出现，水土保持生态建设成果在减少入黄泥沙方面发挥了关键作用；2013年和2018年典型"大沙"年潼关站泥沙来源解析表明，河道淤积泥沙冲刷和水库排沙成为新时期黄河潼关站沙量波动变化的主要影响因素。     

Petrography and geochemical characteristics of the sediments of the small River Hemavati, Southern India: Implications for provenance and weathering processes

Small rivers (≤ 100 km length) are likely to drain fewer rock types. Therefore, their solutes and sediments are good indicators of weathering environments typical of their basins and help constraining the nature of their source rocks. To understand this, the texture, mineralogy, major and trace element compositions of the sediments deposited by the River Hemavati, a northern upland tributary of the Cauvery River in southern India, are analyzed and discussed.

The Hemavati sediments are overall of fine sand size (mean 2–3), and have high concentrations of FeO (≤ 7 wt.%), TiO₂ (≤ 1.2 wt.%), Cr (≤ 350 ppm) and Ni (≤ 125 ppm). Major and trace element distribution call for a binary source for the sediments, and particularly point to contrasting climatic conditions of their provenances. The source areas in the upstream and downstream parts are exposed to sub-humid high relief and sub-arid low relief conditions, respectively, with distinct weathering characteristics. The CIA values (85–48) decrease from near the source to downstream, suggesting that the downstream rain-shadow part of the catchment suffered only minor chemical weathering.

On the other hand, the REE distribution in the Hemavati sediments indicates contrasting lithologies in their provenance, and is not controlled by chemical weathering. On the basis of REE patterns, the sediments are divided into two compositional groups. The Type 1 sediments have a REE chemistry similar to the upper continental crust, and have been derived from the > 3.2 Ga composite peninsular gneisses occurring in the low-lying, semi-arid Mysore Plateau. The Type 2 sediments, however, have dominantly intermediate to mafic granulite contributions from the tectonically uplifted Western Ghats, weathered under sub-humid conditions. High concentrations of FeO, TiO₂, Cr and Ni in the sediments suggest mafic-dominated source lithologies in the upper catchment, a feature also confirmed by field observations and petrographic study.     

Suspended sediment dynamics and morphodynamics in the Yellow River, China

The Yellow River in China carries large amounts of sediments in suspension at concentrations up to several hundreds of kilograms per cubic metre; the sediment is composed mainly of silt. These high sediment concentrations influence the hydrodynamics (flow velocity and turbulence) which, in turn, determine the sediment concentration profile, whereas both the high sediment concentrations and pseudo-cohesive properties of silt determine the morphodynamics of the Yellow River. The effect of sediment on the hydrodynamics is analysed using the Richardson number and the Reynolds number to provide a framework to differentiate between various flow regimes in the Yellow River, which is calibrated and validated with Yellow River data. The flow may be sub-saturated (stable flow), super-saturated (unstable flow characterized by high deposition rates, caused by collapse of turbulence), or hyperconcentrated sub-saturated (stable flow because of hindered settling effects), depending on the Richardson number. Independent of this, the flow may be turbulent, transitional or laminar, depending on the Reynolds number. Analysis of these flow types improves understanding of the flow regimes and morphodynamics of the Yellow River. The morphodynamics of the Yellow River are also affected by pseudo-cohesive behaviour caused by shear dilatance, which results in increasing critical shear stress for erosion at decreasing grain-size. This pseudo-cohesive behaviour may be partly responsible not only for the high deposition rates which characterize the lower Yellow River, but also for mass erosion during river floods.     

黄河内蒙古河段输沙量与淤积量计算方法

基于多沙河流"多来多排"输沙基本公式,建立了考虑上站来沙量、前期累计淤积量、临界输沙水量及干支流泥沙粒径影响的输沙量一般表达式。进而根据黄河内蒙古河段1953—2010年实测水沙资料,得到了内蒙古巴彦高勒—头道拐全河段及巴彦高勒—三湖河口和三湖河口—头道拐分河段的年输沙量公式,并根据输沙率法采用建立的输沙量公式计算了各河段1953—2010年的逐年冲淤量。选取三湖河口—头道拐河段的计算结果分析表明,在输沙基本公式基础上增加前期累计淤积量、临界输沙水量及干支流泥沙粒径参数,所得公式计算的年冲淤量与实测值之间的相关系数R2由基本公式的0.41依次提高到0.50、0.75和0.80,说明在基本公式基础上进一步考虑这些参数的必要性。此外,全河及分河段输沙公式计算所得输沙量及各河段冲淤量和累计淤积量与实测值的符合程度均较好,表明建立的输沙公式能够用于不同水沙条件下的输沙量和冲淤量计算,可为分析内蒙古河段的输沙特性和长期淤积趋势提供参考。     

Flowing against the current: The socio-technical mediation of water (in)security in periurban Gurgaon,India

This research is located at the intersection of three canals in periurban Gurugram. Two of these canals were built to provide water for the growing city of Gurugram and one of them carries the wastewater of the city back to the villages. These canals cut through periurban villages that are excluded in principle from taking benefit of these canals. They are meant to be at their receiving end, as recipients of these waters. The paper, using a socio-technical lens, explores the mixed impacts of these canals on the villages through which they traverse. The paper further describes the strategies that periurban communities devise to circumvent the situation of exclusion. Using a qualitative, ethnographic research design, the paper describes the socio-technical mediation of periurban water insecurity, focusing on the mix of technologies and institutions that spring up around these canals that shape the periurban water users’ access to water. The paper concludes that approaches for promoting community resilience and periurban water security need to start from an understanding of the strategies devised by periurban communities to improve their access to water. In the larger discourse on building community resilience in the face of urbanization and climate change it is important to pay attention to local norms of cooperation that enable periurban communities to access water, rather than start from a premise that water insecurity caused by urbanization and climate change will lead to conflicts or necessitate capacity-building to promote avoid conflict and promote cooperation.     

Characteristics and sources of microplastic pollution in the water and sediments of the Jinjiang River Basin,Fujian Province,China

Microplastic pollution is widely distributed from surface water to sediments to groundwater vertically and from land to the ocean horizontally. This study collected samples from surface water, groundwater, and sediments from upper to lower reaches and then to the estuary in 16 typical areas in the Jinjiang River Basin, Fujian Province, China. Afterward, it determined the components and abundance of the microplastics and analyzed the possible microplastic sources through principal component analysis (PCA). As a result, seven main components of microplastics were detected, i.e., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyformaldehyde (POM), nylon 6 (PA6), and polystyrene (PS). Among them, PE and PP were found to have the highest proportion in the surface water and sediments and in the groundwater, respectively. The surface water, groundwater, and sediments had average microplastic abundance of 1.6 n/L, 2.7 n/L and 33.8 n/kg, respectively. The microplastics in the sediments had the largest particle size, while those in the groundwater had the smallest particle size. Compared with water bodies and sediments in other areas, those in the study area generally have medium-low-level microplastic abundance. Three pollution sources were determined according to PCA, i.e., the dominant agriculture-forestry-fishery source, domestic wastewater, and industrial production. This study can provide a scientific basis for the control of microplastics in rivers.©2022 China Geology Editorial Office.     

乌鲁木齐河流域北部平原地下水流模拟

本文运用数字水文地质概念模型的方法建立了乌鲁木齐河流域北部平原的地下水流模型,并用流量边界与柴窝堡盆地和河谷区的地下水流模型相接,构成一个统一的流域地下水模型,为乌鲁木齐河流域水资源整体规划利用提供了模拟分析工具。北部平原的南部倾斜平原为砂卵砾石组成的大厚度潜水含水层,北部细土平原为多层结构。地下水总体上由南向北径流,天然状态下在交界地带溢出成泉或流入沙漠。目前,地下水循环基本上由人为控制。农田灌溉回归补给量与河流和山前侧向补给量持平;而开采量已是绝对的排泄量。季节性开采造成地下水位季节性大幅度变化。水位的下降使蒸发蒸腾量减少,减轻了由于灌溉造成的土壤盐碱化问题。