Dry Season River Research Articles

A historical Llewellyn Ivor Price fossil fish collection from the Middle to Late Miocene of the Brazilian Amazon

Brazilian Miocene fluvial and lacustrine deposits are mainly found in the southwestern Amazon basin in the state of Acre, where fossiliferous sections from the Middle to Late Miocene of the Solimões Formation (Fm.) emerge in riverbanks during the dry season and low river-water level periods. The Solimões Fm. is notable for its high fossil vertebrate diversity (Myliobatiformes, Siluriformes, Ceratodontiformes, Osteoglossiformes, Characiformes, Acregoliathidae, Squamata, Crocodilia, Testudines, Suliformes, Rodentia, Notoungulata, Litopterna, Astrapotheria, Proboscidea, Didelphimorphia, Pilosa, Sirenia, Cetacea, Primates, Chiroptera, and Artiodactyla) deposited in the paleo-Amazon context. This fossiliferous faunal assemblage reflects the major geological and paleoclimatic Miocene/Pliocene transition events that triggered the greatest extinction of megafauna and other groups of animals in the Paleo-Amazon and, alongside the establishment of the largest Amazon transcontinental river in South America, led to species turnover and the diversity explosion to current levels. Paleontological expeditions carried out between 1950s and 1970s at Solimões Fm. outcrops along the Acre and Upper Juruá rivers allowed the recovery of an extraordinary vertebrate paleontological collection, albeit published in fragmentary contributions. Despite supporting the largest continental fish fauna, comprising ca. 2400 valid extant species, the Amazon hydrographic system harbors a still poorly known fossil ichthyofauna. This study describes a fossil fish assemblage from the Solimões Fm. for the first time based on high accuracy data acquired by improved microCT techniques, computerized systems, and examinations of the best recent and fossil fish collections. This fish assemblage is employed to elucidate ancestral Amazonian fauna paleodiversity and paleoenvironmental context interpretations and explore the elements that led to coeval paleo-ichthyofauna from the northwestern paleo-Amazon region. Miocene species Phractocephalus (†P. acreornatus and †P. nassi) are proposed as fossil guides.

Husbandry Practices of Indigenous Goats Types in South West Shewa Zone, Oromia, Ethiopia

This study was conducted in South west Shewa zone, to identify Husbandry practices in Tole and Becho districts. Data were collected through questionnaire and, focal group discussion. A total of 180 households were selected for interview. Data collected via questionnaire were summarized with descriptive statistics and analyzed using SPSS, V.21. Chi–square test was employed for categorical data. Indices were calculated to provide ranking. Castration was primarily practiced to improve the fattening potential and acquire better price by selling fattened goats. Most of castration carried out at the age of >6months. Majority of respondents use shelter constructed in the main house and the remaining respondents use separate house. The primary feed resource during dry season was natural pasture followed by Shrubs and during wet season the primary feed resource was Shrubs and bushes followed by natural pasture. Majority of the respondents herd their goats separated from kids adult mainly to protect kids from attack by predators and to protect the does from losing their weight. The primary source of water during dry season River followed by spring and the primary source of water during wet season was Rain water followed by river. The primary disease affects goats were Orf followed by Foot root. The primary cause of death for goats was disease followed by accident. Generally, goats play a significant role for farmers as source of income generation and home consumption throughout the year. The primary feed resource during dry season was natural pasture followed by Shrubs, to increase production productive the goats in the study its better if focused on improving feed source and concentrated feed.

Occurrence and environmental risks of contaminants of emerging concern across the River Athi Basin, Kenya, in dry and wet seasons

Globally, the environmental occurrence of Contaminants of Emerging Concern (CECs) including pharmaceuticals (PhACs), personal care products (PCPs) and modern polar pesticides has raised ecological and human health awareness. However, as the developed world races against time to establish regulatory measures to mitigate their effects, developing nations including Kenya are lagging behind, partly due to unavailability of adequate data. In this work, a multi-residue analysis of 86 CECs was carried out on 198 surface water and 18 effluent samples collected at 24 sites across the River Athi basin area, Kenya, in both dry and rainy seasons. Overall, 57 CECs comprising 31 PhACs (0.4 ng L−1–142 μg L−1), 6 PCPs (0.7–570 ng L−1) and 20 pesticides (0.3 ng L−1–8.3 μg L−1) were detected. The maximum loads varied from 217 g day−1 (PCPs) to 46 kg day−1 (PhACs). Individually, carbamazepine, nevirapine, sulfamethoxazole and DEET were the most ubiquitous CECs, with detection frequencies (DF) higher than 80 %. The highest concentrations were observed at river sites that are heavily impacted by informal settlements, highlighting the critical role of slums in urban rivers pollution. At least 8 CECs including acetamiprid, alachlor, atrazine, diuron, nevirapine and paracetamol show potential risk to algae, Daphnia magna and fish, as exemplified by Risk Quotients (RQ) up to 174. Similarly, potential risk of antibiotic resistant bacteria development is evident (RQ up to 64), being driven by metronidazole, sulfamethoxazole and trimethoprim. Ultimately, further studies on the occurrence and distribution of antibiotic resistant bacteria within the basin and among the communities consuming untreated river water for drinking is merited.

Water quality and heavy metal levels in the Sinú River, a drinking water source in the Colombian Caribbean

The objective of this work was to evaluate water quality in the Sinú River in northern Colombia, duringits dry and rainy seasons. The water quality index (WQI), the heavy metal pollution index (HPI),the heavy metal evaluation index (HEI), the heavy metal toxicity load (HMTL), and the degree ofcontamination (Cd) were calculated based on analyses of water samples taken along the entire lengthof the river at sixteen sampling sites. Comprehensive and in some cases punctual samplings wereperformed depending on the morphology of the current. Five samplings were carried out in the dry andrainy periods from March 2008 to April 2009. All samples were taken in triplicate at each samplingsite. For the determination of metals, a Thermo electron atomic absorption spectrometer, modelS4AA System was used. Of the metals monitored, only zinc, iron, and manganese were identified atquantifiable levels, with average values of 8.5 x 10⁻⁵ kg m-3, 0.004 424 kg m-3 and 8.5x10⁻⁵ kg m-3,respectively in the rainy season. The obtained index values altogether (WQI =63.5, HPI=145, HEI=24, HMTL=0.1329, and Cd= 20.8) revealed the presence of contamination by heavy metals in the Sinú River, although the observed toxicity level does not imply a hazard to human health.

The Seasonal Dynamics of Organic and Inorganic Carbon along the Tropical Usumacinta River Basin (Mexico)

Rivers are important sites for carbon (C) transport and critical components of the global C cycle that is currently not well constrained. However, little is known about C species’ longitudinal and temporal changes in large tropical rivers. The Usumacinta River is Mexico’s main lotic system and the tenth largest in North America. Being a tropical river, it has a strong climatic seasonality. This study aims to evaluate how organic (DOC and POC) and inorganic (DIC and PIC) carbon change spatially and seasonally along the Usumacinta River (medium and lower basin) in rainy (RS-2017) and dry (DS-2018) seasons and to estimate C fluxes into the southern Gulf of Mexico. Concentrations of DOC, POC, DIC, and PIC ranged from 0.88 to 7.11 mg L−1, 0.21 to 3.78 mg L−1, 15.59 to 48.27 mg L−1, and 0.05 to 1.51 mg L−1, respectively. DOC was the dominant organic species (DOC/POC > 1). It was ~doubled in RS and showed a longitudinal increase, probably through exchange with wetlands and floodplains. Particulate carbon showed a positive relationship with the total suspended solids, suggesting that in RS, it derived from surface erosion and runoff in the watershed. DIC is reported for the first time as the highest concentration measured in tropical rivers in America. It was higher in the dry season without a longitudinal trend. The C mass inflow–outflow balance in the RS suggested net retention (DOC and POC sink) in floodplains. In contrast, in the DS, the balance suggested that floodplains supply (C source) autochthonous DOC and POC. The lower Usumacinta River basin is a sink for DIC in both seasons. Finally, the estimated annual C export for the Usumacinta-Grijalva River was 2.88 (2.65 to 3.14) Tg yr−1, of which DIC was the largest transported fraction (85%), followed by DOC (10%), POC (4%), and PIC (<1%). This investigation is the first to present the C loads in a Mexican river.

Flow regimes among rivers influences benthic biota biodiversity, but not abundance or biomass, in intertidal mudflats and sandflats in wet-dry tropical estuaries

Flow is a fundamental driver of ecological processes in river networks and estuaries. In estuaries, river flow interacts with tidal and wave energy to structure the physiochemical environment and the relative strength of these interactions changes in space and time. Thus, ecological processes in estuaries are best understood within the context of these physical processes. In this study, we explore how changes in river flow regime influence the structure of benthic communities in three estuaries in northern Australia's Gulf of Carpentaria. This region resides in the wet-dry tropics and the rivers have among the most variable flow regimes in the world. During two sequential dry seasons, we compared measures of benthic macroinvertebrate biodiversity, abundance, and biomass in intertidal mudflats and sandflats among three estuaries with differing river flow regimes. We found that the number of consecutive days of zero river flow during the preceding dry season best explained inter- and intra-annual patterns in benthic community composition. Specifically, we suggest that the dry season river flow regime dictated the salinity regime of each estuary, which in-turn influenced benthic community composition. However, neither the differences in the salinity regime or community composition influenced total abundance or biomass of the benthic community, indicating that the regional taxa pool currently contains enough functional redundancy to maintain abundances and biomasses under various physicochemical conditions. This in turn provides consistent resources for higher trophic levels such as birds and fish.

Amazonian run‐of‐river dam reservoir impacts underestimated: Evidence from a before–after control–impact study of freshwater turtle nesting areas

Abstract Hydropower dams are associated with adverse impacts on biodiversity, yet there remains a lack of robust scientific evidence documenting the magnitude of these impacts, particularly across highly biodiverse tropical waterways. Aquatic and semi‐aquatic vertebrates are disproportionately affected by human changes to aquatic environments and hydropower expansion is an increasing threat to the Endangered yellow‐spotted river turtle (Podocnemis unifilis) across its tropical South American range. Yellow‐spotted river turtle nesting areas were monitored as an indicator of dry season river level changes following run‐of‐river dam reservoir filling. A before–after control–impact (BACI) study design was used with multi‐year field campaigns monitoring turtle nesting areas upstream of the dam. The cause and extent of changes in nesting areas were established using generalized additive models. Nesting area density was evaluated in relation to time (before vs. after), treatment (control vs. impact), time–treatment interaction (BACI), distance to the dam and precipitation. The extent of changes was examined by comparing the remaining proportion of nesting areas after reservoir filling. Dam construction generated an immediate and apparently permanent dry season river‐level rise that extended more than 20 km beyond impact assessment limits. On average the density of nesting areas declined by 69% (from 0.48 to 0.15 per km) across 33 km of river directly affected by the dam. This loss was reflected in a significant BACI interaction. Nesting area density was not explained by seasonal precipitation. Monitoring of freshwater turtle nesting areas provided an effective means to quantify hydropower dam impacts across biodiverse yet rapidly changing waterways. The adverse impacts documented in this study should be preventable by mitigation actions including habitat creation and dry season flow regulation. Such measures are also likely to benefit multiple sandbar‐nesting species (including turtles, crocodiles and birds) in tropical rivers increasingly influenced by run‐of‐river dams.

Water Quality Modelling of River Mahanadi using Principal Component Analysis (PCA) and Multiple Linear Regression (MLR)

Surface water quality is one of the critical environmental concerns of the globe and water quality management is top priority worldwide. In India, River water quality has considerably deteriorated over the years and there is an urgent need for improving the surface water quality. The present study aims at use of multivariate statistical approaches for interpretation of water quality data of Mahanadi River in India. Monthly water quality data pertaining to 16 parameters collected from 12 sampling locations on the river by Central Water Commission (CWC) and Central Pollution Control Board (CPCB) is used for the study. Cluster analysis (CA), is used to group the sampling locations on the river into homogeneous clusters with similar behaviour. Principal component analysis (PCA) is quite effective in identifying the critical parameters for describing the water quality of the river in dry and monsoon seasons. PCA and Factor Analysis (FA) was effective in explaining 69 and 66% of the total cumulative variance in the water quality if dry and wet seasons respectively. Industrial and domestic wastewaters, soil erosion and weathering, soil leaching organic pollution and natural pollution were identified as critical sources contribution to pollution of river water. However, the quantitative contributions were variable based on the season. Results of multiple linear regression (MLR) are effective in explaining the factor loadings and source contributions for most water quality parameters. The study results indicate suitability of multivariate statistical approaches to design and plan sampling and sampling programs for controlling water quality management programs in river basins.

Seasonal changes of sediment fluxes in the Yangtze River: roles of precipitation change, human conservation measures in sub-basins, and large dams

Abstract Seasonal sediment flux change is a key issue in riverbed evolution and flood control. This paper analyzed variations in sediment fluxes of the Yangtze River in dry and flood seasons during 1961–2014 and the impacts of precipitation change and human interference. Sediment fluxes in both dry and flood seasons decreased by 6.8–74.6 and 14.6–38.7%, respectively, based on daily sediment observations at six mainstream stations. However, precipitation increased sediment yields in both dry and flood seasons by 0.72–4.22 t/km2 (3.5–17.8%) and 4.95–73.32 t/km2 (1.9–25.5%), respectively, based on the reconstructed sediment series without anthropogenic interference. Therefore, sediment reduction due to human conservation measures and dam construction was up to 0.07–20.74 t/km2 (0.9–64.6%) in dry seasons and 27.47–85.35 t/km2 (6.5–23.7%) in flood seasons during 1980–2002, and further reduced 3.61–41.31 t/km2 (46.0–102.9%) in dry seasons and 175.63–471.52 t/km2 (59.6–126.2%) in flood seasons after the Three Gorges Reservoir (TGR) became operational in 2003. Contributions of human activities in six subregions to the reduction of the seaward sediment fluxes were calculated. Therein, the TGR only took up 3.2 and 23.9% in dry and flood seasons, respectively, which is below expectation.

The change of metal pollution in the water and sediment of the Bartın River in rainy and dry seasons

In this study, it was aimed to determine the heavy metal pollution and the factors causing this pollution in the water and sediment of the Bartın River during rainy and dry periods. Concentrations of Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As and some other metals in water and sediment samples collected from 4 different points during rainy and dry periods were investigated. It has been determined that both natural sources (soil erosion) and anthropogenic sources (runoff in urban and agricultural areas) affect metal concentrations in water and sediment during the rainy period. Heavy metal accumulation was less at the point with the least water depth (≈ 2 m). Higher concentrations were determined at the point where soil transport was highest during the rainy period. Since EF values of As, Pb, Zn and Li were greater than two in both periods, it was determined that they were affected by anthropogenic sources (wastewater discharges, agricultural and urban activities). EF values less than one showed that Co, Cr, Ba, Ni, Mn were related to lithogenic actions and riverbank runoff. Non-carcinogenic effects caused by metals did not pose a risk to adults and children.

Impact of Land Use and Land Cover Changes on Surface Runoff and Sediment Yield in the Little Ruaha River Catchment

Little Ruaha River catchment (6370 Km2) in the Southern Agricultural Growth Corridor of Tanzania (SAGCOT), is one of the country’s most significant waterways due to its ecological composition and economic value. Regardless of its ecological and economical value, the regional hydrologic condition has been tremendously affected due to land uses alteration, influenced by different socio-economic factors. This study aimed to understand the associated impacts of the present Land Use Land Cover (LULC) change on the surface runoff and sediment yield in the Little Ruaha River Catchment. Hydrological modelling using Soil and Water Assessment Tool (SWAT Model) was done to quantify the impact of land use and land cover dynamics on catchment water balance and sediment loads. The calibration and validation of the SWAT model were performed using sequential uncertainty fitting (SUFI-2). The results showed that, for the given LULC change, the average annual surface runoff increased by 2.78 mm while average annual total sediment loading increased by 3.56 t/ha, the average annual base flow decreased by 2.68 mm, ground water shallow aquifer recharge decreased from 2.97 mm and a slight decrease in average annual ground water deep aquifer recharge by 0.14 mm. The model predicts that in the future, there will be a further increase in both surface runoff and sediment load. Such changes, increased runoff generation and sediment yield with decreased base flow have implications on the sustenance flow regimes particularly the observed reduced dry season river flow of the Little Ruaha River, which in turn cause adverse impacts to the biotic component of the ecosystem, reduced water storage and energy production at Mtera Hydroelectrical dam also increasing the chances of flooding at some times of the year. The study recommends land use planning at the village level, and conservation agricultural practices to ameliorate the current situation. Developing multidisciplinary approaches for integrated catchment management is the key to the sustainability of Little Ruaha River catchment.

Hydropower’s hidden transformation of rivers in the Mekong

Despite efforts to understand the hydrologic impact of hydropower dams, their influence on downstream river temperatures has gone unnoticed in data limited regions. Using 30 years of Landsat thermal infrared observations (1988–2018), we identified a relationship between dry season water temperature cooling trends and dam development in the 3S Basin, a major tributary of the Mekong River. Within a year of the beginning of operations of major dams in the 3S River Basin, rapid decreases in annual average dry season river temperature were observed ranging between 0.7 ° C and 2 ° C. Furthermore, in situ water temperature observations confirmed decreasing river temperature for two major dam development events. Evidence was found that the 3S outflow has been cooling the Mekong River downstream of the confluence, by as much as 0.8 ° C in recent years. Our findings are critically important for understanding how fish and aquatic ecosystems will behave in the future as more hydropower dams are built in the Mekong River Basin.

Characteristics of three-dimensional fluorescence spectra and its correlation with water quality of surface water during dry and wet seasons in Lake Ebinur Watershed, Xinjiang

以艾比湖流域主要入湖河流为研究对象，在5月（丰水期）和8月（枯水期）分别沿博尔塔拉河（博河）和精河进行采样，采用平行因子模型（PARAFAC）和三维荧光区域积分法对水体三维荧光特性进行研究并对其与水质的关系在枯、丰水期下的变化进行探讨.结果表明①河流DOM在枯水期与丰水期都含有C1（240、425 nm） UVC类腐殖质，C2（225、290 nm）紫外区内络氨酸类有机物，C3（230/280、330 nm）蛋白类有机物，C4（265、260 nm）腐殖质类共4种组分.通过对水体三维荧光进行区域积分可以看出DOM荧光成分的占比在不同时期的变化.博河在枯水期时EEM光谱中的区域Ⅲ富里酸含量低于丰水期，枯水期时区域Ⅱ芳香类蛋白质、区域Ⅳ可溶性微生物代谢物以及区域Ⅴ类腐殖质酸高于丰水期；对于精河来说，区域Ⅱ芳香类蛋白质和区域Ⅳ可溶性微生物代谢物在枯水期的含量高于丰水期，区域Ⅲ富里酸和区域Ⅴ类腐殖质酸的含量枯水期低于丰水期，这表明水体腐质化程度较高.②本研究选取了一些常规的荧光指数来描述枯、丰水期水体的荧光指数特性.经研究发现，精河的荧光指数、自生源指数和腐殖化指数在不同时期的变化幅度较小，而博河的变化幅度较大.③将荧光指数与水质参数进行相关性分析并建模，结果表明枯水期自生源指数（BIX）与化学需氧量呈显著正相关，相关系数R=0.688；丰水期时BIX与铵态氮浓度呈显著负相关，相关系数R=-0.493.通过对比分析艾比湖主要入湖河流的三维荧光光谱特性与水质在枯、丰水期时的关系进一步表明水体中DOM的特性以及在枯、丰水期下的差异，为艾比湖流域的治理改善提供一定的理论支持和参考依据.;This study takes the main lakes in Lake Ebinur Watershed as the research object, and samples along the Bortala River and Jing River in May (wet season) and August (dry season). The PARAFAC analysis method and the three-dimensional fluorescence region integration method is used to study the three-dimensional fluorescence characteristics of water and its seasonal variation with water quality. The results show that:1)In both dry and wet seasons, river DOM contains C1 (240, 425 nm) and C4 (265, 260 nm) kind of humus, C2 (225, 290 nm) uranium-like organic matter compounds. It found that fulvic acid is lower, while the aromatic protein, soluble microbial and humic acid were highest in dry season than wet season in Bortala River. The concentration of the aromatic protein and soluble microbial in dry season was higher than in wet season, and the fulvic acid and humic acid in dry season was lower than in the wet season in Jing River, based on fluorescence regional integral (FRI) analysis and the regional standards related to water quality and fluorescence. This indicates that the degree of decomposition in water is relatively high; 2)In this study, some conventional fluorescence indexes were selected to describe the fluorescence index characteristics of water in wet and dry season. It found that the three indexes (FI, BIX, HIX) of the water quality of Jing River and Bortala River in dry and wet seasons showed slight changes, comparing to larger changes in the Bortala River. In general, the change of water quality of Jing River and Bortala River in dry and wet seasons is mainly influenced by microbial activities and human activities; 3) In terms of the correlation coefficients of water quality parameters and fluorescence indexes in different seasons, the results showed that the relationship between BIX and COD concentration was best and a significant positive correlation in dry season(R=0.688, P<0.01). Secondly, there is a significant negative correlation between BIX and ammonium nitrogen concentration in wet season (R=-0.493, P<0.05). The study provides theoretical support and reference basis for the improvement of the governance of Lake Ebinur Watershed, which further proved that exogenous characteristics and the differences in different periods of DOM sources in the water.

Participatory Modelling of Surface and Groundwater to Support Strategic Planning in the Ganga Basin in India

The Ganga Basin in India experiences problems related to water availability, water quality and ecological degradation because of over-abstraction of surface and groundwater, the presence of various hydraulic infrastructure, discharge of untreated sewage water, and other point and non-point source pollution. The basin is experiencing rapid socio-economic development that will increase both the demand for water and pollution load. Climate change adds to the uncertainty and future variability of water availability. To support strategic planning for the Ganga Basin by the Indian Ministry of Water Resources, River Development and Ganga Rejuvenation and the governments of the concerned Indian states, a river basin model was developed that integrates hydrology, geohydrology, water resources management, water quality and ecology. The model was developed with the involvement of key basin stakeholders across central and state governments. No previous models of the Ganga Basin integrate all these aspects, and this is the first time that a participatory approach was applied for the development of a Ganga Basin model. The model was applied to assess the impact of future socio-economic and climate change scenarios and management strategies. The results suggest that the impact of socio-economic development will far exceed the impacts of climate change. To balance the use of surface and groundwater to support sustained economic growth and an ecologically healthy river, it is necessary to combine investments in wastewater treatment and reservoir capacity with interventions that reduce water demand, especially for irrigation, and that increase dry season river flow. An important option for further investigation is the greater use of alluvial aquifers for temporary water storage.

The Global Social and Economic Consequences of Mountain Cryospheric Change

Mountain cryosphere provides fresh water and other ecosystem services to half of humanity. The loss of mountain cryosphere due to global warming is already evident in many parts of the world, which has direct implications to people living in mountain areas and indirect implication to people living downstream of glaciated river basins. Despite the growing concerns, the relationship between cryosphere change and human society has yet to be assessed systematically. A better understanding of how cryosphere change affects human systems and human security would provide much needed support to the planning of global and regional actions to mitigate impacts and facilitate adaptation. This paper synthesizes the current evidence for and potential impacts of cryosphere change on water, energy, food, and the environment in different mountain regions in the world. The analysis reveals that the changes in the cryosphere and the associated environmental change has already impacted people living in high mountain areas and are likely to introduce new challenges for water, energy, and food security, and exacerbate ecosystem and environmental degradation in the future. The effects of cryospheric changes are also likely to extend to downstream river basins where glacier melt contributes significantly to dry season river flows and supports irrigation, fisheries, and navigation, as well as water supply to many big cities. Appropriate adaptive and mitigative measures are needed to prevent risks and uncertainties being further compounded

Dry season habitat use of fishes in an Australian tropical river

The modification of river flow regimes poses a significant threat to the world’s freshwater ecosystems. Northern Australia’s freshwater resources, particularly dry season river flows, are being increasingly modified to support human development, potentially threatening aquatic ecosystems and biodiversity, including fish. More information is urgently needed on the ecology of fishes in this region, including their habitat requirements, to support water policy and management to ensure future sustainable development. This study used electrofishing and habitat survey methods to quantify the dry season habitat use of 20 common freshwater fish taxa in the Daly River in Australia’s wet-dry tropics. Of twenty measured habitat variables, water depth and velocity were the two most important factors discriminating fish habitat use for the majority of taxa. Four distinct fish habitat guilds were identified, largely classified according to depth, velocity and structural complexity. Ontogenetic shifts in habitat use were also observed in three species. This study highlights the need to maintain dry season river flows that support a diversity of riverine mesohabitats for freshwater fishes. In particular, shallow fast-flowing areas provided critical nursery and refuge habitats for some species, but are vulnerable to water level reductions due to water extraction. By highlighting the importance of a diversity of habitats for fishes, this study assists water managers in future decision making on the ecological risks of water extractions from tropical rivers, and especially the need to maintain dry season low flows to protect the habitats of native fish.

Polybrominated diphenyl ethers (PBDEs) in water, surface sediment, and suspended particulate matter from the Yellow River, China: Levels, spatial and seasonal distribution, and source contribution

Fourteen polybrominated diphenyl ether (PBDE) congeners were measured in water, suspended particulate matter (SPM), and sediment samples collected from the entire expanse of the Yellow River in dry and wet seasons. Higher concentrations of PBDEs were found in the middle and lower reaches of the river compared with those in the upper reaches, ascribed to the relatively developed and urbanized cities located in the areas near the middle and lower reaches. The PBDE concentrations in the samples collected during the dry season were lower than those in the samples collected during the wet season because of thaw and rainfall. The dominant congener, with a contribution of 44.6–90.3%, was BDE-209, which originated from the residual of commercial deca-BDE. Three groups of congeners in all the samples showed good correlations with the coefficient ranging from 0.662 to 0.999 (p < 0.01), indicating common sources and similar environmental behaviors. Regression analysis suggested that the local industrial product (IP) and population density (PD) were good indicators of PBDEs in the water and sediment of the Yellow River.

Study of Relationship between Water Quality Parameters, Selective Heavy Metals and Radioactive Elements Content in Rivers at Gebeng, Kuantan, Pahang, Malaysia

This study was focused on the correlation between water quality parameters with the level of radioactive elements and heavy metals at six different sampling points of rivers. For achieving these objectives, collected data was done for Balok river and Tunggak river in dry seasons. Both of the rivers selected were located in Gebeng industrial area, Pahang, Malaysia. The physical parameters such as temperature, specific conductivity, pH, turbidity and dissolved oxygen were measured by using hydrolab. The water samples were then collected for tracing the radioactive elements and heavy metals by using inductively coupled plasma-mass spectrometry (ICP-MS). The readings obtained from both in situ and ex situ analysis was analyzed by using SPSS to know the correlation between water quality parameter, radioactive elements and heavy metals. There were significant relationships found between all water quality parameters and most heavy metals selected (lead and cadmium), except for arsenic. While, for radioactive elements, in the year 2015, there were significant relationships found between most water quality parameters and thorium, exception for uranium. However, for year 2014, there is no significant relationship observed. The findings of the study showed some of the presence of pollutants such as heavy metals and radioactive elements concentrations were reflected some of the water quality parameters at all the sampling locations. © 2019 Chemical Publishing Co. All rights reserved.

Development of a HEC-HMS-based watershed modeling system for identification, allocation, and optimization of reservoirs in a river basin.

One of the primary objectives of river basin planning and management is to assess the behavior of the river towards man-made and natural changes. In recent times, the self-purifying capacity of the river is found to be substantially affected because of extensive use of water for agricultural and industrial purposes. Any variation in the flow regime of a river poses a severe impact on the aquatic ecosystem, which affects its self-purifying capacity. Diverting river water for industrial and agricultural uses through dams and barrages reduces the natural flow rate of the river. The present study develops a novel approach by coupling Watershed Modeling System (WMS ver. 10.1) with linear optimization to provide an alternate means of water supply for such users. To explain the effectiveness of the model, a case study on the Ganges river basin of India has been considered. The ecosystem of the Ganges provides such a magnificent biological fabric, that its self-purifying capacity exceeds that of any other river water across the globe. However, the industries found in the river's most polluted stretch consume around 1200 million liters of water every day. In addition, 80% of the river water diverts at Narora barrage for agricultural purposes. As a result, the flow of the river in dry seasons is as less as 300m3/s. The study suggests the need to develop economically feasible and efficient storage reservoirs to store the rainwater, which can be used to supply industrial and agricultural needs. The WMS software is used to acquire the watershed basin, outlet location, simulated runoff volume, proposed reservoir site, and the hydrograph using the monitored rainfall data of 5years (2010-2014). The simulated runoff volume is then used to develop an optimization model to determine the required capacity of each reservoir using LINGO software (ver. 16.0). Four different storage reservoirs are proposed in the selected industrial sites of Unnao district, Uttar Pradesh, India. These reservoirs can supply the needs of industries, and thus reducing their dependency on the river Ganges. The model developed herein acts as an effective tool for giving a possible solution to large-scale water supply problems in the river basins, and also guides the decision makers towards restoring the stream flow.

Reviving the “Ganges Water Machine”: where and how much?

Abstract. Runoff generated in the monsoon months in the upstream parts of the Ganges River basin (GRB) contributes substantially to downstream floods, while water shortages in the dry months affect agricultural production in the basin. This paper examines the potential for subsurface storage (SSS) in the Ganges basin to mitigate floods in the downstream areas and increase the availability of water during drier months. The Soil and Water Assessment Tool (SWAT) is used to estimate sub-basin water availability. The water availability estimated is then compared with the sub-basin-wise unmet water demand for agriculture. Hydrological analysis reveals that some of the unmet water demand in the sub-basin can be met provided it is possible to capture the runoff in sub-surface storage during the monsoon season (June to September). Some of the groundwater recharge is returned to the stream as baseflow and has the potential to increase dry season river flows. To examine the impacts of groundwater recharge on flood inundation and flows in the dry season (October to May), two groundwater recharge scenarios are tested in the Ramganga sub-basin. Increasing groundwater recharge by 35 and 65 % of the current level would increase the baseflow during the dry season by 1.46 billion m3 (34.5 % of the baseline) and 3.01 billion m3 (71.3 % of the baseline), respectively. Analysis of pumping scenarios indicates that 80 000 to 112 000 ha of additional wheat area can be irrigated in the Ramganga sub-basin by additional SSS without reducing the current baseflow volumes. Augmenting SSS reduces the peak flow and flood inundated areas in Ramganga (by up to 13.0 % for the 65 % scenario compared to the baseline), indicating the effectiveness of SSS in reducing areas inundated under floods in the sub-basin. However, this may not be sufficient to effectively control the flood in the downstream areas of the GRB, such as in the state of Bihar (prone to floods), which receives a total flow of 277 billion m3 from upstream sub-basins.