Main River Channel Research Articles

Environmental magnetic properties of core sediments in the Yellow River subaqueous delta and their chronologicalapplications

The Yellow River has shifted frequently in the downstream region since 1885; it has flowed into the sea through the Qingshuigou channel from 1976 onward, thus forming the latest delta lobe (1976–present). During the past ~40 years, the sediment load of the Yellow River has been greatly reduced because of human and natural activities, such as reservoir construction, soil and water conservation, and river avulsion. Beginning in 2002, the water-sediment regulation scheme (WSRS) has also changed the sediment loading patterns of the Yellow River. Several studies have reported on the erosion and deposition characteristics of the latest lobe of the Yellow River Delta over the past several decades, based on remote sensing methods and water-depth measurements. However, continuous sedimentary records of delta erosion and deposition and their responses to natural and human activities in the watershed are lacking. Here, we obtained three sediments cores, YD01, YD02, and YD03, from the subaqueous delta of the latest lobe of the Yellow River Delta. These cores contain sediments deposited from 1976 to 2018. We analyzed the environmental magnetism and lithological characteristics of these cores, and investigated their responses to natural and human activities in the watershed of the Yellow River, as well as possible applications to sediment dating in the Yellow River Delta. The results show that frequency-dependent susceptibility ( χ fd%) and anhysteretic remanent magnetization susceptibility ( χ ARM) values were high in core sediments deposited from 1976 to 1996, indicating abundant contents of fine single-domain (SD) and superparamagnetic (SP) magnetic particles, and therefore a dominant sediment supply from the Chinese Loess Plateau. Small decreases in χ fd% and χ ARM in sediments deposited after 1986 revealed slight reduction of the sediment load from the Yellow River, which was likely caused by sediment retention related to the construction of the Longyangxia Reservoir. Rapid rises in χ fd% and χ ARM occurred in core YD01 sediments deposited during 2002 and ~2007, likely in response to the implementation of the WSRS, which resulted in an increase in sediment transportation. Increases in hard isothermal remanent magnetization (HIRM) values, an indicator of high-coercivity magnetic minerals such as goethite and hematite, in cores YD02 and YD03 from 2002 to ~2007 may also represent the start of the WSRS. This is because the downstream riverbed of the Xiaolangdi Reservoir underwent intense erosion during the implementation of the WSRS, leading to large-scale transportation of coarse sediments enriched in goethite and hematite, which were deposited on the riverbed before the implementation of the WSRS. The lack of increased contents of fine SD and SP magnetic minerals in cores YD02 and YD03 compared with YD01 in the interval deposited between 2002 and ~2007 was attributed to erosion and redeposition in the areas around cores YD02 and YD03. Large drops in SD and SP contents after ~2007 were detected in all three cores, revealing intense erosion near the river mouth likely caused by river channel shift and reduced capability of the WSRS to remove sediments. Contents of SD and SP particles increased again in sediments deposited after 2014 in cores YD02 and YD03, likely related to erosion of the present (after 1996) Yellow River mouth and transportation of fine particles to the region near cores YD02 and YD03. In summary, the magnetic parameters χ fd% and χ ARM and the lithological characteristics of cores YD01, YD02, and YD03 recorded sediment delivery changes caused by four events in the Yellow River watershed: The main river channel shift in 1976, construction of the Longyangxia Reservoir in 1986, the beginning of the WSRS in 2002, and weakened capability of the WSRS to remove sediments after ~2007. The notable changes of χ fd%, χ ARM, and lithology at the 1976, 1986, 2002, and ~2007 horizons may be used as dating points in future research of sediment cores from the Yellow River Mouth.

Nuisance phytoplankton transport is enhanced by high flow in the main river for drinking water in Uruguay.

Eutrophication, climate change, and river flow fragmentation are the main cause of nuisance algal blooms worldwide. This study evaluated the conditions that trigger the growth and occurrence of nuisance phytoplankton in the Santa Lucía River, a subtropical floodplain lotic system that supplies drinking water to 60% of the population of Uruguay. The main variables that explained phytoplankton biovolume were extracted from generalized linear models (GLM). The potential impact of nuisance organism advection on water utility was estimated by the phytoplankton biovolume transport (BVTR, m3 day-1), an indicator of biomass load. Santa Lucía River had a wide flow range (0.7×105-1438×105 m3 day-1) and eutrophic conditions (median, TP: 0.139 mg L-1; TN: 0.589 mg L-1). GLMs indicated that phytoplankton biomass increased with temperature and soluble reactive phosphorus. Contrary to expectations, the presence of cyanobacteria was positively associated with periods of high flow that result in high cyanobacterial biovolume transport, with a probability of 3.35 times higher when flow increased by one standard deviation. The cyanobacterial biovolume transported (max: 9.5 m3 day-1) suggests that biomass was subsidized by allochthonous inocula. Biovolume from other nuisance groups (diatoms, cryptophytes, and euglenophytes) was positively associated with low-flow conditions and high nutrient concentrations in the main river channel, thereby indicating that these conditions boost eukaryote blooms. The evaluation of BVTR allows a better understanding of the dynamics of fluvial phytoplankton and can help to anticipate scenarios of nuisance species transport.

Light-trapped caddisflies to decipher the role of species traits and habitats in Hg accumulation and transfer

We present a novel meta-community approach to explore the influence of species traits, such as adult body size, larval feeding type and microhabitat, as well as larval macrohabitat (main river channel vs. floodplain water bodies) on the concentration of total Hg accumulated ([THg]) in assemblages of adult caddisflies. We analyzed [THg] in 157 light-trapped adult caddisflies in a floodplain sector of the French upper Rhône River and used a linear mixed effect model to decipher the role of species traits and habitats in Hg accumulation. Variation of [THg] between species was best explained by the larval feeding type, whereas the contributions of adult size and larval micro and macro-habitat were minor. Results showed that [THg] in species associated with floodplain macrohabitats in the larval stage was lower than in those associated with the main river channel. This difference could depend on complexation of Hg by DOM (in the floodplain) and MES (in the main channel). This research provides a first evidence of the potential of an entire caddisfly assemblage for the assessment of contamination in large alluvial rivers. The implications of the results are discussed in view of the possible role of caddisflies as vectors of Hg to riparian predators.

The Beautiful and the Dammed: Defining Multi-Stressor Disturbance Regimes in an Atlantic River Floodplain Wetland

Natural hydrological fluctuations within river floodplains generate habitat diversity through variable connections between habitat patches and the main river channel. Human modification of floodplains can alter the magnitude and frequency of large floods and associated sediment movement by interrupting these floodplain connections. The lower Wolastoq | Saint John River and its associated floodplain wetlands are experiencing anthropogenic disturbances arising from climate change, increased urbanization in the watershed, changing upstream agricultural landscape practices, and, most notably, major road and dam construction. By comparing digitized aerial images, we identified key periods of change in wetland extent throughout an ecologically significant component of the floodplain, the Grand Lake Meadows and Portobello Creek wetland complex, with significant erosion evident in coves and backwater areas across the landscape following dam construction and significant accretion around the Jemseg River following highway construction. Connectivity and hydrological regime also influenced other habitat components, namely nutrients and metals retention, as well as the composition of the local macrophyte community. These findings address two key aspects of floodplain management: (1) understanding how hydrological alteration has historically influenced floodplain wetlands can inform us of how the ecosystem may respond under future conditions, such as climate change, and (2) the mechanisms by which habitat diversity and disturbance regimes filter biological communities, with the potential for patches to host a rich biodiversity continuously supporting critical ecosystem functions.

Dynamics of river flows towards sustaining floodplain wetland fisheries under climate change: A case study

Abstract Wetlands play an important ecological role by providing shelter and habitat for diverse fish species, migratory birds, macrophytes and other aquatic organisms. Hydrological connectivity with the main river channel has a critical role in fish diversity and production in floodplain wetland. The present study showed the seasonal hydrological alteration on fish species distribution in Ansupa wetland, connected with tropical river Mahanadi, India. The river discharge showed a variation from 4549 cusec during lean season (April) to 204716 cusec during monsoon (August). It has been recorded that water flows/discharge above 200000 cusec only, inundate the wetland resulting in exchange of free flows of fish species and nutrients. The study period for the fish species diversity was undertaken during 2017-18. A total of 46 fish species were observed under the orders Cypriniformes (18), Perciformes (12), Siluriformes (7), Synbranchiformes (2), Cyprinodontiformes (1), Clupeiformes (1), Beloniformes (1), Osteoglossiformes (1), Mugiliformes (1), Anguilliformes (1) and Tetraodontiformes (1). According to the conservation status of the International Union for Conservation of Nature, four species Parambassis lala, Ompok bimaculatus, and Anguilla bengalensis are in the category of Near Threatened. Analysis showed that taxonomic distinctness is more during winter than the monsoon and pre-monsoon, indicating monsoon could play a significant role in the fish species recruitment through river connectivity. Climatic data was analysed for a period of 34 years and indicated that an increment of 0.20C in water temperature and average increase of 129mm rainfall at the study site. This slight increase in rainfall over the years could be one of the factors responsible for the fish recruitment in the Ansupa wetland, through river connectivity underlining the importance of flood for wetland fisheries recruitment and sustainability.

Trees as sentinels of metallic pollution induced by mining along the Odiel River (Southern Iberian Peninsula)

Mining activity is often responsible for the drainage of acid or metal-enriched waters to fluvial systems. The release of metals is especially disturbing due to the toxicity and persistence of these products and their accumulation in the biosphere. Hence, a systematic detection and delimitation of highly polluted floodplains and linkages between pollution and high-flow stages would likely assist the improvement of land management and ease the design of mitigation or rehabilitation measures. Here we test how trees growing in different geomorphic positions along a fluvial system uptake metal during floods and how these uptakes can be documented “a posteriori”. To this end, we apply dendrogeochemical analyses to twenty Pinus pinaster Ait. trees growing on the banks of Odiel River (south-western Spain) as well as to five reference trees growing outside the river channel. In the field, trees were sampled with a large-diameter (1 cm) increment borer. In the lab, tree-ring series were dendrochronologically cross dated and separated into 5-yr blocks, so that wood blocks contained the dates of major floods. Then, Inductively Coupled Plasma Mass Spectrometry (ICPM) was employed to evaluate toxic metal concentrations in trees. Results point to clear correlations between the accumulation of toxic metals and the geomorphic position of trees within the fluvial network. We show that morphological units along a river exert control on toxic metal concentrations in trees, with uptake being much higher in trees located on meander cut banks than in trees growing on point-bar structures. Besides, we detect chemical signatures in trees located farthest away from the main river channel after the largest floods, but not in the aftermath of smaller events. We conclude that tree position is the single-most important determinant for metallic pollution in an environment controlled by fluvial processes, but also find that more studies are still needed to determine linkages with individual floods and interactions of metal uptake in roots via the water table in the river corridor.

The life of a plastic butter tub in riverine environments

Plastic pollution in the world's ocean is one of the major environmental challenges that affects the society today, due to their persistence at sea, adverse consequences to marine life and being potentially harmful to human health. Rivers are now widely recognized as being the major input source of land-based plastic waste into the seas. Despite their key role in plastic transportation, riverine plastic pollution research is still in its infancy and plastic sources, hot-spots and degradation processes in riverine systems are to date poorly understood. In this contribution, we introduce a novel concept of following the aging of polypropylene based post-consumer goods placed in known trapping and mobility zones of macroplastics on a fluvial point bar, which was determined through repeated field surveys of macroplastic densities on this bar. As a proof-of-concept, we followed the degradation of 5 identical plastic butter tubs in 5 different locations on a riverbank and significant differences in the aging of the tubs were observed. The degree of aging of the tubs can to some extent be correlated to their proximity to the main river channel, exposure to natural conditions, such as solar radiation, and its storage time on land.

Apparent roughness coefficient in overbank flows

Overbank flows occur in alluvial valleys during flood events when the conveyance of main channel of rivers is exceeded. Once floodplains are inundated and the so-called compound channel flow is observed, the faster flow in the main channel interacts with the slower flow in the floodplain featuring a much more pronounced 3D flow structure compared to single channel flow. These flow mechanisms comprise a shear layer near the interface, lateral momentum transfer and strong secondary currents due to the non-isotropic turbulence. This paper starts by giving an overview of the main flow mechanisms in compound channels pointing out the importance of taking into account the apparent shear stress generated between the main channel and the floodplain flows due to the interaction of these flows. A new simple model was developed to include the apparent shear stress concept as a correction of the Manning roughness coefficient of main channel and floodplains. The proposed method for predicting stage–discharge relationships was calibrated and validated by experimental data from several compound channel facilities. A significant improvement in prediction of the compound channel conveyance in comparison with the traditional methods was achieved.

Hydrological Study of the Nakayasu Hydrograph Method for Design of Water Retention in the JIIPE Gresik Industrial Estate

The development area of the JIIPE industrial estate could change the land use around the development site. The research area mostly has clay lithology. This development area must be protected from flood. This study aims to plan a reservoir that can process the drainage system. The data needed are geographic data, rainfall data, meteorological data, area data, and land function data. This study used the Nakayasu Hydrograph method. The Nakayasu hydrograph method parameters are time interval from the rain surface to the top of the hydrograph, period time from the center of gravity of the rain to the center of gravity of the hydrograph, period time for the hydrograph, the area of the river basin, and the length of the longest main river channel. The calculation result from this method is the peak discharge value and this calculated based on the existing and planned conditions. In this study, the calculation of the probability of discharge in the return period of 25 years is carried out. From this calculation, a hydrograph graph of the flood discharge from the existing and planned conditions is generated. The calculation for the difference between the maximum debit between of existing and planned conditions is to determine the debit that must be held every second in the storage. The generated discharge value is 18.7 m3 / s. The calculation of storage volume the reservoir to control the volume need is 168,300 m3. The calculation of the storage volume based on the area of the reservoir is used as the volume of availability, which is 169,956 m3, so that the recommended water retention dimensions are obtained with an area value of 36,947 m2 and depth of water retention of 4,5 m.

Fine-scale genetic structure of suckermouth Hypostomus ancistroides populations: the importance of Neotropical streams for fish conservation

Abstract In the Neotropics, freshwater streams harbour high fish diversity and are constantly threatened by anthropogenic disturbance. However, there are few studies on the genetic diversity of fish populations inhabiting these streams. We aimed to assess, based on microsatellite and mitochondrial DNA markers, the population structure and genetic diversity of the suckermouth catfish, Hypostomus ancistroides, a Neotropical species widely distributed across the Upper Paraná River Basin in South America. Twenty-five locations were sampled, distributed across 18 sites in six tributary streams and another seven sites in the main river channel. Our analyses revealed a spatial heterogeneity in genetic diversity within the basin, indicating fine-scale genetic structuring. Samples from all streams showed exclusive haplotypes and private alleles, reinforcing the importance of preserving the tributaries for the conservation of the genetic diversity of the studied populations. The fine-scale genetic structuring of H. ancistroides is probably related to the limited displacement capacity of this species.

Effects of source digital elevation models in assessment of gross runoff-river hydropower potential: A case study of West Rapti Basin, Nepal

Advancements in Geographical Information System (GIS), Remote Sensing (RS) technology, hydrologic modeling and availability of wider coverage hydrometeorological data have facilitated the use of GIS and hydrological modelling tools in studies related to hydropower potential. Digital Elevation Model (DEM) is the primary data required for these tools. They have become more accessible and many are freely available. These DEMs have different resolution and their errors vary due to their primary data acquisition techniques and processing methods. However, their effects on the hydropower potential assessment are less investigated. This study evaluates the effects of 6 freely available DEMs: ALOS 12.5 m, SRTM 90 m, SRTM 30 m, ASTER G-DEM version-3 30 m, AW3D 30 m and Cartosat-1 version-3 30 m on the Gross Run-off-River Hydropower Potential (GRHP) assessment, using GIS and hydrological modelling tools. West Rapti River (WRR) basin in Nepal was chosen for the case study.
 Soil and Water Tool (SWAT) hydrological model, coupled with GIS was used to discretize the WRR basin into several sub-basins/streams. Flow at the inlet and outlet of streams were estimated from the SWAT model whereas the topographic head was extracted from the DEMs. The GRHP of the streams were computed using the estimated stream flow and the topographic head for flows at 40% to 60% Probability of Exceedance (PoE). The total potential of the basin was computed by summing up the potential of all streams. The GRHP of WRR basin for flows at 40% PoE was estimated as 512 MW for ALOS 12.5 m resolution DEM, referred as a base case in this study. The GRHP estimated from the remaining DEMs showed the variation of less than 6% compared to the base case. The topographic head was found to be sensitive with respect to the DEM resolution and the highest variations were observed in the main river channels.

Incorporation of local dissolved organic carbon into floodplain aquatic ecosystems

Environmental flow releases in lowland Australian rivers are currently timed to avoid high-carbon production on floodplains. Moreover, return flows (water draining from floodplains back into rivers) are avoided if there exists a risk of introducing deoxygenated “blackwater” into the main channel. This concern has restricted the range of possible watering scenarios being considered by environmental flow managers. We utilised a series of blackwater flows in the lower Murrumbidgee floodplain, Australia, in 2016 and 2017 to determine the origin and trophic contribution of blackwater dissolved organic carbon (DOC) in a floodplain wetland. We demonstrate a consistent difference in the isotope signature of blackwater DOC compared to both dissolved inorganic carbon (DIC) and river water DOC, explained by the greater contribution of floodplain vegetation (including the river red gum Eucalyptus camaldulensis) to blackwater DOC. Stable carbon isotope signatures suggest a contribution of blackwater to algal production, whereby microbial-mediated conversion of blackwater DOC into DIC may create opportunities for primary autotrophic productivity. This carbon signature was incorporated by the common yabby Cherax destructor. In the main river channel, C. destructor, the native gudgeon Hypseleotris spp. and the introduced European carp Cyprinus carpio may utilise the same basal carbon source. The use of small to moderate floodplain inundation with return flow to the river, properly monitored, would ameliorate the risk of hypoxia while providing the benefit of floodplain-derived DOC and associated increases to in-stream productivity.

A ~ 40-year paleoenvironmental record from the Swan Oxbow, Yangtze River, China, inferred from testate amoebae and sedimentary pigments

We present a ~ 40–year record of environmental change in the Swan Oxbow, Yangtze River, China, inferred from testate amoeba and sedimentary pigment data, combined with remote sensing and analysis of local socio–economic growth. These data indicate there were several distinct phases of aquatic conditions linked to human activities in the region: (1) Between ca. AD 1970 and 1984, there may have been some exchange of water and organic matter between the Swan Oxbow and the main river channel, following initial hydrologic disconnection in 1972. The lake area was relatively large in the early phase after the oxbow first formed, and the trophic state generally increased during that time frame, (2) From ca. AD 1984 to 1992, the lake area was about a third smaller in size, while the human population and GDP increased about 10% and 10x, respectively, compared to values in 1975. The nutrient status (inferred from testate amoeba and pigment data) increased, owing to the greater discharge of nutrients and separation of the Swan Oxbow from the main Yangtze River, which reduced water supply and increased sedimentation in the oxbow, (3) From ca. AD 1992 to 2003, the lake continued to diminish in size, to an area < 20 km2, except in 1998, when a major flood occurred. The testate amoeba and pigment data suggest that water quality had improved by that time, which probably reflects efforts to control agricultural and industrial activities, including establishment of two national reserves in 1992 and 1993, created to protect the rare Pere David’s deer (Elaphurus davidianus) and the freshwater Baiji dolphin (Neophocaena phocaenoides asiaeorientalis), (4) From ca. AD 2003 to 2005, the water area remained relatively unchanged, owing to construction of a dam following the 1998 flood. Occurrence of testate amoeba species Difflugia biwae and D. tuberspinifera, however, indicates that water pollution and eutrophication had been controlled in Swan Oxbow. The Swan Oxbow yielded important information about the effects of environmental protection and restoration in the middle reaches of the Yangtze River.

Quantitative Prediction of Outburst Flood Hazard of the Zhouqu “8.8” Debris Flow-Barrier Dam in Western China

In recent years, the intensified influences of global climate change and human activities have increased the frequency of large-scale debris flow disasters. As a result, main river channels often become blocked, thus forming a disaster chain of rivers dammed by debris flow followed by outburst flooding. In order to quickly and easily reveal the dynamic process of a debris flow dam breach, and quantitatively predict the outburst flood hazard, this study takes the Zhouqu “8.8” debris flow barrier dam in Western China as an example. Based on a stability assessment, China Institute of Water Resources and Hydropower Research’s Dam Breach Slope (DBS-IWHR), China Institute of Water Resources and Hydropower Research’s Dam Breach (DB-IWHR), and Hydrologic Engineering Center’s River Analysis System (HEC-RAS) were integrated to simulate the development of dam breach, breach flood, and outburst flood evolution, respectively, under different scenarios. The simulated peak discharge flow of the actual spillway was 317.15 m3/s, which was consistent with the actual discharge of 316 m3/s. The results under different scenarios showed that, with the increased inflow of the barrier lake, the erosion rate of the dam increased, the peak discharge of the dam break flood increased, the peak arrival time shortened, and the downstream flooding area increased. These findings could provide scientific support for risk management and emergency decision-making with respect to barrier dam failure.

Spatial and temporal variations of nutrients and chlorophyll a in the Indus River and its deltaic creeks and coastal waters (Northwest Indian Ocean, Pakistan)

Nutrient dynamics play an important role in mangroves and adjacent coastal ecosystems. This paper discusses the spatiotemporal variation of physicochemical factors in two monsoons and intermonsoons and their influence on chlorophyll a and the dissolved inorganic nutrient concentrations in selected creeks. The present study focused on dense mangrove cover creeks (Waddi Khuddi (WK) and Dabbo (DC)), sparse mangrove cover creek (Hajamro (HC)), and no mangrove to mixed terrestrial and agricultural vegetation (Khobar (KC)) along with the Indus River and adjacent NE Arabian Sea. Silicate (SiO32–) was the most abundant nutrient, and its concentration increased from the northeast to the southwest monsoon and decreased during the fall intermonsoon. Erosion of the riverbank catchment area, weathering, and sand mining are the major sources of elevated SiO32–. The highest concentration of nitrate (NO3–) was found in the main river channel (KC) throughout the year, with maximum concentration (37.42 ± 5.05 μM) in the river (KC) during the rainy season (SW monsoon) due to the agricultural runoff that resulted in an increase in chlorophyll a. The concentration of nitrite (NO2–) was high in the creek (DC) with mangroves and agricultural runoff input. The concentration of phosphate (PO43–) was high in mangrove-dominated creeks (WK and DC), suggesting litterfall as a major source of PO43− from the creeks. The river with no mangrove cover (KC) indicated that PO43– was a limiting factor. In the case of DSi:DIN ratios, SiO32–was not limited throughout the sampling period for primary production. The chlorophyll a concentration increased from upstream to downstream in the river and was positively correlated with SiO32– and NO3–, resulting in the dominance of diatoms during the SW monsoon. The study confirms that natural sources (river/terrestrial runoff and geomorphological factors) and anthropogenic factors (application of fertilizers, manure, construction of dams, and industrialization) significantly influenced the nutrients and chlorophyll a, both spatially and temporally. On a global scale, SiO32– concentrations in the Indus River during the southwest monsoon were lower than those in the Himalayan rivers (Brahmaputra, Ganges, Huanghe, and Yangtze Rivers). The NO3– concentration is comparable with that of Narmada, Tapti, and Pangani Rivers but lower than that for rivers originating from the Himalayas. Nutrient enrichment and eutrophication in coastal waters were mainly caused by urbanization and population increase, which affect the higher trophic level productivity and fish abundance in the coastal and shelf areas. Therefore, an integrated approach for the management and monitoring of upstream river systems is required for a better future.

Multivariate statistics for spatial and seasonal quality assessment of water in the Doce River basin, Southeastern Brazil.

This study employed multivariate statistical techniques in one of the main river basins in Brazil, the Doce River basin, to select and evaluate the most representative parameters of the current water quality aspects, and to group the stations according to the similarity of the selected parameters, for both dry and rainy seasons. Data from 63 qualitative monitoring stations, belonging to the Minas Gerais Water Management Institute network were used, considering 38 parameters for the hydrological year 2017/2018. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to reduce the total number of variables and to group stations with similar characteristics, respectively. Using PCA, four principal components were selected as indicators of water quality, explaining the cumulative variance of 68% in the rainy season and 65% in the dry season. The HCA grouped the stations into four groups in the rainy season and three groups in the dry season, showing the influence of seasonality on the grouping of stations. Moreover, the HCA made it possible to differentiate water quality stations located in the headwaters of the basin, in the main river channel, and near urban centers. The results obtained through multivariate statistics proved to be important in understanding the current water quality situation in the basin and can be used to improve the management of water resources because the collection and analysis of all parameters in all monitoring stations require greater availability of financial resources.

Eco-restoration of river water quality during COVID-19 lockdown in the industrial belt of eastern India.

The sudden lockdown recovers the health of the total environment particularly air and water while the country’s economic growth and socio-cultural tempo of people have been completely hampered due to the COVID-19 pandemic. Most of the industries within the catchment area of river Damodar have been closed; as a result, significant changes have been reflected throughout the stretch of river Damodar. The main objective of the study is to analyze the impact of lockdown on the water quality of river Damodar. A total of 55 samples was collected from eleven different confluence sites of nallas with the main river channel during and pre-lockdown period. The relevant methods like WQI, TSI, Pearson’s correlation coefficient, and “t” test have been applied to evaluate the physical, chemical, and biological status of river water. The result of “t” test indicated that there are significant differences (α = 0.05) of each parameter between pre and during lockdown. Water quality index (WQI) is used for analysis of drinking water quality suitability followed by BIS. The values of WQI showed “very poor” (S1, S2, S3, S6, S7, and S11) to “unfit for drinking” (S4, S5, S8, S9, and S10) of river water during pre-monsoon season. The nutrient enrichment status of the river was analyzed by Trophic State Index (TSI) method and it shows the “High” eutrophic condition with a heavy concentration of algal blooms in almost an entire stretch. During lockdown, nutrient supplies like TN and TP have been reduced and is designated as “Low” (S1, S2) to “Moderate” (S3 to S11) eutrophic condition of middle stretch of Damodar. This research output of river Damodar will definitely assist to policy makers for sustainable environmental management despite the dilemma between development and conservation.

SUAS Remote Sensing to Evaluate Geothermal Seep Interactions with the Yellowstone River, Montana, USA

Small unmanned aerial systems (sUAS) are becoming increasingly popular due to their affordability and logistical ease for repeated surveys. While sUAS-based remote sensing has many applications in water resource management, their applicability and limitations in fluvial settings is not well defined. This study uses a combined thermal-optic sUAS to monitor the seasonal geothermal influence of a 1-km-long reach of the Yellowstone River, paired with in-situ streambed temperature profiles to evaluate geothermal seep interactions with Yellowstone River in Montana, USA. Accurate river water surface elevation along the shoreline was estimated using structure from motion (SfM) photogrammetry digital surface models (DSMs); however, water surface elevations were unreliable in the main river channel. Water temperature in thermal infrared (TIR) orthomosaics was accurate in temperature ranges of tens of degrees (&gt;≈30 °C), but not as accurate in temperature ranges of several degrees (&gt;≈15 °C) as compared to in-situ water temperature measurements. This allowed for identification of geothermal features but limited the ability to identify small-scale temperature changes due to river features, such as pools and riffles. The study concludes that rivers with an average width greater than or equal to 123% of the ground area covered by a TIR image will be difficult to study using structure from motion photogrammetry, given Federal Aviation Administration (FAA) altitude restrictions and sensor field of view. This study demonstrates the potential of combined thermal-optic sUAS systems to collect data over large river systems, and when combined with in-situ measurements, can further increase the sUAS utility in identifying river characteristics.

A holistic view of Shisper Glacier surge and outburst floods: from physical processes to downstream impacts

We observed the surge velocity, terminus advance, lake formation and outburst, as well as its downstream impacts at Shisper Glacier in the Karakoram, Pakistan and suggest potential nature-based risk-reduction solutions. A recent surge started in late 2017 with increased velocity since April 2018 and a resulting terminus advance from June 2018. Bi-modal peak velocity of 19.2 ± 0.16 m/day was observed in April-May 2018 and May-June 2019. Also, the terminus advance blocked the river from the adjacent Muchuhar Glacier repeatedly since November 2018. Lake outbursts were observed in June 2019 and April 2020. Relying on observations of the lake area and peak discharge of 142 m3 s−1 in 2019 and 85 m3 s−1 April 2020, outburst were simulated using the BASEMENT software. Simulations and field observations show that even at high discharge, damages were mainly observed along the main river channel, causing strong bank erosion rather than widespread inundation of land. The ice-dammed lake is potentially hazardous until the blocked stream completely disappears in future. Our results suggest that the biggest lake outburst hazard lies in its erosion potential with damages to infrastructure closest to the river and large sediments transport to the downstream Hunza River.

The ichthyofauna of the Rio Carinhanha basin, one of the main tributaries of the Rio São Francisco

The ichthyofauna of the Rio São Francisco basin is relatively well-documented. However, most of this knowledge is concentrated at the upper stretch of its catchment area. In this study, we compile a list of species encompassing almost the entire length of the Rio Carinhanha, an important tributary from upper-middle section of the Rio São Francisco, including a comprehensive diversity of environments. A total of 99 species from 8 orders and 27 families were recorded. Five species are considered non-native, six classifieds as long distance migrants, and three as vulnerable. The orders with the greatest richness of native species were Characiformes and Siluriformes. Characidae was the most represented family, followed by Loricariidae. The main river channels were the richest environments sampled, followed by floodplain lagoons, veredas, and streams. The Carinhanha basin has important lotic remnants, thus it has several migratory fish populations as well as endangered species. This study demonstrates the importance of cataloguing the still poorly explored tributaries of the upper-middle section of the Rio São Francisco basin.