scholarly journals Major stressors influencing the river ecosystems of Far and Mid Western Development Regions of Nepal

2019 ◽  
Vol 14 (2) ◽  
pp. 231-238
Author(s):  
Subodh Sharma ◽  
Ram Devi Tachamo Shah
Keyword(s):  
Benthic Macroinvertebrates ◽  
Ecological Integrity ◽  
Morphological Characteristics ◽  
River Systems ◽  
Aquatic Biodiversity ◽  
River Ecosystems ◽  
River Bed ◽  
Western Development ◽  
High Dominance ◽  
Natural Flow Regimes

Maintaining healthy river ecosystem is essential both from aquatic biodiversity conservation perspective as well as for the socio-cultural and economic development of nations all over the world. Many rivers in Nepal have largely been modified with the purpose of supplying drinking water, irrigating agricultural lands, producing hydro-electricity, and operating water mills. During the process, rivers are channelized and the river bed materials are removed. Such activities of river bed excavation have changed both the natural flow regimes and morphological characteristics of rivers. Studies on the impacts caused by such stressors on river ecosystems are lacking in the context of Nepalese river systems. Therefore we have assessed how these stressors might change the faunal composition of benthic macroinvertebrates in headwaters of the Western region of Nepal. The study was conducted in the headwaters of rivers of Mahakali and Karnali rivers. Habitat specific benthic macroinvertebrates were sampled from 33 sites seasonally in the year 2016 and 2017. Physical characteristics of rivers including river bed composition, water abstractions and other local stressors including waste dumping and washing-bathing were noted in the field. The study showed that macroinvertebrates community structures were significantly different in the habitat modified sites compared to reference sites. In general, abstracted sites coupled with river bed removals were found to be colonized by fewer taxa with high dominance of pool preference biota such as genera of Mayflies (Torleya spp., Caenis spp., Choroterpes spp.) and families of true flies (Chironomidae and Ceratopogoniidae). Macroinvertebrates’ abundance was significantly lower in the habitat modified sites. This study envisages that maintaining river’s habitats with minimal flows all round year could preserve ecological integrity of river systems.

scholarly journals An Overview of DNA-Based Applications for the Assessment of Benthic Macroinvertebrates Biodiversity in Mediterranean Aquatic Ecosystems

Diversity ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 112
Author(s):  
Eftychia Tzafesta ◽  
Francesco Zangaro ◽  
Valeria Specchia ◽  
Maurizio Pinna
Keyword(s):  
Benthic Macroinvertebrates ◽  
Aquatic Ecosystems ◽  
Biodiversity Monitoring ◽  
Biodiversity Data ◽  
Management Tools ◽  
Aquatic Biodiversity ◽  
Current State ◽  
Dna Metabarcoding ◽  
Ecosystem Condition ◽  
Macroinvertebrate Species

The loss of aquatic biodiversity is increasing at a rapid rate globally. There is a worldwide effort to protect, preserve and restore aquatic ecosystems. For efficient biodiversity monitoring and reliable management tools, comprehensive biodiversity data are required. The abundance and species diversity of benthic macroinvertebrates are commonly used as indicators of the aquatic ecosystem condition. Currently, macroinvertebrate species biodiversity assessment is based on morpho-taxonomy, which could be enhanced by recent advances in DNA-based tools for species identification. In particular, DNA metabarcoding has the potential to identify simultaneously many different taxa in a pool of species and to improve aquatic biomonitoring significantly, especially for indicator species. This review is focused on the current state of DNA-based aquatic biomonitoring using benthic macroinvertebrates in the Mediterranean region.

scholarly journals MORPHOLOGICAL CHARACTERISTICS OF THE GIANH RIVER (FROM CO CANG TO CUA GIANH) IN RELATION TO THE EROSION AND ACCUMULATION

2019 ◽  
Vol 18 (4) ◽  
pp. 384-392
Author(s):  
Hai Nguyen Tien ◽  
Dang Vu Hai ◽  
Phuc La The ◽  
Ha Nguyen Thai
Keyword(s):  
River Flow ◽  
Dominant Role ◽  
Morphological Characteristics ◽  
Straight Channel ◽  
Meandering Channel ◽  
Braided Channel ◽  
River Bed ◽  
Erosion And Accretion ◽  
Channel Bar

On the basis of morphological characteristics and erosion - accumulation of sediment, it is possible to divide the stretch of the Gianh River from Co Cang to Cua Gianh (about 54km in length) into 3 sections as follows: Meandering channel (from Co Cang to Tien Xuan Isles): the length of the channel is 27.69km and the width of the channel is 80-250m. The channel is in the form of a meandering, narrow riverbed, flow plays a dominant role, deposition activities develop strongly at the convex side, while erosion occurs strongly in the concave side (cut side); Braided channel (from Tien Xuan Isles to Quang Phu): the length of the channel is 17.06km and the width of the channel is 800-2,200m. The channel is straight, the river bed is large and the depth of the river bed is 2-11m. Sedimentation occurs mainly at the bottom of the channel and creates bar in the middle of the channel; Straight channel (from Quang Phu to Cua Gianh): the length of the channel is 9.23km and the width of the channel is 800-1,000m. The channel is straight and the depth of the river bed is 8-12.5m. In addition to the role of river flow, it is strongly influenced by marine dynamics. The erosion and accretion activities occur mainly in estuaries. The results above show trend of river development: i) Meandering channel is the most vulnerable to changes for morphology of channel by erosion and accretion of sediment and can create 1-2 horseshoe pools by the river change line; ii) Braided channel mainly changes in the bottom of channel by the formation of channel bar; iii) Straight channel mainly changes in the estuary (the mouth of the river can be moved, enlarged or narrowed).

scholarly journals Hidrogeomorfologia em confluência fluvial obtusa, Guarapuava, Paraná

2021 ◽  
Vol 14 (4) ◽  
pp. 2131-2148
Author(s):  
Leandro Redin Vestena ◽  
Alessandro Kominecki
Keyword(s):  
Land Use ◽  
Sediment Transport ◽  
Liquid Mixtures ◽  
Hydraulic Characteristics ◽  
Specific Flow ◽  
River Ecosystems ◽  
River Bed ◽  
River Confluence ◽  
Land Use And Management ◽  
Junction Angle

Solid and liquid mixtures in river courses intensify in areas of river confluence, conditioned mainly by the angular opening of the junction. Knowledge of hydrosedimentological dynamics in bedrock junctions with different angular openings is essential for understanding morphological adjustment at confluences and for supporting actions for the preservation and conservation of river ecosystems. For this reason, this article presents the results of a hydrogeomorphologic study on a river confluence with an obtuse junction angle (>100º), in a plateau bedrock river, in the Serra Geral Formation. The research evaluated a fluvial segment upstream and downstream of the Pedras River and in the Pombas River tributary, in Guarapuava, Paraná, through observations and measurements of morphological and hydraulic characteristics, width, talweg depth, bed declivity and bankfull flow. Morphological adjustment in obtuse confluences is peculiar in that the fluvial junction angle conditions specific flow, erosion, sediment transport and deposition dynamics, mainly resulting from its association with the geological nature of the river bed and types of land use and management upstream of the confluence.

Macroinverfebrate Abundance and Production of Psammophifous Chironomidae in Shifting Sand Areas of a Lowland River

1985 ◽  
Vol 42 (7) ◽  
pp. 1296-1302 ◽  
Author(s):  
Daniel A. Soluk
Keyword(s):  
Benthic Macroinvertebrates ◽  
Secondary Production ◽  
Unit Area ◽  
Larval Growth ◽  
Dry Mass ◽  
Total Biomass ◽  
River Bed ◽  
Chironomid Species ◽  
Shifting Sand ◽  
Macroinvertebrate Density

Abundance and biomass of benthic macroinvertebrates from shifting sand areas in the bed of the Sand River in central Alberta, Canada, were examined for 1 yr. Macroinvertebrate density ranged from 12 000 to 78 000 individuals/m2, but total biomass was low (50–490 mg/m2 dry mass) due to the small size of most organisms. The interstitial larvae of two chironomid species (Robackia demeijerei and Rheosmittia sp.) contributed a mean of 80.6% biomass and 92.8% of total number of macroinvertebrates. Total annual secondary production of these two species (752.0 ± 144.5 mg∙m−2∙yr−1) was used as an estimate of total secondary production of benthic macroinvertebrates in shifting sand areas. Both R. demeijerei and Rheosmittia sp. exhibited larval growth and development rates much slower than those reported for comparably sized species in other habitats. Food or frequent disturbance may limit the growth of these species. Although unit area biomass and production were low relative to other lotie habitats, shifting sand areas make significant contributions to the river ecosystem because they occupy a large proportion of the river bed.

scholarly journals METHODS OF IMPROVING THE EFFICIENCY OF MONITORING OF CHANNEL DEFORMATIONS OF MOUNTAIN RIVERS NEAR BUILT-IN SETTLEMENTS: ON THE EXAMPLE OF THE BUKTYRMA RIVER

2018 ◽  
Vol 44 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Talgat TAUKENOV ◽  
Kulchikhan DZHANALEEVA ◽  
Zhuldyz YERZHANOVA
Keyword(s):  
Public Space ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Mountain Rivers ◽  
Channel Processes ◽  
Channel Deformations ◽  
Geoinformation Systems ◽  
The Earth ◽  
River Bed ◽  
Scientific Justification

The results of research on the development of methods for increasing the efficiency of monitoring the channel deformations of mountain rivers using the methods of aerospace studies of the Earth and geoinformation systems are presented. Examples are given of estimating channel deformations, compiling morphological characteristics of the valley, floodplain and river bed, determining the scheme for the development of channel processes using public space imagery, scientific justification for erosion control measures.

Effects of Urbanization on Stream Ecosystems

2005 ◽  
Keyword(s):  
Water Quality ◽  
Benthic Macroinvertebrates ◽  
Biological Indicators ◽  
Taxonomic Composition ◽  
The State ◽  
Aquatic Biodiversity ◽  
Urban Sewage ◽  
Rehabilitation Potential ◽  
State Capital ◽  
Belo Horizonte

<em>Abstract.</em>—In Brazil, most urban sewage is discharged without treatment into rivers. This is the situation for the Rio das Velhas, which receives in its upper course the sewage of the state capital of Minas Gerais, Belo Horizonte, with more than 2.4 million inhabitants. Our study focuses on the effects of basin urbanization on aquatic biodiversity and water quality in the Rio das Velhas. We use the assemblage structure and taxonomic composition of fishes and benthic macroinvertebrates as biological indicators of water quality. Effects of Belo Horizonte’s discharge included changes in water quality and declines in fish and benthos richness and diversity. However, the absence of dams in the Rio das Velhas main course, associated with connectivity with the Rio São Francisco system and tributaries in excellent condition, increase its rehabilitation potential.

scholarly journals Structure of Benthic Macroinvertebrate Communities in the Rivers of Western Himalaya, Nepal

Geosciences ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 150
Author(s):  
Ram Devi Tachamo Shah ◽  
Subodh Sharma ◽  
Deep Narayan Shah ◽  
Deepak Rijal
Keyword(s):  
Water Quality ◽  
River Basin ◽  
Benthic Macroinvertebrates ◽  
Western Himalaya ◽  
Freshwater Ecosystems ◽  
Benthic Macroinvertebrate ◽  
Macroinvertebrate Communities ◽  
River Systems ◽  
River Continuum ◽  
River Types

According to River Continuum Concept (RCC), channel morphology, including sediment loads and channel width, river habitat, flow regimes and water quality, differs from the tributary to the downstream river’s mainstem, allowing shifts in faunal composition from dominance of shredders to collectors downstream, respectively. Tributaries are responsible for contributing organic carbons, nutrients and water. However, such knowledge is still limited in the monsoon-dominated river systems of the Himalaya. The study was conducted in the river’s mainstem and tributaries of the Karnali River Basin, which are glacier and spring-fed river systems, respectively, in the western Himalaya, Nepal. A total of 38 river stretches in the river’s mainstem and tributaries were sampled during post-monsoon and pre-monsoon seasons in the years 2018 and 2019. Water quality parameters, such as pH, temperature, electrical conductivity, total dissolved solids, dissolved oxygen, alkalinity and hardness, and the benthic macroinvertebrates were studied. Ten subsamples of benthic macroinvertebrates were collected following the multi-habitat sampling approach at each site. High taxa richness was recorded in tributaries compared to the river’s mainstem while abundance was similar between river types. Non-metric multidimensional scaling (NMDS) formed two distinct groups, reflecting high similarities in benthic macroinvertebrate composition within the tributaries and river’s mainstem rather than between river types. Redundancy analysis (RDA) indicated water temperature and pH as major environmental predictors for benthic macroinvertebrate variability between river types. Therefore, river type-based conservation efforts that account for upstream–downstream linkages of aquatic biota and resources in freshwater ecosystems can ensure the ecological integrity of the whole river basin.

scholarly journals Morphologische Untersuchungen im nordöstlichen Matmata-Vorland (nördliche Djeffara, Südtunesien)

1975 ◽  
Vol 26 (1) ◽  
pp. 218-240 ◽  
Author(s):  
Karl-Ulrich Brosche ◽  
Hans-Georg Molle
Keyword(s):  
Climatic Conditions ◽  
The Other ◽  
Early Holocene ◽  
Distribution Area ◽  
River Systems ◽  
14C Dating ◽  
Entire Area ◽  
Fine Sediments ◽  
River Bed ◽  
14C Age

Abstract. Geomorphological investigations into the sequence of formation phases in the area of the two river-systems Oued Termamane — Oued Zigzaou and Oued en Negueb — Oued El Hallouf — Oued Oum Es Zessar in N. Djeffara in S. Tunisia permit us to distinguish above the recent river-bed, apart from youngest, anthropogenically caused deposits, a "younger accumulation" composed of fine sediments, a "main accumulation" consisting for the most part of coarse pebbles and remainders of at least 2 older, higher-lying levels which cannot be reliably correlated. The "main accumulation" is found in the entire area of the aforementioned Oueds, the „younger accumulation" on the other hand only in their middle and lower courses. The latter is missing in the main distribution area of the Matmata silts (primarily wind-deposited, later fluviatile remodelled sediments), in the mountains and on their edges. On the strength of the 14C-dating of 2 charcoal specimens (Hv 5566 and Hv 5400) the deposits of the „younger accumulation" may be placed in the period between 9000 — 7000 B.P. The dating of a calccrust from the top of the "main accumulation" showed a 14C-age of 21385 ± 235 B.P. (Hv 5402). Even taking into account the considerable possibilities of error in this dating, a Würm age may be assumed for the "main accumulation". The silts of Matmata overlie the "main accumulation" and come into consideration as supplier of material for the sediments of the "younger accumulation", accordingly the age of the silts may be assumed to be Würm to Early Holocene. Climatic conditions more humid than those today are indicated by a fossilized "Kalkbraunerde" in the Matmata silts, the occurence of calccrusts and a transport of pebbles at the time of the "main accumulation" reaching considerably further into the Matmata foreland than the pebble-transport of the recent river-beds.

Sign in / Sign up

Export Citation Format

Share Document