Impact Des Aménagements Hydroélectriques Sur Le Peuplement Des Poissons Du Lac De Barrage De Buyo Et De La Zone Périphérique (Côte d’Ivoire)

L’objectif de ce travail était de déterminer l’impact des variations des niveaux d’eau sur la distribution des poissons dans le lac de Buyo et le cours principal du fleuve Sassandra. Les campagnes ont lieu de Juin 2018 à Mai 2019. Les changements hydrologiques ont été observés après la mise en eau d’un deuxième barrage sur le fleuve Sassandra. Ces changements hydrologiques ont eu un impact sur la diversité piscicole. Les poissons ont été capturés à l’aide des filets maillants et des nasses artisanales. Ces poissons sont repartis en 6 ordres, 14 familles et 42 espèces. Dans le lac de Buyo, l’espèce Synodontis punctifer domine le peuplement en période de crue alors que Coptodon zillii est prépondérante en période de décrue. Dans le cours principal l’espèce Synodontis punctifer domine le peuplement durant les périodes d’ouverture et de fermeture des vannes du barrage, cette espèce est plus adaptée aux changements hydrologiques. Une bonne organisation du peuplement est observée en période de crue dans le lac. Dans le cours principal, une bonne organisation du peuplement est avérée en période de décrue lorsque les vannes du barrage sont fermées. Le modèle de prévision a montré que dans le lac de Buyo, la richesse spécifique est influencée positivement les cotes de retenue mais négativement par le débit d’apport d’eau et le volume d’eau déversé. Dans le milieu fluviatile, le modèle a montré que la richesse spécifique est influencée négativement par la profondeur et le débit d’eau turbiné mais influencé positivement par la vitesse du courant. The objective of this work was to determine the impact of water level variations on fish distribution in Lake Buyo and the main course of the Sassandra River. The campaigns will take place from June 2018 to May 2019. The hydrological changes are proven after the impoundment of a second dam on the Sassandra River. These hydrological changes have had an impact on fish diversity. The fish were caught using gillnets and artisanal traps. These fish are divided into 6 orders, 14 families and 42 species. In Lake Buyo, the species Synodontis punctifer dominates the population during the flood period while Coptodon zillii is predominant during the low water season. In the mainstream, the species Synodontis punctifer dominates the population during the periods of opening and closing of the gates of the dam, this species is more adapted to hydrological changes. A good organization of the population is observed during the period of flooding in the lake. In the main river, a good organization of the population is proven during the flood period when the gates of the dam are closed. The predictive model showed that in Lake Buyo, the species richness is positively influenced by the impoundment rating but negatively by the inflow rate and the volume of water discharged. In the fluvial environment, the model showed that the specific richness is negatively influenced by the depth and the turbinated water flow but positively influenced by the current speed.

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Fish diversity

10.1093/oso/9780198785552.003.0001 ◽

2017 ◽

Author(s):

Derek Burton ◽

Margaret Burton

Keyword(s):

Life Style ◽

Fish Diversity ◽

Additional Species ◽

The Impact ◽

Current Species

Fish diversity is considered in terms of variety of their morphological, taxonomic, habitat and population attributes. Fish, with over 30, 000 current species, represent the largest group of vertebrates. The complexity of classification of a group of this size and antiquity, together with recognition of additional species, demands continuous ongoing revision. The impact of the recent fundamental changes in fish classification in 2016 is discussed. Life in water involves adaptations to widely different habitats which can result in physiological morphological and life-style variations which are reviewed.

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Fish Ecology of the Alto Madre de Dios River Basin (Peru): Notes on Electrofishing Surveys, Elevation, Palm Swamp and Headwater Fishes

Water ◽

10.3390/w13081038 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1038

Author(s):

Ibon Tobes ◽

Adrián Ramos-Merchante ◽

Julio Araujo-Flores ◽

Andrea Pino-del-Carpio ◽

Hernán Ortega ◽

...

Keyword(s):

Environmental Variables ◽

Biosphere Reserve ◽

Fish Distribution ◽

Fish Diversity ◽

Fish Ecology ◽

Aquatic Habitats ◽

Madre De Dios ◽

Distribution Of Fish ◽

Important Shift ◽

Electric Fishing

Our study analyzes the distribution of fish communities related to the environmental variables of the Alto Madre de Dios River, an Andean-Amazon watershed of southern Peru, between 300 and 2811 m a.s.l. within the Manu Biosphere Reserve. We provide new ecological and diversity data on fishes for these poorly studied rivers and new data for palm swamp habitats. With electric fishing techniques, we collected a total of 1934 fish specimens belonging to 78 species, 42 genera and 15 families. To assess main patterns of diversity we combined SIMPER and ANOSIM with canonical correspondence analysis to obtain an overview of the community structure of fish and their distribution related to aquatic habitats. Our results show an important shift on fish diversity at 700 m a.s.l. separating headwater and middle-lowland communities. Electrofishing was a hindrance due to the depth, flow and low conductivity of the rivers, but also allowed us to capture fish not observed with other techniques. We also compared the use of elevation with slope as an alternative variable for statistical analysis. Our results show that slope offers a solid and equivalent explanation for fish distribution variability, avoids redundance, and instead of giving geographical data offers ecologically solid information.

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Strip yield model for multiple straight cracks with coalesced yield zones: A theoretical study

Strength Fracture and Complexity ◽

10.3233/sfc-210276 ◽

2021 ◽

pp. 1-15

Author(s):

S. Hasan ◽

N. Akhtar ◽

S. Shekhar

Keyword(s):

Numerical Study ◽

Multiple Cracks ◽

Principle Of Superposition ◽

Yield Model ◽

Zone Length ◽

Yield Zone ◽

Strip Yield Model ◽

Opening And Closing ◽

The Impact ◽

Analytical Expressions

The paper presents a complicated case of coalescence of yield zones between two internal cracks out of four collinear straight cracks weakened an infinite isotropic plate. Two solutions are presented for the case of opening and closing of multiple cracks under general yielding conditions. Using these two solutions and the principle of superposition, we found the analytical expressions for load-bearing capacity of the plate using complex variable method. A numerical study has been carried out to investigate the behavior of yield zone length concerning remotely applied stresses at the boundary of the plate and the impact of two outer cracks on the propagation of inner cracks due to coalesced yield zones. Results obtained are reported graphically.

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Purwarupa Alat Deteksi Ketinggian Banjir Perbantuan SMS Gateway Dan Mikrontroler

INOVA-TIF ◽

10.32832/inova-tif.v1i2.2747 ◽

2020 ◽

Vol 2 (1) ◽

pp. 51

Author(s):

Muhammad Ardi

Keyword(s):

Detection System ◽

Water Levels ◽

Design Flood ◽

Loss Of Life ◽

Data Processor ◽

Working Principle ◽

Arduino Uno ◽

Flood Elevation ◽

Opening And Closing ◽

The Impact

Flood disasters still occur regularly and continuously in Indonesia. Flooding can occur due to the volume of water in the river beyond the river body. Many impacts caused by flooding, not only material losses, flooding can also cause loss of life. The impact of flooding can be reduced if people are better prepared to face the flood. One way is to quickly disseminate information on river water levels to the community. It is necessary to make a solution on how to design an automatic sluice using Arduino UNO R3 and how to monitor the water situation during floods. The working principle of this tool uses an ultrasonic sensor as a water level detector, Arduino as a data processor, servo motor as opening and closing the door bar automatically and the modem as an SMS notification. Because design based detection system is needed In this study there are two formulations of the problem (i) How to design flood altitude detection devices using Arduino uno r3 which can open and close automatically. (ii) How to test the flood altitude detection system using a wavecome modem. The research objective is divided into two parts (i) Creating a series of flood elevation devices using Arduino r3 so that it can open and close automatically (ii) Gets the results of flood elevation system testing with an sms gateway

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HYDRODYNAMIC MODELLING IN INSHORE REEF AREA WITHIN KUANTAN COASTAL REGION

Journal CleanWAS ◽

10.26480/jcleanwas.01.2020.01.07 ◽

2020 ◽

Vol 4 (1) ◽

pp. 01-07

Author(s):

Muhammad Faiz Mohd Hanapiah ◽

Shahbudin Saad ◽

Zuhairi Ahmad

Keyword(s):

Model Simulation ◽

Coastal Region ◽

Flow Speed ◽

Current Speed ◽

Benthic Organism ◽

Reef Area ◽

Inshore Reef ◽

Highly Correlated ◽

The Impact ◽

Current Circulation

Current circulation provides major transport mechanism especially for benthic organism in the ocean. The present study described current circulation in inshore reef area within Kuantan coastal region by applying a numerical modelling of MIKE 21 Flow Model FM software. Model simulation produced good outcomes when compared with field data measurement with root mean square error (RMSE) for surface elevation, current speed and direction were below 20. Results also clearly indicated that current speed in inshore reef area was highly correlated with local tidal pattern in which higher flow speed were observed during high tides compared to low tide. Contrary to previous belief, our results clearly show the prevalence of tidal forcing in shaping current flow pattern in the study area since the impact of wind forcing was minimal during different monsoon seasons. This study gave new insight into how local tidal properties can regulate hydrodynamic pattern especially in fine-scale inshore reef area.

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Development and validation of numerical habitat models for juveniles of Atlantic salmon (Salmo salar)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-162 ◽

2000 ◽

Vol 57 (10) ◽

pp. 2065-2075 ◽

Cited By ~ 85

Author(s):

J C Guay ◽

D Boisclair ◽

D Rioux ◽

M Leclerc ◽

M Lapointe ◽

...

Keyword(s):

Logistic Regression ◽

Atlantic Salmon ◽

Salmo Salar ◽

Water Depth ◽

Current Speed ◽

Fish Distribution ◽

Biological Model ◽

Habitat Models ◽

Physical Conditions ◽

Atlantic Salmon Salmo Salar

We evaluated the ability of numerical habitat models (NHM) to predict the distribution of juveniles of Atlantic salmon (Salmo salar) in a river. NHMs comprise a hydrodynamic model (to predict water depth and current speed for any given flow) and a biological model (to predict habitat quality for fish using water depth, current speed, and substrate composition). We implemented NHMs with a biological model based on (i) preference curves defined by the ratio of the use to the availability of physical conditions and (ii) a multivariate logistic regression that distinguished between the physical conditions used and avoided by fish. Preference curves provided a habitat suitability index (HSI) ranging from 0 to 1, and the logistic regression produced a habitat probabilistic index (HPI) representing the probability of observing a parr under given physical conditions. Pearson's correlation coefficients between HSI and local densities of parr ranged from 0.39 to 0.63 depending on flow. Corresponding values for HPI ranged from 0.81 to 0.98. We concluded that HPI may be a more powerful biological model than HSI for predicting local variations in fish density, forecasting fish distribution patterns, and performing summer habitat modelling for Atlantic salmon juveniles.

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Riparian Vegetation Dynamic and River Stability on Intermittent Rivers: Impact of Water Transfer Project on Tropical Drylands

10.5194/egusphere-egu21-13485 ◽

2021 ◽

Author(s):

Camilla Santos ◽

Leonardo Dantas Martins ◽

Kenia Sousa da Cruz ◽

Jonas Otaviano Praça de Souza

Keyword(s):

Vegetation Cover ◽

Riparian Vegetation ◽

Google Earth ◽

Water Transfer ◽

Lateral Stability ◽

Hydrological Changes ◽

Vertical Incision ◽

Short Period ◽

Geomorphic Units ◽

The Impact

Rivers on semiarid landscapes typically are characterised by sandy geomorphic units and riverbanks, a natural factor that enhances lateral mobility. Vegetation cover is a crucial factor on lateral instability due to its impact on riverbank and geomorphic units erosion resistance. Nevertheless, riparian vegetation on intermittent and ephemeral channels show growing patterns directly affect by the flow temporality, that controls the water availability. Extended dry intervals hinder the succession ecological on geomorphic units, like bars and islands, and riverbanks and retard the growing process. This work analysed the effects of hydrological changes, caused by one water transfer project, on the bio-geomorphological patterns on riverbanks of a main intermittent river of Brazilian Drylands. Flow data series was used to understand the hydrological pattern changes; Google Earth images and UAV surveys to analyse the vegetation and riverbank behaviour from 2008 to 2020.&#160; Lastly, the identification of riverbank material resistance was based on sedimentology analysis. &#160;The water transfer Project PISF (Projeto de Integra&#231;&#227;o do S&#227;o Francisco), operating since 2017 March, increase the average flow days from 137,5 to 260/300 days and decreasing the continuous dry period from 200 to 30/45 days. The impact on average annual discharge was slightest, whereas the average water transfer volume was 3m3/s. It is essential to highlight the short period of data posterior to the water transfer and the non-regulatiry of water volume transferred; what limits the temporal representativity of the results. There were different types, and level of impacts depending on the river reach characteristics. However, in general, the longer flow permanence increases riparian vegetation density, vertical incision, and lateral stability. Riparian vegetation cover increase, from 20% to 100% on the 9 reaches analysed, across the entire channel, including bedrock reaches, with riverbanks having some rock outcrops percentage. The main changes were on sand bed reaches, that used to have, before 2017, a dynamic braiding pattern, without a clear main incised channel and thalweg shifting. Afterwards, the flow permanence, due to the water transfer project, enabled herbaceous stratus temporal continuity, contributing to surface stability and progressive bushes/trees cover growing. Lastly, the increase in lateral stability, mainly on thalweg position, facilitates the vertical incision on the sand bed reaches, representing 85% of this channel. As a secondary impact, there were necessary, to the road network, built floodway crossings at several points, which changes the channel morphology and the (dis)connectivity process. It can generate distinct channel position and morphology changes causing water and sediment retention upstream and erosion downstream. Lastly, there were slight differences in textural characteristics on riverbanks and geomorphic units, with a rise in fine sediment on the most vegetated areas/units. This analysis reveals that a fast response of riparian vegetation and sand bed reaches morphology, affecting the bio-geomorphological process and all environmental dynamic. It points to fundamental elements which need monitoring after hydrological changes, especially to intermittent and ephemeral rivers.

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Hydro-climatic fluctuations and their impact on Lake Abhe environments (Ethiopia & Djibouti): a lesson from the past 10,000 years

10.5194/egusphere-egu21-4634 ◽

2021 ◽

Author(s):

Carlo Mologni ◽

Laurent Bruxelles ◽

Fabien Arnaud ◽

Pierre Sabatier ◽

Anne-Lise Develle ◽

...

Keyword(s):

East African ◽

Climatic Fluctuations ◽

Climatic Oscillations ◽

Sedimentary Records ◽

Hydrological Changes ◽

Precession Cycle ◽

Afar Region ◽

Geomorphic Features ◽

Sedimentary System ◽

The Impact

Throughout the last 14 ka, tropical Africa experienced significant hydrological changes that were mainly driven by the orbital precession cycle, which controls the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that long-term monsoon humid oscillations (African Humid Period / AHP ~14 &#8211; ~6 ka) were punctuated by centennial-scale episodes of hyperaridity. However, the abrupt or gradual aridification modalities since the end of the AHP and the modalities of the centennial-scale episodes, as well as their impacts on past and current environments are still debated.The Lake Abhe basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater originating in the Ethiopian Highlands, and represents a hydro-sedimentary system sensitive to hydro-climatic changes in East Africa. Today it is characterized by residual lakes (Gamari and Afambo lakes) and a hyper-arid climate, while during the AHP, the Abhe basin was occupied by a Mega-lake and by humid environmental conditions. Holocene climatic disruptions drastically changed the landscapes and ways of life along this basin.&#160;&#160;The aim of this study is to describe, interpret and estimate the impact of hydro-climatic oscillations on the evolution of Lake Abhe&#8217;s littoral lacustrine environments and palaeolandscapes since the AHP from different viewpoints.Indeed, this research combines paleoclimatological and geomorphological studies based on a new set of 14C ages on two lacustrine cores and on several morpho-sedimentary outcrops spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the hydrological modalities of the AHP including short-term arid episodes linked to Younger Dryas and 8.2 ka North Atlantic events; b) recognise some paleo-shoreline geomorphic features linked to lake level fluctuations, as well as the development littoral pedological horizons and the activation/shutdown of the perilacustrine fluvial network during humid and arid events; c) track these changes until the present day, and discuss their evolution scenario in the near future.Comparing with other regional climatic records, we show how Lake Abhe basin was highly reactive to East African monsoonal regimes, and how current hydrological changes could impact its environments.&#160; &#160;&#160;&#160;&#160;

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Anatomy of simultaneous flood peaks at a lowland confluence

Hydrology and Earth System Sciences ◽

10.5194/hess-22-5599-2018 ◽

2018 ◽

Vol 22 (10) ◽

pp. 5599-5613 ◽

Cited By ~ 3

Author(s):

Tjitske J. Geertsema ◽

Adriaan J. Teuling ◽

Remko Uijlenhoet ◽

Paul J. J. F. Torfs ◽

Antonius J. F. Hoitink

Keyword(s):

Economic Value ◽

Water Levels ◽

Simultaneous Occurrence ◽

Main Stream ◽

Time Lags ◽

Main River ◽

Long Duration ◽

Independent Observations ◽

Flood Peaks ◽

The Impact

Abstract. Lowlands are vulnerable to flooding due to their mild topography in often densely populated areas with high social and economic value. Moreover, multiple physical processes coincide in lowland areas, such as those involved in river–sea interactions and in merging rivers at confluences. Simultaneous occurrence of such processes can result in amplifying or attenuating effects on water levels. Our aim is to understand the mechanisms behind simultaneous occurrence of discharge waves in a river and its lowland tributaries. Here, we introduce a new way of analyzing lowland discharge and water level dynamics, by tracing individual flood waves based on dynamic time warping. We take the confluence of the Meuse River (∼33 000 km2) with the joining tributaries of the Dommel and Aa rivers as an example, especially because the January 1995 flood at this confluence was the result of the simultaneous occurrence of discharge peaks in the main stream and the tributaries and because independent observations of water levels and discharge are available for a longer period. The analysis shows that the exact timing of the arrival of discharge peaks is of little relevance because of the long duration of the average discharge wave compared to typical time lags between peaks. The discharge waves last on average 9 days, whereas the lag time between discharge peaks in the main river and the tributaries is typically 3 days. This results in backwaters that can rise up to 1.5 m over a distance of 4 km from the confluence. Thus, local measures to reduce the impact of flooding around the confluence should account for the long duration of flood peaks in the main system.

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Recent changes to the hydrological cycle of an Arctic basin at the tundra–taiga transition

Hydrology and Earth System Sciences ◽

10.5194/hess-22-3993-2018 ◽

2018 ◽

Vol 22 (7) ◽

pp. 3993-4014 ◽

Cited By ~ 9

Author(s):

Sebastian A. Krogh ◽

John W. Pomeroy

Keyword(s):

Layer Thickness ◽

Active Layer ◽

Snow Water Equivalent ◽

Hydrological Cycle ◽

Arctic Basin ◽

Hydrological Processes ◽

Active Layer Thickness ◽

Blowing Snow ◽

Hydrological Changes ◽

The Impact

Abstract. The impact of transient changes in climate and vegetation on the hydrology of small Arctic headwater basins has not been investigated before, particularly in the tundra–taiga transition region. This study uses weather and land cover observations and a hydrological model suitable for cold regions to investigate historical changes in modelled hydrological processes driving the streamflow response of a small Arctic basin at the treeline. The physical processes found in this environment and explicit changes in vegetation extent and density were simulated and validated against observations of streamflow discharge, snow water equivalent and active layer thickness. Mean air temperature and all-wave irradiance have increased by 3.7 ∘C and 8.4 W m−2, respectively, while precipitation has decreased 48 mm (10 %) since 1960. Two modelling scenarios were created to separate the effects of changing climate and vegetation on hydrological processes. Results show that over 1960–2016 most hydrological changes were driven by climate changes, such as decreasing snowfall, evapotranspiration, deepening active layer thickness, earlier snow cover depletion and diminishing annual sublimation and soil moisture. However, changing vegetation has a significant impact on decreasing blowing snow redistribution and sublimation, counteracting the impact of decreasing precipitation on streamflow, demonstrating the importance of including transient changes in vegetation in long-term hydrological studies. Streamflow dropped by 38 mm as a response to the 48 mm decrease in precipitation, suggesting a small degree of hydrological resiliency. These results represent the first detailed estimate of hydrological changes occurring in small Arctic basins, and can be used as a reference to inform other studies of Arctic climate change impacts.

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