A new method for dividing flood period in the variable-parameter Muskingum models

The Muskingum routing model is favored by water engineers owing to its simplicity and accuracy. A large amount of research is done to improve the accuracy of the model. One way to do so is to consider variable hydrological parameters during the flood routing period. In this study, the random selection (RS) method was proposed to divide the flood period of the nonlinear Muskingum model into three sub-periods. The proposed method was based on RS of members in each sub-region. It was applied to rout three flood hydrographs, and the objective function was the sum of squared errors. Comparing the results from the three variable-parameter nonlinear Muskingum model with those from the variable-parameter nonlinear Muskingum models in previous studies, the proposed model optimized the objective function in these hydrographs up to 61%. The uncertainty analysis of Muskingum parameters for Wilson's hydrograph was performed by the fuzzy alpha cut method, and it was found that the uncertainty of the parameter x is greater than the uncertainty of the parameters k and m.

Estuarine zooplankton responses to flood pulses and a hypoxic blackwater event

Flood pulses in estuaries following storms and rainfall events, are short-lived but important moments for a range of ecosystem processes including the delivery of resources and promoting productivity. Conversely some flood pulses can lead to adverse outcomes such as poor water quality conditions. The aim of this study was to determine how zooplankton abundance and community composition responded to flood pulses and if they responded differently during a flood pulse that led to hypoxic conditions. To do this we conducted a two-year observational study in the Hunter River estuary, Australia, monitoring zooplankton communities monthly for a period that covered two major flood pulse events including one that caused widespread hypoxia and a major fish kill. The results showed zooplankton abundance was higher or no different following the 2012 flood when dissolved oxygen remained stable compared to pre-flood conditions. During the 2013 flood when hypoxia occurred the abundance of copepods, nauplii and rotifers were at their lowest for the study period. Zooplankton assemblages were not distinctly different following the 2012 flood pulse compared to the pre-flood period but were different during the hypoxic 2013 flood, though quickly returned to resemble pre-flood conditions in the proceeding months. The study provides useful insights in how zooplankton populations may respond to flood events and recover after hypoxic conditions in estuarine ecosystems.

Modeling of chloroform content in drinking water of infiltration water intake by periods of the annual cycle. Part 1. Extended flood period

A relationship was found between the chloroform content in drinking water and the parameters characterizing the water quality (turbidity, chromaticity, oxidizability) during the extended flood period (March - June), isolated from the eighteen-year period of the infiltration water intake operation. Two time series were formed, including the monthly average values of the parameters for the entire observation period (72 values) and the averaged values of the parameters corresponding to each year (18 values). Two time series were formed, including the monthly average values of the parameters for the entire observation period (72 values) and the averaged values of the parameters corresponding to each year (18 values). Correlation-regression analysis showed that none of the parameters have a decisive significance for the chloroform content. Multiple correlation-regression analysis revealed that the regression equation for the time series of the averaged values of the parameters corresponding to each year is statistically reliable, is characterized by an acceptable mean error (about 12%) and can be used to assess the chloroform content in drinking water.

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.

Hydrochemical water quality monitoring of natural water bodies of the Ural river basin

A general characteristic of the river basin of the interstate Ural river and information on the economic use of the Ural river in its upper, middle and lower reaches are given. Information on the hydrology of the liquid and solid flow of the Ural river is presented. Hydrochemical monitoring of water bodies of the Ural river basin was conducted during the flood period, during the summer low water period and during the autumn low water period of 2017–2018. The hydrochemical monitoring of the water quality in natural reservoirs of the Ural drainage basin made it possible to identify an excess of the MPCs for residential use and for fishery of heavy metal ions in the water of the examined reservoirs. An excess of cadmium ions by (1.2–1.4) MPC for residential use was found in the Ilek river during its low water as well as in the Ural river near the border with the Russian Federation during the flood period in the amount of (3.1–3.4) MPC for residential use and near the village Zharsuat in the period of summer and autumn low water in the amount of (1.5–2.6) MAC for residential use. An excessive concentration of lead ions by (1.2–1.4) of MPC for fresh water fisheries in the middle and lower reaches of the Ural river at different times of the year was found. Excessive concentrations of ions of different heavy metals in comparison with their MPC for fresh water fisheries were found in all water bodies in different periods of the year. The greatest excess of zinc ions in comparison with its MPC for fresh water fisheries was observed during low water.

Modeling of Spacio-temporal Evolution of Salt Dispersion on Nokoue Lake

The numerical modeling of spatio-temporal evolution of lagoon has an important role in predicting the behaviour of these systems. Knowing the concentration of the pollutant field distribution in time and space contributes significantly to the prediction of exceptional phenomena. The purpose of this paper is to simulate the transport and dispersion of salt at Nokoue Lake. To this end, the 2D hydrodynamic model SMS (Surface Water Modeling System) has been used. Results showed that in flood period the freshwater inflows produce a net seaward transport, while in low water period the tides lead to periodic seaward and landward transport. The developed numerical model is useful for predicting pollutants transport in this system, for water quality management of the Nokoue Lake, and therefore, fight against eutrophication.

Study the Relationship between Selective Characteristics of Farmers and Their Practicing Coping Strategies towards Household Food Security during Flood Period

A study was carried out at flood affected reverine villages of three upazilas (small administrative unit) under Jamalpur district in Bangladesh during September, 2011 to May, 2012 to explore the relationship, contribution and direct–indirect effect between personal attributes and their coping strategies towards household food security practiced by the farmers during flood. Data were collected from randomly selected respondents and analyzed through both the qualitative and quantitative techniques by using a statistical program. Out of 18 personal, economic, social and psychological characteristics of the farmers, the personal education, housing condition, annual income, annual expenditure, savings, organizational participation, participation in IGAs, cosmopoliteness, environmental awareness, knowledge on flood coping mechanisms and household food security had positive but both credit received and utilization of received credit had negative. In addition, age, family size, training received, risk orientation and involvement in safety net programs are insignificant with coping strategies towards household food security during flood period.

Study of the Characteristics of Farmers on Practicing Coping Strategies towards Household Food Security during Flood Period

A study was carried out at flood affected reverine villages of three upazilas under Jamalpur district in Bangladesh during September, 2011 to May, 2012 to explore the relationship, contribution and direct–indirect effect between personal attributes and their coping strategies towards household food security practiced by the farmers during flood. Data were collected from randomly selected respondents through both the qualitative and quantitative techniques and analyzed with the help of SSPS. Out of 18 personal, economic, social and psychological characteristics of the farmers, the personal education, housing condition, annual income, annual expenditure, savings, organizational participation, participation in IGAs, cosmopoliteness, environmental awareness, knowledge on flood coping mechanisms and household food security had positive and credit received and utilization of received credit had negative while age, family size, training received, risk orientation and involvement in safety net programmes had no significant relation with coping strategies towards household food security during flood period.

Reservoir Sediment Management Practices in Sudan: A Case Study of Khashm El-Girba Dam

The sedimentation problem is a hot issue currently affecting the operations of reservoirs and irrigation networks in Sudan. Most of the rivers that cross Sudanese borders come from the Eastern African Plateau, which acts as a sediment source for the Nile River and its tributaries. Khashm el-Girba Dam (KEGD), which crosses the Atbara River in Eastern Sudan, is a multipurpose dam that was constructed in 1964. The Atbara River is a branch of the Nile River system, and the river carries a large amount of sediment during the flood period. Seven years after construction, in 1970, the dam faced a critical problem that could have led to a disaster; it was discovered that, due to sediment deposition, the water storage was not enough to satisfy the downstream requirements. This study discusses the sediment management practices used in KEGD and their impacts on maintaining the reservoir capacity. Practices including operation policy (OP), trap efficiency (TE), sluicing, sediment sluicing, and flushing operation (FO) were discussed. The adopted management practices succeeded in removing a considerable amount of silt and maintaining the lifetime of the reservoir.

JUSTIFICATION OF GEOMETRIC PARAMETERS OF A MOBILE SMALL-SIZED WAY FOR TRANSSHIPMENT OF TIMBER CARGO

The volumes of relatively inexpensive ship transportation of wood raw materials can be significantly increased by more actively using middle rivers for these purposes. However, the existing technologies for loading timber onto ships do not allow this. To solve the problem, the design of a mobile small-sized pier and the corresponding technologies for transshipment of timber cargo using logging equipment have been proposed. The design of a mobile berth involves the substantiation of its geometric parameters. In this regard, using the graphic-analytical method, recommendations are given, and empirical dependences are proposed for calculating the calculated values of the ship’s draft, the width and length of the loader, on which the indicated parameters of the mobile pier depend. The recommended value of the angle between the lower and upper surfaces of the berth α, as well as between the aft surface and the vertical B. A general algorithm for calculating the geometric parameters of a mobile pier is proposed. Using this algorithm, for example, the geometric parameters of the berth designed for loading timber onto barges on the middle rivers of the North Dvina basin during the flood period were determined. The pier height is 2.8 m, the length is 9.0 m, the width is 5.0 m, the height in the bow is 0.42 m, the length of the coastal ramp is 1.46 m, angles α=16gr, B =15gr.