The objective of flood frequency analysis (FFA) is to associate flood intensity with a probability of exceedance and for making probabilistic estimates of a future flood event in Allala basin based on the historical discharge record at Sidi Akkacha gauging station, the peak floods discharge of Allala river for 5, 10, 50, 100 years return period are estimated using exponential distribution and the stage at different position of river are calculated using HEC RAS model . Based on the modeling study carried out considering 62 cross sections for 8 km length of river, The Output HEC-RAS model show that the existing embankments system on the banks of Allala River is not sufficient to resist the peak flood discharge of 100 years return period, water level profile shows that a maximum of 1.25m in left bank((at 1.2 km downstream) is needed to protect the inundation of the low laying areas of Old tenes.
The study was conducted at the reclamation water intake facility of Tikhovsky hydroelectric complex. We used data from long-term observations and results of laboratory studies on a 1:20 scale physical model of the Zapan fish protection device. The effectiveness of the model was evaluated using simulators of juvenile fish. Increasing the efficiency of the Zapan fish protection facility is achieved by additional placement in the bottom threshold, which directs the bottom flow along with the young fish to the springboard, where there is an airlift in the form of a bubble curtain that lifts the young along the springboard into the fish-receiving holes of permeable shields. Fish protection design and location in the middle of the water stream do not create a backwater due to low resistance and provide protection for young fish. This increases not only the survival rate of young fish, but also the efficiency of reclamation water intakes. A new design of a fish protection structure for reclamation water intakes of the Zapan type was developed, which provides a fish protection effect of 3 groups of young fish formed by their swimming ability, which allowed determining the size of the elements of the fish protection structure.
In Algeria, the problems of erosion and sediment transport are critical, since they have the most dramatic consequences of the degradation of agricultural soils on the one hand and the siltation of the dam on the other .The sediment transport in the Algerian basins is very important especially during the periods of floods, It is in this sense that this study, which consists of estimating the sediment transport in suspension and determining the models of relation linking the liquid discharge and the sediment discharge in order to estimate the solid transport in the absence of suspended sediments concentration data at the Sidi Akkacha station at the outlet of the basin of Oued Allala which is subject to a high water erosion, it degrades from one year to the other under the effect of this phenomenon especially during the floods which drain high amounts of fine particles exceeding in general, the concentration of 150 g/l, the results obtained from the application of the models are very encouraging since the correlation between liquid and solid discharge exceeds 80 %.
One of the main reasons for the increase in the ecological tension of aquatic ecosystems remains the discharge into water bodies of domestic wastewater containing toxic substances and pathogenic microorganisms. This is due to the imperfection of water treatment technologies, including due to wear and tear of utility networks and violations in the technological process, accompanied by salvo emissions. Reducing the anthropogenic load on water bodies is possible by retechnologizing various stages of wastewater treatment. The paper describes the design of a sedimentation tank with aeration elements for clarification of urban wastewater, providing an increase in the efficiency of sedimentation of suspended solids. Spraying fine air bubbles contributes to the collision and enlargement of aggregate-unstable elements without the use of coagulants and flocculants. The paper presents a mathematical algorithm for calculating the required deposition surface, taking into account the wastewater flow rate, the nominal diameter of the dispersed phase particles and the required degree of purification. Numerical experiments have shown that for a settlement with a population of 100,000 people, a treatment plant with a standard sedimentation tank is required, the area of which is 130 m2. The use of a sedimentation tank with aeration elements in similar conditions allows reducing the required clarification surface to 120.9 m2 without reducing the clarification efficiency. It has been proven that the spraying of finely dispersed air bubbles helps to reduce the required settling area of the sump by 8%.
The parameters of the process of vegetation removing from the water surface have been justified. An experiment was conducted to determine the strength of the screw-type tool and matching the most appropriate parameters. It was established that the channel clean-up quality depends on the screw diameter. It was also investigated the influence of the screw rotation speed on the channel clean-up quality. The dependence of the cleanup quality on the flight screw pitch has been determined.
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