Hydrological Assessment of the Water Replenishment Possibility of the Uzh River Urbanized Floodplain on the Example of Bozdosky Park, Ukraine

Abstract

Over the last twenty years, the number of projects aimed at river restoration and rehabilitation increased significantly. In the city it is impossible to provide full river restoration, but at the same time it is possible to create a comfortable natural environment both for flora and fauna and for the citizens. In our work it was assessed the possibility of the floodplain restoration by the water replenishment of the dry old riverbed during the vegetation season on the example of the river inside the city. The simulation of the current state allowed to verify the main parameters of the model with the existing observations of the water levels in the river and lake and water levels in the wells located in the park. The several models of the river -floodplain interaction were simulated: floodplain was separated from the river by the flood control dyke, the water replenishment of the lake and the old riverbed was due to seepage (current state); the connection of the floodplain with the river by the culvert and the replenishment of the lake and the old riverbed with surface river water. The simulation showed that the lake isolated from the river is filled to a depth of not more than 0.5 m, the old riverbed is filled with water only during spring floods. The water balance calculations of the lake showed that in the conditions of isolation from the river, the lake volume is significantly affected by precipitation and evaporation from the lake water surface area. The connection of the lake with the river surface water significantly reduces the impact of the vertical components of the water balance, at the same time increases the seepage losses from the lake because of the water level raising. The connection of the river with the floodplain makes it possible to replenish the old riverbed and the lake in the mean year, but in the dry years the water level in the lake does not allow to replenish the old riverbed during the vegetation season. Calculations showed that to be able to keep the constant water level in the lake and old riverbed, it is necessary to increase the water level in the lake.

Development of the hydrological regime of the Uzh River under backwater conditions to minimize the urban environment risks

“…Bozdos Park is located in the middle of the river loop, and the ground flow in the middle loop has the direction from upstream side of the dam to the downstream of the river loop. These seepage losses were calculated according to equation (4) of the article [3] as the seepage losses from the river with backwater to the river downstream. The methodology for determining precipitation, evaporation from the water surface as components of the water balance is described in work [3].…”

“…These seepage losses were calculated according to equation (4) of the article [3] as the seepage losses from the river with backwater to the river downstream. The methodology for determining precipitation, evaporation from the water surface as components of the water balance is described in work [3].…”

“…The problem of disconnection between the floodplain and the river takes plays as a result of the flood control dykes' construction in the urbanized areas, and the water replenishment problem of the floodplain and oxbow lakes is possible to solve by the river flow management and artificial structures. The article [3] analyses the prospects of watering the old river bed and the oxbow lake in the urbanized area, which is protected from floods by earth dykes. It is not possible to restore the connection between the floodplain and 1254 (2023) 012082 IOP Publishing doi:10.1088/1755-1315/1254/1/012082 2 the river by destroying dykes on the urbanized areas.…”

Testing a numerically-analytical method for prediction design maxima discharges of floods using plotting position formulas: the river Uzh case, the “Uzhhorod” gauging station data

“…The runoff of the Uzh River is very variable. It is only about 29.6 m 3 /s of the mean annual water discharge near Uzhhorod [65,66], a minimum 7-day summerautumn flow can decrease below 2 m 3 /s [67], but a maximum peak one can exceed 1,000 m 3 /s and more during floods. The Uzh River is known for its heavy snowmelt and rain flash floods, which can occur 3-8 times per year.…”