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

Velychko Svitlana, Dupliak Olena

Ecological Engineering & Environmental Technology

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2021

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Vol. 22, iss. 4

30--38

EN

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 river – floodplain interaction was 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 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.

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Temporal fluctuations of the phytoplankton community in an isolated floodplain lake (North Mollaköy Lake) of the Sakarya River (Northern Turkey)

Sevindik T. O., Tunca H., Önem B., Tamer S. A.

Oceanological and Hydrobiological Studies

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2014

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Vol. 43, No. 4

381--392

EN

The aim of this study was to determine the spatial and temporal variation of phytoplankton and water quality in response to the hydrological regime in an isolated floodplain lake (North Mollaköy Lake) of the Sakarya River. Variations in the composition, biomass and functional groups of phytoplankton and environmental parameters were monthly analyzed in sub-surface samples collected from the pelagic zone at four stations from July 2012 to June 2013. A total of 109 taxa were identified, and the species which contributed the most to the phytoplankton biomass were grouped into 14 functional groups (FGs). The distribution of FGs was linked to the transition (T1 and T2), high (HW) and low (LW) water periods in North Mollaköy Lake. FGs J, MP, N, G, X1, X2, Y, W1, W2, S1, H1, B and C were the contributors to the phytoplankton biomass during the low-water period (LW) and the transition periods (T1 and T2), while Lo contributed the most during the high-water period (HW). RDA revealed that the most important factor affecting the temporal distribution of FGs was the water discharge and that there are some differences between stations in terms of Si, pH values and the distribution of FGs.

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Distribution of ephemeropteran nymphs associated with different stolon sections of Eichhornia azurea (Schwartz) in two floodplain lakes of the Upper Parana River (Brazil)

Melo S. M. de, Takeda A. M., Grzybkowska M., Monkolski A.

Polish Journal of Ecology

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2004

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Vol. 52, nr 3

369-376

EN

Eichhornia azurea (Schwartz) Kunth is one of the most abundant species of aquatic macrophyte in the Upper Parana River floodplain, and ephemeropteran nymphs frequently inhabit this plant. The objective of this study was to analyze the distribution of ephemeropteran nymphs associated with three sections (apical, intermediate, and basal) of E. azurea in two floodplain lakes of the Upper Parana River as well as to establish the relation of this distribution to biotic and abiotic factors. The samplings of apical, intermediate and basal sections of E. azurea were carried out monthly from October 1997 to October 1998. Higher concentration of dissolved oxygen may contribute to greater density of nymphs on the apical plant segments near the water surface. Callibaetes willineri was the most abundant taxon, occuring on the apical and intermediate plant sections whereas Campsurus spp. were recorded on the basal and intermediate sections of the plant, near the sediment and, mainly during high water. Lower dissolvedoxygen concentrations near the lake bottom during the high water phase might suggest that during this phase the nymphs of Campsurus violaceus also migrate to E. azurea roots. It was found that changes in water level influenced the variation of the abundance of nymphs. Other genera, such as Tricorythodes and leptohyphes, were recorded during the high water phase, when river water enters the lakes and their shores are flooded.