Post‐damming Flow Regime Development in a Large Lowland River (Volga, Russian Federation): Implications for Floodplain Inundation and Fisheries

Abstract

Periodic flooding plays a key role in the ecology of floodplain rivers. Damming of such rivers can disturb flooding patterns and have a negative impact on commercial fish yield. The Volga River, the largest river in Europe, has a regulated flow regime after completion of a cascade of dams. Here, we study effects of damming on long-term discharge variability and flood pulse characteristics. In addition, we evaluate the effects of the altered flood pulse on floodplain ecosystem functioning and commercial fish yields. Our results indicate that both flood pulse and fish populations of the Volga-Akhtuba floodplain have varied considerably over the past decades. After damming, annual maximum peak discharges have decreased, minimum discharges increased, but average discharges remained similar to pre-damming conditions. Moreover, because of bed level incision of over 1.5 m, a higher discharge is needed to reach bankfull level and inundate the floodplains. Despite this significantly altered hydrological regime and subsequent morphological changes, current discharge management still provides significant spring flooding. However, commercial fish catches did decrease after damming, both in the main channel and in the floodplain lakes. All catches were dominated by species with a eurytopic flow preference, although catches from the main channel contained more rheophilic species, and floodplain catches contained more limnophilic and phytophilic species. The strong increase of opportunistic gibel carp (Carassius gibelio) around 1985 was apparent in the main channel and the floodplain lakes. Despite the hydrological changes, the decrease in overall catches, and the upsurge of gibel, we found a strong positive effect of flood magnitude in the previous year on commercial fish yield in the floodplain lakes. This suggests that under the current discharge management there still is an increased fish growth and/or survival during high floods and that functioning of the floodplain is at least partly intact.

Decision Support System for Urbanization of the Northern Part of the Volga-Akhtuba Floodplain (Russia) on the Basis of Interdisciplinary Computer Modeling

“…Circles indicate the positions of solutions (2) and (4). Figure 5 demonstrates that the decrease of the equilibrium value S in problem (3) stabilizes the unstable cycle in Figure 1 for large values of the ecological criterion in comparison with problem (1). In addition, the use of environmental urbanization strategies leads to a significant increase in its effectiveness, both in terms of environmental and socio-economic criterion.…”

“…The exact form of the function S f (S) is determined by the features of the topography and the flooding regime of the VAF. To simulate the dependences of S f (S) in the problems (1) and (3), we used here the subsystems of geoinformation and hydrodynamic modeling.…”

“…Volzhskaya HPP (VHPP) usually regulates the hydrological regime of the Volga in the interests of hydropower industry, and it has significantly been reducing the spring water volume compared to natural flooding since 11 large dams appeared on the river [1]. In recent years, the VolgaAkhtuba plain has been flooded rarely more than 40 % of its total area.…”

Summer co‐existence of small‐sized cyprinid and percid individuals in natural and impounded stretches of a lowland river: food niche partitioning among fishes

“…Damming is one of the most pervasive anthropogenic stressors of the world's freshwater ecosystems, both for small streams and large rivers (Ward & Stanford, ; Petts, ; Graf, ; Górski et al ., ; Zhang et al ., ). It affects many riverine characteristics, such as flow regime, river‐channel geomorphology and sediment quality, all of which may be potential drivers of instream macrophyte colonization and persistence (Bednarek, ; Feld et al ., ).…”

Post-dam Channel and Floodplain Adjustment along the Lower Volga River, Russia

“…In this period the Volga discharges about one third of its total annual discharge volume. During peak flow, the large floodplain between both branches inundates to a large extent for a period of several weeks (Górski et al 2011).…”