Optimising hydrological conditions to sustain wintering waterbird populations in Poyang Lake National Natural Reserve: implications for dam operations

Abstract

1. Poyang Lake is the largest freshwater lake in China and is of global importance for the conservation of migratory waterbirds of the East Asian -Australasian Flyway. Recent dam construction on the Yangtze River and its tributaries for agriculture and hydroelectric power has affected the hydrological regimes in downstream lakes. The Three Gorges Dam changed the hydrological regime of downstream lakes by reducing wet season flooding and expanding water storage in the dry season. 2. Despite the critical role of Poyang Lake in regional and global biodiversity conservation and the potential adverse ecological impacts of the Three Gorges Dam on downstream lakes, there have been few studies of the hydrological requirements of wintering waterbirds in the middle Yangtze floodplains. 3. We assembled a predictor matrix including three hydrological variables (annual inflow, maximum water level in high water season or MaxWL and minimum water level in low water season or MinWL) and two climatic variables (annual rainfall and biological cumulative temperature or BioT). Using the predictor matrix and annual waterbird census, we built group-specific generalised additive models (GAM) to investigate how waterbird population variations were related to climatic and hydrological factors in the Poyang Lake National Natural Reserve. We then used the modelled predictor-response curves to identify the optimal lake water levels for each waterbird group. 4. The community-level model selected group and the group-varying-coefficient term of BioT, Inflow and MaxWL as explanatory variables. At group level, tuber eaters and sedge foragers responded positively to BioT and MinWL. Seed eaters, invertebrate eaters and fish eaters responded positively to Inflow and negatively to MaxWL and MinWL. Based on the modelled predictor-response curves, we propose the following optimal water level ranges for Poyang Lake wintering waterbird conservation: a) maximum high water season level should be less than 17.4 m; and b) minimum low water level should be between 8.2 m and 8.8 m.

Impact of the Three Gorges Dam on the Hydrology and Ecology of the Yangtze River

“…(1) More research should be conducted to determine the appropriate level for the lake (e.g., [74]) and how best to operate the dam so as to minimize its adverse influences. (2) Intra-provincial and inter-provincial hearings should be held on a large scale.…”

Potential effects of dam cascade on fish: lessons from the Yangtze River

“…Construction of hydroelectric dams affect river ecosystems and undermine fish diversity and fisheries yields (Poff et al 2007;Jiao et al 2007;Wang et al 2013). The effects of individual dams on fish diversity have been studied extensively and are now relatively well understood (López-Pujol and Ren 2009;Young et al 2011;Azami et al 2012).…”

Integrating Economic and Ecological Benchmarking for a Sustainable Development of Hydropower

“…In appreciation of the importance to model future hydropower developments and environmental effects, there is a growing number of modelling studies. However, like most ecological effect studies, existing models focus on environmental effects downstream of the dam while largely disregarding the effect of WLF on the ecology of the reservoir itself [17][18][19]. Moreover, existing models rarely consider how future developments of the energy market affect economic benchmarks.…”