Review of Effects of Dam Construction on the Ecosystems of River Estuary and Nearby Marine Areas

Abstract

Dams have made great contributions to human society, facilitating flood control, power generation, shipping, agriculture, and industry. However, the construction of dams greatly impacts downstream ecological environments and nearby marine areas. The present manuscript presents a comprehensive review of the influence of human activities on the environment, especially the effect of dam construction on the ecosystems of river estuaries and nearby marine areas, so as to provide a scientific basis for ecological environment protection. To summarize these impacts, this review used recent studies to comprehensively analyze how dam construction has affected river hydrology, geomorphology, and downstream ecosystems globally. Effects of dams on ecosystems occur through reduced river flow, reduced sediment flux, altered water temperature, changed estuary delta, altered composition and distribution of nutrients, altered structure and distribution of phytoplankton populations, habitat fragmentation, and blocked migration routes in river sections and adjacent seas. Effects of dam construction (especially the Three Gorges Dam) on the Yangtze River were also reviewed. Performing community and mitigation planning before dam construction, exploring new reservoir management strategies (including targeted control of dam storage and flushing sediment operations), banning fishing activities, and removing unnecessary dams (obsolete or small dams) are becoming crucial tools for ecosystem restoration.

Dynamics of land cover changes and carbon emissions driven by large dams in China

“…Though the land cover changes driven by dams can change the dynamics of the carbon pools in terrestrial ecosystems, eventually altering carbon cycles between terrestrial ecosystems and the atmosphere, 26 such dynamics are not adequately emphasized in projects, particularly dams, in China. 27 Much like the role of ecological construction in reducing carbon emissions, 28 studies supporting the promotion of carbon stock through dams argue that dams can stimulate the regeneration of vegetation on unoccupied lands.…”

Study of the River Discharge Alteration

“…While the scientific literature contains numerous studies on this subject, a comprehensive critique is essential. There is a pressing need to examine how much dam constructions deviate river flows from their natural state, preserving intact ecological functions [16][17][18].…”

Research on the Sustainable Development of the Bistrita Ardeleana River in Order to Stop the Erosion of the Riverbanks and the Thalweg

“…The impact of dams and reservoirs on the aquatic environment of rivers is an important topic in global water resources management. These hydrotechnical constructions change the natural hydromorphological regime of rivers, negatively affecting their functionality and are associated with several environmental impacts, such as habitat fragmentation, poor water quality, nutrient depletion, loss or modification of biodiversity, remodeling of trophic networks, ichthyofauna, reduction of riparian biodiversity the river [5,[9][10][11][12][13][14][15][16][17][18]. Worldwide, the decline of river biodiversity has recently been linked to the reduced functionality of the riverbed substrate.…”

“…The impact of large dams is not only limited to direct effects on the hydromorphology of the aquatic or riverine ecosystem but also on downstream localities, which extend to ecological environments [16].…”