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Ecological impact of water conservancy projects and its causes

As we all know, water conservancy projects include flood control, farmland water conservancy, hydropower generation, shipping, inter-basin water transfer, urban and rural water supply, coastal protection, reclamation projects, beach utilization and so on. The construction of water conservancy project is the practical activity of human beings to transform nature, and it is the control, regulation and governance of water in nature by human beings through engineering means. The purpose of building water conservancy projects is to reduce and avoid floods and droughts and meet the needs of human social development.

Water conservancy projects play an important role in flood control, irrigation, water supply and power generation, and their construction and operation have various effects on the structure and function of river ecosystem. Here we summarize the possible negative impacts of water conservancy projects on ecology into the following six main aspects.

Influence of dam barrier

The dam blocked the river, changed the natural flow pattern of the river and broke the balance of the natural ecosystem of the river. For example, the migration route of migratory organisms is destroyed, sediment deposition in the upper reaches, river erosion in the lower reaches, estuary retreat, and the self-purification ability of water bodies is reduced.

Influence of reservoir inundation

The inundation of the upper reaches of the reservoir has caused the loss and destruction of land, natural and cultural heritage, landscape, migration, animal and plant habitats and biodiversity.

Influence of reservoir regulation and storage

Reservoir regulation and storage will have an impact on the geological structure, groundwater level and climate in the reservoir area and its surrounding areas, which may induce salinization and swamp of land, eutrophication of water quality, and increase of water surface evaporation caused by earthquakes, landslides and rising groundwater level.

Impact of dam-break risk

Dam break that may be caused by flood, earthquake, war, etc. It will increase the risk of people's lives and property safety in downstream areas.

Influence of water transfer project

Inter-basin water transfer will have an ecological impact on the downstream of the water transfer basin due to the reduction of water volume, such as water supply safety, river cut-off, estuary shrinkage and so on. The possible impacts on the transfer basin mainly include resettlement along the project, water pollution and diseases spread by aquatic microorganisms.

Influence of irrigation

It is mainly due to excessive water diversion and improper irrigation methods in irrigation areas, which lead to river interruption, river ecological degradation, groundwater level decline and soil secondary salinization.

Among these impacts, resettlement, siltation and biodiversity destruction caused by dam blocking and flood are the most prominent problems in the ecological impact of water conservancy projects.

The above-mentioned ecological impact problems exist objectively, and the causes are different, but there are three main aspects.

First, the defects of the project itself. The inherent characteristics of water conservancy engineering technology itself are the root of some ecological problems, and the existence of engineering often means the existence of some ecological problems.

The second is the limitation of human understanding level. Under certain time and space conditions, human understanding of natural laws has certain limitations. Some ecological problems that may occur in water conservancy projects are not fully recognized or considered.

The third is the lack of system. Although people have realized some ecological problems of water conservancy projects and taken corresponding measures to eliminate these ecological problems. However, due to insufficient attention or improper institutional arrangements, these ecological problems have intensified.