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The flushing flow method involves partially or completely emptying the reservoir behind a dam to erode the sediment stored on the bottom and transport it downstream. [7] [6] Flushing flows aim to restore natural water and sediment fluxes in the river downstream of the dam, however the flushing flow method is less costly compared to removing dams or constructing bypass tunnels.
Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients.It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth. [1]
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organism that may deplete the oxygen in the water. [1] [2] Eutrophication may occur naturally or as a result of human actions.
The United Nations' FAO states that by 2025 1.9 billion people will live in countries or regions with absolute water scarcity. It says two thirds of the world's population could be under stress conditions. [55] The World Bank says that climate change could profoundly alter future patterns of water availability and use.
The impact of climate change and human activities on desertification are exemplified in the Sahel region of Africa. The region is characterized by a dry hot climate, high temperatures and low rainfall (100–600 mm per year). [44] So, droughts are the rule in the Sahel region. [45]
They are especially susceptible to damage from excessive human land use pressure. [3] The causes of desertification are a combination of natural and human factors, with climate change exacerbating the problem. Despite this, there is a common misconception that desertification in Africa is solely the result of natural causes like climate change ...
Climate activists are engaged in a range of activities around the world that seek to ameliorate these issues or prevent them from happening. [163] The effects of climate change vary in timing and location. Up until now the Arctic has warmed faster than most other regions due to climate change feedbacks. [164]
Global climate change will probably make it more complex and expensive to ensure water security. [2] It creates new threats and adaptation challenges. [1] This is because climate change leads to increased hydrological variability and extremes. Climate change has many impacts on the water cycle. These result in higher climatic and hydrological ...