Methane is the primary greenhouse gas emitted during the construction and operation of dams and irrigation projects, particularly from the decomposition of organic matter in flooded areas.

Methane is a potent greenhouse gas with a global warming potential 25 times higher than carbon dioxide. Its release from dams and irrigation projects contributes to increased global warming.

Dams and irrigation projects often reduce the flow of water downstream by diverting water for irrigation, hydropower generation, and other purposes.

Reduced water flow downstream of dams and irrigation projects can lead to the degradation of aquatic habitats, affecting fish populations, biodiversity, and water quality.

Dams and irrigation projects can alter local and regional climate patterns by changing the flow of water and heat, which in turn affects wind patterns and precipitation.

Hydroclimatic modification refers to the intentional or unintentional alteration of local and regional climate patterns through the construction and operation of dams and irrigation projects.

Hydroclimatic modification caused by dams and irrigation projects can lead to exacerbated extreme weather events, such as droughts, floods, and heatwaves.

Dams and irrigation projects can decrease carbon sequestration by inundating forests and wetlands, which are natural carbon sinks.

Reservoir degassing refers to the release of carbon dioxide and methane from reservoirs behind dams due to the decomposition of organic matter and the disturbance of natural carbon cycles.

Reservoir degassing contributes to increased global warming by releasing greenhouse gases into the atmosphere.

Dams and irrigation projects can increase nitrogen fixation by creating favorable conditions for nitrogen-fixing bacteria.

Nitrogen fixation is the process by which nitrogen-fixing bacteria convert atmospheric nitrogen into forms usable by plants.

Increased nitrogen fixation caused by dams and irrigation projects can lead to exacerbated eutrophication, a process that results in excessive nutrient enrichment of water bodies, leading to algal blooms and water quality degradation.

Dams and irrigation projects can increase phosphorus retention by trapping sediment and preventing its downstream transport.

Increased phosphorus retention caused by dams and irrigation projects can lead to exacerbated algal blooms, which can result in water quality degradation and ecological imbalances.