Dams are primarily constructed to control floods by storing excess water during heavy rainfall and releasing it gradually over time.

Dams disrupt the natural flow of rivers by reducing the downstream flow rate, as a significant portion of the water is stored in the reservoir.

Irrigation projects often lead to reduced water quality due to the increased use of fertilizers and pesticides, which can contaminate water sources.

Dams trap sediment upstream, reducing the amount of sediment transported downstream, which can have negative impacts on aquatic ecosystems.

Eutrophication is primarily caused by excessive nutrient input, often from agricultural runoff or wastewater discharge, leading to an overabundance of plant growth and a decline in water quality.

Dams can disrupt fish migration patterns by creating physical barriers that prevent fish from moving upstream or downstream.

Salinization in irrigation projects is primarily caused by poor drainage systems, which allow salts to accumulate in the soil, affecting crop growth and soil fertility.

Irrigation projects often lead to the loss of biodiversity in aquatic ecosystems by altering natural habitats, reducing water quality, and introducing non-native species.

Waterlogging in irrigation projects is primarily caused by excessive water use, which exceeds the capacity of the soil to absorb and drain the water.

Dams can reduce the downstream water temperature by releasing cold water from the bottom of the reservoir, which can have negative impacts on aquatic ecosystems.

Sedimentation in aquatic ecosystems downstream of dams is primarily caused by reduced sediment input due to the trapping of sediment in the reservoir.

Irrigation projects can increase the risk of waterborne diseases by creating favorable conditions for the growth and transmission of pathogens.

Algal blooms in aquatic ecosystems downstream of dams are primarily caused by increased nutrient input from agricultural runoff or wastewater discharge.

Dams can reduce the downstream dissolved oxygen levels by releasing water from the bottom of the reservoir, which is often depleted in oxygen.

Fish kills in aquatic ecosystems downstream of dams are primarily caused by reduced dissolved oxygen levels due to the release of water from the bottom of the reservoir.