The “river discharge,” or volume of water flowing through a river channel, is calculated in cubic meters per second. An increase in discharge causes a rise in river levels. Flooding happens when a river’s bankfull capacity is reached (water spills over the banks of the river). Flooding is a physical problem that has several causes.

Prolonged rainfall

After heavy rains, the soil becomes saturated. Rainfall cannot penetrate the soil. As a result, increasing surface run-off. As a result, the river channel receives more water, which raises the risk of floods.

Heavy rainfall

Water may arrive during a strong downpour too quickly to penetrate the soil. This raises the risk of floods by increasing surface runoff, which causes water to enter the river channel earlier.

Building HUMAN CAUSES OF FLOODS

Building construction results in impervious surfaces that increase surface run-off. Surrounding roads and walks also contribute to this. Additionally, drains enhance the water flow into nearby rivers, raising the risk of flooding.

Deforestation

Rainfall is intercepted by vegetation, notably trees, which slows its progression. Before evaporation adds moisture back to the atmosphere, some of this water is stored. Additionally, trees draw moisture from the soil, enhancing soil penetration and lowering surface run-off. Surface runoff increases, and infiltration and interception decrease when vegetation is eliminated. As a result, the risk of flooding increases as more water enters the river channel.