Deforestation - Due to the loss of vegetation, water cannot be returned back into the atmosphere through transpiration. This reduces the evapotranspiration rate, and slows down the hydrological process. As less water is returned into the atmosphere, subsequently, there is less precipitation. This can result in droughts, and dehydration for plants in the surrounding area. Vegetation also prevents flooding by intercepting precipitation. Without this interception, there will be an increase in surface runoff. Too much surface runoff will result in flooding. An increase in deforestation will result in an increase in the size, scale and impact on subsequent flooding. As less water is in the flood, the flood damage will decrease, therefore resulting in less fatalities and injuries. The peak flow will also decrease as there is less water required to be discharged from the area, again resulting in less damages done by the water.
Urbanization - Human development can lead to many unwanted results and impacts on the hydrological cycle. There will be an increase in surface runoff and erosion as there is less vegetation to slow water down. Increased surface runoff will accumulate pollutants and sediments, bringing them into streams, polluting and decreasing the water quality, affecting fish population. There will also be an increased flood risk due to change in water drainage patterns. This increases the size, scale and impact on subsequent flooding because as water cannot escape through infiltration, it will stay as surface area and prolong peak flow. As more water is within an area, the water will slightly erode buildings, and cause extra damages which would have been prevented if the water could have escaped through infiltration.
Urbanization - Human development can lead to many unwanted results and impacts on the hydrological cycle. There will be an increase in surface runoff and erosion as there is less vegetation to slow water down. Increased surface runoff will accumulate pollutants and sediments, bringing them into streams, polluting and decreasing the water quality, affecting fish population. There will also be an increased flood risk due to change in water drainage patterns. This increases the size, scale and impact on subsequent flooding because as water cannot escape through infiltration, it will stay as surface area and prolong peak flow. As more water is within an area, the water will slightly erode buildings, and cause extra damages which would have been prevented if the water could have escaped through infiltration.
Increase in Impermeable Surfaces - An increase in impermeable surfaces such as rooftops, parking lots, streets etc. is part of urbanization, and will increase surface runoff and decrease infiltration. This is because water cannot pass through the surface and into the groundwater flow. Below is a table of the consequences of an increase in impermeable surfaces:
Global Warming - Global warming has resulted in an increase of 0.6ºc (1ºF). This results in an increase in evaporation and a more higher water-vapor concentration. This indicates that water is returned to the atmosphere at a faster rate, allowing storms to produce more precipitation. An increase in precipitation will lead to an increase of water that is required to be returned back into the atmosphere, and before the majority of the water can be recycled, may causes flooding.