When rain water falls it causes soil or water erosion. Rainwater sweeps away the topsoil, which exposes the layers beneath it to the natural elements, and increases carbon dioxide release. This is a slow process that develops over time and is not always harmful to ecosystems. However, the process can happen very quickly and cause negative effects on various aspects of the ecosystem.

When soil erosion happens quickly and removes the topsoil, it can have adverse effects on plants. According to the Iowa State University Extension, soil erosion causes a diminished water capacity, which reduces carbon and nutrients in the water, resulting in decreased crop productivity. The amount of nutrients reaching the plants can be greatly reduced. This is particularly detrimental to farmers, which an lose crop productivity due to water erosion.

Heavy water erosion can create negative effects for ecosystems such as flooding, according to the World Wildlife Fund. Because the swept-away topsoil cannot absorb the rainwater, locations susceptible to flooding could see greatly increased flooding. This is seen in banana plantations, where there is limited drainage capabilities, or low-lying areas. Flooding can be extremely devastating and, in severe cases, it sweeps away roads, buildings and houses.

The adverse effects of water erosion eventually lead to wildlife. Because the absence of the topsoil reduces water quality and increased pollutants, animals, fish and algae are negatively effected. According to the World Wildlife Fund, there has been a reduction in fish numbers, most likely due to soil erosion and pesticide runoff. Excessive topsoil could conceal fish breeding areas and pollute downstream waters.

Water erosion not only effects the soil, plants and wildlife, but the water supply itself. When the rainwater erodes the soil, it can lead to diminished water quality problems. After the eroded topsoil reaches the water sources, it increases the presence of nitrogen and phosphorous in the water. This results in reduced water oxygen levels and diminished water quality. The presence of harmful chemicals, such as pesticides in the topsoil, can reach water sources such as rivers, lakes and oceans.