Geographical regions often come under the effect of sudden heavy downpours and lashing rainfall resulting in deluged expanses. In case of urban cities, heavy rainfall can lead to water clogging on roads and over flowing of ill-equipped sewage drains. Floods not only cause terrible loss to the fiscal system of the region, bringing the entire county to a standstill by cutting off the efficacy of its lifelines, but also impact the environment at large. The most prevalent effects of flood are noticed on the geological features of the affected region.
Effects of Floods with Respect to Environmental Geology
The top soil of the earth’s crust is the most vulnerable component that can be affected by flood. If devoid of vegetation or foliage of any kind, the upper crust is exposed to the harshest weather conditions. When floods strike the barren top soil layer instantly washes along with the water currents. The land is thus stripped of the basic properties that support healthy vegetation or regeneration of any kind. The washed away soil flows into adjacent water-bodies such as lakes and rivers and later gets swept away into the sea.
Under constant wet conditions, when flood waters remain stagnant for days on a particular land area, there are grave implications on the soil chemistry. As the earth remains underwater for such a long period of time, there is considerable reduction in oxygen content of the soil. As the layer of water cuts off the supply of air to the earth, the fundamental chemistry of the soil is totally disturbed. Subsequently this destroys the basic characteristics of soil that negatively affects the crop productivity and farming activities.
Soil aggregation is positively correlated to the physical and chemical properties of the soil which helps in improving the soil quality. However, when the soil aggregation quality is depleted, harsh damages and growth deterrence occurs to the plants and crops trapped under such flooded conditions. This also induces pH imbalance in the soil as flooded conditions boosts acidity and reduces alkalinity.
Many a time, refuse and other similar biodegradable garbage get trapped under the flood water. Submerged under the water, the garbage’s regular degradation process is disturbed and slashed to half the speed compared to the decomposition of organic matter in normal soil. Moreover, the final result of such decay or decomposition is the production of large concentrations of ethanol and hydrogen sulphide, which are harmful to the soil and its productivity.
Flood waters also gush past different landscapes without discrimination, causing layers of sand and infertile soil to be swept onto the fertile lands of fields and thickets of tree. This infertile sand and silt form a layer over the roots of crops, plants and trees, choking them and cutting off the air supply completely. This process is called sedimentation, which destroys the vigour and growth process of the roots. In some cases, the flood water also washes away small plants and similar vegetation, stripping the soil of nutrients and making it gullible to further erosion. In case of rigorous and continuous occurrence of such trends, desertification and constant erosion of rocks take place.