Action Area Number Three: River Floodplain health
The flood plains are the area comprising lively and non-active river channels having a complex of vegetation or non-vegetation bars. A flood plain is the boarding of the rivers having a large flat area on either side of the river and it is the deltaic region where the flooding occurs. A healthy floodplain can control the spilling of water from the river by reducing the velocity of water by increasing the friction between the floodplain and water. The floodplain regions are covered by a layer of alluvium and are fertile rich soil and provide suitable habitat for reeds and marsh plants.
The degradation of flood plain occurs through powerful overbank floods, lateral erosions, floodplain land use for agriculture or other infrastructures, reduced floodplain width by the erosions, and other human activities. Extensive loss and damage to the floodplains’ natural habitat will happen by the developmental activities in the river corridors. The management of flood plain is a community-based effort for a healthy riverine ecosystem.
Flood plains Physical features
Flood water inundates the floodplain; the major role of floodplains is flood protectionwhichis designed to reduce inundation. It has a key role in protecting the biological, physical, and chemical integrity of water. It has the property to improve the water quality of rivers by filtering the water and removing the sediments, pollutants, and other excess nutrients and minerals in the water. The degradation of floodplains can cause changes in water quality and the recharging capacity of the aquifers. Floodplains are the area where the flow of water is less than the main river channel, the slow runoff of water will provide no cost infiltration and purification of water and underground recharge.
Lateral connectivity of Flood plains
Lateral connectivity is the transfer of materials through the periodic inundation of floodplains in the hydrological cycle. The exchange of riverine materials such as organic matter, nutrients, energy, minerals, and other materials through the river and the floodplain interaction. Lateral connectivity can be greatly influenced and will be altered by human activities in floodplain areas. The human development activities and the construction of flood mitigation structures on the river corridors adversely affect and decrease the events of lateral connectivity in the areas.
Floodplain Land uses & Erosion
Floods shape the floodplain of a river, and vice versa, the shape of the floodplain have a great influence on the flow of a flood. A series of natural processes such as erosion and deposition, water flow, hydrological cycle, physical and biological process, and other extreme events constantly change the shape of a floodplain. The natural and beneficial value of the riverine ecosystem depends on human activities in the area. Thus, the developmental pressure by the floodplain land use, encroachments in the river corridors, and the change in the natural condition cause the degradation of the floodplain by loss of biological activities.
Floodplain soil and farming
The floodplain soils are mostly fertile; they are the alluvial lowland soil having nutrient-rich status. The productivity in the area is abundant with good quality water and nutrient inputs. The natural vegetation in the floodplain can help to enrich the area by filtering the flood water and trapping the sediments. The rich nutrients, sufficient water quantity, and sustainable biological productivity by the availability of organic matter from the littering of vegetation attract farming in the floodplain areas. But on the other side, the floodplain land used for agriculture or other farming purposes will lead to the degradation of the environment due to the change in natural ecosystems.