Urban floods and environmental impact

Urban floods Flooding in urban areas can be caused by flash floods, or coastal floods, or river floods, but there is also a specific flood type that is called urban flooding. Urban flooding is specific in the fact that the cause is a lack of drainage in an urban area. Urban flooding is the inundation of land or property in a built environment, particularly in more densely populated areas, caused by rainfall exceeding the capacity of drainage systems, such as storm sewers

CAUSES OF URBAN FLOODING Natural Causes Heavy Rainfall / Flash floods Lack of Lakes Silting

Human Causes Population pressure Deforestation Trespassing on water storm drains. Unplanned urbanisation Un Authorised colonies Poor Water and Sewerage Management Lack of attention to the nature of hydrological system. Lack of flood control measures. Multiple authorities in a city but owning responsibility by none.

Impact on Built and Natural Environments Flooding can have any of the following effects on housing or other small buildings. Houses washed away due to the impact of the water under high stream velocity. Flotation of houses caused by rising waters. Damage caused by inundation of house. Undercutting of house. Damage caused by debris

Impact on Built and Natural Environments Health-Related Effects Lack of proper drinking water facilities, contamination of water (well, ground water, piped water supply) leads to outbreak of epidemics, diarrhoea, viral infection, malaria and many other infectious diseases.

Impact on Agriculture Flooding also leads to a large area of agricultural land getting inundated as a Result there is a huge crop loss. This results in shortage of food, and animal fodder. Floods may also affect the soil characteristics. The land may be rendered infertile due to erosion of top layer or may turn saline if sea water floods the area

Impact on Development Widespread floods can have a significant effect local and national economy may include reduction in family income, decline in the production of business and industrial enterprises, inflation(a sudden increase in prices), unemployment, increase in income disparities, and decline in national income. In addition, relief and reconstruction efforts often compete with development programs for available funds. The loss of crops and the need to find alternate sources of income have often caused small scale migrations of farmers and skilled workers from rural areas to cities.

Positive impact of floods For some agricultural areas flooding is a positive and necessary event. These lands depend on the periodic silt deposits for added nutrients to the soil. Flooding also serves other advantages including the filtering or dilution of pollutants that enter the waterways, flushing of nutrients in river systems, preserving of wetlands, recharging of groundwater, and maintaining of river ecosystems by providing breeding, nesting, feeding and nursery(deep water species) areas for fish, shell fish, migrating waterfowl, and others.