Today we will discuss Causes Of Flood and Cyclones Types And Effects. So let’s start.
A flood is an overflow of an expanse of water that submerges land. However, The International Commission on Irrigation and Drainage defined flood as a relatively high flow or stage in a river, and markedly higher than the usual which results in an inundation of low land. However flooding may result from the volume of water within a water body (such as the river or lake), and which overflows or breaks levees, so some water escapes its usual boundaries.
TYPES OF FLOOD
We can classify floods as flash floods, and river floods, and coastal floods.
Flash Floods: it usually defines These as floods which occur within six hours of the beginning of rainfall and associates with towering cumulus clouds, severe thunderstorms, and tropical cyclones or during passaging cold weather fronts.
River Floods: River floods usually causes precipitation over large catchment areas or by melting of the snow accumulated during the winter or sometimes both. However when the river water increases the river flood arrives. because the water level is so high
Coastal Floods: Such flooding associated with tropical cyclones (also called hurricanes and typhoons). Therefore Catastrophic flooding from rainwater often aggravates by wind-induced storm sullages along the coast. however, As in river floods and intense rain falling over a large geographic area will produce extreme flooding in coastal river basins.
1. Floods can damage the structures by the force of impact, and rising waters, and erosion and by water-borne debris.
2. Damage is likely to be much greater in valleys than in open low-lying areas.
3. Flash floods often sweep away everything in their paths.
4. Major floods may affect public health and may cause many deaths from drowning.
5. An entire harvest may lose together with animal fodder resulting in long-term food shortages. So they may lose many animals if it does not move them to safety.
There are many structural and non-structural mitigation measures. Therefore It helps to reduce the impact of floods in affected areas frequently battered by floods. For example:
Structural Mitigation :
Buildings on the elevated area
Natural water retention basins
Reforestation, protection of vegetation, and cleaning of debris from streams, etc. are other measures helps to reduce the runoff.
Non-structural mitigation :
Mapping of flood plains
Land use control
Flood forecasting and warning
Causes Of Floods and Cyclones Types And Effects
Hurricanes are violent storms, Therefore often in huge quantities and characterized by high winds that revolve around a quiet center of low atmospheric pressure. therefore this center moves onward therefore often with a velocity of 50 km an hour. On the other hand, In an early manner, anticyclones are large rotary air systems that move across much of the globe beyond the equatorial belt.
Cyclones usually associate with belts of cloud and rain or snow, So whereas anticyclones which have lighter winds are typically free from precipitation. Therefore Cyclones and anticyclones have a diameter of less than 1000 to 4000 km. Therefore A cyclone is an area of the lowered atmosphere with the lowest pressure at the center of wind circulation, and commonly known as depressions. However Tropical cyclones test according to several objective criteria like:
(i) Minimum pressure
(ii) Speed measures over a 5, 3 or 1 minute
(iii) Wind direction
(iv) Rainfall quantity and intensity
(v) Area of the diameter of the widest closed isobar or diameter with winds over 47 to 64 knots
(vi) Point of origin and characteristic of tract
Constructing multipurpose cyclone shelters with suitable designs in locations helps to mitigate in coastal areas.
Engineered structures that can withstand wind forces, and need to be built.
protection against wind
However coastal belt plantation along the coastal line will reduce the effect/impact of strong winds & also check soil erosion and inward sand drift.
By constructing the elevated roads, So cyclone impact can be mitigated.
Non-structural Mitigation :
A Hazard map will depict the areas most vulnerable to the cyclone any year. Therefore It is an effective mitigation tool.
It designs the use of land in such a way that it places the least critical activity in the risk zone. AS a result, the location of settlements in the floodplains is of utmost risk. And Vulnerable areas must keep for parks, grazing or playgrounds.
Better forecasts of cyclones, early and timely warnings of people in the affected area make better preparations. So It also reduces the impact of life, property, and livelihood, and infrastructure.