O level Notes : Natural disasters in agriculture - Floods & Cyclones

A fllood is an overflow of water that usually submerges land the was once dry without water.

Effects of floods on crops

1. Most crops grown by farmers are not adapted to survive under water logged conditions. Such crops may be destroyed by flooding conditions.
2. Flood waters uproot crops by weakening the root anchorage.
3. When flood waters subside, they may leave crops bent down and covered with clayey mud. The crops will
   no longer be as productive as expected as some crops may die from lack of sunlight and oxygen as the clay
   coat on crops dries out.
4. When flood water flows at high speeds, it sweeps away crops from fields and may deposit some unwanted
   materials in the fields that will hinder operations.
5.  Floods result in death of livestock animals due to drowning.
6. Floods may destroy grasses and plants reducing livestock feeds.
7. Flood water may introduce water borne diseases to
   livestock.

Effects of floods on farm infrastructure

1. Farm infrastructure that is important for farm production such as fences, animal handling facilities and farm buildings may be swept away or get damaged by flowing flood water.
2. Floods damage farm roads and bridges, and this will cut off farming communities from other communities, markets and important services for farmers. Farmers may fail to get inputs and fail to sell their perishable produce in good time. This results in low productivity and loss of income due to failure to supply markets.
   The effects of floods can be short term or long term as damage to structures such as roads, bridges may take time to repair or replace.
3. Irrigation equipment is damaged by flood water that
   carries along with it many materials swept along the
   water paths.

Cyclones

Cyclones are environmental conditions where excessive rains associated with high speed (velocity) winds last for several days resulting in floods, crop destruction by heavy winds and waterlogged conditions.

Cyclones are often named after human names and traditionally, ladies names were used, for example cyclone Eline. Duringperiods of cyclones very few operations can be carried out on the farm due to wet conditions and associated windy conditions. Cyclones are often detected using satellite pictures. Their paths and travelling speeds are established in advance so that management strategies are in place to minimize their damage.

Effects of cyclones on crops

1.  Heavy rains and high-speed winds result in logging of crops, breakage of fruit crop yields, leading to a greatly reduced harvest.
2. Cyclones can result in waterlogging conditions where the soil becomes saturated with water displacing oxygen in the soil. Plant roots will experience anaerobic conditions resulting in plant death. Under waterlogged conditions, some nutrients such as phosphorous become unavailable to plants and crops
   suffer nutrient deficiency.
3. Prolonged cyclonic conditions over several weeks with total cloud cover, result in rank growth, stunted
   growth and reduced crop productivity.
4. Southern Africa experienced cyclone Eline which affected Zimbabwe, South Africa, Mozambique, Zambia and parts of Mauritius

Effects of cyclones on livestock

1. Livestock animals that are not properly housed or sheltered are usually killed during cyclones.
2. Effects of cyclones on infrastructure
3. High intensity rainfall during cyclones result in flash floods which destroy roads, bridges and houses for farmers.
4. Strong winds associated with cyclone may damage roofing of farm buildings.