DROUGHT AND FLOOD Prepared by M. U. Kale Assistant professor Deptt DROUGHT AND FLOOD Prepared by M .U. Kale Assistant professor Deptt. Irrigation & Drainage Engineering Dr. P.D.K.V. Akola

Drought According to IMD, if seasonal rainfall is less than 75% then there is drought situation. the scarcity of water in the surface or sub-surface water resources like river, reservoir and groundwater is called drought.

Types of drought Meteorological drought: It occurs when seasonal rainfall is less than 75%. Hydrological drought: It indicates the scarcity of water in surface or subsurface water. Agricultural drought: It occurs when rainfall and soil moisture are inadequate to meet the crop water requirement for healthy growth and maturity.

Socio-economic drought: Socio-economic effect of meteorological, hydrological and agricultural drought in supply and demand is known as socio-economic drought. Moderate drought – between 26% to 50% Sever drought – more than 50%

Causes of drought Onset of monsoon Soil physical characteristics Crop varietal characteristics Duration of water stress period and crop stage Intensity of water stress.

Management of drought The recommended practices may be broadly grouped as: Crop management practices Water management practices

A. Crop management practices Selection of appropriate crop Intercropping Planting densities Weed management Integrated nutrient management

B. Water management practices Integrated management of water resources development Development of new resources Optimal utilization of new developed water resources Preserving the resources Runoff collection and recycling

Strategies for drought protection, mitigation or relief include: Dams - many dams and their associated reservoirs supply additional water in times of drought. Cloud seeding - a form of intentional weather modification to induce rainfall. Desalination - of sea water for irrigation or consumption. Drought monitoring - Continuous observation of rainfall levels and comparisons with current usage levels can help prevent man-made drought.

Land use - Carefully planned crop rotation can help to minimize erosion and allow farmers to plant less water-dependent crops in drier years. Outdoor water-use restriction - Regulating the use of sprinklers, hoses or buckets on outdoor plants, filling pools, and other water-intensive home maintenance tasks. Rainwater harvesting - Collection and storage of rainwater from roofs or other suitable catchments. Recycled water - Former wastewater (sewage) that has been treated and purified for reuse. Transvasement - Building canals or redirecting rivers as massive attempts at irrigation in drought-prone areas.

flood Overflows of river inudating vast areas of agricultural land leads to submergence of crop

Causes of flood River in spate Snow melt Storm surges Short intense storm causing flash flood Cyclone and heavy rainfall

Damages: Damages Irrigation system Breakages of tanks and embankments Drainage system altered Effect on living habitat

Management of flood Watershed management Natural detention of basins Safe disposal of surplus runoff Timely warning system flood proofing Contingency planning land management ('keeping people away from floods') Water management (storage operation); Structural protection (dykes) ('keeping floods away from people');

Flood management can aim at: Reduced risk of floods, Reduced vulnerability to floods improved preparedness, Streamlined emergency management once a flood damage has occurred, Improved knowledge (about cause-effect relationships, driving forces and management options).

Thank you!