Floods

Definition: A flood is an overflow of water that submerges normally dry land, caused by excessive rainfall, river overflow, dam failure, or coastal storms.

Causes of Floods

Floods occur due to a combination of natural and human-made factors. These causes are explained below:

Natural Causes of Floods

1. Heavy and Continuous Rainfall: Prolonged or intense rainfall exceeds the capacity of rivers, lakes, and drainage systems, causing water to overflow onto land.
2. River Overflow / Swollen Rivers: When rivers receive more water than their carrying capacity—due to rainfall or upstream release—they overflow and flood nearby areas.
3. Cyclones and Storms: Cyclones bring extremely heavy rainfall and strong winds, causing storm surges and massive flooding in coastal regions.
4. Melting of Snow and Glaciers: During summer or due to sudden temperature rise, melting snow increases river water volume, leading to flooding, especially in Himalayan regions.
5. Cloudburst: A cloudburst releases a very large amount of rain in a very short time, causing flash floods in hilly and urban areas.
6. Poor Drainage in Low-Lying Areas: Regions with poor natural or artificial drainage systems quickly accumulate water, resulting in urban or localized flooding.

Human Causes of Floods

1. Deforestation: Cutting down forests reduces water absorption by soil, increases surface runoff, and leads to higher chances of floods.
2. Encroachment of Floodplains: Construction of houses, industries, and farms on natural floodplain areas blocks the natural flow of rivers and increases flood intensity.
3. Urbanization & Blocked Drainage: Cities with concrete surfaces have less infiltration and more runoff. Blocked drains and improper sewage systems cause frequent urban flooding.
4. Poorly Managed Dams: Sudden release of excess water from dams, structural failure, or mismanagement can cause large-scale downstream flooding.
5. Mining and Soil Erosion: Mining loosens the soil and removes vegetation, increasing sedimentation in rivers. This reduces river depth and increases the likelihood of flooding.

Effects of Floods

1. Loss of Life and Property: Floods cause drowning, injuries, and destruction of houses, roads, and public infrastructure, leading to major human and material losses.
2. Damage to Crops and Livestock: Standing crops get submerged and destroyed. Floods also kill cattle, poultry, and other domestic animals, affecting farmers’ livelihoods.
3. Waterlogging & Soil Erosion: Excess water leads to waterlogging in fields, reducing soil fertility. Strong currents erode riverbanks, removing topsoil and damaging land quality.
4. Spread of Diseases (Cholera, Diarrhea): Contaminated water during floods causes outbreaks of water-borne diseases like cholera, diarrhea, typhoid, and skin infections.
5. Disruption of Transport & Communication: Roads, bridges, and communication networks are damaged, making rescue operations and supply of essential items difficult.
6. Economic Loss & Displacement of People: Floods destroy property, businesses, crops, and infrastructure, causing huge economic damage. People are often forced to leave their homes and live in relief camps.

Control & Management Measures

1. Structural Measures
2. Construction of Dams and Reservoirs: Dams store excess rainwater and regulate river flow, reducing the chances of downstream flooding.
3. Embankments and Levees: Raised banks along rivers prevent water from overflowing into nearby land during floods.
4. Flood Channels and Diversion Canals: These channels divert excess river water into safer areas or storage basins to protect populated regions.
5. Stormwater Drainage Systems: Well-planned drainage systems in cities help remove rainwater quickly and prevent urban flooding.
6. River Desilting: Removing silt from riverbeds increases their depth and carrying capacity, reducing the risk of overflow.

Non-Structural Measures

1. Flood Forecasting & Early Warning: Weather forecasting and timely alerts help people evacuate early and reduce loss of life.
2. Afforestation in Catchment Areas: Planting trees increases soil absorption and reduces runoff, lowering flood intensity.
3. Flood-Plain Zoning: Regulating construction in flood-prone zones ensures that vulnerable areas remain free from settlements.
4. Proper Urban Planning: Designing cities with open spaces, proper drains, permeable surfaces, and rainwater management reduces urban flooding.
5. Community Awareness Programs: Training communities in flood preparedness, rescue techniques, and safe practices helps minimize damage.
6. Emergency Relief and Evacuation Plans: Organizing rescue teams, shelters, food supply, and medical services ensures quick response during floods.

Drought

Definition: A drought is a prolonged period of abnormally low rainfall leading to water shortage and ecological imbalance.

Types of Drought 

1. Meteorological Drought: Occurs when rainfall is much below the normal average for a region. It is the earliest indicator of drought.
2. Hydrological Drought: Happens when water levels in rivers, lakes, reservoirs, and groundwater become very low due to prolonged dry conditions.
3. Agricultural Drought: Develops when soil moisture becomes insufficient for crop growth, leading to wilting and failure of crops.
4. Socio-Economic Drought: Occurs when water shortage begins to affect society and the economy, causing reduced agricultural output, unemployment, and increased poverty.

Causes of Drought

1. Natural Causes
2. Low and Erratic Rainfall: Irregular or insufficient rainfall is the primary reason for drought formation.
3. High Temperature & Evaporation: Hot conditions increase evaporation from soil and water bodies, worsening drought.
4. El Niño Effect: El Niño disturbs monsoon patterns, reducing rainfall in many regions, including India.
5. Global Climate Change: Rising global temperatures increase weather unpredictability and intensify drought frequency.

Human Causes

1. Deforestation: Cutting trees reduces soil moisture and rainfall, making areas more drought-prone.
2. Overgrazing: Excess grazing removes grass cover, leading to soil degradation and reduced water retention.
3. Excessive Groundwater Extraction: Over-pumping for irrigation lowers the water table, causing artificial dryness.
4. Poor Irrigation Practices: Inefficient methods waste water and reduce availability during dry periods.
5. Increased Demand for Water: Population growth, agriculture, and industry increase pressure on limited water resources.

Effects of Drought

1. Crop Failure and Food Shortage: Lack of water affects crops at all stages, resulting in low yield and food scarcity.
2. Water Scarcity (Drinking & Irrigation): Rivers, wells, and reservoirs dry up, creating drinking water problems for humans and animals.
3. Livestock Deaths: Animals suffer from dehydration and lack of fodder, causing high mortality.
4. Migration of People: Rural populations migrate to cities in search of water, food, and employment.
5. Famine and Malnutrition: Long-term drought leads to hunger, poor nutrition, and increased disease vulnerability.
6. Lower Groundwater Levels: Continuous dry conditions reduce infiltration and cause a drastic drop in water table.
7. Loss of Biodiversity: Plants and animals perish due to lack of water, affecting the whole ecosystem.
8. Economic Losses: Agriculture, industries, and livelihoods are heavily hit, slowing down regional development.

Control & Management Measures of Drought 

Short-Term Measures

1. Water Rationing: Controlled and limited supply of water to ensure that available water is distributed fairly during drought.
2. Tanker Water Supply: Water is delivered to drought-hit villages and towns through tankers to meet drinking water needs.
3. Drought-Resistant Crops: Planting crops like millets, sorghum, and pulses that require less water helps farmers sustain during dry seasons.
4. Emergency Employment Schemes: Government provides temporary jobs (like MNREGA works) to support income during crop failure and economic hardship.

Long-Term Measures

1. Rainwater Harvesting: Collecting and storing rainwater from rooftops and open areas to increase water availability and recharge groundwater.
2. Watershed Management: Protecting and developing an entire drainage basin by soil conservation, water storage, and vegetation improvement.
3. Construction of Check Dams & Percolation Tanks: Small structures built across streams to slow water flow, increase infiltration, and recharge groundwater.
4. Afforestation: Planting trees improves soil moisture, reduces evaporation, and enhances rainfall over time.
5. Efficient Irrigation (Drip & Sprinkler): These methods reduce water wastage and ensure crops receive water directly at the roots, saving 30–60% water.
6. Sustainable Groundwater Use: Regulating borewell use, preventing over-extraction, and promoting recharge methods to maintain groundwater balance.
7. Crop Diversification: Shifting from water-intensive crops (like sugarcane, paddy) to low-water crops helps reduce pressure on water resources.