Impact on the Environment:

Though the lives lost in floods may not be as high as in case of earthquakes or cyclones, the damage to the environment is immense. The problem is further aggravated if the floods last for a longer duration of time.

Floods not only damage property and endanger if lives of humans and animals, but have other effects as well, such as:

1. Floods cause the spread of many epidemic diseases.

2. Rapid runoff causes soil erosion.

3. Wildlife habitat and forests are often destroyed.

4. Manmade structures like buildings, bridges, roads, sewer lines, power lines, etc. are damaged.

5. Floods cause widespread damage to the standing crops and degrade the agricultural land.

6. Flood affected areas are faced with acute shortage of food and drinking water.

Prevention, Control and Mitigation:

Though floods are a natural hazard, it is sometimes intensified due to undesirable human activities. The measures that can be taken to control the extent of flood damage include land use planning, building of physical barriers, preventing human encroachment and use of technology for relief.

Land use planning:

Proper land use planning in flood prone areas includes:

1. Demarcation of the flood-prone areas that are first inundated during floods.

2. Construction work and concentration of human population should be avoided in the floodplains.

3. Afforestation on the upper reaches of the river (catchment areas) to control soil erosion and excessive runoff.

Building of physical barriers:

Flood can be prevented by building certain structures, such as:

1. Embankments along the banks of rivers in densely populated areas.

2. Building of reservoirs to collect excess water during floods.

3. The construction of channels that divert floodwater.

Preventing human encroachment:

Human encroachment should be avoided in the following areas:

1. Floodplains and catchment areas.

2. This would control deforestation and soil erosion which would prevent excessive runoff.

Use of technology for relief:

Advanced technology can be used in the following ways:

1. Advanced communication techniques for flood forecasting and warning.

2. Fast evacuation of people.

3. To provide relief in temporary shelters.

4. Immediate supply of medicines, drinking water, food and clothes.

5. Epidemic diseases must be controlled through spraying, vaccination, etc.

Drought:

Drought is a condition of abnormally dry weather within a geographic region. Drought refers to the lack or insufficiency of rain for an extended period of time in a specific region. During droughts, rainfall is less than normal causing a water imbalance and resultant water shortage. It occurs when the rate of evaporation and transpiration exceeds precipitation for a considerable period. Drought should not be confused with dry climate, as in the Sahara or Thar Desert. It is marked by an unusual scarcity of water and food for the humans as well as animals.

Certain regions of the world, such as parts of Central Africa, are characterized by low amount of rainfall resulting in perennial drought-like conditions. Some part of India is often affected by drought even during the rainy season. As India is primarily an agricultural country, droughts cause untold miseries to the common people.

Many Indian farmers are still totally dependent on rainfall for irrigation and because of abnormally dry spells there is extensive crop damage. The main drought prone areas of the country are parts of Rajasthan, Maharashtra, Karnataka, Orissa, Tamil Nadu and Chhattisgarh. However, sometimes drought-like conditions also prevail in the Gangetic Plain also.