Floods & Droughts | Geography Optional for UPSC (Notes) PDF Download

Floods

• A flood occurs when the water level in a stream or river rises and overflows its natural banks, affecting any portion of the watercourse. This typically happens when the stream's discharge exceeds the capacity of its channel, causing excess water to spill over onto the adjacent dry land. In such situations, both the channel and the floodplain work together to accommodate the flow of water.
• Floods and droughts can both be considered cumulative hazards, as they can impact different areas of a country simultaneously, particularly due to the unpredictable nature of the Indian monsoon. Consequently, floods may be seasonal or even manifest as flash floods, affecting various regions at the same time of the year.

Causes of Floods

Flood conditions

Floods, unlike other natural disasters, have well-established causes. They usually happen slowly and often occur in specific regions during certain times of the year. There are numerous reasons for floods, including:

Natural Causes
Heavy rainfall and cloud bursts - Intense rainfall can overwhelm a river's capacity to handle additional surface runoff, causing water to overflow into surrounding areas. Cloud bursts are powerful thunderstorms that produce extremely heavy rain (more than 50-100 cm within a few hours), causing extensive damage in a short time.

• Rapid melting of ice and snow.
• Changes in river systems and large catchment areas.
• Sediment deposition or silting of river beds.
• Dam collapses.
• Sea transgression during tropical cyclones.
• Tsunamis in coastal areas and landslides along river courses.

Man-made/Anthropogenic Causes
Humans play a significant role in the development and spread of floods, unlike other natural disasters.

• Deforestation - This leads to soil erosion and landslides. Deforestation is responsible for the loss of vegetation and soils, which help hold the soil in place and act as a sponge to absorb water during rainfall. It also contributes to the silting of river beds.
• Unsustainable land use and poor farming practices - Some farmers can inadvertently cause soil and water to enter rivers by leaving fields unprotected. Even plowing in the wrong direction can contribute to flooding.
• Increased urbanization - Urban development reduces the land's ability to absorb rainwater due to the introduction of hard, impermeable surfaces. This leads to an increase in the volume and rate of surface runoff, as less water infiltrates the ground.

Consequences of Floods

• Although floods are temporary occurrences, their impact is becoming more severe due to the increasing frequency, intensity, and magnitude of these events. Floods now cause more damage than any other single type of disaster.
• Every year, floods claim thousands of lives and cause significant property damage. Agricultural crops are negatively affected by the temporary loss of growing seasons and the erosion of fertile soil. These events also lead to changes in habitats, the destruction of ecosystems, and the loss of wildlife through drowning.
• In addition to environmental impacts, floods disrupt transportation networks, including rail and road systems, and essential services. This creates significant challenges for the movement of people and goods. Furthermore, floods can lead to the spread of waterborne and infectious diseases, such as cholera and gastroenteritis, in the aftermath of the disaster.
• Despite the numerous negative consequences, floods do have some positive effects. For example, they deposit fertile silt on agricultural fields, which can benefit crop growth. Additionally, floods can help recharge groundwater tables by replenishing aquifers and other underground water sources.

Flood distribution in India

Floods are a recurring issue in India, causing significant damage to lives, property, livelihood systems, infrastructure, and public utilities. India's vulnerability to floods is evident as 40 million hectares, or 12%, of its total geographical area of 3290 lakh hectares are prone to flooding.
A state-wise analysis reveals that Bihar experiences about 27% of the country's flood damage, while Uttar Pradesh and Uttarakhand account for 33%, and Punjab and Haryana make up 15%. The primary flood-prone areas in India are within the Ganges-Brahmaputra-Meghna Basin, which is responsible for nearly 60% of the country's total river flow.
Floodplains in India are distributed across several regions:

• Brahmaputra River Region
• Ganga River Region
• North-West River Region
• Central and Deccan India

The middle and lower courses of North Indian rivers, such as the Ganga, Brahmaputra, Kosi, Damodar, and Mahanadi, are susceptible to floods due to their low gradient. The flat plains in these areas lack sufficient gradient for proper drainage, increasing the risk of flooding.

In contrast, peninsular rivers are more mature and possess hard rock beds, resulting in shallow basins. This characteristic makes them more prone to flooding as well.

Certain parts of India's eastern coast are especially vulnerable to cyclones during October and November. These cyclones bring strong winds, storm surges, tidal waves, and heavy rainfall, further exacerbating the risk of floods in the affected regions.

Flood Control Management

To mitigate the impact of floods, both the central and state governments in India have implemented various measures, which include the following:

• Flood Forecasting - This involves providing advance information about potential floods, which is crucial for taking timely action to minimize the loss of human lives, livestock, and property. The Central Water Commission established the first flood forecasting station near the old railway bridge in Delhi in November 1985. Currently, there are 175 flood forecasting stations across the country, covering flood-prone areas. These stations issue daily flood warnings throughout the flood season, which typically lasts from May to October.
• Reducing Run-Off - Reducing run-off is an effective flood control method, which can be achieved by promoting and increasing the infiltration of surface water into the ground in catchment areas. This can be accomplished through large-scale afforestation, particularly in upper catchment regions.
• Construction of Dams - Dams and multi-purpose projects are built across rivers to store excess water in reservoirs. Numerous reservoirs were constructed during the 1st Five-Year Plan, and many more have been built in subsequent plans. These dams help reduce run-off and allow for the controlled release of stored water.
• Channel Improvements and Construction of Embankments - Improving river channels by deepening and widening them can help reduce the risk of flooding. Additionally, river water can be diverted into canals. Both the central and state governments have constructed embankments along several rivers, such as the Brahmaputra, Krishna, Godavari, Gandak, Kosi, Narmada, Tapi, Son, Sutlej, and their tributaries, to minimize the threat of floods.
• Flood Plain Zoning - This strategy involves identifying flood-prone areas and implementing appropriate land-use regulations to minimize the impact of flooding. This is done by gathering information on flood plains and identifying floodways in relation to land use.

NDMA Guidelines for Flood Management

Government Programmes for Flood Management
To manage and prevent floods, governments have implemented various legislative measures, including restrictions on construction in flood-prone areas. These measures prohibit the construction of residential and industrial buildings near river channels, and promote the establishment of green belts and social forestry in floodplains.

• National Flood Control Management Programme, 1954: The first policy statement on flood control in India was introduced on September 3, 1954. This policy outlined three types of flood control measures: intermediate, short-term, and long-term. These measures aimed to address the different stages of flood prevention and management.
• National Hydrology Project, 2016: This project is a central sector scheme, with 50% of its funding coming from a World Bank loan. The project focuses on collecting hydro-meteorological data, which will be stored and analyzed in real-time. This data can then be easily accessed by users at various levels, such as state, district, or village, to inform decision-making and improve flood management efforts.

Mitigation (Post – Flood Management)

• Rescue Operations
• Speedy restoration of the transport system
• Supply of safe drinking water
• Repair of power, telephone, and sewerage lines
• Supply of food, shelter, and clothing
• Survey to assess the loss and compensation
• Rehabilitation of properties
• Desilting and dewatering of inundated areas
• Contingency Plan for the agriculture sector
  
  Mitigation

Drought

• Drought refers to a temporary decrease in water or moisture levels below the usual or expected amount for a specific time period. It occurs when there is significantly less precipitation than average during a season that typically has sufficient rainfall to support various types of crops, both cereal and non-cereal.
• The quantity, timing, and distribution of rainfall are critical factors. In India, the unpredictable nature of the summer monsoon, along with extended dry spells and high temperatures, contributes to drought conditions. On average, one out of every five years experiences a drought. In Rajasthan, drought occurs in one out of every three years.
• It is important to note that drought is a relative concept, as the insufficiency of water or moisture is determined in relation to the existing agro-climatic conditions of the area. Unlike aridity, which is a permanent state, drought is a temporary situation. Areas with arid and semi-arid climates are more susceptible to experiencing droughts.

Types & Causes of Drought

1. Meteorological Drought

• It is a situation where there is a reduction in rainfall for a specific period below a specific amount i.e. the actual rainfall in an area is significantly less than the climatologically mean of that area. According to Indian Meteorological Department (IMD), a drought exists when the average annual rainfall is less than 75% of the normal.
• IMD also mentioned that rather than the total amount of rainfall, its evenness matters more. We can observe that even though India gets an average annual rainfall of 110 cm, the evenness of rainfall, due to the erratic and concentrated nature of rainfall, there are frequent droughts.
  • Causes of Meteorological droughts:
  • Lean monsoon and below-average rainfall.
  • Late-onset or early withdrawal of monsoons.
  • Prolonged breaks in Monsoon.

 2. Hydrological Drought

• It is associated with the reduction of water levels. There are 2 types of Hydrological Droughts
  • Surface water Drought – It is concerned with the drying up of surface water resources such as rivers, streams, lakes, ponds, tanks, reservoirs, etc.
  • Groundwater Drought – It is associated with the fall in the groundwater level.
• Causes of Hydrological Drought:
  • Large scale deforestation.
  • Ecologically hazardous mining.
  • Excessive pumping of groundwater.

3. Agricultural Drought

• It occurs when soil moisture goes below the level needed to sustain plant growth. It is also called as Soil Moisture Drought. The erratic rainfall conditions and inadequate soil moisture result in crop failures.
• Causes of Agricultural Droughts:
  • Excessive use of High Yielding Seeds (HYV) as these seeds requires more water and proper irrigation.
  • Change in cropping pattern. E.g. with the introduction of the green revolution, we increased our production of wheat and rice. Rice is a water-intensive crop and growing them in an area where less water is available made the area prone to agricultural drought.

4. Socio-Economic Drought

• It reflects reduced availability of food and income loss due to crop failure.

5. Ecological Drought

• It occurs when the productivity of the natural ecosystem fails due to a shortage of water and causes environmental damages like the deaths of cattle, wildlife, and trees in the forest.

Droughts in India

Droughts in India have their own peculiarities requiring an appreciation of some basic facts.

These are:-

• India has an average annual rainfall of around 1150 mm. No other country has such a high annual average; however, there is considerable annual variation.
• More than 80% of rainfall is received in less than 100 days during the south-west monsoon and the geographic spread is uneven.
• 21% area receives less than 700 mm rains annually making such areas the hot spot of drought. Inadequacy of rains coupled with adverse land-man ratio compels the farmers to practice rain-fed agriculture in large parts of the country (approx 45%).
• Per capita, water availability in the country is steadily declining. Irrigation, using groundwater aggravates the situation in the long run as groundwater withdrawal exceeds replenishment. In the peninsular region availability of surface water itself becomes scarce in years of rainfall insufficiency.

Most Drought Prone areas in India

• The Northwest Region of India, characterized by its arid and semi-arid climate, experiences a short monsoon season of about two months. This area includes Rajasthan and some parts of the west-central region. Additionally, the Kutch and Thar desert regions are naturally prone to drought and cannot be entirely rectified. However, the impact can be reduced by employing appropriate irrigation methods and cultivating crops suitable for these regions.
• In the Peninsular region, the leeward (rainshadow) side of the Western Ghats receives limited rainfall, and the area suffers from insufficient irrigation. Furthermore, the choice of crops for commercial cultivation in this region, such as cotton and sugarcane in Marathwada, is unsuitable due to their high water requirements.
• Approximately 30% of India's total land area is prone to drought, which affects 68% of the country's overall sown area. In terms of severity, the droughts of 1965, 1972, 1979, 1987, 2002, 2009, and 2012 were the most extreme in post-independence India.

Consequences of Droughts

Consequences of droughts can be broadly categorized into social, economic, and environmental impacts. The extent of these consequences varies depending on the specific characteristics of the affected region.

• Economic consequences: Droughts can cause a significant decrease in agricultural production, leading to a reduction in cultivated areas. This, in turn, slows down secondary and tertiary economic activities and results in a decline in purchasing power.
• Environmental consequences: Droughts can have numerous negative effects on the environment, including damage to plant and animal species, wildlife habitats, air and water quality, and an increase in forest and range fires. They can also lead to landscape degradation and soil erosion. Furthermore, droughts adversely affect soil moisture, surface runoff, and groundwater tables.
• Social consequences: Droughts can force people to migrate from affected areas in search of food and livelihood opportunities. In some cases, farmers may resort to suicide due to the severity of the situation, with states like Maharashtra, Andhra Pradesh, and Karnataka reporting the highest numbers of farmer suicides in India. Droughts can also disrupt social institutions and lead to an increase in crime. They often result in a scarcity of drinking water and food grains, causing famine and starvation. Moreover, droughts can contribute to poor health and the spread of diseases such as diarrhea, cholera, and other malnutrition-related illnesses, which can sometimes lead to death.

Drought Management

Drought management involves a comprehensive three-step approach, which requires a holistic perspective to achieve effective results. These three components include:

• Assessing and monitoring drought intensity
• Declaring drought and prioritizing affected areas for management
• Developing and implementing drought management strategies

The National Disaster Management Authority (NDMA) provides guidelines for drought management which include:

• Developing vulnerability profiles for different regions, communities, population groups, and other relevant entities, in order to gather crucial information that can be integrated into the planning process to improve the identification and prioritization of specific areas.
• Establishing dedicated Drought Management Cells (DMCs) at the state level under the State Disaster Management Authority (SDMA). These DMCs will be responsible for preparing vulnerability maps for their respective states, with priority given to arid and semi-arid areas where drought is a recurring issue with varying degrees of severity.
• Providing specific guidelines on the use of Information and Communication Technology (ICT) and outlining the role of the National Informatics Center (NIC) in facilitating online interaction and access to real-time drought-related information, which will aid in early warning and assessment.
• Evaluating the potential damage that may result from drought, including factors such as agricultural production, depletion of water resources, livestock population, land degradation, deforestation, and human health.

By following these guidelines, authorities can better manage drought situations and mitigate the negative impacts on affected areas and populations.

Conclusion

In conclusion, floods and droughts are significant natural disasters that pose a recurring threat to India, causing extensive damage to lives, property, and the environment. Both events are influenced by various natural and anthropogenic factors, such as heavy rainfall, deforestation, and urbanization. Effective flood and drought management strategies, including flood forecasting, sustainable land use, and the establishment of dedicated Drought Management Cells, are crucial for mitigating the negative impacts of these disasters. By adopting a holistic approach and following the guidelines provided by organizations like the NDMA, India can better manage and reduce the consequences of floods and droughts on its population and environment.

Frequently Asked Questions (FAQs) of Floods & Droughts

What are the main causes of floods in India?

The main causes of floods in India include heavy rainfall and cloud bursts, rapid melting of ice and snow, changes in river systems and large catchment areas, sediment deposition or silting of river beds, dam collapses, sea transgression during tropical cyclones, and tsunamis in coastal areas.

How do floods and droughts impact different areas of India?

Floods and droughts can impact different areas of India simultaneously due to the unpredictable nature of the Indian monsoon. Floods may be seasonal or manifest as flash floods, affecting various regions at the same time of the year. Droughts, on the other hand, occur when there is a significant decrease in water or moisture levels below the usual or expected amount for a specific time period.

What are the different types of droughts, and what causes them?

There are five main types of droughts: meteorological, hydrological, agricultural, socio-economic, and ecological. Meteorological droughts are caused by a reduction in rainfall, while hydrological droughts result from a decrease in water levels in surface water and groundwater resources. Agricultural droughts occur when soil moisture levels fall below the required amount to sustain plant growth, and socio-economic droughts reflect reduced availability of food and income loss due to crop failure. Ecological droughts occur when the productivity of natural ecosystems fails due to a shortage of water, causing environmental damage.

Which regions in India are most prone to droughts?

The Northwest Region of India, including Rajasthan and parts of the west-central region, is prone to droughts due to its arid and semi-arid climate and a short monsoon season. The leeward side of the Western Ghats in the Peninsular region also experiences droughts due to limited rainfall and insufficient irrigation.

What are the main components of drought management in India?

Drought management in India involves assessing and monitoring drought intensity, declaring drought and prioritizing affected areas for management, and developing and implementing drought management strategies. The National Disaster Management Authority (NDMA) provides guidelines for drought management, including developing vulnerability profiles, establishing dedicated Drought Management Cells, and providing specific guidelines on the use of Information and Communication Technology (ICT) for early warning and assessment.