Preamble
Disasters, both natural and anthropogenic, are recurrent events that inflict profound devastation upon human lives, livelihoods, socio-economic fabric, infrastructure, and the environment itself. The relationship between the environment and disasters is not merely incidental but deeply intertwined and bidirectional.
On one hand, a degraded or mismanaged environment can significantly amplify the vulnerability of communities and ecosystems to hazards, often increasing the frequency and intensity of disaster events. On the other hand, disasters themselves can cause severe, often long-lasting, damage to ecological systems, further perpetuating a cycle of vulnerability.
Conversely, healthy, well-managed ecosystems possess inherent resilience and can play a crucial role in disaster risk reduction (DRR), mitigation, and facilitating more effective post-disaster recovery. This chapter aims to undertake an exhaustive exploration of these complex interlinkages. We will first meticulously examine the various environmental factors – both natural and human-induced alterations of the environment – that contribute to the occurrence and severity of disasters. Subsequently, we will delve into the critical and increasingly recognized role of environmental management and ecosystem-based approaches in disaster mitigation, preparedness, response, and recovery, a theme of paramount importance for contemporary governance and sustainable development, and consequently, for the UPSC Civil Services Examination.
21.1 Environmental Factors Contributing to Disasters
While the trigger for a disaster might be a natural hazard (e.g., heavy rainfall, seismic activity, cyclonic winds), the scale of the disaster – the extent of loss of life, property, and environmental damage – is often significantly influenced by pre-existing environmental conditions and human interactions with the environment. Environmental degradation and unsustainable practices can transform a manageable hazard into a catastrophic disaster.
This is perhaps one of the most significant environmental factors exacerbating a wide range of disasters.
Mechanism:
- 1Loss of Root Anchorage: Tree roots bind soil. Deforestation removes this reinforcement.
- 2Increased Soil Saturation: Cleared forests lead to direct rainfall impact, increased runoff, and soil saturation, reducing soil shear strength.
- 3Loss of Transpiration Effect: Trees remove soil moisture via transpiration. Deforestation leads to wetter, less stable soils.
- 4Weathering of Exposed Slopes: Exposed soil and rock weather faster, making slopes susceptible to mass movement.
Historical Context & Timeline:
Centuries Ago
The link between deforestation and landslides observed in mountainous regions globally.
1970s - Chipko Movement
In the Indian Himalayas, this movement was partly a response to deforestation's impacts, including increased landslides and floods.
Ongoing
Large-scale deforestation in Himalayas & Western Ghats (India) linked to higher landslide incidence, especially during monsoons.
Examples & Case Studies:
- Himalayan Region, India: Uttarakhand (2013 floods/landslides attributed partly to deforestation), Himachal Pradesh, Sikkim, Northeast India.
- Western Ghats, India: Kerala (2018 floods/landslides), Karnataka, Maharashtra, linked to deforestation and land use changes.
- Global Examples: Haiti (catastrophic mudslides post-hurricanes due to severe deforestation), Philippines, Southeast Asia, Central America.
Mechanism:
- 1Reduced Interception and Infiltration: Higher proportion of rainfall becomes immediate surface runoff.
- 2Increased Surface Runoff Velocity and Volume: Faster, larger water volumes flow into rivers.
- 3Reduced Lag Time: Shorter time between peak rainfall and peak river discharge, leading to rapid, higher flood peaks.
- 4Siltation of Riverbeds: Increased soil erosion leads to sediment deposition, reducing river depth and carrying capacity.
- 5Loss of Natural Floodplains/Wetlands: Reduces natural flood storage capacity of river basins.
Historical Context & Timeline:
Forests' role in flood moderation recognized in traditional land management. Large-scale deforestation in major river basins (Ganges-Brahmaputra, Yangtze, Mississippi) linked to increased flood frequency/severity over the past century.
Examples & Case Studies:
- Ganges-Brahmaputra Basin: Deforestation in Himalayan foothills/plains contributes to recurrent floods in Bihar, UP, Assam, West Bengal, Bangladesh.
- Kosi River Floods (e.g., 2008): High sediment load from deforested upper catchment contributes to catastrophic floods.
- Floods in Peninsular India: Deforestation in Mahanadi, Godavari, Krishna catchments linked to increased flood risk.
Mechanism:
- 1Reduced Local Rainfall (Plausible regionally): Disruption of local hydrological cycles (evapotranspiration, "biotic pump" theory).
- 2Reduced Groundwater Recharge: Lower infiltration and higher runoff reduce aquifer recharge.
- 3Increased Soil Moisture Evaporation: Exposed soil dries out more quickly.
- 4Reduced Water Retention Capacity of Soil: Degraded soils (low organic matter) hold less water.
Historical Context & Timeline:
19th/20th-century concerns of "desiccation" due to deforestation. Modern climate science explores these links more rigorously.
Examples & Case Studies:
- Sahel Region, Africa: Deforestation and land degradation exacerbated drought conditions and desertification.
- Parts of India: Regions like Bundelkhand, Marathwada, vulnerable to drought, linkage complex.
Mechanism: (Desertification is land degradation in arid/semi-arid/dry sub-humid areas)
- 1Removes protective vegetation cover, exposing soil to wind/water erosion.
- 2Reduces soil organic matter and fertility.
- 3Alters local microclimates, making them hotter and drier.
- 4Reduces water availability.
(Covered in more detail under UNCCD in Chapter 14.9 - Not part of this extract)
Mechanism:
Cultivating on steep slopes without terracing, clearing forests on marginal lands, or farming in floodplains increases susceptibility to soil erosion, landslides, and floods. Shifting cultivation (jhum) with short fallow periods leads to severe land degradation.
Examples:
Jhum cultivation in Northeast India, agricultural encroachment in Western Ghats.
Mechanism:
Excessive grazing removes vegetation cover, compacts soil (reducing infiltration, increasing runoff), leads to soil erosion, and can cause desertification in arid/semi-arid areas. Degrades grasslands.
Examples:
Common in arid/semi-arid regions of India (Rajasthan, Gujarat, Deccan Plateau), and some Himalayan pastures.
Mechanism:
- Open-cast mining: Removes vegetation/topsoil, creates pits/overburden dumps prone to erosion/landslides.
- Acid Mine Drainage (AMD): Sulfide minerals produce sulfuric acid, leaching heavy metals, polluting water.
- Destabilization of slopes due to blasting/excavation.
- Dust and noise pollution.
Examples & Case Studies:
- Coal mining (Jharia, Raniganj): Land subsidence, mine fires, air/water pollution.
- Iron ore mining (Goa, Karnataka): Deforestation, water body impact, dust pollution.
- Illegal sand mining: Destroys aquatic habitats, alters river morphology, destabilizes banks, lowers water table, damages infrastructure. Widespread in India.
Mechanism:
- Encroachment on Floodplains, Wetlands, Coastal Areas increases vulnerability and destroys protective ecological functions.
- Increased Impervious Surfaces (roads, buildings) reduce infiltration, leading to increased runoff and urban flooding.
- Blockage of Natural Drainage Systems by construction exacerbates waterlogging and floods.
- Destabilization of Slopes by hill cutting for roads/buildings in mountainous areas.
- Concentration of Population and Assets increases potential damage.
Examples & Case Studies:
- Mumbai Floods (e.g., 2005): Partly attributed to unplanned development, loss of mangroves/wetlands, Mithi river floodplain encroachment.
- Chennai Floods (e.g., 2015): Linked to encroachment on lakes/riverbeds/marshlands, inadequate drainage.
- Urban Heat Island Effect: Cities warmer than rural areas, exacerbating heatwaves.
Mechanism:
Wetlands (marshes, swamps, lakes, floodplains, mangroves) act as natural sponges, absorbing/storing floodwater and releasing it slowly. Their drainage, filling, or conversion significantly reduces this buffering capacity, leading to higher/faster flood peaks.
Historical Context:
Often considered "wastelands" and drained. Ecological/hydrological value recognized recently, partly due to increased flood events.
Examples:
Loss of wetlands in the Gangetic plains, coastal areas of India.
Mechanism:
- Mangroves: "Living shoreline," dissipating wave energy, reducing storm surge/cyclone/tsunami impact, trapping sediments.
- Coral Reefs: Natural submerged breakwaters, reducing wave energy.
- Destruction/degradation (coastal development, aquaculture, pollution, climate change) removes this natural protection.
Case Study: 2004 Indian Ocean Tsunami
Post-tsunami studies (India, Sri Lanka) showed coastal areas with intact mangroves/reefs experienced significantly less damage/loss of life. Stark evidence of their protective role.
(Covered extensively in Chapter 8.2, key points reiterated here for disaster context)
Increased Hydro-Meteorological Hazards
- Heatwaves & Droughts: Water scarcity, crop failures, wildfires, health impacts.
- Intense Rainfall & Floods: Urban, riverine, flash floods.
- Tropical Cyclones: Stronger winds, heavier rainfall, larger storm surges.
- Wildfires: Longer fire seasons, more conducive conditions.
Sea Level Rise & Ocean Impacts
- Sea Level Rise: Exacerbates coastal flooding, erosion, saltwater intrusion.
- Glacial Melt and GLOFs: Increased risk in Himalayan/mountain regions.
- Ocean Acidification and Warming: Impacts marine ecosystems (coral bleaching), fisheries, coastal protection.
Feedback Loops: Climate change can further degrade ecosystems (e.g., forest dieback due to drought), reducing their capacity to mitigate disaster risks, creating a vicious cycle.
- Weakening Ecosystem Resilience: Chemical pollution can damage ecosystems (e.g., kill mangroves, harm soil biota), reducing their natural capacity to buffer against hazards.
- Exacerbating Health Impacts during Disasters: Pre-existing pollution can worsen health outcomes when disasters strike (e.g., contaminated floodwaters carrying industrial toxins or sewage).
- Industrial Accidents as Disasters: Leaks/spills of hazardous materials (e.g., Bhopal Gas Tragedy, Ennore oil spill). Poor environmental management and safety standards in industries contribute to this risk.
Altering Ecosystem Structure and Function:
- Some invasive plants outcompete native vegetation important for slope stabilization or flood moderation.
- Invasive aquatic plants (e.g., water hyacinth) clog waterways, impede drainage, exacerbating flooding.
- Some invasive grasses alter fire regimes, increasing wildfire frequency/intensity.
Excessive withdrawal leads to compaction of underlying sediments and gradual land sinking (subsidence). Increases flood risk in low-lying coastal/riverine areas and damages infrastructure.
Examples: Parts of Jakarta, Bangkok, Venice, some US coastal cities. Concerns for some Indian cities.
Depletion of aquifers reduces water availability during droughts, making communities/ecosystems more vulnerable.
In coastal areas, over-pumping of fresh groundwater lowers the water table, allowing saline seawater to intrude into freshwater aquifers, rendering them unusable.
While geological factors are natural, human activities can sometimes trigger or exacerbate geologically-induced disasters.
Construction of large dams/reservoirs can, in some geologically susceptible areas, alter local stress patterns in Earth's crust and potentially trigger minor to moderate earthquakes.
Example: Koyna Dam, Maharashtra, associated with RIS.
Blasting, excavation, and improper slope cutting for roads, tunnels, buildings in hilly areas can destabilize slopes even in areas not naturally prone to frequent landslides.
Case Study: The Uttarakhand Floods (2013)
Event:
Devastating floods and landslides triggered by unusually heavy rainfall in Uttarakhand.
Environmental Contributing Factors:
- Deforestation & loss of vegetation in catchment areas.
- Unplanned construction & infrastructure (roads, buildings, hydropower projects) on fragile slopes & riverbanks.
- Obstruction of natural drainage by construction.
- Potential impact of hydropower project construction (blasting, muck disposal).
- General vulnerability of the geologically fragile Himalayan region.
Significance:
Highlighted extreme vulnerability of Himalayan region to hydro-meteorological disasters and how anthropogenic environmental changes amplify these risks. Led to increased focus on disaster preparedness, regulated development, and watershed management.
Conclusion for Section 21.1
It is evident that while natural hazards are an inherent part of Earth's systems, the scale and impact of disasters are significantly modulated by the state of the environment and human interventions within it. Environmental degradation often acts as a potent risk multiplier, increasing vulnerability and reducing the coping capacity of both ecosystems and human communities. Recognizing these linkages is the first step towards integrating environmental management into a holistic disaster risk reduction framework.
21.2 Role of Environment in Disaster Mitigation and Management
Content for this section is forthcoming. It will delve into the critical and increasingly recognized role of environmental management and ecosystem-based approaches in disaster mitigation, preparedness, response, and recovery.