Disaster in Himalayan Region & its effect on the Indo Gangetic Plain

The spread of non-regulated developmental activities has transformed many natural disasters into man-made events.Such calamities play a grave negative socioeconomic role on the national economy and exert additional pressure on the economy. When these disasters occur with high intensity at or near human settlements, the results are often deadly. Remote sensing analysis of recent disasters coupled with demography, news accounts, and field studies indicate that there is a component of human responsibility. Therefore, special attention should be paid while undertaking major developmental activities like human settlements, urbanization, road building, and laying of railway tracks in the region.

Himalayas, as a region, have always been susceptible to disasters due to the neo-tectonic mountain-building process, like earthquakes, landslides, and floods. Natural disasters in this region are nothing new. Earthquakes, floods, landslides, avalanches, and debris flows have occurred in the Himalayas since the mountains first grew from the sea. Simply put, the Himalayan region, being South Asia’s ‘water tower’ and an active plate tectonic collision zone, must shed water and debris to the lowlands and the sea.

MAJOR DISASTERS IN HIMALAYAN REGION EARTHQUAKE

More than ninety percent of the earthquakes occurring in India fall within the Himalayan mountain zone and its foothills. Three regions – one between central Himachal and north Bihar, the other between the Shillong plateau and the Mishmi Hills in Arunachal and another in Kashmir– are likely epicentres of future disasters.

Landslide

Landslides are defined as the mass movement of rocks, debris or earth down a slope dislodging earthen material on its way. Often they are associated with other calamities like earthquake, floods or volcanoes, involving movement of earth.

Prolonged rainfall also causes heavy landslides, especially in mountain areas devoid of vegetation cover, blocking the flow of rivers. These river blocks, if and when they burst, can cause havoc to the settlements downstream. Landslides are common occurrence in the hilly states of India.

Flood and Flash Flood

There is a lack of planned systematic strategy for dealing with the floods which has resulted in massive damages in the last few years. This also reflects a failure at the policy level. The flash flood – called Glacial Lake Outburst Flood (GLOF) by scientists – is a direct impact of climate change. Dams and tunnels for hydroelectricity projects as well as roads are being built in the area ignoring the destabilising effect on mountain slopes.

Cloudburst

Generally, when clouds traversing pass over an area of low atmospheric pressure and temperature, vapours are condensed into raindrops, which fall on the ground by virtue of their weight. However, in mountains areas clouds are multi-layered. When one layer traversing at higher altitude enter into a zone of extremely low atmospheric pressure, then suddenly all the vapours are converted into water simultaneously. This water-column, while falling from the height, also takes the water from the clouds of other lower layers and rapidly falls on the earth.

VULNERABILITY IN INDO-GANGETIC PLAINS

Indo-Gangetic Plain is the north- central section of the Indian subcontinent which includes the combined delta of the Brahmaputra and Ganges (Ganga) rivers to the Indus River valley. The region contains the subcontinent’s richest and most densely populated areas. About 40 per cent of India’s population resides in the seven states and union territories comprising the bulk of the Indo- Gangetic Plain region of north India namely Bihar, Jharkhand, Delhi, Haryana, Punjab, Uttar Pradesh and West Bengal. This area is considered to be the region of great concern due to its thick sediments and proximity to the seismically most active zone of India, the Himalayan collision zone.

With the rapid increase in population during recent years, the demand for food, fuel, fodder and grazing-land has increased considerably, putting increased biotic stress on the critical environmental components, like land, water, and forests. Consequently, the human transformation has brought about drastic changes in the resource-use practices and land-use pattern of the region. Agriculture is being pushed to forests, marginal and sub-marginal areas and areas with steep slopes, without taking into consideration the suitability of these lands for crop farming. The destabilisation of fragile mountain slopes, through deforestation, agricultural expansion, housing needs, excessive and indiscriminate grazing and expansion of the road network, has disrupted the hydrological cycle of all major river basins. As a result, the Himalayan mountains are on the verge of a major ecological crisis threatening the collapse of the very life-support system. The impact of unscientific and irrational resource development processes and the resultant deteriorating environmental conditions in the Himalayas are not confined to the region itself but also adversely affect the environment and economy of the adjoining plains of the entire Indian sub-continent through the disruption of the hydrological cycle of the region.

Reason for Human Impacts

Two overarching human elements which are affecting the disasters in this region include: settlement and infrastructure encroachment into hazardous mountain areas and aggravation of climate change. Both are substantially responsible – separately or together – for most of the recent tragedies. These conclusions provide the answer to when the disasters will end: not soon. Unfortunately, disasters will almost surely increase. Whether natural disasters have increased in frequency over the region’s long history may be debated and must be researched.

It may be noted that the damages in the event of an earthquake, floods, and cloudbursts primarily result from the unplanned developmental activities in seismicity-prone areas, which increase the casualties of life and loss of property manifold.

While Himalayan tectonism, rock mechanics, glaciation, and climate are fundamental causes of the disasters, so are human land uses. A disaster in the Himalayan region affects not only the mountainous region but also largely the cities in the Indo-Gangetic plain.

Predictions of the Disasters

Predicting with precision where, when and what size of disaster may strike is really difficult but predicting their impact on built environment is a useful area of work. For example, if an earthquake is to occur, say, in the Himalayas, how would the built environments in the near and far regions (such as the Indo-Gangetic plains) respond to the shaking effects. These things should become part of the planning exercise and should be kept in mind before infrastructure development is planned and implemented.

BETTER LAND-USE PLANNING

India has to improve its methodologies of risk assessment with intense field studies and developing models using data on the frequency and severity of a particular type of natural hazard striking an area. This information needs to be combined with the nature and class of vulnerable structures. Experts need to develop computing packages, including the Geographic Information System (GIS) to estimate the costs and to generate different disaster mitigation scenarios.

Another area that needs attention is the development of land-use planning, with potentially great impact in areas prone to flooding. However, implementing this programme will not be easy; from a practical point of view, it needs the participation and support of the local people. Instead of enacting mandates in a high-handed manner, we must try to provide incentives for compliance, such as lower building and property taxes to those who prefer to live away from hazardous areas.

Focus on encroachments & unplanned growth

Encroaching development into ever-hazardous zones is a paramount cause of much human tragedy. Encroachments in cities is happening at an alarming rate and so is the unplanned development and growth. The problem is compounded by unauthorised development in and around the cities, poor land use control and unplanned growth in peri urban and rural areas. Holistic planning looking into the hinterland is needed to minimise the losses in the future.

A MULTIDISCIPLINARY APPROACH

Proper data collection, analysis and data dissemination can be useful for proper mitigation. For example, advances in seismic sensor technology, data acquisition systems, digital communication and computer hardware and software allow us to develop real-time disaster information systems. In fact, real-time data dissemination should become a norm in all the fields. Free sharing of data is the backbone of any knowledge based society. We must develop an online disaster information network that includes spatial maps delineating hazard zones.