Volunteers of Chattogram alerting people using loudspeakers in Lalkhan Bazar and Motijharna areas fallowing a landslide. -Collected
The Chattogram region is especially vulnerable due to various aspects, ranging from physical, social, political and environmental factors. It goes without saying that comprehensive, well-coordinated steps by the government are needed for sustainable landslide hazard management.
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material. Debris flows and rock falls are examples of common landslide types.
Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Causes include factors that increase the effects of down-slope forces and factors that contribute to low or reduced strength.
Landslides can be initiated in slopes already on the verge of movement by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors. Earthquake shaking and other factors can also induce landslides underwater. These landslides are called submarine landslides. Submarine landslides sometimes cause tsunamis that damage coastal areas.
Landslide has always been a geological hazard in Bangladesh, especially in the southeastern part of the country. Southwest monsoon flows over the Bay of Bengal, heading towards northeast India and Bangladesh, picking up more moisture from the Bay from June through September.
The winds arrive at the Eastern Himalayas with large amounts of rain. Bangladesh and certain regions of India frequently experience heavy rains during this season, and most landslides occur after heavy rainfall. In recent times, landslides have increased both in frequency and intensity, causing widespread loss and damage to life, infrastructure, assets and property, and posing serious challenges to the existing development process. This increase has been prompted by a blend of several elements (morphometric, climatic and anthropogenic) that cause slope instability, most of which is human-induced.
How, one might ask, can we prevent a natural disaster of such scale? Actually, there are several ways. First of all, by controlling the grabbing of state-owned land, such occurrences can definitely be limited. Moreover, understanding the rainfall pattern and its exact relationship with landslide in the region could also help us be prepared.
Detailed land use planning of the vulnerable areas, a landslide database, landslide mapping and geophysical analysis of the region are essential to minimise landslides and their impacts in the region. For locals living in the hills, it is imperative that they are taught how to secure themselves against landslides. They could also be taught how to control landslides through proper drainage, protection, soil conservation, and watershed management.
Early warning systems need to be strengthened, with active participation of community leaders. Proper communication amidst the Bangladesh Meteorological Department, community based organisations, the civil defence wing and local government authorities is needed to receive regular data relevant to the area as soon as the monsoon season sets. Volunteers or representatives of the vulnerable communities could also be involved to assist in the alertness and preparedness process. Moreover, existing cross departmental coordination and cooperation on landslide management should be reviewed and strengthened with necessary resources.
In order to ensure sustainable landslide management, contingency planning at different levels for emergency response should be developed and updated at least once a year. The focus of these plans should be on landslide prone areas and their vulnerability status, and the availability of resources and capacity, apart from other requisite elements that feature in such a plan.
Capacity building courses on landslide hazard management is needed after a proper gap analysis. Moreover, the constant planning process should include volunteers, managers, workers, government officials, local government representatives, relevant military authorities and media of the vulnerable districts.
---Abu Sufian, AA
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