In the urban context of Bangladesh, the increasing frequency of natural hazards due to climate change poses significant risk to city dwellers. Hazards mainly include floods and water-logging, earthquakes and liquefaction and the fires. Climate change aggravates these hazards through direct and indirect ways. It increases the frequency and severity of floods and water-logging, and thereby multi-faceted environmental problems.
Moreover, with rural-urban migration increasing as a result of the climatic changes experienced throughout the country and hazards in urban areas are magnified. Increasing population pressures accompanied by poor infrastructure and a lack of public services heightens the risks severely. Within Dhaka, hazards are most extreme amongst communities inhabiting low-lying slum areas and in unplanned and congested areas. The existing physical, economic and social vulnerabilities of slum residents heighten their poverty, marginality and disenfranchisement, making them highly susceptible to disasters and their lasting effects. Within slum communities and in low-income areas, children, women and the elderly can be understood to be more vulnerable due to having a greater lack of autonomy.
The government budget for Disaster Risk Reductions is severely limited, and there is also a critical lack of insurance, development plans, emergency teams and early warning systems. But now many donor agencies, academic institutions, United Nations including a few NGOs has been providing supports to Bangladesh in the areas to reduce these hazards and climatic vulnerabilities.
Floods and waterlogging
Due to the location of Dhaka surrounded by relatively low-lying terrain, flooding and water-logging are common here. Slum and bastees along the water’s edge are particularly exposed, where yet inhabits almost 25 percent of Dhaka’s population. The problem became severe after the independence, when there were huge influx of population and floods in every year. There were devastating floods in 1988 and 1998 and after that by virtue of various protection measures (embankment, wall, road construction etc.) flooding problems in the inner-city reduced remarkably. But then the capital city started to face extensive water-logging during the monsoon (May to October) mainly due to multiple drainage problems like encroachment and filling of khals/canals, haphazard development, inadequate drainage, disposal of solid waste into drains, non-maintenance of drainage and poor sewage system. Many road and areas (say in DND Triangle and peri-urban areas) remains inundated and inaccessible for long time, thus creating so many problems, which pose a great health hazards to the residents, by making them exposed to various water-borne diseases and lack of basic public services. It is magnified during the flooding times, when the drains become congested and mobility is restricted resulting in a complete lack of access to clean water and hygienic sanitation facilities.
Earthquakes and liquefaction
Bangladesh has also been directly affected by earthquakes in the recent and distant past and is likely to suffer more in the near future as forecasted by the international earthquake experts. In 1762, a major earthquake submerged 150 square kilometers of land and about five hundred people in Dhaka were killed. Between 1850 and 1950, seven earthquakes with magnitude from 7.0 to 8.7 on the Richter scale struck the region. More recently, since 1997 Bangladesh has experienced several earthquakes of magnitude higher than 5 on the Richter scale. The last major earthquake in Bangladesh occurred in early 2016 on 6.9 in Richter scale, when a good number of buildings tilted or collapsed and cracks were developed in many buildings! There were also many ‘aftershocks’ after this earthquake. Experts says that any moment there might be more devastating earthquakes in the country, some says it is ‘over-due’!
In the National Building Code of Bangladesh (BNBC), it specifies three seismic zones, identified through a series of seismic-tectonic studies. These zones identify the level of earthquake risk faced by particular areas; Zone III being the most at risk, and Zone I the least at risk. Seismic zoning in Bangladesh indicates that Dhaka is under Zone II and as such is at a real risk of an earthquake of significant magnitude. In fact, globally Dhaka is one of the most vulnerable cities to earthquake according to the International Earthquake Disaster Risk Index. In the urban context, major earthquake risk is associated with the high vulnerability of buildings to collapse due to poor construction materials and processes. Just a few years back, a Comprehensive Disaster Management Program (CDMP) prepared have identified that there are some about 78,000 out 326,000 buildings in Dhaka which are vulnerable to collapse, though the actual figure would be much larger than that. Such vulnerability was demonstrated in a few recent past experiences of building collapses, and mainly in ‘Rana Plaza’ collapse on April 2013.
Earthquakes can also cause liquefaction of soils, rendering built-up areas further vulnerable to structural collapse. Liquefaction is a process wherein sand and silt become more compact and force ground water upwards. The resulting fluidity at the upper level fails to support structures, causing buildings to sink and collapse.
Dhaka’s shallow water table and soft sediment terrain make it highly susceptible to this phenomenon. Experts mentioned that many low-laying area and slums in Dhaka are located close to the epicenter of liquefaction zones, whilst the simple and lightweight infrastructure of slum settlements withdraws them from the immediate risks of building collapses, but liquefaction of surrounding buildings can cause much destruction. The projected levels of liquefaction damage likely to be caused in Dhaka in the event of an earthquake as indicated. It is to note that much of Dhaka’s eastern side are at risk of high damage from liquefaction.
Fire and rescue
Fire is a frequently occurring hazard in urban areas and causes huge losses in life and assets every year. Within the urban context, mainly the tall buildings, chemical warehouses and slum areas are at great risk from fire hazards, as has been evidenced by past fire events in Dhaka. Fire incidences at Nimtoii and Churihatta of old Dhaka, fire in F.R Tower at Banani, and too often fires at various slums in garment industries are a few glaring examples of time. Nimtoli tragedy on June 2010 due to unauthorized chemical stocking in residential buildings caused 125 people died and about 200 people suffered critical burns. Due to narrow road, Fire Service Rescue Team could not reach there timely nor there are prevailed any hydrants or water tanks in nearby areas. In Churihatta incidence, we saw the similar situations. Similarly, in the past years, a few modern buildings like BSEC building at Karwan Bazar, Basundhara City Mall at Panthapath, Tazreen Fashion Garment Building at Gazipur was also under fire and burnt. Urban fires are also often a result of various anthropogenic activities and the overlapping of mix-zones notably industrial and residential establishments put residents at high risk in Dhaka.
In old Dhaka, there are large number of residential housing contains unauthorized factories, chemical warehouses. Due to lack of government enforcement, fostered by an understaffed inspection and the adverse interests of politicians with ownership stakes heightens the fire risks and hazards there.
(To be continued)
Md Emdadul Islam is an Engineer-Planner -cum- Urban Analyst.
