Roads to the Rescue
Posted by Cecilia Borgia
Februray 8, 2017
Coastal Bangladesh is a vast area. It spans over 19 of the 64 Districts, 133 of the 484 Upazilas (sub-Districts), represents 32% of the country’s surface and hosts 28% of the national population. With 1000 people per square kilometre, it is a very densely populated area. Despite the high risks of flooding, cyclones, and salinization making these lands often unsuitable for agriculture; these areas are becoming more and more densely populated due to migration.
Besides larger floods caused by cyclones and storm surges, particularly in the polder areas, flooding is often caused by intense rain events which are not adequately managed and drained. This causes considerable damage to people, goods, and farming.
Polders are areas that have been protected by an embankment. Polders are provided with an internal road network and public facilities. An often overlooked aspect is that roads, bridges, and culverts within polders strongly influence the water flow, distribution, and water levels both in waterways (khals) and farmland. The network of different types of internal roads, including village feeder roads and pathways, interrupts the connectivity of the natural drainage system consisting of khals. This divides the polder into disconnected compartments where water stagnates.
Waterlogging can be also the consequence of under-dimensioned/non-functional outfall sluice gates that hinder the evacuation of excess water generated inside the polder during heavy rainfall. Even if sluices were functional, during heavy monsoons and in times of very high river water levels outside the polder, pumping would be the only solution as the water level in the khal approaching the sluice would be lower than the water level of the river downstream of the sluice gate.
Too often, these technical challenges can be attributed to a lack of synergy and coordination between authorities concerned with road development and those responsible for polder water management and flood protection. Fieldwork and meetings with concerned authorities has highlighted the need to synchronise design specifications for embankments (responsibility of Bangladesh Water Development Board-BWDB) and roads (Local Government Engineering Department-LGED), larger drainage (khal) system and water structures (BWDB), and cross-drainage structures (LGED).
But there is more to it. Waterlogging and drainage problems in the polders are not only of technical nature but very importantly also the consequence of socio-political processes of land accretion and appropriation within the polder. Polder inhabitants accelerate siltation of khals by constructing cross-dams in the canals in order to gain new land to put under cultivation or to construct houses. This is in a context of extreme land scarcity where every useful centimetre of surface needs to be claimed and exploited.