THE CHALLENGES OF GEOTECHNICAL EXPLORATION IN BANGLADESH FOR SUSTAINABLE URBAN DEVELOPMENT AND RISK REDUCTIONS IN ENGINEERING GEOLOGY

Bangladesh is a unique example of rapid urbanization where the urban population increased from 5 to 58 million in last four decades. Due to complex geology and active tectonic setting, the urban ground is impacted by fluvio-deltaic processes and regional seismicity. The densely populated cities of the country are facing risks from many natural hazards like floods, tidal surge, riverbank and coastal erosion, scour, landslides, soil collapse and foundation failures. Geologists anticipate severe seismic threats from yet-undefined tectonic structures and seek to determine their consequential geo-structural responses and conformance to the national building code. With rapid growth, demands on infrastructure have driven the need for better understanding of geotechnical exploration and geologic factors that will contribute to a more manageable, livable, resilient and sustainable infrastructure. The relationship of geo-hazards, geotechnical exploration methods and engineering geologic practices are discussed here. The study indicates that geotechnical exploration method, reporting and laboratory testing practices in current use have yet to adopt standard and quality control techniques. Engineering geology is concerned with subsurface construction, operation and maintenance for safe and sustainable structures. Modified large-scale (1:5000) engineering geologic maps are prepared for selected parts of Dhaka to evaluate and integrate the geologic hazards and engineering geologic risk. Because of unplanned urban expansion, many cities of Bangladesh will require intense modification to the exiting infrastructures including effective utilization of underground space and construction of multilevel transportation system. Risk is always present in any alteration of geologic environment during and after construction. Although the underlying thick hard clay and very dense sand in Dhaka provide advantageous ground condition comparing to other cities of the world, the country is confronting difficult geo-engineering challenges for sustainable development and needs to have standardized geotechnical exploration methods, updated geologic maps and improved laboratory testing system to accurately characterize geologic materials for modeling to meet challenges of sustainable development and risk reduction.