Introduction
Nestled in the scenic hills of the Chittagong Hill Tracts, Kaptai Lake stands as the largest man-made lake in Bangladesh and one of the most significant artificial reservoirs in South Asia. Located in Kaptai Upazila under Rangamati District, this expansive lake spans approximately 68,800 hectares and is a vital resource for the region, supporting hydropower generation, fisheries, agriculture, and tourism. However, its creation came at a profound cost, displacing thousands of indigenous people and submerging vast tracts of fertile land. This article explores the lake’s history, ecological and economic contributions, environmental challenges, and its role as a premier tourist destination.
History and Creation
Kaptai Lake was formed as a result of the construction of the Kaptai Dam on the Karnaphuli River, a project initiated by the government of then-East Pakistan in 1956 and completed in 1962. The dam, built primarily for the Karnafuli Hydroelectric Power Station, was financed by the United States through USAID and constructed by the International Engineering Company and Utah International Inc. The dam, measuring 670.8 meters long and 54.7 meters high, created a reservoir with a water storage capacity of 6,477 million cubic meters.
The lake’s formation submerged 54,000 acres (220 km²) of farmland, representing 40% of the total arable land in the Rangamati District, along with 29 square miles of government-owned forest and 234 square miles of other forest land. This inundation displaced approximately 100,000 people, primarily from indigenous communities such as the Chakma, and submerged significant cultural sites, including the palace of the Chakma king. The event, known as the "Bor Porong" or "Great Exodus," forced many to migrate to neighboring India, with over 35,000 Chakmas and Hajongs relocating. The lack of compensation for those displaced remains a significant point of contention.
Geographic and Morphometric Features
Kaptai Lake, often described as H-shaped, consists of two main arms connected by a narrow gorge near Shubalong, part of the original Karnaphuli River course. The right arm, Kasalong, is fed by the Mayni and Kasalong rivers, while the left arm, Rangamati-Kaptai, is nourished by the Chengi and Rinkhyong rivers. The lake’s surface elevation is approximately 31.1 meters, with an average depth of 9 meters and a maximum depth of 36 meters, though some sources report a maximum depth of up to 150 meters. Its irregular shoreline and rocky basin, composed of sandstone, shale, and silty shale, contribute to its unique geological profile.
The lake’s water level fluctuates significantly, with an annual variation of about 8.14 meters, impacting its usability for agriculture and navigation. In September 2024, heavy rainfall and upstream water flow pushed the lake’s water level to 108.74 MSL, close to its maximum capacity of 109 MSL, necessitating the opening of 16 sluice gates to release 68,000 cusecs of water per second into the Karnaphuli River.
Ecological and Economic Significance
Kaptai Lake serves multiple purposes beyond its original intent of hydroelectric power generation, which produces about 5% of Bangladesh’s electricity through the 230 MW Karnafuli Hydroelectric Power Station. The lake supports:
Fisheries: Kaptai Lake is a critical source of freshwater fish, contributing significantly to the region’s food security. However, over-harvesting has led to a decline in Indian Major Carp populations, with pelagic clupeids like Chapila and Keski now dominating over 50% of the catch. Research suggests the need for multi-species Maximum Sustainable Yield assessments to ensure sustainable fisheries management.
Agriculture: The lake’s fluctuating water levels create fertile shores ideal for leasehold farming on approximately 6,075 hectares. These areas benefit from an automatic irrigation system, enhancing agricultural productivity.
Navigation and Tourism: The lake facilitates inland navigation and is a major tourist attraction, often called the "Lake City" of Rangamati. Boating on the lake, surrounded by lush green hills and islands (the tops of submerged hills), is a highlight for visitors. Nearby attractions, such as the Shubalong Waterfall, enhance its appeal, particularly during the rainy season.
Flood Control and Water Supply: The lake plays a role in flood control for the Chittagong Hill Tracts and supports municipal water supply and seaport operations.
Environmental Challenges
Despite its benefits, Kaptai Lake faces significant environmental threats. Deforestation and the removal of protective vegetation around the lake have led to soil erosion and landslides, particularly during monsoon rains, which deposit loose rock material into the lake. This sedimentation reduces the lake’s usable lifespan and navigability. Heavy metal contamination, particularly chromium and nickel in sediments, poses low but notable ecological risks, with some metals originating from anthropogenic sources like vehicle emissions and agricultural activities.
The decline in fish diversity, with some native species nearing extinction, is another concern. Anthropogenic activities, including waste dumping, pesticide use, and pollution from boat operations, further degrade water quality. Ongoing research emphasizes the need for conservation strategies, such as protecting natural breeding grounds and restoring fish populations.
Tourism and Cultural Significance
Kaptai Lake’s breathtaking scenery, with its crystal-clear waters, forested hills, and dramatic landscapes, makes it a top tourist destination in Bangladesh. Visitors can explore the lake via motorized boats, available for hire at approximately Tk 800-1,000 per hour, offering a serene experience amidst nature. Rangamati, often described as floating on the lake, is accessible by road from major cities like Chittagong, making it a convenient getaway. Resorts like Hotel Green Castle and Hotel Sufia provide comfortable accommodations for tourists.
For the indigenous Jumma peoples, particularly the Chakma, the lake holds a complex legacy. While it has brought economic opportunities, the "Great Exodus" and loss of ancestral lands remain a painful memory. Artists like Tufan Chakma have used visual storytelling to highlight this history, ensuring the narrative of displacement is not forgotten.
Conclusion
Kaptai Lake is a testament to human ingenuity and its profound consequences. As a vital resource for hydropower, fisheries, and tourism, it has transformed the Chittagong Hill Tracts, yet its creation displaced thousands and altered ecosystems. Balancing its economic benefits with environmental conservation and addressing the historical injustices faced by indigenous communities are critical for its sustainable future. For visitors, Kaptai Lake offers an unforgettable experience of natural beauty, while for locals, it remains a symbol of both opportunity and loss.
For those planning a visit, the rainy season enhances the lake’s allure, with vibrant greenery and the nearby Shubalong Waterfall at its most spectacular. However, pre-booking accommodations and boats is recommended to ensure a seamless trip. Kaptai Lake continues to captivate, but its story urges us to reflect on the costs of progress and the importance of sustainable stewardship.
