It is often asked why a significant amount of river water is wasted into the sea or why it is necessary to let water flow into the sea. To understand this, we must first understand the concept of a delta and then explore mangrove forests.
A delta is a triangular landform created at the mouth of a river due to the slowing of its flow. This occurs when the river splits into smaller branches before entering the sea, depositing sediment in the process. The term “delta” is derived from the Greek letter “Delta” (Δ). Not all rivers form deltas. Rivers flowing through lakes deposit their sediment there, and rivers with frequent tidal movements at their mouths also do not form deltas. Only slow-moving rivers that carry sediment from plains create deltas. The soil of a delta is highly fertile and supports the growth of natural mangrove forests. These forests prevent soil erosion and act as barriers against tsunami waves.
Globally, countries value mangroves and consider them the “lungs” of the environment. Like lungs, they are essential for survival. Rivers like the Indus, Nile, Orinoco, Danube, Volga, Euphrates, and Ganges form deltas.
The natural mangrove forests of the Indus Delta serve as critical habitats for various aquatic species, including fish, crabs, and shellfish (like shrimp). It is estimated that fish from these forests generate an annual revenue of approximately $20 million. The region also produces a significant amount of shrimp, valued at around $70 million, with export prices exceeding this amount by 1.5 times. Crab exports bring in an additional $3 million annually. These forests are vital to the local economy.
Mangroves also provide fuelwood for the local population, estimated at 18,000 tons annually, valued at $460,000. Their leaves and branches serve as fodder for livestock, with approximately 67,000 tons of leaves and 20,000 tons of grass used annually, valued at $1.35 million.
Nearly 1.2 million people live in Pakistan’s coastal regions, with 90,000 residing in the Indus Delta. Over 135,000 depend on mangroves for their livelihood. The lack of water flow in the river directly impacts the drying up of the delta and the loss of mangroves, with devastating consequences for the ecosystem and local communities. Despite this, policymakers have largely ignored the issue.
A study reveals that mangrove degradation has affected the livelihoods of approximately 135,000 people, leading to annual losses of $1.8 million in terms of fuel, fodder, and aquatic resources. Export revenue from fish alone, once valued at $125 million annually, has also suffered. Over the decades, the Indus Delta has seen a dramatic reduction in mangrove cover. In 1978, the delta had 263,000 hectares of mangroves, which shrank to 158,300 hectares by the late 1990s. Satellite observations in 1998 showed that the remaining mangrove forests covered only 400,000 acres, of which just 125,000 acres were in healthy condition.
Experts note that the devastating cyclone of 1999 did not reach Karachi due to the protective barrier provided by mangrove forests. According to a World Bank report, these forests supply wood and fuel to over 120,000 people in the delta. In addition to protecting marine biodiversity, mangroves act as nurseries for 44 species of commercially important seafood, such as tiger shrimp, hilsa fish, croaker, and pomfret. However, their populations are rapidly declining.
It is our primary duty to ensure adequate river flow and to prevent the further loss of these vital ecosystems. Protecting mangroves and the diverse life they sustain is essential for preserving this natural heritage for future generations.