Wetland

Wetlands are recognized as important features in the landscape that provide numerous beneficial services for people and for fish and wildlife. Some of these services, or functions include protecting and improving water quality, providing fish and wildlife habitats, storing floodwaters, and maintaining surface water flow during dry periods. These beneficial services, considered valuable to societies worldwide, are the result of the inherent and unique natural characteristics of wetlands.

Functions versus values

Wetland functions include water quality improvement, floodwater storage, fish and wildlife habitat, aesthetics, and biological productivity. The value of a wetland is an estimate of the importance or worth of one or more of its functions to society. For example, a value can be determined by the revenue generated from the sale of fish that depend on the wetland, by the tourist visiting the wetland, or by public support for protecting fish and wildlife. Although large-scale benefits of functions can be valued, determining the value of individual wetlands is difficult because they differ widely and do not all perform the same functions or perform functions equally well. Decision makers must understand that impacts on wetland functions can eliminate or diminish the values of wetlands.

Water storage

Wetlands function like natural tubs or sponges, storing water and slowly releasing it. This process slows the water's momentum and erosive potential, reduces flood heights, and allows for ground water recharge, which contributes to base flow to surface water systems during dry periods. It is not out of subject to mention here that in the last decade the country is suffering from severe groundwater shortages, especially Dhaka city's groundwater level is depleting at an alarming rate. In every dry season, most of the WASA pumps in Dhaka fall short of water to abstract and are unable to serve the city dwellers. Although a small wetland might not store much water, a network of many small wetlands can store an enormous amount of water. Most of the wetlands in Dhaka city are diminishing at an alarming rate (Gulshan and Banani lake, Dhanmondi lake, jheels in Rampura, Rayerbazar and all others). The ability of wetlands to store floodwaters reduces the risk of costly property damage and loss of life -- benefits that have economic value to us.

Water filtration

After being slowed by a wetland, water moves around plants, allowing the suspended sediment to drop out and settle to the wetland floor. Plant roots and microorganisms in the soil often absorb nutrients from fertilizer application, manure, leaking septic tanks, and municipal sewage that are dissolved in the water. Other pollutants stick to soil particles. In many cases, this filtration process removes much of the water's nutrient and pollutant load by the time it leaves a wetland. Some types of wetlands are so good at this filtration function that many countries around the world construct similar artificial wetlands to treat storm water and wastewater.

Biological productivity

Wetlands are some of the most biologically productive natural ecosystems in the world, comparable to tropical rain forests and coral reefs in their productivity and the diversity of species they support. Abundant vegetation and shallow water provide diverse habitats for fish and wildlife. Aquatic plant life flourishes in the nutrient-rich environment, and energy converted by the plants is passed up the food chain to fish, waterfowl, and other wildlife and to us as well. This function supports valuable commercial fish and shellfish industries.

Conclusion

Having all these importance of wetland in preserving natural eco-system, is it too much to expect from the politicians and policy makers to strictly enforce the existing laws and deter the unscrupulous and uneducated land grabbers from encroaching these natural resources? We have to understand that the cycle of destruction is no way helping our natural environment to protect the eco-system. It is the mass population who will suffer including the land grabbers and the policymakers, in the day ahead.

Dr. Masud Karim is the Manager of Environmental Planning and Management, Engconsult Ltd., Canada.