ON February 2 Zimbabwe and the World celebrated World Wetlands Day.
Celebrations ran under the theme ‘Wetlands for our future, Sustainable livelihoods’.
The theme demonstrates the important role of wetlands for the future of humanity and specifically their relevance towards achieving the new Sustainable Development Goals (SDGs).
The celebrations were held at a time the country’s wetlands, both in rural and urban areas, are in danger of extinction due to human activities.
Activities like unsanctioned building, farming, fishing and even hunting on wetlands are causing more harm than good.
Unfortunately, residential structures built on wetlands have been severely affected as the country experiences heavy rainfall.
Wetlands are waterlogged areas all year round or for varying periods of time during the year.
Water saturation largely determines how the soil develops and the types of plant and animal communities living in and on the soil.
Wetlands may support both aquatic and terrestrial species.
The prolonged presence of water creates conditions that favour the growth of specially adapted plants (hydrophytes) and promote the development of characteristic wetland (hydric) soils.
Wetlands vary widely because of regional and local differences in soils, topography, climate, hydrology, water chemistry, vegetation and other factors, including human disturbance.
Indeed, wetlands are found from the tundra to the tropics and on every continent except the Antarctica.
Two general categories of wetlands are recognised; coastal or tidal wetlands and inland or non-tidal wetlands.
Wetlands protect water quality by trapping sediments and retaining excess nutrients and other pollutants such as heavy metals.
These functions are especially important when a wetland is connected to groundwater or surface water sources (such as rivers and lakes) that are in turn used by humans for drinking, swimming, fishing and other activities.
These same functions are also critical for the fish and other wildlife that inhabit these waters.
Sediments, which are particles of soil, settle into the gravel of streambeds and disrupt or prevent fish from spawning and can smother fish eggs.
Other pollutants, notably heavy metals, are often attached to sediments and present the potential for further water contamination.
Wetlands remove these pollutants by trapping the sediments and holding them.
The slow speed of water in wetlands allows the sediments to settle to the bottom where wetland plants hold the accumulated sediments in place.
Toxic chemicals reach surface waters in the same way as nutrients and can cause disease, death or other problems upon exposure to plants and animals (including humans).
In a function similar to nutrient removal, wetlands trap and bury these chemicals or may even convert some of them to less harmful forms.

Flood protection
Almost any wetland can provide some measure of flood protection by holding the excess runoff after a storm and then releasing it slowly.
The size, shape, location and soil type of a wetland determine its capacity to reduce local and downstream flooding.
While wetlands cannot prevent flooding, they do lower flood peaks by temporarily holding water and by slowing the water’s velocity.
Wetland soil acts as a sponge, holding much more water than other soil types.
Even isolated wetlands can reduce local flooding — if the wetlands were not there to hold storm water runoff, backyards and basements might end up under water.
Groundwater recharge and stream flow maintenance
Aquifers and groundwater are ‘recharged’, that is, replenished with water by precipitation that seeps into the ground and by surface waters.
Those wetlands connected to groundwater systems or aquifers are important areas for groundwater exchange.
They retain water and so provide time for infiltration to occur.
Groundwater, in turn, provides water for drinking, irrigation and maintenance of stream flow and lake and reservoir levels.
During periods of low stream flow (or low lake water levels), the slow discharge of groundwater often helps maintain minimum water levels.
In addition, wetlands located along streams, lakes and reservoirs may release stored water directly into these systems, thus also contributing to their maintenance.
Wetlands’ many intricate connections with groundwater, stream flow and lake and reservoir water levels make them essential in the proper functioning of the hydrologic cycle.

Fish and wildlife habitat
Many species of birds, fish, mammals, reptiles and amphibians rely on wetland habitats for breeding, foraging and cover.
The special wetland conditions provide unique habitat for species that cannot survive elsewhere.
Migratory birds depend on wetlands and many endangered and threatened animal species require wetlands during part of their life cycle.
The incredibly high rate of wetlands loss has contributed to their demise.
Wetland plants and small animals — especially insects — are essential links at the lowest levels of the food chain.
A wetland environment supports these plants and animals, which in turn support the larger animals that feed on them.

Economic benefits
The economic benefits associated with these environmental values of wetlands can also be substantial.
If, for example, a community had to build flood control or water treatment systems to replace those functions provided by wetlands, the costs could far outweigh the land purchase price of preserving the natural wetland systems.
Similarly, when wetlands lose their value as fish habitat, this value is difficult to replace, and the consequent losses to the recreational and commercial fishing industries can be significant.
There are as yet no precise formulas that we can use to determine the accurate dollar-value per acre of wetland, but the more we learn about wetlands, the higher that value becomes.
– Source – [email protected]