360 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. Floodwater Control Wetlands contain overfl ow from water bodies due to fl ooding caused by storms, such as hurri- canes, and extreme amounts of precipitation from rain and/or snowmelt. The wetland vegetation holds sediment and other organic materials and slows fl oodwaters which are then slowly released into connected waterways. In many areas, wet- lands are being constructed to help control over- fl ow due to building and road construction that reduces the amount of permeable surface area onto which water would naturally fl ow or infi ltrate. Erosion Control Wetland vegetation can reduce erosion along shorelines of coastal regions as well as the shorelines of streams and rivers. The roots of wetland plants and trees hold soil in place and prevent it from being washed into the waterway. Wetland plants and trees on the coast also help absorb and reduce the force of waves that can wash away the sand and soil, Figure 15-3. Carbon Sink A carbon sink is a natural environment that has the ability to absorb and retain carbon dioxide (CO 2 ) from the atmosphere. Oceans, forests, prairies, and wetlands are all types of carbon sinks. If a carbon sink is left undisturbed, it will contain the carbon for an indefi nite period of time. The carbon in the wet- land plants is also retained because organic materials decompose more slowly without oxygen and the soil in wetlands contains very little oxygen. Recreational Activities Recreational activities enjoyed in wetlands include waterfowl hunting, bird watching, fi sh- ing, hiking, canoeing, and boating, Figure 15-4. While it is diffi cult to determine the exact rev- enue from recreational use of wetlands, some estimates are between $50 and $100 billion annu- ally. Wetland tourism has great economic value for local economies, but it also helps fi nance edu- cational programs and conservation and resto- ration efforts. The money generated from fees, such as hunting and fi shing licenses or boat and canoe rentals, are sources of income that help maintain and preserve wetlands and other natu- ral areas. What is the missing carbon sink? Thinking Critically Fred S. Pinheiro/Shutterstock.com Figure 15-3. Beaches and coastlines are important wetlands that can be damaged severely by storms. Here, along the Brazilian coastline, plant materials help minimize erosion from wind and storms. Kuznetcov_Konstantin/Shutterstock.com Figure 15-4. Many wetland areas have facilities that rent kayaks and canoes for people to enjoy and observe wildlife from a different point of view.