Riparian Zone
The Riparian Zone
Riparian zones are the areas bordering rivers and other bodies of surface water. They include the floodplain as well as the riparian buffers adjacent to the floodplain. Riparian zones provide many environmental and recreational benefits to streams, groundwater and downstream land areas. Groundwater is usually found at shallower depths in riparian zones than in the surrounding landscape. Riparian zones are visually defined by a greenbelt with a characteristic suite of plants that are adapted to and depend on the shallow water table.
The extra moisture in riparian zones and associated wetlands, combined with the abundance of vegetation, creates a mat of decomposing material on top of the soil. It is often damp because the water table is at or near the soil surface. This organic-rich layer aids in conserving moisture. The vegetation and spongelike quality of soils in wetlands, floodplains and riparian zones protect surface water in several ways.
Often, interactions between shallow groundwater in the riparian zone and surface water in the river regulate stream temperature in ways beneficial to fish and other aquatic creatures. Streambank vegetation helps cool surface water temperatures.
Riparian vegetation along streambanks and in floodplains reduces the velocity of floodwaters, lessening the erosive force of the flood and capturing nutrient-laden sediment. Soils in this area absorb water during the wet seasons and slowly release moisture into the stream. This buffers the effect of peak runoff and keeps streams flowing longer.
These areas serve as nature’s water treatment facilities for our watersheds. They can capture and filter surface runoff that flows from higher ground. Live vegetation and the absorbent mat of accumulated plant litter and humus help to trap sediments before they reach the river. Soil microbes that thrive in this moist environment break down chemical pollutants like hydrocarbons, further protecting water quality.
Riparian areas and wetlands are especially valuable in or downstream of urban areas. Their natural functions can counteract the effects of concentrated runoff from pavement and buildings, protecting water quality and the river channel itself.
In New Mexico, floodplains, wetlands, and riparian areas provide important habitat for numerous species of birds, mammals, amphibians and reptiles. The water bodies that support these critical areas are home to the state’s native fish.
