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Riparian Volumes and Their Management

A restored Utah stream. Notice the stone-filled wire baskets at the left in the stream barrier.

Healthy riparian areas are ones that maintained cool water temperatures, clean water, stable banks, aquatic diversity, wildlife habitat, landscape connectivity, and water flow while providing wood, other forest products, energy, fish as food, and recreation for people. (Carey et al.1999)

They have vegetation or physical characteristics that reflect the influence of the permanent water. Lakeshores and streambanks are typical riparian areas but certain ephemeral streams or "washes" are excluded that do not exhibit the presence of vegetation dependent upon free water in the soil.

Riparian areas (also with the silly name of "linear foraging areas") are described in many ways, mostly by their functions. They:

1. provide values and benefits far beyond the small percentage of the land occupied,
2. are hydrologic sources of stream flow,
3. are important habitats for a wide range of terrestrial plant and animal species.
4. stabilize soil and earth banks (when well vegetated)
5. harbor fish and supply fish food
6. maintain instream biota,
7. provide special places for diverse plants and animals (especially the songbirds and furbearers for feeding, nesting, etc.)
8. provide the majority of food and cover and special energy sources for animals at critical periods of their life cycle within the aquatic food chain,
9. provide shade, woody debris, terrestrial litter, and arthropods for fish,
10. provide critical areas along migratory routes,
11. provide water and soil to encourage vegetation growth,
12. provide (when managed) for quality livestock feeding and resting (protective shelter, shade, forage and water),
13. exert strong influences on the character of stream environments,
14. contribute to improved water quality, especially for downstream users,
15. improve groundwater reserves,
16. remove sediment as water moves through them,
17. cool water,
18. act as a sponge, releasing water slowly,
19. hold flood waters and lessen risks of flash floods, reducing peak flows,
20. dissipate energy in flood periods (reducing erosion),
21. provide recreationists with cool shade, desirable scenery, serene waters, and areas for fishing, winter sports, picnicking and camping.

Throughout the US, riparian areas were dominantly influenced by beavers (Castor canadensis). There were some 60 to 400 million of them before settlers arrived. They greatly modified the flood plains of most waterways and created expansive changing sediment and organic "steps" and plateaus throughout the land. Stream channels meandered and shifted throughout these flat areas, dynamically changing since the end of the Pleistocene. Beaver removals had a universal effect of channels. It was followed by the direct but localized effects of human dam building and land use.

Efforts to manage, protect, and restore riparian areas are increasing worldwide. Management work typically includes restoring and reclaiming areas disturbed by road building, mining, logging, and fossil-energy development. Progress has been made in understanding the functions of riparian areas within individual land uses, but knowledge about the integrated functions of riparian areas in watersheds that have many uses of the land is still quite limited. Soil, forest, wildlife and other physical and ecological problems are many, but to these must be added legal and political issues. Upstream changes in the land or water can affect downstream riparian areas. Management, not a hands-off approach, is needed for the riparian area as well as areas above and below it.

Caution is needed, however, for if riparian zones are designated with excessive width or combined with excessively stringent inspection, very large areas can be excluded from conventional forest activities. Under the Northwest Forest plan of the US Forest Service, 40% of the land base was withdrawn from management because of riparian constraints alone, and parts of the remaining landscape were so fragmented and dispersed that logging and other management activity became impractical.

Riparian "zones" are usually addressed as areas but they are volumes with width, depth, height and length along waterways and sources. Of course areas along rivers influenced by tides create a problem for a precise definition. Occasionally a salinity of 0.5 ppt is used as the dividing content, less being riverine, more being estuarine. The riparian volume usually supports vegetation significantly different from that of adjacent inland areas. It is a distinctively different aggregation of plants and animals than that adjacent to it, more influenced by wetness than dryness. Some people think of them as the ecosystem between the aquatic and terrestrial.

The riparian volumes are very conspicuous in the dry areas of the western US. Large federal programs have been created for protecting and restoring these areas. The western funding attracted renewed interest in similar treatment for the zones of the eastern US.In the Eastern US, favoring conifers over hardwood species alters the nutritional subsidies to organisms in these volumes. There are species differences, but generally, the subsidy is of lower quality and quantity in conifer-cover riparian areas.

Maintaining existing high quality riparian area values before they are altered adversely by development can preserve these functions. In the event these lands have already been developed, these values can be restored by returning the land to a natural vegetated condition.

Constructing well sites and roads in streamside areas results in altering or losing riparian values. Timber harvesting can significantly affect riparian volume values. The removal of streamside overhead cover can increase water temperature. Earth-moving activities such as constructing skid roads, log landings, and bridges, by removing duff and organic matter, destroy the sediment-filtering ability of the forest floor in riparian areas. The resulting sedimentation alters water quality. Clearing of riparian and streamside vegetation may also remove important wildlife habitat. These adverse effects can be reduced or eliminated by limiting access of soil-disturbing activities within the riparian area. When it is necessary to use these areas, additional erosion control and sediment detention can be used.

The natural functions of almost all floodplains has already been altered by constructing some facilities. Flow patterns may change, floodflows may be constricted, and the flow velocity accelerated. Such changes result in increased stream bank and channel erosion. Minore and Weatherly 1994 found that in Oregon riparian areas, conifer basal area increased with elevation, stream gradient, and time since disturbance, and decreased with latitude and stream width.

The plan, simply put, is to minimize using and disturbing the vegetated or protected state (with structures, etc.), to stabilize the current volume, to develop potentially profitable uses that enhance (or not harm) the area, and to reduce destructive forces from up-stream and surrounding water use and development.

Locating roads in riparian areas is guided by minimum setback distance, depending on slope, that a road must be from streams and lakes. The setback distance is intended to provide an area wide enough to trap any sediment washed close to the water, additional erosion control measures such as diversion, straw bales, erosion cloth, and sediment basins must be installed.

Bear Creek, Oregon, 1976 before riparian management (above) and after management in 1986 (from BLM)

While the cutting of trees rarely has a major effect on physical water quality, the removal of forest products from the woods by skidding and truck hauling can adversely affect water quality. The forest floor is disturbed and compacted where skid trails, skid roads, log landings, and haul roads are located. Unprotected mineral soil is exposed, and subject to wind, rain, and surface runoff. The potential for erosion increases as the slope of the land increases and as the area being disturbed increases.

The amount and type of groundcover, obstructions, and distance, up to a point, affect potential sedimentation of streams by disturbance. The potential for adding sediments to streams increases the closer that disturbed areas are to streams. The greatest potential for erosion and sedimentation is improperly located log landings and logging roads.

Appropriate management efforts that significantly reduce or eliminate sedimentation from timber harvesting operations or other intensive land use. These include: adding water bars to skid and temporary haul roads; revegetating roads; controlling the size, shape, and location of harvest areas; curtailing logging operations during wet weather; locating landings on nearly-level ridgetop sites, providing filter strips along streams; placing skid trails on contours; seeding and using water bars on roads and trails; placing lead-off ditches; using retaining walls; and avoiding soil loss at stream crossings by using appropriate structures such as bridges, culverts, and rock fords.

Riparian improvement and management cannot be separated from watershed and stream cleanup. These measures, almost self-evident (but continually ignored) include: removing plumbing systems that send sewage into streams, treating urban stream-sides with the same general practices and concerns as described herein, developing plans and implementing storm water control, managing the quantity and characteristics (pollution?) of roadway and roadside runoff, reclaiming mined sites, fencing livestock out of stream areas and adding alternative watering sites for them.

More detailed planned procedures to be used in riparian volumes (and to protect them) are:

1. Develop GIS units and an inventory of the areas and volumes. Analyze areas by "stream reach." Riparian communities often differ along each reach. They differ on each side. Prescriptions need to be made by reach, left and right (looking up-stream).
2. Develop prescriptions for each reach-side. (Each side of the volume along a stream is usually different in character and use.)
3. Permit light grazing, if carefully regulated (and only then).
4. Determine soil compaction potentials throughout the year and adjust livestock and recreational use to minimize compaction.
5. Use rest rotation of grazing (or deferred grazing)(typically for 2 years)or limit recreational use based on compaction and plant vigor to allow use and yet achieve protection. (Plant use should never exceed 40% of available forage.)
6. Build trails, baffles, fences, livestock salt, and signs to influence cattle and human use.
7. Change the type of animal use. In select areas, different livestock can be used (e.g., goats or sheep can use steeper areas than cows).
8. Use undulating fencing to keep livestock out of riparian areas (or control its use).
9. Pipe water from the stream or use springs to provide drinking water and to prevent animal use of the stream bed or banks.
10. Influence animal use of the waters. Animal use is related to water, nutritious feed, and shade -- all three of which can be replaced to protect the riparian areas. (Seasonal insect abundance must be included in use rate analyses.)These are the three major functions of such areas for livestock and large wildlife.
11. Protect select stream reaches by fencing out all use (human and livestock)
12. Feed animals and make camping areas away from riparian area.
13. Make plantings (e.g., of willows) to restore and revegetate riparian areas.
14. Use gabians (rock-filled wire baskets) or logs to create streams that are small-stair-step in their cross-section appearance. Leave large stable debris.
15. Encourage meanders.
16. Judiciously use rip-rap.
17. Build structures (if essential to be placed in the volume)on supports to escape normal flooding.
18. Build and maintain collectors for silt when flood waters occur.

Generally allow clear cuts no closer than 66 feet (1 chain) from stream (thereby defining a type of wooded riparian zone of this width). Studies of the proper width to achieve a set of objectives cost effectively over time, that is to change the value of R, are needed. Selection harvests from such areas are feasible and large wood (cull and large limbs) can be placed in streams to form stair-steps in the water flow and thereby preserve site quality and allow a return to watershed conditions more similar to pre-settlement than those that now exist.

Perfect, well managed and maintained riparian volumes, by any criteria, are at risk from improper use and development of upstream lands and waters. There are some natural floods that impact riparian volumes but upstream land use changes the frequency, timing, and intensity of flooding and thus its effects on the riparian volume. Of course the quality of the water is influential. Floods bring silt and riparian areas are adapted for receiving and using limited amounts of it. It is essential to continue to work with landuse planning, policy, and governmental groups to encourage responsible landuse upstream and in surrounding areas. Such work is part of riparian volume management. Enforcement of existing laws and ordinances is essential. An alternative last-line-of-defense local legal strategy needs to be developed.

Mentioned several times above, it is essential to realize the importance of the volume in producing insects and arthropods that fall into the water and are borne by the currents to fish and other organisms in the waters downstream. The headwaters-volumes, usually small and often not called " riparian" are productive sites for these essential foods added to the streams. It is notable that some arthropod species of the riparian areas emerge at night, thus suggesting defensive strategies against predation... and the need for diverse sampling strategies.

These volumes are typically rich in bird life and thus foot trails can increase human use and benefits. They often have unusual wildflowers and lepidoptera groups. Often growing walnut trees, a grassy understory develops (due to plant toxins) suggesting grazing and recreational potentials.

Old forests within the Red River flood plain had 7.2 metric tons per acre of coarse woody debris which is about 10 percent of the mass of the overstory. Shearer et al. (1997) proposed that red maple and American beech are likely to become more common in old-growth Red River bottomland forests because of fire suppression and reduced flooding.

Perhaps unnecessarily said, each riparian reach-side volume is unique and dynamic. Brown and Peet (2003) observed that for Southern Appalachian plant communities, overall riparian areas had more exotic and native species than upland areas. Both native and exotic species diversity increased with flood frequency within the riparian zone. GIS allows special inventory and descriptions of each reach side volume. Studies are needed but the risks of waiting for the results far exceed not applying the above practices, and using policy, revegetation, controlled use, fences, and fertilizer to bring these volumes under control and into production. It may be years before prescriptions for each can be formulated but it will be even longer before they are implemented on many areas. Trying to understand and express "the functioning condition" of such areas, some expression of their health, remains to be done. Now the condition is expressed in terms of the processes, the above long list. The more evident the many processes, the more healthy seems the riparian area.

The BLM stresses interdisciplinary planning, on-the-ground improvements, preventing further degradation, monitoring, training of employees about techniques, and work with volunteers.

Riparian work is part of improving the health of a watershed and that includes such endeavors as economic development, land use, recreation opportunities, fire prevention and protection, and flood management. Collaborative efforts and cooperation are essential in promoting and achieving a healthy watershed.

A riparian conference was announced: Draft "Focus Statement" and Session Themes (rev 11/19/99)

Focus Statement: The key focus will be on California riparian and floodplain conservation, partnerships, education, policy, and biota associated with these habitat types, using integration across disciplines and bringing experts from various fields together.

The same or a related conference in California (2000) may be of help.

An Eastern riparian area, a headwaters trout stream, formerly grazed and now under USFS management.

Conventional measures and inventory include: a valley cross-section, a greenline (describing the streamside vegetation), and woody species density and age classes (Winward 2000).

References

BLM Manual 1737, Interior Dept Manual 520

Brown, R.L. and R.K. Peet. Diversity and invasibility of Southern Appalachian plant communities. Ecology 84(1): 32-39.

Carey, A.B. et al. 1999. Reverse technology transfer:obtaining feedback from managers. Western. J. Forestry 14(3):153-163.

Gregory, S.V., F.J. Swanson, W.A. McKee, and K.W. Cummins. 1991. An ecosystem perspective of riparian zones. BioScience 41: 540-551. Minore, D. and H.G. Weatherly. 1994. Riparian trees, shrubs, and forest regeneration in the coastal mountains of Oregon. New Forests 8:249-263

USDI - Bureau of Land Management. 1991. Riparian-Wetland Initiative for the 1990's, BLM/WO/GI-91/001+4340, 50 PP.

Welsch, D.J., J.W. Hornbeck, E.S. Verry, et al. 2000. Riparian area management: themes and recommendations p. 321-340 in E.S. Verry, J.W. Hornbeck and C.A. Doloff eds. Riparian management in the forests of of the continental Eastern United States, CRC Press, Boca Raton, FL

Winward, A.H. 2000. Monitoring the vegetation resources in riparian areas, USDA For Serv. , Rocky Mt Research Station,Gen Tech Rpt RMRS-GTR-47 Ogden, Utah 49p.

The following (2-2001) note about flood maps offers extra resources for analyzing and working within the riparian volume.

E-Government at the Map Service Center

Over the past twelve months, the Mitigation Directorate's Mapping Modernization effort has been developing an Electronic Commerce (E-commerce) capability at our Map Service Center (MSC). E-commerce allows on-line ordering and payment for flood maps and related products. We are pleased to announce that the system is "live" effective today. The first stage, which allows us to accept payment for on-line orders, is in operation. The next stage, which will allow us to accept on-line orders from fee-exempt Federal, state, and local government agencies, will be operable during the summer of 2001. This exciting initiative is part an overall project to build a state-of-the-art Digital Distribution Center at the MSC.

The FEMA Flood Map Store has at first simply taken the familiar physical warehouse and created a counterpart in the electronic world. As technology advances, the FEMA Flood Map Store will provide functionality that does not exist in the physical warehouse. More interactive, transaction-based applications will come online to create a compelling online experience for the user. Keep your eyes on our web site at E-Government at the Map Service Center at WWW.FEMA.GOV/MSC for the unveiling of other great products and services.

The EPA Biweekly Update provides current information on wetland and river corridor restoration projects, recognizes outstanding restoration projects, and provides a forum for information sharing.

Riparian "values" have been said (2002) to be:

• Streambank stability
• Water quality
• Vegetative and faunal diversity
• Stream flows
• Subsurface water supplies
• Aquatic/fish habitat
• Terrestrial wildlife habitat
• Forage production
• Recreation/aesthetic qualities
• Education

A M.S. study of riparian volumes of the Nottoway River system (Virginia; Octiber 2007;Va Tech) found low correlation between an Index of Riparian Condition and IBI (Index of Biological Integrity?) and raised the importance of defining the objectives of riparian management, restoration, or protection. What is intended, by active restoration or protection and at what costs? Reduced soil loss, more fish species, improved instream conditions (presumably bottom conditions for invertebrates… for fish), or stable year-around stream temperatures or … what specifically? Caution: Deforested riparian zones contained diseased fish and this needs further observation.

See Naiman, R.J., H. Decamps, and M. E. McClain. 2005. Riparia: ecology, conservation, and management of streamside communities. Elsevier, Burlington, MA xv + 430 ISBN 0 - 12 - 663315-0

See the Planner's Guide to Wetland Buffers for Local Governments identifies both the state-of-the-art and the range of current practice in protection of wetland buffers by local governments.

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This Web site is maintained by R. H. Giles, Jr.
Last revision October 20, 2007.