An adaptation of an old proverb states: Give a man a fish, feed him for a day.  Teach a man how to fish, feed him for a lifetime. Destroy his streams and wetlands so he can’t fish, feed him no more. In a report presented to Congress in 1990, Thomas Dahl (National Wetlands Inventory, USFWS) testified that the lower continental 48 states has lost an estimated 53% of over 221 million acres of wetland, an average of over 60 acres every hour over the past 200 years! Twenty-two states have lost more than 50% of their original wetlands. Eight have lost more than 85%![1] Canaan Valley Institute (CVI) has accepted the challenge and is completely committed to the cause of combating this astonishing trend.  By collecting LiDAR (Light Detection and Ranging) terrain data with its own airborne Optech ALTM 3100 laser system and integrated 3-band digital camera, CVI is capable of producing the most accurate and highest resolution elevation data possible. LiDAR is an optical remote sensing technology that measures properties of scattered light to find range and additional information of the earth’s surface and other features. LiDAR is also extremely valuable in the detection of jurisdictional wetlands and other small remote streams. The Army Corps of Engineers’ Wetlands Delineation Manual, cites LiDAR as “one of the most useful information sources available for wetland delineation.”

LiDAR is the source data for extremely accurate up to date surface models. Using this LiDAR data, CVI engenders elevation models that are specifically intended for natural stream design (NSD). Since streams are complex ecosystems with morphological characteristics that are dependent on appropriate geomorphic dimension, pattern, and profile as well as biological and chemical integrity, the proper function of these streams are essential. NSD addresses the entire complex stream system, based on fluvial geomorphology, which is the study of a stream’s interactions with the local climate, geology, topography, vegetation, and land use. The underlying concept of NSD is to use a stable natural channel as a blueprint or template. Based on Dave Rosgen’s[2] stream classification system, when morphological changes exceed a ‘geomorphic threshold,’ a stream type may change and there are new quantitative values of dimension, pattern, and profile. The only way to be certain of a stream’s evolutionary phase is to quantitatively evaluate the degree to which the stream’s existing conditions differ from its full range of operating potential. CVI chiefly employs this data to simulate flood modeling and visualization of a stream before and after new designs structures are in place. 

LiDAR can also be very beneficial for wetland (and stream) assessment and design to help identify, and later delineate, poorly drained depressions that may contain jurisdictional wetlands. These jurisdictional wetlands are areas subject to the regulations of the Clean Water Act of 1977 (Section 404); generally concave or low-lying topographic forms that collect, store, or flow water frequently enough to favor a majority of plants that are adapted to saturated soil conditions and are very important in mitigation, and consequently, mitigation banking. The act authorizes the Secretary of the Army, acting through the Chief of Engineers, to issue permits for the discharge of dredged or fill material into the waters of the United States, including wetlands. Heavy fines, and possibly up to a year in jail, can be imposed on unsuspecting landowners or organizations that violate these regulations. LiDAR can ascertain these often covert areas and alleviate frustrations.

Another great benefit of LiDAR is that it can help estimate cut and fill at a restoration site. At a recent mission in Mingo County, West Virginia, Canaan Valley Institute estimated the volume of a mountaintop removal/valley fill operation. By using existing elevation data (pre-mining conditions) versus LiDAR data (post mining conditions), CVI calculated fill to be 91,874,645 cubic yards and the cut to be 4,471,854.90496 cubic yards.  In addition to these volumes, CVI also generated two foot contour lines, which are much more accurate and precise than contour data generated from a public lower-resolution digital elevation model.  

A few other benefits of LiDAR in regards to stream and wetland design are (1) LiDAR cross sections can be generated and used in hydraulic modeling for both channel and floodplain analysis for determining the location and frequency of the flood plain when inundated by out-of-bank flows; (2) when combined with soil and water level data, LiDAR can be used to quickly and accurately model current and restored hydrology at a wetland restoration site; and (3) LiDAR can be used to help calculate a water budget by assisting in watershed and overland flow path delineations.

For additional information regarding the benefits of LiDAR with respect to stream or wetland delineation and restoration, mitigation banking, or natural stream design, please contact:

Adam Riley

Canaan Valley Institute

240 Scott Avenue, Suite 4

Morgantown, WV  26508

USA

Telephone: 1.888.291.5320

Email: Adam.Riley@canaanvi.org