Using LiDAR to reconstruct the history of a coastal environment influenced by legacy mining Foad Yousef a , W. Charles Kerfoot a, ⁎, Colin N. Brooks b , Robert Shuchman b, c , Bruce Sabol d , Mark Graves d a Lake Superior Ecosystems Research Center and Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931, USA b Michigan Tech Research Institute, Michigan Technological University, Ann Arbor, MI, 48105, USA c Department of Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, MI 49931, USA d U.S. Army Engineer Research and Development Center (ERDC-Environmental Laboratory), Vicksburg, MS 39180, USA abstract article info Article history: Received 20 December 2011 Accepted 21 December 2012 Available online xxxx Communicated by George Leshkevich Keywords: Remote sensing LiDAR Coastal erosion Tailings pile Nipissing dunes Lake Superior LiDAR (light detection and ranging) data can be used to create fine digital elevation and bathymetric models (DEMs). Here we examine natural coastal erosion in Grand Traverse Bay, Michigan, a part of Keweenaw Bay in Lake Superior, and discuss how a variety of geological features (submersed river bed and channels associated with the Houghton Low; Nipissing dunes) interact with long-term sediment accumulation patterns. The geological features also modify migrating tailings from a legacy mining site. The combination of LiDAR derived images and aerial photographs allowed us to reconstruct the historical movement of tailings along the coastline. A total of 22.8 million metric tonnes (Mt) of stamp sand were discharged into the coastal environment off Gay, MI. Over a span of 80 years, beaches to the southwest of Gay have progressively received 7.0 Mt (30.7%) of the mass eroded from the original pile, whereas 11.1 Mt (48.7%) have moved into the bay. The total amount accumulated along the beaches now greatly exceeds the mass remaining on the original tailings pile (3.7 Mt; 16.2%). Bathymetric dif- ferences between two LiDAR surveys (2008 and 2010) were also used to estimate the mass, and to track the move- ment of migrating underwater stamp sand bars. These bars are moving southwesterly towards Buffalo Reef, creating a threat to the lake trout and lake whitefish breeding ground. © 2013 Published by Elsevier B.V. on behalf of International Association for Great Lakes Research Introduction Airborne LiDAR bathymetry (ALB) or airborne light detection and ranging (LiDAR) is a remote sensing technique for measuring water depths with an airborne scanning pulsed laser beam (Guenther, 1985). The technique is well suited to nearshore mapping in clear water because it provides the three-dimensional data needed to create a digital terrain model with a ± 10–50 centimeter (cm) vertical accuracy for topographic and bathymetric mapping (Irish et al., 2000). Compared with passive remote sensing systems (e.g. aerial photos, Landsat), which are quite lim- ited with respect to the depth to which they can measure, active LiDAR technology can penetrate up to three times Secchi depth, i.e. considerably beyond passive light penetration. Modern LiDAR systems reach up to a maximum of 50 meters (m) in very clear, marine water, and between 20 and 35 m in clear coastal waters (Guenther et al., 2000). Commercial topographic LiDAR systems operate at a pulse repetition frequency of at least 20,000 Hz and a footprint diameter of 15–20 cm. A topographic LiDAR operating in the infrared (IR) band can image the water sur- face, but cannot penetrate it. An ALB system, however, operates at a lower pulse-repetition frequency than the topographic LiDAR [up to 3000 hertz (Hz)], with a footprint diameter of 2 m (Table 1). In the CHARTS ALB system used here (Table 1), the LiDAR sensor records the time difference between two signals (an infrared wavelength that reflects off the lake surface, and a green water-penetrating wavelength that returns from the bottom sediments) to derive measurements of water depth. As opposed to SHOALS (Scanning Hydrographic Opera- tional Airborne LiDAR Survey), CHARTS (Compact Hydrographic Air- borne Rapid Total Survey), and LADS (Laser Airborne Depth Sounder) sensors, the newer USGS EAARL (Experimental Advanced Airborne Re- search LiDAR) and CZMIL (Coastal Zone Mapping and Imaging LiDAR) bathymetric LiDARs do not utilize an infrared band. During coastal surveys using CHARTS, the aircraft travels over water at about 60 m per second, pulsing two varying laser beams towards the earth through an opening in the plane's fuselage. The first wavelength (green) is intended for lakebed detection because of its water penetration ability, whereas the second wavelength (infrared) allows sensing of the water surface, which behaves as a near opaque surface at this wavelength (Fig. 1). The LiDAR sensor records the time difference between the two signals to derive measurements of water depth. Today, airborne LiDAR bathymetry and topographic LiDAR are used as standard tools for coastal mapping around the globe. Flood maps, shoreline mapping, monitoring of coastal erosion, and habitat protection are only a few of the applications (Guenther, 2007; Pe'eri and Long, 2011). Marine applications of Journal of Great Lakes Research xxx (2013) xxx–xxx ⁎ Corresponding author. Tel.: +1 906 487 2791. E-mail addresses: fyousef@mtu.edu (F. Yousef), wkerfoot@mtu.edu (W.C. Kerfoot), cnbrooks@mtu.edu (C.N. Brooks), shuchman@mtu.edu (R. Shuchman), Bruce.M.Sabol@usace.army.mil (B. Sabol), Mark.R.Graves@usace.army.mil (M. Graves). JGLR-00550; No. of pages: 12; 4C: 3, 6, 11 0380-1330/$ – see front matter © 2013 Published by Elsevier B.V. on behalf of International Association for Great Lakes Research http://dx.doi.org/10.1016/j.jglr.2013.01.003 Contents lists available at SciVerse ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr Please cite this article as: Yousef, F., et al., Using LiDAR to reconstruct the history of a coastal environment influenced by legacy mining, J Great Lakes Res (2013), http://dx.doi.org/10.1016/j.jglr.2013.01.003