TECHNICAL NOTES ABOUT USING IKONOS IMAGERY TO MONITOR AND MAP COASTAL LANDSCAPE CHANGE ALONG THE GREAT LAKES

Frequent monitoring of coastal erosion and dune behavior is essential to identify precisely causes and effects associated with these phenomena. Coastal zone morphology has traditionally been monitored and mapped using field survey and/or photogrammetric methods. Important information can be acquired from data gathered via these methods, although some intrinsic problems exist. Specifically, these methods are time and labor intensive, and subsequently, have constraining implications for the spatial extents or temporal frequencies used to sample a landscape of interest. Because many coastal changes are event-driven (e.g., storm winds and surges), an exogenously constrained sampling scheme may not capture even-driven changes nor match the operational scales of acting coastal phenomena.

This paper reports results achieved during an effort to establish a high-resolution monitoring protocol for Michigan's coastal zone. IKONOS imagery was acquired during spring and late summer seasons for three sites along Lake Michigan and one site along Lake Huron. Ground surveys were conducted to assess the positional accuracy associated with georeferencing information sold with image data; results suggest positional accuracies fall well within the advertised range of error. Images were interpreted and classified to generate temporal snapshots of land cover and water boundary positions; the methods used were sensitive to small changes in vegetation senescence and extents, and water boundary positions. Budgets were constructed to compare costs associated with the high-resolution protocol to costs associated with softcopy photogrammetric methods required to map the same spatial extents with the same temporal frequencies; IKONOS imagery can be a cost effective option for coastal monitoring purposes. Because Michigan's coastal zone is adjacent to four of the five Great Lakes, results reported here may be useful to others working in the Great Lakes Basin or along other coastal zones.