APPLIED TERRESTRIAL PHOTOGRAMMETRY OF SOIL SLUMPS ON ASHMUN CREEK, SAULT SAINTE MARIE, MI

The purpose of this study is to monitor and quantify soil slumps along a 1.3 km long tributary of Ashmun Creek in Sault Sainte Marie, Michigan using close range terrestrial photogrammetry. Ashmun Creek is part of the largest sub-watershed in Sault Ste. Marie (approx. 2,558 acres) and its core cuts directly through the business spur of town. Being that the creek runs through one of the oldest towns in the United States it has experienced significant impacts from human development and land use changes. The tributary is on city property and runs nearly parallel to Sanderson Field Municipal Airport. Like most of Ashmun Creek this section is turbid most of the year, flowing over mainly clay soils. Since these clays are generally impervious, surface runoff reaches the creek quickly and takes with it suspended clay particles. These fine suspended particles can have very adverse affects downstream from damaging aquatic river habitat for invertebrates and fish, to traveling great lengths and backing up both wetlands in Ashmun Bay and the Soo Locks. Close range terrestrial photogrammetry, is well documented for its spatial resolution and noninvasive approach. Conducted (land based) topographic surveys created a georeferenced datum and act as a control on volume estimation for photogramic analysis. Access to survey equipment also allowed for the addition of four targeted measured cross channel profiles to assist with slump volume estimations. Preliminary site investigations suggest that the stream is very flashy. A review of historical seasonal imagery suggests that there may be a connection between snow removal practices from the neighboring airport and the observed slumping. Preliminary results show a connection between increased runoff and slumping along the stream. Concurrently, snow melt and heavy rain continue to be the most likely source of slumping along the creek. This evidence suggests the the need for ongoing monitoring and potential remediation.