A Historical Perspective of Erosion and Sedimentation at Curved Sections Along the Mohawk River

摘要

Erosion and sedimentation at curved sections along waterways constitute a major soil stability challenge. The Mohawk River in New York and its two major tributaries (the Schoharie Creek and West Canada Creek) are illustration of how severe this problem could be. The riverbanks are continuously exposed to erosion and sedimentation, which compromise its stability and the infrastructure in its vicinity. This problem is aggravated at times of floods where both the quantity of discharge and flow velocity increase. With the availability of historical images of various sections of the river, one can detect the pattern of erosion and sedimentation over time and see the effect of repeated flooding on the structural stability of the soil in the area. This study was undertaken to identify, along the Mohawk River length, the sections that have been seriously impacted by both erosion and sedimentation problems and to classify these sections according to its level of severity and the need for remediation. In absence of sufficient funds to address all river problems simultaneously, it is necessary to prioritize areas where hazardous conditions exist. The Mohawk River waterway was surveyed and sections where erosion and sedimentation were marked according to their coordinates. The angle and radius of curvature at each section were determined. Depending on aerial survey images of a given section, the damage that the section exhibited was identified, and the level of danger of a structural collapse was assessed. In light of these conditions, various solutions to remedy the hazardous conditions at these sections were suggested. These solutions varied between simple ones such as re-grading the earth slope to make it milder to more comprehensive ones such as the construction of sheet piles walls. This study resulted in an extensive database of numbered sections along the Mohawk River starting from its origin in the west throughout its entire length to where it discharges into the Hudso- River. This database involves coordinates of all identified sections, historical images of the section under consideration at different times and the pattern of instability that the sections experience, and proposed solutions to address hazardous conditions at the locations of these sections. It is anticipated that this database would serve as a helpful tool to researchers, government agencies, and parties interested in making critical decisions regarding maintaining the waterway in good and stable condition.