The Charles River Alliance of Boaters and MIT Sea Grant Chart the Charles River

MIT Sea Grant is using low cost, commercially available, fish finding equipment mounted on both autonomous surface vehicles and volunteer driven boats to chart parts of the Charles River that haven’t been mapped for decades. Sediment deposition has been a long standing problem in the Charles River. It was highlighted in an article published in the Boston Globe in 2011 and seems to be a larger problem where major tributaries empty into the Charles: Laundry Brook, Hyde Brook, Faneuil Brook, Muddy River and Stony Brook. Once the sediment is in the river, it can spread to other areas, causing further problems especially in the upper stretch of the Lower Charles where the water depth is already shallow. While this seems to be a bigger concern for users of the upper stretches of the river, several years ago a significant bar up-river of the Massachusetts Avenue Bridge was shallow enough and large enough to be a navigation hazard to both sailboats and motorboats. There are also the extraordinary events such as the water main breaks in Weston in May 2010 and near the Anderson Bridge in August 2015, both of which caused large amounts of sediment to be moved. In trying to remedy the sediment issues, it has been difficult to motivate various government agencies since the river is not used for commercial navigation and much of the knowledge about the shallows and bars has been anecdotal, coming from the daily experiences of the boaters on the river but not backed up by quantitative data.To assist in resolving the problem of sediment deposition, the Charles River Alliance of Boaters (CRAB) has developed a partnership with the MIT Sea Grant College Program to create a chart of the river depth between Science Park and the Watertown Dam, and to monitor changes in the river bottom in the future. While this work is in the early stages, the MIT Sea Grant has already mapped portions of the sailing basin and the Muddy River delta. Moreover, the MIT Sea Grant has done a lower resolution survey of the river from the Massachusetts Avenue Bridge to the Newton Yacht Club. This is a great start to this new partnership and we’re very thankful for MIT’s contribution to the users of the river. This survey is probably the first time such a measurement has been done of the upper reaches of the Lower Charles since 1902, although more recent surveys have been done of select areas below the BU Bridge.The data measured by the MIT Sea Grant College is preliminary and should be taken as such and not used for navigational purposes. The goal in this project is to survey the depth of the Charles and to identify areas which may be a hazard to safe boating and areas which may need further monitoring and remediation. Initial Steps:The MIT Sea Grant is conducting measurements in the lower basin to refine how best to do the measurements. They are using both human-driven boats and an autonomous robotic 16-foot catamaran, outfitted with instrumentation to measure and record data along a pre-programmed course. If you see this autonomous vessel, or smaller autonomous kayaks used by another group at MIT, please give it a wide berth with minimal wake. The nice thing about the autonomous vessels is that they move in straight well-defined lines without becoming bored or tired for hours at a time, gathering data the whole time. the MIT Sea Grant College is also exploring software options to deliver the data to the users via Google Earth, Google Maps, printable PDFs, and uploads to common navigation instruments.Spring 2016:While the MIT Sea Grant will continue to make measurements, CRAB can contribute to the project by taking measurements above the Mass Ave Bridge, especially above the BU Bridge, as you travel up and down the river doing your normal activities. The concept here is to have a few fish-finders that can be simply and temporarily installed on boats, record data while they are traveling along the river, and then upload the data to a central repository so it can be shared with everyone. By collecting data in finer detail, we will be able to better determine any changes in the bathymetry of the river bottom. If everyone pitches in their little bit, we can have the entire river mapped out in fine detail in short order. If you are interested in participating, please contact zimba.carl@gmail.com for more information.This article adapted from the originally published article on https://www.charlesriverallianceofboaters.org by Dave Amicangiolo.