Mad River Watch volunteers conducted their final field visits of the summer on August 18 and 19, checking their regular sites to observe to collect data and make environmental observations.
WHAT IS FLUVIAL GEOMORPHOLOGY?
“Technical terms like fluvial geomorphology that are commonplace within the scientific community are not always meaningful to the public at large,” said Friends of the Mad River director Ira Shadis.
“Programs like Mad River Watch help bring these complex ideas back down to earth by giving volunteers a chance to see the river and its processes in action,” he added.
The term “fluvial geomorphology” refers to the way moving water interacts with the material in and around it. Fluvial is the word that points to the river. The “geo” prefix points to the geological context the river is situated within. In the case of the Mad River, the geological conditions are drawn from a complicated history of multiple mountain-forming events, inland seas and lakes, and scouring of glaciers during the last ice age. The result is a mixture of many different soils in a mosaic across The Valley, from sandy benches to bedrock outcrops. The “morphology” part of the word asks how the river and the geology interact and form the particular features, like the step-pools at Warren Falls or the meanders in flats south of Moretown, that exist along the Mad River.
“The study of fluvial geomorphology also considers the way life, including humans, interact with and change the system. The whole field of study is a great reminder that the river is so much more than just the water flowing along the valley bottom,” said Shadis.
RIVERS IN ACTION
“There are a lot of elements at play in what the river is telling our volunteers during their site visits,” Shadis noted. “The volume and flow of water, the supply and size of sediment, the channel of the river or its access to a flood plain, the slope, and the presence of logs, boulders, and beaver dams can all play a part in shaping the evolution of the river.”
Mad River Watch volunteers observe the forming and reforming of the Mad River and its tributaries in a few different ways. They monitor the flow of the water to determine if it is base flow (normal river conditions) or freshet (after a recent rainfall). Identifying the difference can help them understand if any observed turbidity (amount of sediment suspended in the water) is coming from stormwater runoff or from something like an eroding bank upstream. The volunteers also directly observe erosion and sedimentation at their field sites, documenting changing bank cuts and gravel bars through photographs and notes in their journals.
STREAM GEOMORPHIC ASSESSMENTS
In addition to the work of the Mad River Watch volunteers, Friends of the Mad River has partnered with river scientists to bring more data to the community. In 2006-08, and again in 2018, stream geomorphic assessments were completed that provided information about individual “reaches” of the waterway.
“The assessments and the river corridor plans that followed provided a scientific analysis of the history of the river, the areas prone to erosion or flooding now, and the opportunities for restoration,” explained Shadis. “Some of our Mad River Watch sites are also restoration project sites. It’s great to look back at the descriptions of these sites in the 2008 assessments and then to review our volunteer’s observations and data. At sites like the Austin Parcel in Waitsfield we can see the development of a healthy flood plain forest and woody material building up in the Mill Brook, two restoration strategies called out in the assessments.”
This article is part of an ongoing series that shares highlights from this field work as well as lessons learned from this year and the past 40 years of Friends of the Mad River’s Mad River Watch program.
