This post is a photo essay documenting the state of a segment of the Don River Bank. In Limnology which is the study of inland waters a river banks is defined as the terrain alongside the bed of a river, creek or stream(Luna et al 1995). The bank is the land on the sides referred to as the channels between which the flow of the water is contained (Luna et al 1995). In ecology river banks garner special interest as they contain riparian habitats/areas . Riparian areas act as the interface between land and the river, the transitional zones between terrestrial and aquatic ecosystems. Riparian areas provide many ecosystem services which include but are not limited to: Gas regulation (Wilson et al. 2005), Water Regulation (Williams 1986), Soil Conversion (Waters 1995), Soil Retention (Castelle et al.1984), act as a Nursery for aquatic and amphibian ecosystem (Semlitsch 1998) and breakdown and removal of waste (Semlitsch 1998).
This photo-essay documents the current conditions of a 100 m segment of the Don River Bank located on York University’s Glendon Campus. My partner Michael and I documented segment 2 of the river bank which is stretch of the river bank right before the segment of the river bank documented by Nick and Mohammad and right after the segment documented by Liron and Gaby. Our observation focus strictly on the right bank of our segment because we were unable to get to the other side of the river to take pictures of the left bank.
Our stretch of the riverbank began at a bridge. As you can see from the photo below this small beginning portion of the right bank of our segment presents clear evidence of Riverbank failure, particularly slumping seen by the bank toppling into the stream. Riverbank failure occurs when the forces acting on the bank exceeds the forces which hold the sediment together. All river banks experience erosion, but riverbank where failure occurs when there is too much erosion. Slumping specifically occurs when erosion causes “a block of earth moves downward along a curved failure plane, commonly with a backward rotation to the slump blocks” (Minnesota Survey).
Moving a little further along our segment, as seen in the pictures below there is not as much erosion as the beginning portion of our segment. But as you can see there is a lack of vegetation, there just a few patches here and there. If you compare this with the below picture of what a healthy level of vegetation should look like, you can see the huge difference. Vegetation in river banks, i.e. riparian vegetation is essential as it shades water, mitigating temperature, it provide forage for wildlife and it transfer nutrients from the terrestrial vegetation (i.e. plant litter and insect droppings) to the aquatic food web, as well as the other ecosystem .
Moving further along our segment we find a drainage pipe. The origin of this drainage pipe, and what it is adding to the stream is unknown (my partner said he smelt a stench!!,so its probably is nothing good). Although we don’t know what is coming of the pipe it should be noted that outflow from sewage treatment plants and wastewater from industrial facilities causes water pollution which destroy aquatic ecosystems. So if the runoff is either of those things it is not good for stream.
As we move further along our segment we find more evidence of slumping. It is not as pronounced as in the beginning of our segment but it definitely noticeable. Moreover there is a lack of vegetation.
A little further along our segment we find a example of riverbank stabilization. The technique used here appear to be “Riprap.” In riprap rocks are arranged in such a way it inhibits the erosion process along a riverbank (Cass County Government).
As we move further down our segment we come across an area that is stabilized and one that it not. From the picture below you can see how riprap technique protects the riverbank from erosion, as you see the large extent of slumping that occurred in the not stabilized section of the riverbank.
As we come to the end of our segment there was evidence of lots of slumping. In addition in this regions there is are many tree with their roots exposed, and some where parts of their roots were completely out of the soil. Exposed tree roots have been positively correlated with riverbank erosion (Stotts et al 2014). This meaning the more exposed tree roots are on the riverbank the more riverbank erosion has occurred at that region. Thus these exposed tree roots are a sign of riverbank, especially the one where part of the roots are completely exposed.
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Cass County Government Riverbank Slumping. Retrieved December 6th 2016.
Stotts S, Oneal M, Pizzuto J, Hupp C. 2014. Exposed tree root analysis as a dendrogeomorphic approach to estimating bank retreat at the South River, Virginia. Geomorphology. 224:10-18.