Pere Marquette Oxbow Lake
The Pere Marquette Oxbow is one of the most famous Oxbows in the United States of America. It forms an Oxbow curve on the same river, near Ludington in Michigan City. “Pere Marquette River is located in the Manistee National Forest that is surrounded by streams and forests” (Bharatdwaj 255). This region is 1.5 miles from the national celebrated Pere Marquette River. The Pere Marquette Oxbow has long been an important component of the national geography. Tourist prefers spending their holidays in this zone since it is characterized with many features resulting from the river actions. Moreover, families’ schedule of events makes this region a lovely place for spending time and getting away to have fun in the cool environment.
The Geographical location of Pere Marquette Oxbow Lake. Retrieved from; https://www.google.com/search?q=The+Pere+Marquette+River+makes+an+oxbow+curve+near+Ludington,+Michigan+%28map+on+location%29&biw=1366&bih=625&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMI9ITvyaOExwIV6hTbCh2P7Q2j#imgrc=lz-eHGe5c0Mc2M%3A
The formation of Pere Marquette Oxbow starts with meandering of the mother river. The meanders begin by creating two sets of curves: one curves outwards the linear path of the river alignment while the other set moves backwards along the river alignment. “Subsequently, the thalweg oscillates transversely and initiates the formation of the bends (Bharatdwaj 276). Thalwegs may change continuously especially if the current is not distributed uniformly through the cross-section but rather deflected from one bank to the other.
The Pere Marquette River meandering to form an oxbow lake. Retrieved from; http://www.gettyimages.com.au/detail/photo/meandering-river-and-oxbow-lake-michigan-high-res-stock-photography/108437075
According to Whitney and Anne Rudloe (2004), sloughing of the banks of Pere Marquette River occurs due to non-uniform deposition of the bed loads by debris. At the area of the currents on the river banks, erosion occurs and might be deflected away thus impinging upon the opposite bank further downstream. Behind the river’s levees, and protected by them for most of the years, are the bottomland hardwood forests. Here, tremendous trees stand on massive root systems in the muddy earth. Some trees have toppled over, forming deep holes on the mud.
Manisteee National Forest is one of America’s most towering forest; getting waters from Pere Marquette Oxbow. Many of the tree species grow taller, faster, in river bottomland than anywhere else. The alternation of floods and retreat of the flood of flood waters speeds up the decay and release of nutrients on the forest floor. Continued flooding of Pere Marquette Oxbow lakes deprives the decomposer organisms of oxygen, and so inhibits decays. However, alternating wet and dry conditions give decomposers both the water and oxygen they require to carry out their activities. Alternatively, soil moisture held in place between floods by leaf mulch feeds needed water to growing trees throughout dry times.
Origin of Oxbows
“Oxbow lakes start to form when the lowland rivers start changing the course, following the path of least resistance” (Whitney and Anne Rudloe 352). As the river meanders, it erodes the shore of its outside bends, and loops of water are severed from the mainstream. The ends of the loops finally succumb to the sediments deposited by the parent stream, and the crescent-shaped lake is left behind. The name “Oxbow lakes” is coined from the ‘U’ shape taken by these lakes.
In general, the bends along the river channels are created by the process of erosion and deposition. Erosion without deposition to assist in bend formation would result only in escalloped banks. If this happens, channels will broaden to an extent that the erosion would come to an end. The materials eroded from the bank are normally deposited over a time on the point bars that are formed downstream. “The point bars constricts the bend and enables erosion in the bend to continue, accounting for the lateral and longitudinal migration of the meandering stream” (Whitney and Anne Rudloe 388). Different researches have confirmed that erosion is usually extreme at the point bar of the river channels. “As the point build out from the downstream sides of the points, the bends gradually migrate down the valley” (Bharatdwaj 350).
Oxbow lakes have enormous differences from man-made lakes, with each having unique characteristics from the other. For instance, when an Oxbow is cut off from the river, its nature immediately begins changing. Sediments transported from seasonal flooding builds up, and the old meander scar becomes shallower and relatively flat bottomed. Water-tolerant plants like cypress, tupelo, buckbrush and willow start growing along the lake edges. Occasionally, shallow Oxbows start drying up during the drought seasons, hence allowing plants to gain a foothold and encroach still father in the lake.
All the above natural processes, from cutting off of a new Oxbow to the building of bottom sediment to the gradual expansion of woody vegetation farther and farther from the bank, are stages in the death of an Oxbow lake. This process may take around 500 years or more, but left undisturbed, all Oxbows finally silting in and turning into a wetland forest. At this stage, fantastic grounds for catching fish are developed since Oxbow lakes are linked to the main river. When the river floods the Oxbow, inflowing nutrients enrich the water and help sustain the thriving communities of the forage animals on which catfish feed. According to Bharatdwaj (2006) annual cycle of spring flooding that progressively suffocates these lakes with the silt also makes then the outstanding fishery grounds. This yearly overflow cycle also provides temporary, but important, spawning habitat for Oxbow cats and often replenishes the lakes with fish and baitfish from the river.
Bharatdwaj, K. Physical Geography (hydrosphere). New Delhi: Discovery Publishing House, 2006. Print.
Whitney, Eleanor N, D B. Means, and Anne Rudloe. Priceless Florida: Natural Ecosystems and Native Species. Sarasota, FL: Pineapple Press, 2004. Print.