Why Do Streams Meander? | Top Q&A

Video Why Rivers Meander When you see a stream from the air, from an airplane or a satellite photo, one thing is quick to notice: the flow is meandering. They are sinusoidal in shape, with bent, curved or ring channels. In steep terrain, the channels are straighter, influenced by the slope, and bounded by valleys. On the wide, low-slope plains, streams flow back and forth. Those bends and turns manage the energy of the water, as it moves through and over the canal terrain, by increasing drag and decreasing the slope of the channel. The shape of the curve minimizes the amount of work or energy consumed, while using that energy uniformly. Flows meander to maintain equilibrium – a dynamically stable form and function. Remember that streams are transport machines, transferring water and sediment from basins downhill endlessly. Curves are created when water in a stream channel erodes the sediment of an outer bend of a stream bank and deposits this and other sediments in subsequent interior bends downstream. This process strengthens the rippling pool structure of a stream. As every angler knows, deep pools form on zigzag outside turns, with low-sloping point bars accumulating gravel or gravel on the inside bend. In these pool sections and bends, one side of the canal is significantly deeper. Further downstream, moving away from the bend, the channel becomes straight and the cross-section of the channel becomes more uniform through the flow. Read: why rivers meander and become more repetitive, currents intensify at outer bends. Eventually, the meander may be cut off from the main channel, forming an oxbow lake. Reptiles along the Ausable River West Branch near Lake Placid, along River Road, easily visible on Google satellite view; they show the river’s previous path before the era of Ausable’s logging.Meandering models are common; examples of long straight flows are difficult to find, and even then, the deepest part of the channel – the thalweg canal – will meander within the straight channel. The undulation models follow a remarkably predictable geometry described by the wavelength, curvature, and bank width – the height of the bank at which, at higher currents, water begins to overflow into the flooded area (see picture below). Regardless of the size of the stream, the wavelength is approximately 11 times the channel width and is always between 10 and 14 times the width. The radius of curvature of the central part of the bend of the channel is on average about one-fifth of the wavelength. Channels around the world follow this meandering shape so closely that the shape of a large river resembles the shape of small streams. Without scale, it can be difficult to distinguish an aerial image. Read more: why jeep wranglers are so popular | Top Q&AThe meandering wave pattern occurs in winter when currents cross. Often the ice is the last to freeze, leaving a visible wisp of water. The Atlantic Gulf current also meanders, as shown in the Wikipedia figure below. Luna Leopold, a pioneer in improving the geomorphology and hydrology of the stream, notes that the Gulf Stream phenomenon shows that the meanders are purely hydrodynamic and independent of fixed boundaries. or sediment loads.The rotation reflects the laws of physics. Streams provide a classic case of an open system – allowing mass and energy to flow through and fine-tuning its boundaries. For streams that manage the downflow of water, opposing needs for work reduction and an even distribution of work, or energy, lead to compromise. The form that the compromise takes is winding to achieve a dynamic but relatively stable form. –Read more: Why do crowns fall Understand that meandering streams are essential to living with free flow. Water is necessary for all forms of life, and fresh springs provide us with many resources. Taking care of them helps ensure that fresh water stays fresh for us and for our environment. Ensuring a stream has room to roam reduces conflicts that occur when, for example, roads are on a bend outside or a house is built inside an old arcade. Whenever possible, minimize disturbances to stream meandering needs – keep new growth out of floodplains and away from streams, minimize movement of banks – reduce losses damage to human infrastructure, protect stream health, and maintain water quality. newsletter to receive weekly updates on the latest stories from the Ausable River Association. Top photo: Courtesy of Geology is EasyMiddle image: adapted from KA LemkeRead more: why can’t I connect with people | Top Q&A