What is the average length of a river

Others are marshy areas fed by mountain snow. What happens in the headwaters is very important to the health of the whole river, because anything that happens upstream affects everything downstream. The shape of a river channel depends on how much water has been flowing in it for how long, over what kinds of soil or rock, and through what vegetation.

There are many different kinds of river channels — some are wide and constantly changing, some crisscross like a braid, and others stay in one main channel between steep banks. Each kind of river channel has unique benefits to the environment. In the West, these riverside areas provide habitat for more bird species than all other vegetation combined.

These areas also provide valuable services like protection from erosion during floods , and filtering polluted run-off from cities and farms. Floodplains are low, flat areas next to rivers, lakes and coastal waters that periodically flood when the water is high. The animals and plants that live in a floodplain often need floods to survive and reproduce. Healthy floodplains benefit communities by absorbing floodwaters that would otherwise rush downstream, threatening people and property.

The end of a river is its mouth, or delta. Usually this happens when the river meets an ocean, lake, or wetland. As the river slows and spreads out, it can no longer transport all of the sand and sediment it has picked up along its journey from the headwaters. Wetlands are lands that are soaked with water from nearby lakes, rivers, oceans, or underground springs. Some wetlands stay soggy all year, while others dry out. Although wetlands are best known for providing habitat to a wide variety of plants and animals, they also help protect our communities by acting as natural sponges, storing and slowly releasing floodwaters.

A single acre of wetland, saturated to a depth of one foot, will retain , gallons of water — enough to flood thirteen average-sized homes thigh-deep. Wetlands also help provide clean water by naturally filtering out pollution. First, there is the amount of water that flows in the river. In the video you may notice that I was hesitant to state that the average sinuosity was truly pi in the real world. Viewer Laurence Roberts got in touch and suggested he build a website to crowdsource the data.

It is then an easy task to calculate the sinuosity of these rivers. Some rivers are relatively straight, such as the Sacramento river in California, which is miles long but with a sinuosity of 1.

On the other hand, the river Liffey is only 75 miles long yet its sinuosity is a staggering 5. The close distribution of the data is more evidence that the average sinuosity of rivers is around 1. Should I be disappointed? The argument that a river is really just a number of arcs, and the idea that this is somehow fractal in nature, in that it repeats on a smaller scale, still feels sound.

Bends in rivers are caused by erosion. As the water moves faster on the outside of a bend more erosion occurs, while soil deposits on the inside of a bend. This causes bends in rivers to become increasing more wild, increasing its sinuosity — until the bend becomes so extreme that the water can take a shortcut, cutting of the bend and forming an oxbow lake. The formation of an oxbow lake results in that section of the river suddenly becoming straight, lowering sinuosity.

Over time this results in rivers behaving chaotically, with the value of sinuosity oscillating between high and low values. If the true value of average river sinuosity is smaller than pi, maybe we need to consider another mathematical constant? Like the golden ratio, aka phi, which is also found in the fractal behaviour of nature. Its value is 1. Coincidence, or something more?