In geography, fluvial processes are associated with rivers and the features formed by them. The fluvial processes are called glaciofluvial when the rivers are associated with glaciers. The fluvial processes involved in the formation of river habitat features include erosion, deposition, and the effect of moving sediments on the river bed (NPS, 2019). Erosion normally happens in two ways. First, the water movement across the river bed exerts shear stress on the bed. If the pressure exerted on the bed is higher than the bed resistance, the river bed will be eroded through the abrasion process while the abrasion tools become eroded themselves through attrition (Alabyan & Chalov, 1997). Some features formed include valleys, plunge pools, and gullies, among others. Glaciers are also involved in the process of river erosion. The glaciers themselves may act like the abrasion tools or materials embedded on the glacier can erode the river bed forming features like hanging valleys, cirques, and arêtes. River features are also formed through deposition. The river carries materials from its source or from along its course. The sediments are often transported as bedload, suspended load, or solution form (Sediment Transport, 2008). Every sediment transported by the river has a certain velocity (entrainment velocity). The velocity increases depending on the topography of the river; the speed is high at the youthful stage but slow at the old stage. At the old stages of the river, where the entrainment velocity is low, most materials are deposited, forming features, like floodplains. During the cold seasons, the water turns to ice and continues the feature formation in rivers. The glacier obtains more load at the youthful stage, but the embedded materials are dropped during the old stage. Features formed during his process include eskers, moraines, and outwash plains, among others. A microclimate is a climate of a restricted area that differs from the climate of other surrounding regions. Rivers, as water bodies, play a huge role in the creation of a microclimate. Rivers are open water sources that facilitate the exchange of heat and moisture with the atmosphere. This exchange influences the radiation, wind patterns, humidity, and other meteorological parameters around the river region. Therefore, rivers influence not only the temperature of the region but also other elements that are part of the thermal environment (Fischereit & Schlunzen, 2017). Rivers often act like heat sinks, where the heat in the atmosphere is absorbed due to the high specific heat capacity of water. When the atmosphere is cold, the river releases the heat stored and, therefore, acts as a heat source. The high temperature in the river region increases the atmospheric pressure due to the difference in air density. In addition, the regions around the river have more humidity due to evaporation from the river. When the relative humidity reaches 100%, clouds are formed, resulting in the formation of rain. The disparity in atmospheric pressure helps in the creation of clouds. Air rises from the lower altitude near the river and rises to higher altitudes where the pressure is low, which leads to condensation and the formation of clouds and rain. All these factors combined help to create a microclimate around the river, where the temperature, humidity, atmospheric pressure, and rainfall are higher than in other surrounding regions. Rivers provide a habitat for many organisms and species. This ranges from animals, both vertebrates and invertebrates, and plants of all kinds. The river bed may be rocky, soft, lush, murky, or slow, but all these environments provide an ideal habitat for different species and life stages. Rivers have three habitats: the riverbank, river bed, and floodplain (NOAA Fisheries, 2019). The river bed is the channel of the water and provides a habitat for water-loving animals, like fish and trees. The floodplains also act as another habitat for plants, animals, and organisms. In river beds, organisms found include freshwater fish, such as perch and catfish; migratory fish, like salmon, trout, and alewife; plants, such as algae, mosses, cattails, bulrushes, and flowering rush; other organisms include mayfly, stonefly crayfish, worms, crocodiles, and crustaceans. In river banks, organisms found include worms, snails, fishing birds, dragonflies, algae, moss, and mangrove, among other organisms. Floodplains offer wildlife diversity. The damp soil creates breeding grounds for amphibians and insects (UNH, 2018). Life found in floodplains include frogs, minks, raccoons, smooth green snakes, wood turtles, snails, algae, moss, papyrus, reeds, cattails, white alder, and willow among others. According to Trayler (2000), the distribution of life in different river habitats is random and is influenced by some biological and physical factors. The first is the presence of water. Life in rivers depend on the amount of water throughout the year; some species, such as crocodile and fish require plenty of water throughout the year. The second is flow conditions; some animals and plants survive in environments where water flows at a slow speed while others survive where the speed is high. Animals like crocodiles survive in regions where the flow speed is low. The third is the presence of other animals; the survival of organisms is dependent on the food chain; animals and organisms depend on each other for food; hence the distribution is determined by the availability of food. The existence of organisms in rivers depends on the microclimate and the landforms. Microclimate promotes the existence of certain species of plants and animals. It creates an entirely different climate, which differs from the climate of the surrounding (American Rivers, 2019). Often, this climate encourages the survival of species that cannot survive in the adjacent regions. The temperature, humidity, and atmospheric pressure affect the biodiversity surviving in a region. Also, the landforms in a region affect the biodiversity in the region (International Rivers, 2011). In rivers, there are different landforms ranging from gorges to flood plains. Species that survive in gorges and valleys where the river velocity is high differ from species surviving in floodplains. This is due to the water speed, breeding methods, and availability of food (Edwards & Laize, 2017). For example, animals like crocodiles exist in areas where the flow speed is low since these regions offer good hunting grounds, breeding areas, and comfort for the animals while migratory animals like salmon can survive in gorges and waterfalls where the river flows at high speed. Human activities have greatly affected the river ecosystems. The relationship that exists between organisms and the environment is very complex, and human activities have diverse effects on the river ecosystem. According to Science Learn (2014), some practices that affect river ecosystems include pollution, modification of flows, harvesting, and introduction of exotic species. Human infrastructure, along with the river, results in pollution. Pollution enters the river in a small but constant amount along the river length. Both rural and urban areas contribute to pollution. Some sources of pollution are deforestation, which causes erosion, agricultural chemicals, like fertilizers, industrial chemicals, and sewage effluents. Pollution affects the pH of water hence affecting biodiversity in the river. Flow modifications alter the temperature and flow of rivers. This affects the aquatic habitat since most depend on the flow as a source of food. Riverside vegetation may also be affected. The temperature change can affect breeding and the animal's life cycle. Also, exotic species introduced in rivers affect the native species by altering their habitats, breeding, and preying on them. They may also introduce diseases and parasites, which reduces the population of the natives (Science Learn, 2014). Finally, harvesting biodiversity in rivers has reduced their population. Excessive fishing has reduced the number of animals in the rivers and the animals that feed on them. Water is an essential element in human living and supplies water for human activities. Preserving quality is, therefore, essential. The composition of water in terms of quality in rivers is impacted by seasonal changes. Numerous factors affect rivers and biodiversity. According to Lenart-Boron et al. (2016), some of them include weather conditions, water levels, seasonal changes, and geological structure. There are different seasons, such as the hot and dry seasons and the cold and wet seasons. The volume of water in rivers depends on the season; during the dry season, the volume is reduced while in rainy seasons, the volume is very high and may result in flooding. During dry seasons, the life in rivers that depends on large water volumes migrate while others die (Xu et al., 2019). Plant species during the dry season may die or shed leaves. According to research, these factors affect the quality of water in terms of chemical composition and biodiversity content.
References
Alabyan, A. M., & Chalov, R. S. (1997). Types of river channel patterns and their natural controls. Earth surface processes and landforms , 467-474. Retrieved from https://onlinelibrary.wiley.com/doi/pdf/10.1002/%28SICI%291096-9837%28199805%2923%3A5%3C467%3A%3AAID-ESP861%3E3.0.CO%3B2-T
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American Rivers . (2019). Retrieved from American Rivers Website: https://www.americanrivers.org/threats-solutions/clean-water/impacts-rivers/
Edwards, F. K., & Laize, C. (2017). Investigating the sensitivity of river wetted habitat to changes in flow: a literature review. Wallingford: Centre for Ecology & Hydrology.
Fischereit, J., & Schlunzen, H. (2017). Impact of rivers and lakes on the thermal microclimate– a human-biometeorological perspective. EMS Annual Meeting Abstracts (p. 362). Hamburg: Meeting Organizer. Retrieved from Meeting Organizer Website: https://meetingorganizer.copernicus.org/EMS2017/EMS2017-362.pdf
International Rivers . (2011, December). Retrieved from International Rivers Website: https://www.internationalrivers.org/rivers-and-biodiversity
Lenart-Boron, A., Wolanin, A., Jelonkiewicz, L., & Zelazny, M. (2016). Factors and Mechanisms Affecting Seasonal Changes in the Prevalence of Microbiological Indicators of Water Quality and Nutrient Concentrations in Waters of the Białka River Catchment, Southern Poland. Water, Air, and Soil Pollution . doi:10.1007/s11270-016-2931-y
NOAA Fisheries . (2019, September 30). Retrieved from Office of Habitat Conservation: https://www.fisheries.noaa.gov/national/habitat-conservation/river-habitat
NPS . (2019, August 6). Retrieved from NPS Website: https://www.nps.gov/subjects/geology/fluvial-landforms.htm
Science Learn . (2014, March 19). Retrieved from Science Learning Hub Website: https://www.sciencelearn.org.nz/resources/440-human-impact-on-rivers
Sediment Transport. (2008). Boston, MA: Springer. doi:https://doi.org/10.1007/978-0-387-68648-6_16
Trayler, K. (2000, January). Water and Rivers Commission. Retrieved from Water and Rivers Commission Website: https://www.water.wa.gov.au/__data/assets/pdf_file/0007/3121/11439.pdf
UNH . (2018, February 2). Retrieved from Extension Website: https://extension.unh.edu/resource/floodplain-forests
Xu, G., Li, P., Lu, K., Tantai, Z., Zhang, J., Ren, Z., . . . Cheng, Y. (2019). Seasonal changes in water quality and its main influencing factors in the Dan River basin. CATENA , 131-140. doi:10.1016/j.catena.2018.10.014
