From raging rapids to small gurgling streams, rivers carry one of the essential resources of life; you guessed it – water. Rivers are not only important to humans but from the smallest of insects to the biggest of land mammals.
Importance of Rivers
Rivers are significant to humans as they supply a range of uses about domestic, industrial, agriculture and recreation. Some examples of this include drinking, irrigation, washing and cleaning, aquaculture, power generation, fishing and boating.
There are two main ecological functions.
1. The first is drainage of different areas particularly catchment areas.
2. Supports ecosystems both within the river and where it flows, transporting nutrients and freshwater. They are connected to the ocean and thus a vital link in the water cycle.
The Structure of Rivers
As water flows away from its origin, it drains in a direction determined by the lay of the land as well as the bedrock formation that are underneath. There are three sections within a river, namely upper, middle and lower reaches. Some river organisms rely on natural plant and animal matter from outside of the river and inside of it. They are found in different sections of the river:
Upper Reaches – fast-moving water, small fish species, (insect types – shredders and collectors with minimal grazers and predators) no industry.
The middle reaches – medium pace water speed, large fish species, (insect types – grazers and collectors with minimal shedders and predators) significant industry inputs and some recreation.
Lower reaches – slow water speed, small to medium-sized fish, (insect types – collectors and predators) light industry, some recreation.
Many threats affect rivers. Different risks affect different aspects of the river such as increased sedimentation, dams, climate change, abstraction, water transfers and alien vegetation all affect river volume. Whereas pollution such as oil and sewage spills, mining, litter, discharge of chemical such as zinc, lead, mercury, pesticides and fertilisers and pharmaceutical products all affect the quality of water.
There is only a limited amount of the world’s rivers free-flowing. Almost all have been dammed repeatedly, channelised or somehow altered. Damming rivers prevents nutrient flow, seasonal fluctuations as well as cuts off areas for fish to breed or migrate.
The Madeira River, one of the Amazon’s major tributaries, is at the attention of intense hydroelectric dam development, part of an immense wave of infrastructure construction occurring across the Amazon basin. As presently planned, the Madeira Hydroelectric Complex, situated in the Brazilian state of Rondônia, will consist of four dams and a manoeuvrable industrial waterway built along the river’s course, with severe consequences for the exceptionally biodiverse freshwater and forest ecosystem, as well as for indigenous people and traditional river communities. A new study, which examined two of the complex’s already completed mega-dams, the Santo Antônio and Jirau dams, has found that the area flooded as an outcome of their construction was significantly higher than predicted by the Environmental Impact Assessment (EIA) carried out before the dams’ licenses being approved. By 2015, the combined reservoirs measured 870 square kilometers (336 square miles), which is 341 square kilometers (132 square miles) more than the EIA projected. What’s more, the EIA only expected impacts in Brazil, but flooding also occurred over the border in Bolivia. When this is taken into account, the total flooded area upstream of the dams increases to 898 square kilometers (347 square miles); an area 69.8 per cent larger than anticipated by the EIA.
The majority (78 per cent) of land that is now underwater was previously undamaged forest, and the area of natural forest that was lost (468 square kilometers; 181 square miles) exceeded EIA predictions by 52 per cent (160 square kilometers; 62 square miles). What does that mean for the wider ecosystem? Cochrane sees two especially essential consequences: the disruption of sediment flow from the Andes into the lower Amazon basin, and the constant inundation of the floodplain varzea ecosystem — a floodplain forest seasonally inundated by whitewater rivers that occurs in the Amazon biome.
Plastic waste production across the globe has reached approximately 6,300million metric tons, most (79%) of which have been disposed of to landfills and more widely into the surrounding environment.The annual flow of plastic pollution to the world’s oceans is estimated to be 4.8 – 12.7 Metric tons, a large proportion of which comes from sources on land and is transported by rivers or wind.
Rivers contain and give so much life on earth, as well as being essential for draining the water back into the ocean. They are a source of freshwater for humans and wildlife. There might be many threats facing our rivers globally, but a lot is being done to clean up our river. Just the other day I saw a whole group of people on the banks of a river in Cape Town picking litter off the banks and out of the river. The Thames river which flows through the city of London used to be one of the most polluted rivers in the UK due to its citizens dumping almost everything you can think of into the river, and it became virtually devoid of life entirely. Now, after some intensive restoration and laws put into place, it has become a much cleaner river with even dolphins being seen in it and seals reproducing in it. It can be seen through this that degraded ecosystems can be restored. Here are some other reasons why we need to care for our environment https://conservationcaptured.com/2018/06/02/nature-why-should-we-care/
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The National Inventory of Dames