Rivers and groundwater
jan. 29th, 2015
How does a river begin?
Rivers begin in mountain valleys. Water at the top of the hill or mountain will take the most direct route downwards. As the water continuously flows, the soil beneath it becomes soggy and waterlogged. At this time, the soil will no longer be able to absorb any more water, so it will seep out onto its surface. This is the beginning of a stream that with time will evolve into a river. All water in the same drainage basin will eventually flow in the same pattern and ultimately, will end up in the same stream or river.
Why do river shapes vary in wet and dry climates?
River shapes change in various climates due to different erosion patterns. In dry, arid regions, the river valleys are often deep and/or steep. This is due to little erosion on the valley walls as the flowing water will erode the floor continuously, digging the valley deeper but not wider. Eventually, a deep canyon or gorge will take shape. In areas of high precipitation, heavy rain erodes the valley walls and the sediment is transported downstream. The river valley then widens but differs in depth compared to dry climates.
Formation and key features of 4 stages of river development: Youth stage:
A young river is shaped as a deep V-shaped valley. It moves quickly, and transports material further downstream. The rapid moving water and high erosion rate doesn’t allow deposition to occur. Features created by youth rivers include rapids, waterfalls, and various rock formations or boulders along the river bed.
As a river matures; the key features and characteristics further develop. Vertical erosion continues and lateral erosion begins to take place. These changes are clearly evident in characteristics such as meanders or flood plains. The speed of the river begins to slow down in this stage allowing deposition to occur.
Old age stage:
During old age flood plains widen and extensive...
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