Urbanisation

Urbanization within a drainage basin can affect flow to and within a river channel. How far do you agree with this statement? Explain your answer. Urbanization within a drainage basin is one of the factors affecting flow to and within a river channel. Flows within a river channel are affected by a number of physical factors such as permeability of rocks and precipitation of rainfall as well. Flow to and within a river channel refers to the various types of transfer processes of water in the drainage basin hydrological cycle like overland flow, infiltration, percolation , throughflow, baseflow and channel flow. Hence, this essay seeks to compare urbanization and the various human and physical factors stated above come into place to determine the velocity and volume of the flows to and within the river channel, and the degree of impact on hydrographs. Through this, it can be seen that urbanization as a human factor are more influential than physical factors in a casualty scale in affecting the flows within a river as they are able to override the impact of physical factors themselves.
The urbanization process has resulted in forested area being replaced with impermeable surfaces such as tarmac. Before urbanisaztion, the forested area will intercept rainfall and promotes greater sub-surface transfers via its root system. The presence of vegetation is another factor that would affect the flows within the drainage basin. Vegetation would intercept rainfall, decreasing the amount of rainfall reaching the surface. Also, it decreases the intensity of raindrops hitting the ground, thus it is more likely to infiltrate and percolate into the ground. Vegetation also loosens soil to make larger air space between the soil particles. Thus, more infiltration and percolation will take place and through flow and overland flow are both relatively low. More infiltration and percolation will result in greater base flow augmenting the normal flow of a river. Through infiltration