How Does Urbanization Affect Hydrologic Cycle

The human population has been soared since the industrial revolution. The increase in human population implies there would be more human activities on the earth and they could affect the earth’s hydrologic cycle in multiple ways. The quantity, as well as the quality of water being circulated in the earth’s hydrologic cycle, is being influenced.

Firstly, urbanization would alter hydrologic cycle because of the reduced water permeability into underground. Underground water is an important component of hydrologic cycle since it accounted for nearly one-third of the global freshwater resource. Urban areas are covered by concrete pavement. When comparing concrete pavement to natural landscape, concrete has much lower porosity than soil. Thus, surface runoff and artificial water drainage would be dominating in urban areas (California Coastal Commission, 2006). Consequently, flooding may easily occur on ground surface and less water can be percolated into underground.

Nowadays, humans cut down forests in large scale so as to provide timber and spaces for urban development. However, deforestation could affect hydrologic cycle due to reduced transpiration rate (Sciencelearn Hub, 2009). Trees play a vital role in hydrologic cycle as the water absorbed by them would be eventually released to the atmosphere again in form of water vapour by transpiration, a process that giving out local humidity in a particular region like rainforests. Once the trees are being cut down, the region