Question

Runoff. An important part of Earth's hydrologic cycle. A significant portion of precipitation in forested watersheds is absorbed into soils (infiltration), is stored as groundwater, and is slowly discharged to streams through seeps and springs. Consider this area in once rural river-side area in Connecticut. This is a recent satellite image of the result of urbanization without consideration of the long-term results of such development. Predict how this development may impact runoff. All BUT ONE of the statements may occur.

Answer 1

A) Impervious (paved) surfaces help direct runoff as well as stormwaters directly to the river to prevent flooding.

B) Extensive drainage systems must be put into place in order to carry runoff, especially stormwater, to the appropriate locations.

C) More water than normal will drain into the river much more quickly, resulting in an increased likelihood of more frequent and more severe flooding.

D) As watersheds are urbanized, much of the vegetation is replaced by impervious (paved) surfaces.

The answer is A.

Answer 2

This question is incomplete as no options are given. However, urbanisation typically leads to a greater percentage of impermeable surfaces, such as roads, parking lots etc. Water is then unable to filter into the soil and groundwater as much as it would on natural land. What then occurs is much more runoff in urban areas during rainfall. This has been problematic in major cities in the developing world, where storm water drains are not maintained. Rainfall can easily result in flooding, and floods can be much worse in urbanised environments. We must also consider that there will be reduced groundwater recharge in urban areas from rainfall, as less water infiltrates the soil. Interestingly, in urban areas, it is generally accepted that up to 60% of tap water is lost through leaks, many underground, so groundwater may be recharged through lost tap water.