How does urbanization (e.g., paving) affect runoff and infiltration in a small, previously forested drainage basin? Runoff increases and infiltration decreases.
Stormwater Runoff and Impervious Surfaces
Impervious surfaces associated with urbanization reduce infiltration and increase surface runoff (see Figure 16), altering the pathways by which water (and any associated contaminants) reach urban streams.
The most important influence on direct runoff change was urban surface change caused by urbanization. Urbanization can cause a large amount of pervious surface to turn into impervious surface, changing the hydrologic cycle and reducing infiltration rates [45,46,47].
Altered urban soils can preclude or retard natural processes such as infiltration and throughflow, resulting in increased ponding or surface runoff (Horton et al. 1994. Effects of compaction on soil hydraulic properties.
How does urbanization (e.g., paving) affect runoff and infiltration in a small, previously forested drainage basin? Runoff increases and infiltration decreases. You just studied 25 terms!
Urbanization generally increases the size and frequency of floods and may expose communities to increasing flood hazards. Current streamflow information provides a scientific foundation for flood planning and management in urban areas.
Urbanization reduces the minimum threshold rainfall for runoff generation, resulting in multi-peak hydrographs reflecting the contribution of both pervious and impervious surfaces. Urban roof water harvesting increases catchment lag time, but reduces downstream peak and total discharge, baseflow and flow velocity.
Flow Alteration in Urban Streams
Decreased infiltration and increased surface runoff of precipitation associated with impervious (and effectively impervious) surfaces. Increased speed and efficiency of runoff delivery to streams, via stormwater drainage infrastructure.
Urbanisation. Urbanisation reduces infiltration to 0 through its use of impermeable surfaces (tarmac, concrete), and drains and gutters transport water quickly to the river channel. This means that lag time is reduced and discharge is increased.
Urbanization is finished by the addition of more roads, houses, and commercial and industrial buildings. More wastewater is discharged into local streams. New water-supply and distribution systems are built to supply the growing population. Reservoirs may be built to supply water.
Meteorological factors affecting runoff:
Rainfall intensity. … Rainfall duration. Distribution of rainfall over the watersheds. Direction of storm movement. Antecedent precipitation and resulting soil moisture.
In “v” shaped valleys on steep slopes, runoff will increase due to gravity. On flatter surfaces runoff is less likely to happen as water will be able to infiltrate into the soil more easily. Equally, depressions in the Earth’s surface and an undulating relief can allow water to collect and reduce runoff.
Define infiltration. the process of entry of water into the soil through the soil surface.
Which one of the following best describes how urbanization affects small-stream watersheds? Infiltration decreases; lag time between storms and peak runoff shortens.
Gradient, cross-sectional shape, channel size and roughness, and discharge all affect a stream’s flow velocity.
The main results showed that urbanization caused the increase of carbon dioxide emissions, which is in compliance with the finding of York et al. (2003). But it hinders the growth of emissions in the middle and high income group, corresponding with Poumanyvong and Kaneko (2010).
Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle. Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
The study argues that urbanisation can cause indirect loss of forest, by encouraging agricultural expansion in forested areas. … Due to this, new agricultural land that was carved out of forests was 139 per cent greater than the area lost to urbanisation.
Greater urban area — and thus more roads, parking lots, and other impermeable surfaces — leads to less water retention from the decreased magnitude of soil and plants. With this reduced ability to store water, these environments contribute to more significant runoff.
In addition to increasing imperviousness, removal of vegetation and soil, grading the land surface, and constructing drainage networks increase runoff volumes and shorten runoff time into streams from rainfall and snowmelt. As a result, the peak discharge, volume, and frequency of floods increase in nearby streams.
The core aspect of urbanisation is the rapid urban population growth together with inadequate planning, pollution, poverty, competing demands on the resource, all contribute to water stress: and consequently the urban water consumption is likely to double by 2025.
For example, increased flooding and pollution, lower dry-weather flows, changes to the stream substrate and riparian vegetation, and channel widening are common results of urbanisation which can lead to degradation of the stream habitat and a loss of diversity in the aquatic community.
Human land use affects soils in the environment and increases the potential for erosion. There is a sharp peak in the amount of soil and sediment erosion after the construction phase of urbanization. … Urbanization disturbs soil and sediment which leads to erosion.
Natural resources are being exploited by human activities at a faster rate than they are being replenished. Urbanization is a key factor that accelerates depletion since an increase in urbanization leads to an increase in natural resource consumption. … Urbanization itself fosters land use change.
Poor air and water quality, insufficient water availability, waste-disposal problems, and high energy consumption are exacerbated by the increasing population density and demands of urban environments. Strong city planning will be essential in managing these and other difficulties as the world’s urban areas swell.
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