Highway development most direct effect on ecosystems is the destruction of a natural habitat through its “conversion” to a transportation land use or “right-of-way”. Although natural vegetation may be preserved within the right-of-way, the original natural characteristics of the land are eliminated within the paved area and adjacent roadsides. The clearing of vegetation (trees, shrubs, grasses) and accompanying leveling operations (that destroy the original topography and soil profile) are the principal changes.
In some cases, the natural vegetation may be replanted while in others different species are planted and the habitat values modified. In wetland environments, road construction may need filling and draining operations that destroy wetland habitats. In aquatic environments, flow alteration (via damming or channelization) may reduce the habitat. Dredging, filling, and draining required by road construction also destroy aquatic habitat.
Impact and Effect of Highway Development
Highway development rarely eliminates entire habitat types, but instead destroys part of a habitat, leaving other areas intact. In most instances, this local habitat destruction is better thought of as habitat fragmentation. Such fragmentation is the principal cause of the loss of “area-sensitive” species and is considered the most serious threat to biological diversity.
Effect of highway development always leads to degradation of the habitat. Degradation of habitats specifically refers to a decrease in the health or ecological integrity of the “intact” habitat. In the case of highway development, this degradation is closely associated with fragmentation and what many researchers call the “edge effect”. This edge effect can be viewed as a reduction in habitat integrity at the boundary of a highway corridor caused by disturbance, contamination, or other degrading factors that extend into the natural habitat.
In addition to direct toxicity and behavioral effects on resident organisms, this degradation includes the alteration of natural processes such as water flow, fire regime, and species interactions. Biological invaders are a particular problem along roadway corridors that can seriously degrade natural systems by modifying species interactions.
Loss of Natural Resources due to Highway Development
Forest: Roads running through forest area and plantations may be the cause of the destruction of trees in the forest and alteration of the ecology of the forest.
Fisheries: Roads prevent longitudinal and lateral migration of fishes in the floodplain. Obstruct movement of fishes onto natural feeding and breeding grounds in the floodplain.
Wetland and Wetland Habitat: The road may encroach wetlands which may alter the ecology of wetlands and may cause the destruction of wetland habitat.
Erosion and Siltation: Causes erosion during flood and siltation in the downstream.
Drainage Congestion /Water logging: Roads interfere with cross drainage and can cause flooding or drainage congestion in adjacent areas during periods of high precipitation. May cause crop damage, water pollution and breeding of mosquitoes.
Regional Hydrology/Flooding: Roads constructed across floodplains perpendicular to the direction of water flow cause backwater effect and increase duration, frequency and the extent of flooding in the upstream.
Obstruction to Wastewater flow: Roads may obstruct the drainage of sewage and industrial wastewater loading to the serious pollution problem.
Loss of Agricultural Lands: Construction of any road is associated with the loss of agricultural lands. Scattered borrow pits, unauthorized growth around road, erosion result in the marred landscape.
Culled from Planning Tank | Impact and effect of developing roads and highways