Water, Sediment, and Chemical Flow Related to Roads

The presence and movement of water affects roads, and roads affect the movement of water and the material transported by water. A few of the ways water can affect roads include; (1) flooding, (2) destruction of bridges and culverts, (3) erosion of unpaved roads and the shoulders of paved roads, (4) inducing landslides onto roads or sliding of the road itself, (5) deterioration of road surfaces through the freeze/thaw cycle in some climates, and (6) groundwater discharge, which can cause road beds to be unstable. Roads can be responsible for transporting water and its various loads through watersheds in many ways. A road segment may act as (1) a source of water when water runs off of a road, especially paved roads. (2) a sink for water when water accumulates on a road, (3) a barrier to the flow of water down a hillside, or (4) a corridor for the flow of water when water runs down ruts and depressions in the road surface. In these ways, roads can disrupt natural flows of surface water and groundwater, create new routes for the flow of water, and (or) serve as sources of chemicals and sediment that are introduced into surface water and groundwater. Although the surface of the earth is complex, it is useful to look at the interactions of roads and water for two basic landforms – sloping terrain and flat terrain.