Infiltration-excess overland flow

Definition

Infiltration-excess overland flow occurs when rainfall intensity exceeds the infiltration capacity of the soil, causing water to accumulate on the surface and flow over the land. This phenomenon is significant in hydrology as it influences surface runoff, erosion, and sediment transport, directly affecting water quality in nearby channels. Understanding this flow type is essential for managing stormwater, designing drainage systems, and predicting flood events.

5 Must Know Facts For Your Next Test

1. Infiltration-excess overland flow typically occurs during intense rainfall events or storms when the rate of precipitation overwhelms the soil's ability to absorb water.
2. This type of flow is particularly common in urban areas with impervious surfaces like roads and buildings that prevent water from infiltrating into the ground.
3. Factors such as soil type, land use, vegetation cover, and moisture content play crucial roles in determining the infiltration capacity and consequently influence overland flow.
4. Excess overland flow can lead to increased erosion and sediment transport, negatively impacting water quality in rivers and lakes by introducing pollutants and sediment.
5. Effective stormwater management practices aim to minimize infiltration-excess overland flow by enhancing soil permeability and incorporating green infrastructure.

Review Questions

• How does infiltration-excess overland flow impact surface runoff and what factors contribute to this phenomenon?
  • Infiltration-excess overland flow significantly increases surface runoff as it occurs when rainfall intensity surpasses the soil's infiltration capacity. Key factors contributing to this phenomenon include soil type, vegetation cover, and existing moisture levels in the soil. In urban environments, impervious surfaces exacerbate the issue by preventing water from being absorbed into the ground, resulting in greater volumes of surface runoff that can lead to flooding and erosion.
• Evaluate the implications of infiltration-excess overland flow on water quality and sediment transport in local waterways.
  • Infiltration-excess overland flow has considerable implications for water quality as it can transport sediments, nutrients, and pollutants into local waterways. When excess runoff occurs, it carries these materials directly into rivers and lakes, leading to increased turbidity and potential eutrophication. This contamination poses risks to aquatic ecosystems and can compromise drinking water sources, making it essential for effective management strategies to mitigate these impacts.
• Assess the effectiveness of various stormwater management practices in reducing infiltration-excess overland flow during heavy rainfall events.
  • Stormwater management practices such as permeable pavements, green roofs, rain gardens, and retention basins can significantly reduce infiltration-excess overland flow during heavy rainfall. By promoting greater soil permeability and capturing runoff for temporary storage or slow release, these practices help enhance the natural hydrologic cycle. Analyzing their effectiveness involves considering factors like design features, local climate conditions, and landscape characteristics to ensure sustainable management of stormwater resources.

Related terms

Infiltration Capacity:

The maximum rate at which soil can absorb water, which varies based on soil type, structure, and moisture content.

Surface Runoff: Water that flows over the land surface when precipitation exceeds the soil's ability to infiltrate it.

Hydrologic Cycle:

The continuous movement of water within the Earth and atmosphere, involving processes like evaporation, condensation, precipitation, infiltration, and runoff.