Infiltration-excess overland flow

Definition

Infiltration-excess overland flow occurs when the rate of rainfall exceeds the soil's ability to absorb water, leading to surface runoff. This phenomenon is significant in areas with saturated soil or impervious surfaces, causing excess water to flow over the land. Understanding this process is crucial as it impacts both hydrological modeling and the management of land use and land cover.

5 Must Know Facts For Your Next Test

1. Infiltration-excess overland flow is most common in urban areas where impervious surfaces like asphalt and concrete prevent water from soaking into the ground.
2. This type of flow can lead to increased flooding risks, erosion, and water quality issues as pollutants are washed into waterways.
3. The occurrence of infiltration-excess overland flow can be influenced by land cover changes, such as deforestation or urbanization, which reduce soil permeability.
4. Modeling infiltration-excess overland flow requires understanding rainfall intensity, duration, and soil moisture conditions to predict runoff behavior accurately.
5. Effective land use planning can mitigate the impacts of infiltration-excess overland flow by incorporating green infrastructure like permeable pavements and vegetated swales.

Review Questions

• How does infiltration-excess overland flow differ from saturation-excess overland flow in terms of their triggers and effects on surface runoff?
  • Infiltration-excess overland flow occurs when rainfall intensity exceeds the soil's infiltration capacity, leading to immediate surface runoff. In contrast, saturation-excess overland flow happens when the soil is already saturated, causing any additional precipitation to run off. Both processes contribute to surface runoff but under different conditions; understanding these differences helps in predicting flood events and managing water resources effectively.
• Discuss the relationship between land use changes and infiltration-excess overland flow, particularly in urban environments.
  • Land use changes, especially urbanization, significantly increase the prevalence of infiltration-excess overland flow. When natural landscapes are replaced with impervious surfaces like roads and buildings, the ability of soil to absorb rainfall decreases dramatically. This results in higher rates of surface runoff during storms, leading to issues such as flooding and increased pollutant transport into nearby water bodies. Effective planning and design can help mitigate these impacts.
• Evaluate strategies that can be implemented to manage infiltration-excess overland flow and improve water quality in urban settings.
  • To manage infiltration-excess overland flow effectively in urban settings, strategies such as implementing green infrastructure are essential. This includes using permeable pavements, rain gardens, and bioswales that allow water to infiltrate instead of running off. Additionally, enhancing vegetation cover through urban forestry can also increase soil absorption capacity. These approaches not only reduce runoff but also help filter pollutants before they reach waterways, ultimately improving overall water quality.

Related terms

Saturation-excess overland flow: A type of overland flow that occurs when the soil becomes saturated, allowing additional rainfall to runoff the surface rather than being absorbed.

Soil permeability: The ability of soil to transmit water through its pores, which significantly affects how quickly water can infiltrate and how much can contribute to surface runoff.

Stormwater management: A set of practices designed to manage the quantity and quality of stormwater runoff, often including measures to reduce infiltration-excess overland flow.