Runoff

Precipitation Types and Measurement: Understanding different forms of precipitation, including rain, snow, hail, and sleet, as well as how to measure them, such as with a rain gauge or snow depths.

Watershed Definition and Characteristics: A watershed is an area of land that drains to a common point. Watersheds can be defined by topography features such as ridgelines and high points. Understanding the fundamentals of watersheds can help identify runoff sources and potential issues.

Runoff Mechanics: Runoff occurs when precipitation is not absorbed into the soil or evaporated into the air. Instead, it flows into the drainage system, which includes streams or out into the ocean. Understanding how flow rates and volumes are computed, such as using the Rational Method.

Surface runoff: Surface runoff occurs when precipitation falls on the ground and is not absorbed by the soil. The water runs off the surface of the land into the nearest water bodies.

Infiltration: Infiltration is the process by which water seeps into the soil pores or bedrock beneath the surface. This process affects how fast water reaches groundwater, but it can also have risks if there is contaminated water.

Evapotranspiration: Evapotranspiration is the process of water being returned to the atmosphere through both evaporation from the soil and transpiration from plants through their leaves. This is important in terms when discussing the Hydrologic Cycle.

Land Use and Land Cover: Land management practices significantly influence the hydrological cycle. Understanding the factors that impact runoff, as they relate to land use and natural cover, enable better understanding of impacts and potential mitigation strategies.

Topography: Topography refers to the steepness, elevation, and shape of the surrounding landscape. These features influence the way that water flows and can create or exacerbate issues.

Soil Properties: Soil properties, such as texture, structure, and permeability, determine how effectively the soil can absorb and infiltrate water. Some soil types, such as clay soils, are more prone to runoff than soils with higher permeability, like sandy soils.

Hydrograph analysis: Hydrograph analysis is a method used for analyzing the timing and magnitude of runoff from a watersheds in response to precipitation. It helps to identify peak flows and volumes for various storm events.

Surface Runoff: It is the flow of excess water on the ground surface to rivers, lakes or any nearby waterbody.

Subsurface Runoff: It is the flow of water through the soil layers, and further infiltrating into the groundwater with the help of gravity.

Interflow Runoff: It is the movement of water in the soil layers above the water table, which is due to the presence of impervious layers of soil that restrict the water movement.

Base flow Runoff: It is the discharge of groundwater that seeps into rivers, lakes or any nearby waterbody, providing a steady stream of water even during dry seasons.

Infiltration Excess Runoff: It occurs when rainfall intensity surpasses the infiltration rate, leading to surface water accumulation and movement.

Saturation Excess Runoff: It occurs when the soil is already saturated completely and fails to infiltrate the incoming rainfall, resulting in surface water flow.

Overland Flow Runoff: It is the surface flow of water on hill slopes or urban pavements, leading to the generation of stormwater.

Channel Initiated Runoff: It occurs when the water flow is initiated by rivers, lakes or other nearby waterbodies, resulting in significant downstream flow.

Sinkhole Runoff: It is the flow of water into sinkholes or subterranean passages, generating underground streams and rivers.

Roadway Runoff: It is the surface runoff from the highways and roads, containing oil, grease and other pollutants.