Watersheds 101 Lingo List

BMPs (BEST MANAGEMENT PRACTICES): Methods, measures or practices to prevent or reduce surface runoff and/or water pollution, including but not limited to, structural and nonstructural controls, operation and maintenance procedures, other requirements and scheduling and distribution of activities.

CHANNELIZATION: The creation of a channel or channels resulting in faster water flow, which increases the chance of erosion and sedimentation. This usually occurs when the natural meander of a steam is removed.

FLOODPLAIN: That portion of a stream valley adjacent to the stream channel that is created by erosion and sediment deposited from the stream and covered with water when the stream overflows its banks at flood stage. Also, the nearly level land situated on either side of a channel that is subject to overflow flooding.

GROUNDWATER RECHARGE: The process of replenishing the water that occurs in the subsurface.

KARST (LIMESTONE) GEOLOGY: Karst geology is prevalent in the valley area of Tredyffrin. It occurs when areas of the bedrock contain soluble minerals, such as limestone, dolomite or marl carbonite rocks. As water flows through the bedrock in karst areas, it dissolves the bedrock and leads to the formation of sinkholes. The tendency of sinkhole formations in karst geology presents many unique challenges to designing stormwater management.

IMPERVIOUS SURFACE: Ground that does not allow, or minimally allows, for infiltration of water - such as roofs, paved parking lots, and roads - and which increases the volume and speed of runoff after a rainfall and decreases groundwater recharge.

INFILTRATION: Movement of surface water into the soil, where it is absorbed by plant roots, evaporated into the atmosphere, or percolates downward to recharge groundwater.

NONPOINT SOURCE POLLUTION: Nutrient and pollution sources not discharged from a single point. It could include runoff from agricultural fields, feedlots, residential lawns, septic leach fields, or urban streets.

RIPARIAN BUFFERS: Vegetated land adjacent to waterways that stabilizes the stream bank, filters pollutants from storms and floods, and provides habitats for a variety of amphibians, aquatic birds, and mammals that depend on the proximity of water for their life functions. Development in riparian buffer areas can impair the functions and subject structures to damage from flooding and the meandering of natural streams.

RUNOFF: Runoff is any surface water (usually rainfall) that is not evaporated, transpired, used or infiltrated into the groundwater system, and thus flows over land to a surface body of water.

SCOUR: Local removal of soil, sediment, or other channel material from a streambed by flowing water.

SEDIMENTATION: Sedimentation occurs when sediment particles that have been suspended within flowing water are deposited on the stream bottom or floodplain.

STORMWATER: Runoff water that results from a storm (usually rainfall) event.

STORMWATER DETENTION/RETENTION BASINS: These basins are constructed to detain/retain stormwater for extended periods of time and allow for the retention of pollutants in the pond through deposition of sediments and attached pollutants.

STORMWATER MANAGEMENT: Means of capturing, detaining, and/or directing the flow of stormwater in a rain event.

STREAM CORRIDORS: Stream corridors include waterways and adjacent riparian lands.

STREAM BANK EROSION: The wearing away of land surface by water or wind which occurs naturally from weather or runoff, but is often intensified by human activities.

WETLANDS: Wetlands are low-lying areas that are saturated or inundated with surface or groundwater at a frequency, duration and depth sufficient to support an environment that allows wetland plants to grow. They provide valuable flood storage, groundwater recharge, and pollutant-filtering functions.

This project has been funded in part by a grant from the Department of Environmental Protection (DEP).

Links

Where are you in the Trout Creek Watershed?

• Trout Creek Watershed Map (1 page(s), 505 KB)

If you have questions or comments, please email us, tredyffrin@tredyffrin.org or call (610) 408-3625.