Stormwater Water Quality Swale

For more information about this layer please see the GIS Data Catalog. Component Types-Basic biofiltration swale: A long, gently sloped, vegetated ditch designed to filter pollutants from stormwater. Grass is the most common vegetation, but wetland vegetation can be used if the soil is saturated. -Wet biofiltration swale: A variation of the basic biofiltration swale used where the longitudinal slope is slight (1 to 2 percent or less), water tables are high, or continuous low base flow is likely to result in saturated soil conditions. Under such conditions, healthy grass growth is not possible and wetland plants are used to provide the biofiltration mechanism.-Continuous inflow biofiltration swale: A biofiltration swale where water enters the swale continuously at numerous discrete inflows with no single inflow contributing more than about 10% of total swale flow.如需了解该图层的更多信息，请参阅地理信息系统（GIS）数据目录。组件类型——基础生物过滤草沟（biofiltration swale）：一种长条形缓坡植被沟渠，用于过滤雨水径流中的污染物。草本植物为最常用的植被类型，但若土壤处于饱和状态，也可采用湿地植被。湿式生物过滤草沟（wet biofiltration swale）：该类型为基础生物过滤草沟的变体，适用于纵向坡度极小（1%至2%或更低）、地下水位较高，或持续低基流易导致土壤饱和的场景。在此类条件下，草本植物无法健康生长，需采用湿地植物实现生物过滤功能。连续进水生物过滤草沟（continuous inflow biofiltration swale）：此类生物过滤草沟通过多个分散的进水点持续注入水流，且任一单点进水的流量均不超过草沟总流量的10%左右。