Hydrology & Hydraulics
This hydraulic parameter affects the shape and peak of the hydrograph and can be altered by changes in imperviousness.
This major federal act, passed in 1972, significantly increased the focus on stormwater management, including detention ponds.
What is the Clean Water Act?
This is the first step in constructing a detention pond, involving removal of trees and debris.
What is clearing and grubbing?
This is the intention of stormwater detention.
What is to mitigate the effect of new development, redevelopment, or site modifications on an existing drainage system?
Flood Zone AE on a FEMA map indicates this level of flood risk.
What is a high-risk flood zone with a 1% annual chance of flooding?
This equation is used to calculate the average velocity and discharge in open channels like rivers, streams, and canals.
What is Manning's Equation?
This city experienced severe flooding in 2005, prompting a major overhaul in stormwater infrastructure, including detention pond upgrades.
What is New Orleans, LA?
This low-maintenance material is commonly used to armor outlet structures and spillways against erosion.
What is riprap?
This is the detention rate in ac-ft/ac for a tract that is entirely impervious (most commercial developments).
What is 0.98 ac-ft/ac?
The elevation a flood is expected to reach during a 100-year flood.
What is the Base Flood Elevation (BFE)?
The rational method (Q=CIA) is generally valid for small drainage areas under this maximum size.
What is 200 ac or less?
This major event in the early 20th century led to a significant shift in stormwater management practices and the introduction of detention ponds in urban planning.
What was the 1927 Great Mississippi Flood?
Detention ponds must be constructed with this minimum slope on the bottom to ensure positive drainage and avoid stagnant water.
What is 1%?
A basin that is within 30 feet of a parking lot or roadway with berms that drain away from the basin does not require this.
What is a backslope swale?
FEMA floodplain maps are created using these three (3) things.
What is topographic data, hydrologic studies, and historical flood events?
This describes the continuous movement of water on, above, and below the surface of the earth.
What is the Hydrologic Cycle?
What is Maryland?
This essential heavy machinery is used during pond construction for earthmoving and grading.
What is Excavators and Graders?
This the minimum berm width for a detention basin that is grass-lined with depth less than or equal to 7 feet.
What is 20 feet?
This was the last year FEMA collaborated with Harris County, Texas to provided updated maps.
What is 2007?
This dimensionless hydrograph model is frequently used in detention pond design to simulate runoff in small watersheds.
What is NRCS (or SCS) Unit Hydrograph?
This international city built an award-winning underground detention system called the "Stormwater Management and Road Tunnel" or SMART Tunnel.
What is Kuala Lumpur, Malaysia?
According to the U.S. Environmental Protection Agency (EPA), this is the range in construction cost per acre of impervious surface treated for a detention pond.
When developing a tract containing only one single family residential home. This is the COH detention volume criteria that should be followed to determine detention volume.
What is detention volume for criteria 1?
FEMA creates flood insurance rate maps (FIRMs) to show areas at risk for flooding. These maps are part of the National Flood Insurance Program (NFIP) and are used for.
What is floodplain management, flood insurance requirements, and development planning.