Storm Water Management Model
It can simulate the rainfall-runoff, runoff, evaporation, infiltration and groundwater connection for roots, streets, grassed areas, rain gardens and ditches and pipes, for example.
Besides, low impact development (LID) and best management practice areas on the subcatchment can be modeled to reduce the impervious and pervious runoff.
The water quality constituents such as water quality constituents can be simulated from buildup on the subcatchments through washoff to a hydraulic network with optional first order decay and linked pollutant removal, best management practice and low-impact development (LID)[9] removal and treatment can be simulated at selected storage nodes.
SWMM is one of the hydrology transport models which the EPA and other agencies have applied widely throughout North America and through consultants and universities throughout the world.
These include: SWMM also contains a flexible set of hydraulic modeling capabilities used to route runoff and external inflows through the drainage system network of pipes, channels, storage/treatment units and diversion structures.
Inflows to this compartment can come from surface runoff, groundwater interflow, sanitary dry weather flow, or from user-defined hydrographs.
The simulated model parameters for subcatchments are surface roughness, depression storage, slope, flow path length; for Infiltration: Horton: max/min rates and decay constant; Green-Ampt: hydraulic conductivity, initial moisture deficit and suction head; Curve Number: NRCS (SCS) Curve number; All: time for saturated soil to fully drain; for Conduits: Manning’s roughness; for Water Quality: buildup/washoff function coefficients, first-order decay coefficients, removal equations.
SWMM uses hourly or more frequent rainfall data as input and can be run for single events or in a continuous fashion for any number of years.
SWMM also contains a flexible set of hydraulic modeling capabilities used to route runoff and external inflows through the drainage system network of pipes, channels, storage/treatment units and diversion structures.
These include the ability to: Infiltration is the process of rainfall penetrating the ground surface into the unsaturated soil zone of pervious subcatchments areas.
The following processes can be modeled for any number of user-defined water quality constituents: Rain gages in SWMM5 supply precipitation data for one or more subcatchment areas in a study region.
Dynamic wave routing solves the complete one-dimensional Saint Venant flow equations and therefore produces the most theoretically accurate results.
Because it couples together the solution for both water levels at nodes and flow in conduits it can be applied to any general network layout, even those containing multiple downstream diversions and loops.
SWMM contains a flexible set of hydraulic modeling capabilities used to route runoff and external inflows through the drainage system network of pipes, channels, storage/treatment units, and diversion structures.
apply user-defined dynamic control rules to simulate the operation of pumps, orifice openings, and weir crest levels.
The term low-impact development (Canada/US) is used in Canada and the United States to describe a land planning and engineering design approach to managing stormwater runoff.
In recent years many states in the US have adopted LID concepts and standards to enhance their approach to reducing the harmful potential for storm water pollution in new construction projects.
LID takes many forms but can generally be thought of as an effort to minimize or prevent concentrated flows of storm water leaving a site.
are used, they are periodically interrupted by pervious areas which can allow the storm water to infiltrate (soak into the earth) A variety of sub-processes in each LID can be defined in SWMM5 such as: surface, pavement, soil, storage, drainmat and drain.
New as of July 2013[update], the EPA's National Stormwater Calculator is a Windows desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States.
The user supplies information about the site's land cover and selects the types of low impact development (LID) controls they would like to use on-site.
The idea behind SUDS is to try to replicate natural systems that use cost effective solutions with low environmental impact to drain away dirty and surface water run-off through collection, storage, and cleaning before allowing it to be released slowly back into the environment, such as into watercourses.
The SWMM 5.0.001 to 5.1.022 main components are rain gages, watersheds, LID controls or BMP features such as Wet and Dry Ponds, nodes, links, pollutants, landuses, time patterns, curves, time series, controls, transects, aquifers, unit hydrographs, snowmelt and shapes (Table 3).
The major objects or hydrology and hydraulic components in SWMM 5 are: The major overall components are called in the SWMM 5 input file and C code of the simulation engine: gage, subcatch, node, link, pollute, landuse, timepattern, curve, tseries, control, transect, aquifer, unithyd, snowmelt, shape and lid.
It is a simple to use software utility that allows future climate change projections to be incorporated into the Storm Water Management Model (SWMM).
SWMM was recently updated to accept a set of monthly adjustment factors for each of these time series that could represent the impact of future changes in climatic conditions.
SWMM-CAT is a utility that adds location-specific climate change adjustments to a Storm Water Management Model (SWMM) project file.
Adjustments can be applied on a monthly basis to air temperature, evaporation rates, and precipitation, as well as to the 24-hour design storm at different recurrence intervals.
[21] The following steps are used to select a set of adjustments to apply to SWMM5: 1) Enter the latitude and longitude coordinates of the location if available or its 5-digit zip code.
Other external programs that aid in the generation of data for the EPA SWMM 5 model include: SUSTAIN,[22] BASINS,[23] SSOAP,[24] and the EPA’s National Stormwater Calculator (SWC)[17] which is a desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States (including Puerto Rico).
