Stormwater Management Model (SWMM) Information for watershed water quality, hydrology and hydraulics modelers (Note this Blog is not associated with the EPA). You will find Blog Posts and Twitter Embeds on the Subjects of SWMM5, InfoSWMM, InfoSewer, SWMMLive, InfoSWMM SUSTAIN, SWMM4 and SWMM in general.
Saving to previous versions of ArcGIS in InfoSWMM and InfoSewer Once you open and save an existing map document (.mxd file) using ArcGIS 10, the map can no longer be opened with earlier versions of ArcGIS because it will now reflect the new functionality added at 10. Similarly, new documents you create with 10 also cannot be opened in earlier versions of the software. However, you can use the Save A Copy command to make a copy of a map document so you can open and work with it in previous versions of ArcGIS. With ArcGIS 10, you can save to ArcGIS 9.3, 9.2, 9.0/9.1, or 8.3. ArcGIS 9.0 and 9.1 map documents are directly compatible with each other and those versions of the software. Each new version of ArcGIS introduces functionality and properties that aren't available in previous versions. When you save a map document, layer file, or 3D document to a previous version of ArcGIS, the format of the file is changed to eliminate properties not available in the older version. This means sav…
Subject: Historical SWMM 5 and SWMM 4 Engines and Examples
The web site has http://swmm5legacycode.ning.com/ historical SWMM 5 installs, SWMM 5 input file examples and SWMM 4 input files and engines. The SWMM 4 engines go back to SWMM 3.5 engines from the 1980’s.
Subject: Link Iterations in the SWMM 5 Dynamic Wave Solution
Link Iterations in the SWMM 5 Dynamic Wave Solutionby dickinsonreSubject: Link Iterations in the SWMM 5 Dynamic Wave Solution Each of the links in the SWMM 5 network can use up to 8 iterations to reach convergence during a time step in the dynamic wave solution of SWMM 5. The rules governing the number of iterations are: 1. A minimum of 2 iterations per time step with the 1st iteration NOT using the underrelaxtion parameter of 0.5 (Figure 1) 2. If both the downstream and upstream nodes are converged then the link drops out of the iteration process during the time step (Figure 2) 3. The number of iterations for each link can vary over the simulation from 2 to 8 depending on how fast the flow is changing. Figure 1. A minimum of two and up to eight iterations per time step in the SWMM 5 dynamic wave solution. Figure 2. The number of iterations for each link vary through out the simulation with less iterations…
Subject: How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5? How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5?by dickinsonreSubject: How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5? An explanation of the four St. Venant Terms in SWMM 5 and how they change for Gravity Mains and Force Mains. The HGL is the water surface elevation in the upstream and downstream nodes of the link. The HGL for a full link goes from the pipe crown elevation up to the rim elevation of the node + the surcharge depth of the node. The four terms are: dq2 = Time Step * Awtd * (Head Downstream – Head Upstream) / Link Length or dq2 = Time Step * Awtd * (HGL) / Link Length Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1) when the force main is full dq3 and dq4 are zero and Qnew = (Qold – dq2) / ( 1 + dq1) The dq4 term in dynamic.c uses the area upstream (a1) and area downstream (a2), the midpoint velocity, the sigma factor (a funct…
SWMM 5 Precipitation Optionsby dickinsonreSubject: SWMM 5 Precipitation Options You can have design storms, monitored storms of any length of the time from minutes to centuries, use intensity, volume or cumulative precipitation, use both rainfall and snowfall in the same rain gage depending on temperature, use both time series or external files for the rain gage and have unlimited rain gages with the limitation of one rain gage per subcatchment .
SWMM 5 Leaping Weir Exampleby dickinsonreSubject: SWMM 5 Leaping Weir Example The attached example shows one way how SWMM 5 RTC Rules can be used to have the low flow go down a leaping weir orifice and the high flow go over the weir to the downstream section of the sewer.
Force Main Friction Loss in InfoSWMM and the Transition from Partial to Full Flowby dickinsonreSubject: Force Main Friction Loss in InfoSWMM and the Transition from Partial to Full Flow You can model Force Main friction loss in InfoSWMM using either Darcy Weisbach or Hazen Williams as the full pipe friction loss method (see Figure 1 for the internal definition of full flow). A function called ForceMain in InfoSWMM whose purpose is to compute the Darcy-Weisbach friction factor for a force main using the Swamee and Jain approximation to the Colebrook-White equation . No matter which method you use for full flow the program will use Manning's equation to calculate the loss in the link when the link is not full (see Figure 2 for the equations used for calculating the friction loss – variable dq1 in the St Venant equation for InfoSWMM). The regions for the different friction loss equations are shown in Figure 3. There is no slot in InfoSWMM for the full pipe flow as a surcharge…
Dry lands getting drier, wet getting wetter: Earths water cycle intensifying with atmospheric warminghttp://www.sciencedaily.com/releases/2012/05/120521104631.htm
May 21, 2012 ScienceDaily (May 21, 2012) — A clear change in salinity has been detected in the world's oceans, signalling shifts and an acceleration in the global rainfall and evaporation cycle.
In a paper just published in the journal Science, Australian scientists from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Lawrence Livermore National Laboratory, California, reported changing patterns of salinity in the global ocean during the past 50 years, marking a clear fingerprint of climate change.
Lead author, Dr Paul Durack, said that by looking at observed ocean salinity changes and the relationship between salinity, rainfall and evaporation in climate models, they determined the water cycle has strengthened by four per cent from 1950-2000. This is twice the response projected by curr…
Example SWMM 5 Snowmelt Modelby dickinsonreSubject: Example SWMM 5 Snowmelt Model Attached is a simple sample snowmelt model in SWMM 5 that has built in snowfall and temperature in a one subcatcment model with snowmelt. You define the separation of precipitation into snowfall and rainfall by setting a base temperature in the Snow Pack Editor. The precipitation that falls with when the air temperature is below the base temperature is stored in a snow pack where it eventually will melt when the temperature rises or is moved via plowing. You can have an initial snow cover, final snow cover and runoff from the melting snow long after the snowfall occurs.
via Blogger http://www.swmm5.net/2013/08/example-swmm-5-snowmelt-model.html
Runoff Routing Options Example in SWMM 5by dickinsonreSubject: Runoff Routing Options Example in SWMM 5 There are six options for runoff routing in SWMM 5: ·All Runoff to an Outlet Node ·All Runoff to another Subcatchment ·All Runoff to the Pervious Area of the Subcatchment or other Subcatchment ·All Runoff to the Impervious Area of the Subcatchment or other Subcatchment ·Partial Runoff to the Pervious Area of the Subcatchment or other Subcatchment ·Partial Runoff to the Impervious Area of the Subcatchment or other Subcatchment The attached example SWMM 5.0.022 file has three catchments in a chain, the 1stSubcatchment Routes to the Pervious area of the 2nd Subcatchment and the 2ndSubcatchment routes the runoff to the Impervious area of the 3rd Subcatchment which routes all runoff to an outlet node. via Bloggerhttp://www.swmm5.net/2013/08/runoff-routing-options-example-in-swmm-5.html
Subject: Example FM SWMM 5 model with and without Surcharge Depth Example FM SWMM 5 model with and without Surcharge Depthby dickinsonreSubject: Example FM SWMM 5 model with and without Surcharge Depth You need to use the surcharge depth for a Force Main in SWMM 5 to allow the engine to find the right point on the pump curve and pump up the rising main. If you do not use a surcharge depth then the flow MAY be very small in the rising main due to a small head difference. Of course the flow in the force main depends on the pump curve you have entered but having the right downstream head of depth for the link matter as well. The attached model was created in SWMM 5.0.022 via Bloggerhttp://www.swmm5.net/2013/08/example-fm-swmm-5-model-with-and.html