We are going to show you several kinds of information from the modeling effort. First, you will choose a "scenario" or model experiment where you pick the kind of land use you are interested in and the amount of that land use change to be simulated. The choices will be shown in a table that shows the percentage of land use of that type overall and how it is distributed around the watershed in the simulation model. After you make this choice you will a set of graphs representing the flow of water associated with the storm discussed earlier.
The example graphs on the left show the depth of flow and the total flow of the Hellbranch at its mouth (the end of the stream where it meets the Big Darby Creek). The depth is important because it is used to test whether the amount of water flowing down the stream exceeds the capacity of the streambanks. If it does, a flood will occur. How the model represents that flood will be seen later. The graphs show at least two simulations so that you can compare the choice you made with the least amount of that land use. The one shown compares the 10% and 20% agricultural land use. The key things to look for in the Total Inflow graph is what is the peak (highest) amount of flow and what is the area under the graph. The peak flow is another indication of whether or not there will be a flood and also reflects the changes in the balance of the hydrologic cycle from interception and infiltration to runoff. The area under the graph shows the amount of total runoff that occurred because of the storm. The units are in cubic feet per second or CFS. One CFS represents a flow of 646,317 gallons per day or 7.48 gallons per second of flow.
The graph on the right shows the amount of pollution over time that flows to the stream with the stormwater for five different water pollution types. The one shwon again compares the two scenarios for Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), soluble phosphorous (SolubleP), and lead (Pb). Notice that no lead is forecast to come from the agricultural land uses. Both the peak and total amounts of pollutants are important. Notice that those numbers are in concentrations. The concentrations can be compared with the standards and guidelines relating to these pollutants you can find in the help files.
Now choose one of four activities by using the numbers below. If you need help, there will be a help menu on the subsequent screens that describes how to analyze the data you will see.
Medium Density Urban Land Uses
