Tabular Data

GeoSWMM utilizes several forms of tabular data to describe the properties of its various objects. These include:

·       Curve

·       Time Series

·       Time Patterns

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Curve objects are used to describe a functional relationship between two quantities. The following types of curves are available in GeoSWMM:

·       Storage - describes how the surface area of a Storage Unit node varies with water depth

·       Shape - describes how the width of a customized cross-sectional shape varies with height for a Conduit link.

·       Diversion - relates diverted outflow to total inflow for a Flow Divider node

·       Tidal - describes how the stage at an Outfall node changes by hour of the day

·       Pump - relates flow through a Pump link to the depth or volume at the upstream node or to the head delivered by the pump

·       Rating - relates flow through an Outlet link to the head difference across the outlet

·       Control - determines how the control setting of a pump or flow regulator varies as a function of some control variable (such as water level at a particular node) as specified in a Modulated Control rule.

Each curve must be given a unique name and can be assigned any number of data points.

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Time Series objects are used to describe how certain object properties vary with time. Time series can be used to describe:

·       temperature data

·       evaporation data

·       rainfall data

·       water stage at outfall nodes

·       external inflow hydrographs at drainage system nodes 

·       external inflow pollutes graphs at drainage system nodes

·       control settings for pumps and flow regulators

 

Each time series must be given a unique name and can be assigned any number of time-value data pairs. Time can be specified either as hours from the start of a simulation or as an absolute date and time-of-day. Time series data can either be entered directly into the program or be accessed from a user-supplied Time Series file.

v For rainfall time series, it is only necessary to enter periods with non-zero rainfall amounts. GeoSWMM interprets the rainfall value as a constant value lasting over the recording interval specified for the rain gage that utilizes the time series. For all other types of time series, GeoSWMM uses interpolation to estimate values at times that fall in between the recorded values.

v For times that fall outside the range of the time series, GeoSWMM will use a value of 0 for rainfall and external inflow time series, and either the first or last series value for temperature, evaporation, and water stage time series.

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Time Patterns allow external Dry Weather Flow (DWF) to vary in a periodic fashion. They consist of a set of adjustment factors applied as multipliers to a baseline DWF flow rate or pollutant concentration. The different types of time patterns include: 

·       Monthly: one multiplier for each month of the year  

·       Daily: one multiplier for each day of the week  

·       Hourly: one multiplier for each hour from 12 AM to 11 PM

·       Weekend: hourly multipliers for weekend days 

Each Time Pattern must have a unique name and there is no limit on the number of patterns that can be created. Each dry weather inflow (either flow or quality) can have up to four patterns associated with it, one for each type listed above.