Tuesday, January 17, 2023

SWMM 5.2.2 Code for Defining LID data in LID.h

 This code defines several structs that are used to store information about different layers of a LID (Low Impact Development) unit. The structs define the properties of each layer, such as thickness, porosity, permeability, and other parameters that are specific to each layer.

The structs defined in this code are:

Struct NameDescription
TSurfaceLayerInformation about the surface layer of the LID unit, such as depression storage or berm height, roughness, slope, and alpha term in Manning equation.
TPavementLayerInformation about the pavement layer of the LID unit, such as thickness, void fraction, permeability, clogging factor, and regeneration interval.
TSoilLayerInformation about the soil layer of the LID unit, such as thickness, porosity, field capacity, wilting point, suction, saturated hydraulic conductivity.
TStorageLayerInformation about the storage layer of the LID unit, such as thickness, void fraction, saturated hydraulic conductivity, clogging factor and information about whether it is covered or not.
TDrainLayerInformation about the underdrain system of the LID unit, such as flow coefficient, head exponent, offset height, delay time, head when drain opens and closes, flow rate curve.
TDrainMatLayerInformation about the drainage mat layer of the LID unit, such as thickness, void fraction, roughness, slope/roughness term in Manning equation.

The fields of all the structs are double type except for the "covered" field which is of int type.

The code also defines a MAX_LAYERS macro which is set to 4. This macro is used as a constant throughout the code to specify the maximum number of layers that are allowed in the LID unit.

This way, the code defines the different layers of LID unit and the properties of each layer with the help of structs. This makes it easy to simulate and analyze the performance of LID unit by using these structs to store the information about different layers and their properties.



#define MAX_LAYERS 4 // LID Surface Layer typedef struct { double thickness; // depression storage or berm ht. (ft) double voidFrac; // available fraction of storage volume double roughness; // surface Mannings n double surfSlope; // land surface slope (fraction) double sideSlope; // swale side slope (run/rise) double alpha; // slope/roughness term in Manning eqn. char canOverflow; // 1 if immediate outflow of excess water } TSurfaceLayer; // LID Pavement Layer typedef struct { double thickness; // layer thickness (ft) double voidFrac; // void volume / total volume double impervFrac; // impervious area fraction double kSat; // permeability (ft/sec) double clogFactor; // clogging factor double regenDays; // clogging regeneration interval (days) double regenDegree; // degree of clogging regeneration } TPavementLayer; // LID Soil Layer typedef struct { double thickness; // layer thickness (ft) double porosity; // void volume / total volume double fieldCap; // field capacity double wiltPoint; // wilting point double suction; // suction head at wetting front (ft) double kSat; // saturated hydraulic conductivity (ft/sec) double kSlope; // slope of log(K) v. moisture content curve } TSoilLayer; // LID Storage Layer typedef struct { double thickness; // layer thickness (ft) double voidFrac; // void volume / total volume double kSat; // saturated hydraulic conductivity (ft/sec) double clogFactor; // clogging factor int covered; // TRUE if rain barrel is covered } TStorageLayer; // Underdrain System (part of Storage Layer) typedef struct { double coeff; // underdrain flow coeff. (in/hr or mm/hr) double expon; // underdrain head exponent (for in or mm) double offset; // offset height of underdrain (ft) double delay; // rain barrel drain delay time (sec) double hOpen; // head when drain opens (ft) double hClose; // head when drain closes (ft) int qCurve; // curve controlling flow rate (optional) } TDrainLayer; // Drainage Mat Layer (for green roofs) typedef struct { double thickness; // layer thickness (ft) double voidFrac; // void volume / total volume double roughness; // Mannings n for green roof drainage mats double alpha; // slope/roughness term in Manning equation } TDrainMatLayer;

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