Boundary Conditions Pollutant Loads WASP 7 Course Watershed
Boundary Conditions & Pollutant Loads WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center What is a Boundary? • Any Exchange of Water from outside the model network in or from inside the network to the outside. Boundary We designate Boundaries as Segment 0 1 2 3 4 5 Limitation in WASP Only 1 Boundary Per Segment WASP 7 Course 6
Watershed & Water Quality Modeling Technical Support Center What is a Boundary? • Defines Mass entering network Mass Loading = Flow ∙ Concentration • WASP Calculates Mass Leaving • What if Flow Reverses? • Implication of Boundaries – Boundary concentrations (BCs) must be specified with reasonable accuracy • Unknown BC is OK only if insensitive (i. e. , changes in BC do not significantly change model prediction in Area of Interest) • If the BC is sensitive and unknown, then extend the boundary location away from Area of Interest WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Specifying Boundaries • Boundaries are defined by – User Specified Flow Paths – User Specified Dispersion Paths – Read from Hydrodynamic Interface File WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Boundaries Steps to specify boundary concentrations (BCs): • Click on “+” by each variable to unpack boundary segments • Highlight segment • In bottom window, fill in concentration values (mg/L) for beginning and ending times • As needed, add time rows by pressing “+ Insert” and edit Date, Time, and Value • Continue entering BC data for all variables and boundary segments • Press “i. OK” and save WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Loads • Mass per Time into Model Network – kg/day • Loading Pathways – Atmospheric Deposition – Groundwater Infiltration – Municipal, Industrial Discharge – Watershed Runoff and Erosion WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Loading Pathways • Direct Discharges (i. e. , point sources) • External Loadings (i. e. , non-point sources) – ASCII File – Created LWWM – Created HSPF – Combined Sewer Overflow – Groundwater Infiltration WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Direct Loading Time Functions Flows, dispersion coefficients, boundary concentrations, and point source loads follow user-specified time functions, with linear interpolation between points; loading values may be specified at arbitrary intervals (fractions of a day to thousands of days): WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center External Loading Time Functions Nonpoint source loads follow step time functions in a formatted external file; loading values may be specified at arbitrary intervals (fractions of a day to thousands of days): WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Direct Loads Steps to specify loads: • Highlight and right click on variable • Select Add/Remove Loads • In new dialogue box, point and click on boxes to select segments receiving loads (not shown in diagram) • Press “i. OK” at bottom of dialogue box • Continue adding loading segments to varables WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Direct Loads, continued Steps to specify loads: Note: variables with concentrations in mg/L have loading values in kg/day WASP 7 Course • Click on + by variable to unpack loading segments • Highlight segment • In bottom window, fill in loading values (kg/day) for beginning and ending times • As needed, add time rows by pressing “+ Insert” and edit Date, Time, and Value • Continue entering loading data for all variables and segments • Press “i. OK” and save
Watershed & Water Quality Modeling Technical Support Center External Loads Steps to specify external NPS loads: • Click on “Use NPS file” box • Click on“ Browse” • In “Open” dialogue box, browse and highlight appropriate nps file, then press “open” • NPS File Name will appear in Parameters Screen • Press “i. OK” at bottom of Parameters Screen and save WASP 7 Course
Watershed & Water Quality Modeling Technical Support Center Example NPS File (for TOXI) Number of loading systems Segment number(s) System number(s) Number of loading segments System names 1 st loading time (day) Loads (kg/day) by segment (column) and by system (row) 2 nd loading time (day) Loads (kg/day) by segment (column) and by system (row) 3 rd loading time (day) Loads (kg/day) by segment (column) and by system (row) 4 th loading time (day) WASP 7 Course Loads (kg/day) by segment (column) and by system (row)
Watershed & Water Quality Modeling Technical Support Center Results from NPS Loadings volume of 1000 m 3, no flows, no decay 1 st Load 2 nd Load WASP 7 Course
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