WASP7 Course Boundary Conditions & Pollutant Loads

Watershed & Water Quality Modeling Technical Support Center WASP7 Course What is a Boundary? Any Exchange of Water from outside the model network in or from inside the network to the outside.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 Limitation in WASP Only 1 Boundary Per Segment Limitation in WASP Only 1 Boundary Per Segment

Watershed & Water Quality Modeling Technical Support Center WASP7 Course What is a Boundary? Defines Mass entering networkDefines Mass entering network WASP Calculates Mass LeavingWASP Calculates Mass Leaving What if Flow Reverses?What if Flow Reverses? Implication of BoundariesImplication 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 Mass Loading = Flow ∙ Concentration

Watershed & Water Quality Modeling Technical Support Center WASP7 Course Specifying Boundaries Boundaries are defined byBoundaries are defined by –User Specified Flow Paths –User Specified Dispersion Paths –Read from Hydrodynamic Interface File

Watershed & Water Quality Modeling Technical Support Center WASP7 Course 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 Boundaries

Watershed & Water Quality Modeling Technical Support Center WASP7 Course Loads Mass per Time into Model NetworkMass per Time into Model Network –kg/day Loading PathwaysLoading Pathways –Atmospheric Deposition –Groundwater Infiltration –Municipal, Industrial Discharge –Watershed Runoff and Erosion

Watershed & Water Quality Modeling Technical Support Center WASP7 Course Loading Pathways Direct Discharges (i.e., point sources)Direct Discharges (i.e., point sources) External Loadings (i.e., non-point sources)External Loadings (i.e., non-point sources) –ASCII File –Created LWWM –Created HSPF –Combined Sewer Overflow –Groundwater Infiltration

Watershed & Water Quality Modeling Technical Support Center WASP7 Course 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):

Watershed & Water Quality Modeling Technical Support Center WASP7 Course 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):

Watershed & Water Quality Modeling Technical Support Center WASP7 Course 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

Watershed & Water Quality Modeling Technical Support Center WASP7 Course Direct Loads, continued Steps to specify loads: 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 “iOK” and save Note: variables with concentrations in mg/L have loading values in kg/day

Watershed & Water Quality Modeling Technical Support Center WASP7 Course 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

Watershed & Water Quality Modeling Technical Support Center WASP7 Course Example NPS File (for TOXI) Number of loading segments Number of loading systems 1st loading time (day) Loads (kg/day) by segment (column) and by system (row) Segment number(s) System number(s) System names 2nd loading time (day) Loads (kg/day) by segment (column) and by system (row) 3rd loading time (day) Loads (kg/day) by segment (column) and by system (row) 4th loading time (day) Loads (kg/day) by segment (column) and by system (row)

Watershed & Water Quality Modeling Technical Support Center WASP7 Course Results from NPS Loadings volume of 1000 m3, no flows, no decay 1 st Load 2 nd Load