Philadelphia Water Department Watershed Protection Program Delaware Estuary Salinity Model Validation May 2020 Philadelphia Water Department May 2020 Table of Contents 1.0 Introduction .................................................................................................................................... 1 2.0 Numerical Model ........................................................................................................................... 1 2.1 Model Objectives ........................................................................................................................ 1 2.2 Modeling Approach ................................................................................................................... 1 2.3 Study Area .................................................................................................................................. 3 2.4 Salinity Conversion Methods ................................................................................................... 5 2.5 Boundary Conditions ................................................................................................................ 5 2.5.1 Tributaries ........................................................................................................................... 5 2.5.2 Open Boundary Condition -Salinity .............................................................................. 18 2.5.3 CSOs ................................................................................................................................... 25 2.5.4 Withdrawals and Discharges in the Model Domain ................................................... 29 2.5.5 Boundary Conditions Summary .................................................................................... 37 2.6 Initial Conditions ..................................................................................................................... 40 2.6.1 Temperature ...................................................................................................................... 40 2.6.2 Salinity ............................................................................................................................... 40 2.7 Grid and Bathymetry ............................................................................................................... 40 3.0 Sensitivity Studies ........................................................................................................................ 42 3.1 Bottom Roughness ................................................................................................................... 43 3.2 Turbulent diffusion and turbulence closure settings .......................................................... 45 3.3 Open Boundary Loading ........................................................................................................ 47 3.3.1 Loading adjustment for stratification ............................................................................ 47 3.3.2 Mixed vs stratified input ................................................................................................. 49 3.4 Grid Adjustment ...................................................................................................................... 50 3.4.1 Fine vs. coarse grid .......................................................................................................... 50 3.5 Tributary loading ..................................................................................................................... 52 3.5.1 Tributary Flow Estimates ................................................................................................ 52 3.5.2 Final adjustment of generated tributary salt loads...................................................... 54 3.6 Salt load analysis ...................................................................................................................... 55 4.0 Salinity Model Validation ........................................................................................................... 56 4.1 Validation configuration - 2014 .............................................................................................. 56 4.1.1 River Discharges ............................................................................................................... 57 Philadelphia Water Department May 2020 4.1.2 Water Level ....................................................................................................................... 57 4.1.3 Salinity ............................................................................................................................... 57 4.1.4 Wind ................................................................................................................................... 57 4.1.5 Grid and bottom roughness ............................................................................................ 57 4.2 Validation Metrics .................................................................................................................... 58 4.2.1 Mean Error, RMSE and Skill Factor ............................................................................... 58 4.2.2 Tidal Analysis Method .................................................................................................... 59 4.3 Validation Results .................................................................................................................... 59 4.3.1 Hydrodynamics ................................................................................................................ 59 4.3.2 Salinity ............................................................................................................................... 65 5.0 Conclusions and Summary ......................................................................................................... 71 6.0 References ..................................................................................................................................... 72 Philadelphia Water Department May 2020 List of Tables Table 2-1: Summary Salinity Modeling Approach Sources ................................................................. 2 Table 2-2: Tributaries included in model domain ................................................................................. 7 Table 2-3: Observed tributary specific conductance data availability and gap filling methodology for 2014 & 2016 ................................................................................................................. 10 Table 2-4: Median grab sample salinity [PSU] for ungaged tributaries. Spr: Spring (3/1 - 6/15), Sum: Summer (6/16 - 9/30), Win: Winter (10/1 - 2/28), D: Dry, W: Wet ....................................... 13 Table 2-5: Vertical adjustment factors for ungaged Tributaries ........................................................ 17 Table 2-6: Salinity time series for tributaries without salinity related data ..................................... 18 Table 2-7: Regression Results ................................................................................................................. 24 Table 2-8: Adjustment factors for 2014 and 2016 ................................................................................. 25 Table 2-9: Discharge Only Facilities Included in PWD Salinity Model ............................................ 32 Table 2-10: Withdrawals Included in PWD Salinity Model ............................................................... 35 Table 2-11: Consumptive Use of Withdrawals and Discharges ........................................................ 36 Table 2-12: Return Flow Facilities .......................................................................................................... 37 Table 2-13: Summary of chloride distribution from model discharge inputs excluding the ocean end open boundary .................................................................................................................................. 38 Table 2-14: Summary of chloride distribution from model discharge inputs excluding the ocean end open boundary .................................................................................................................................. 39 Table 3-1: Model grid metrics ................................................................................................................. 50 Table 3-2: Flow Reduction Targets ........................................................................................................ 54 Table 4-1: EFDC model settings ............................................................................................................. 57 Table 4-2: Modeled Water Level Mean Error, RMSE and Skill Factor ............................................. 59 Table 4-3: Water Level Tidal Analysis for 2014. Validation period of 9/1 – 11/30. ....................... 60 Table 4-4: Water Level Tidal Analysis for 2016. Validation period of 4/1 – 6/30. ......................... 61 Table 4-5: Modeled Velocity Mean Error, RMSE and Skill Factor .................................................... 62 Table 4-6: Current Tidal Analysis for 2014. Validation period of 9/1 – 11/30. .............................. 63 Table 4-7: Current Tidal Analysis for 2016. Validation period of 4/1 – 6/30. ................................ 64 Table 4-8: Salinity validation metrics in PSU and mg/L chloride ...................................................