Effect of Mitigation on U.S. Water Quality Draft, July 31, 2017 1 Climate Change Impacts and Greenhouse Gas Mitigation Effects on US Water Quality 2 3 4 Supplement 2: Demonstration of QUALIDAD Outputs 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Brent Boehlert1,2,*, Kenneth M. Strzepek3, Steven C. Chapra2, Charles Fant3, Yohannes Gebretsadik3, Megan Lickley3, Richard Swanson4, Alyssa McCluskey4, James E. Neumann1, Jeremy Martinich5 1. Industrial Economics, Inc., Cambridge, Massachusetts, USA 2. Tufts University, Medford, Massachusetts, USA 3. Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 4. University of Colorado, Boulder, Colorado, USA 5. U.S. Environmental Protection Agency (EPA), Washington, D.C., USA * Corresponding author, phone: (617) 354-0074, fax: (617) 354-0463, [email protected] 1. INTRODUCTION This supplement presents a set of graphics that demonstrate the responsiveness of the 21 QUALIDAD parsimonious water quality model to (1) loading under constant flow and temperature 22 conditions, and (2) loading of a single constituent at a time given constant flow and time-varying 23 temperature conditions over a single year. Each graphic presents results for a single 24 representative basin with a main channel that is 100 kilometers in length, where loadings occur as 25 a distributed nonpoint source over the length of the river, and the presented concentrations of each 26 constituent occur at the basin outlet. The constituents in each figure include river temperature, 27 particulate organic carbon (Part org C), dissolved organic carbon (Dis org C), organic nitrogen (Org 28 N), river flow, ammonia, nitrate, organic phosphorus (Org P), photosynthetically active radiation 29 (PAR), inorganic phosphorus (Inorg P), phytoplankton (Phyto), and dissolved oxygen (DO). In 30 Section 2, carbon and DO are measured in grams per cubic meter (g/m3), and all other constituents Effect of Mitigation on U.S. Water Quality Draft, July 31, 2017 31 are measured in mg/m3. In Section 3, the carbon and DO are measured in mg/m3, whereas the 32 others are measured in μg/m3. 33 2. RESULTS UNDER CONSTANT LOADINGS, FLOWS AND TEMPERATURES 34 Figure S1 shows the set of constituents evaluated within QUALIDAD, and the effect of 35 introducing a constant loading of each constituent under constant temperature and river flow conditions 36 over a period of 10 days. This exercise simply demonstrates that under constant loading, temperature, 37 and flow, each constituent reaches a steady state concentration within approximately four days. In the 38 case of DO, there is an initial spike toward saturation as reaeration occurs, and then levels fall slightly as 39 the concentration of dissolved organic carbon increases in the basin. 40 41 42 Figure S1: Water quality constituent concentrations at steady state temperatures and flows, and constant nonpoint source loadings 43 3. 44 RESULTS WITH ONE LOADING AT A TIME UNDER VARIED TEMPERATURES Figures S2 through S6 present the effect of adding constant nonpoint source loading of one 45 constituent to the representative basin under time-varying temperature and PAR conditions, while 46 loadings of all other constituents remain at zero. Each graphic presents hourly constituent concentrations 2 Effect of Mitigation on U.S. Water Quality Draft, July 31, 2017 47 over a one-year period. Figure S2 shows loadings of particulate organic carbon transformed into 48 dissolved organic carbon, which then causes slight reductions of DO from full saturation. Note that on 49 the DO graphic, the gray line is DO saturation given river temperature, and the red line is the modeled 50 DO level. Figure S3 shows the significant effect that a larger loading of dissolved organic carbon has on 51 DO levels, and Figure S4 shows an organic nitrogen loading, its breakdown into ammonia, which is 52 subsequently broken down into nitrate. Due to the low levels of organic nitrogen introduced (measured in 53 μg/m3), the resulting effect on DO levels is minimal. The transformation of organic phosphorus loadings 54 to dissolved phosphorus are shown in Figure S5; as with introduction of organic nitrogen, the too little 55 phosphorus is introduced to have a significant effect on DO. Lastly, Figure S6 shows the complex effects 56 of introducing constant levels of phytoplankton to the basin. As can be seen, phytoplankton death 57 introduces organic carbon, nitrogen, and phosphorus to the system, but again at low enough 58 concentrations to have a minimal effect on DO. 59 60 61 62 Figure S2: Constituent concentrations when constant nonpoint source loadings of particulate organic carbon are applied 63 3 Effect of Mitigation on U.S. Water Quality Draft, July 31, 2017 64 65 66 Figure S3: Constituent concentrations when constant nonpoint source loadings of dissolved organic carbon are applied 67 68 69 70 Figure S4: Constituent concentrations when constant nonpoint source loadings of organic nitrogen are applied 71 72 73 4 Effect of Mitigation on U.S. Water Quality Draft, July 31, 2017 74 75 76 77 Figure S5: Constituent concentrations when constant nonpoint source loadings of organic phosphorus are applied 78 79 80 81 Figure S6: Constituent concentrations when constant nonpoint source loadings of phytoplankton are applied 82 5
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