Chapra, L9 (cont.) David A. Reckhow CEE 577 #11 1 Distributed - PowerPoint PPT Presentation

Updated: 23 October 2017 Print version Lecture #11 a (Distributed Sytems) Chapra, L9 (cont.) David A. Reckhow CEE 577 #11 1

Distributed Sources  Source (or sink) that is spread out along the stream length  classical non-point sources  agricultural, urban runoff  Sediment processes  sediment oxygen demand  Atmospheric deposition S D B J in J out H David A. Reckhow CEE 577 #11 2

Distributed source in PFR @SS U dc 0 = − − + kc S D dx ( ) ( )   S k x u  k x u  − − = + − D c c e 1 e   o k S D B J in J out H David A. Reckhow CEE 577 #11 3

3 0.9 mg/L/d 2.5 Concentration (mg/L) 0.6 mg/L/d 2 1.5 0.344 mg/L/d 1 0.5 Increasing S D 0 0 2 4 6 8 10 Distance (miles) K=0.344/d David A. Reckhow CEE 577 #11 4

4 0.23/d 3.5 Concentration (mg/L) 3 0.344/d 2.5 2 0.58/d 1.5 1 0.88/d 0.5 Decreasing k 0 0 2 4 6 8 10 Distance (miles) S D = 0.9 mg/L/d David A. Reckhow CEE 577 #11 5

Variable Channel Geometry ∂ c ∆ V ∂ = − − J A J A rV in c out c t S D B J in J out H David A. Reckhow CEE 577 #11 6

Updated: 23 October 2017 Lecture #11 b (Waste Load Allocations) Chapra, here and there David A. Reckhow CEE 577 #11 7

Graphical Representation 80 70 60 Loading 50 40 30 20 10 0 11 10 Dissolved Oxygen (mg/L) 9 8 7 6 5 4 Fishing Boating 3 Fishing 2 1  See also: Fig 1.2 from 0 Thomann & Mueller -2 0 2 4 6 8 10 12 14 16 David A. Reckhow CEE 577 #11 8 Miles Downstream

WLA: Step by Step  Designate a specific water use  Adopt a Water Quality Criterion  Determine action necessary  formulate several alternatives  evaluate the alternatives No Is cost OK? Yes David A. Reckhow CEE 577 #11 9

WLA: breakdown of steps  Designate a specific water use  recreation: swimming, boating, aesthetics  water supply: municipal, industrial  agriculture  fisheries: commercial or sport  ecological balance  Adopt a Water Quality Criterion  must support the above use  EPA “red book” David A. Reckhow CEE 577 #11 10

WLA: breakdown of steps  Determine the action necessary to meet criterion: usually a discharge or effluent Water Quality Standard (enforceable)  Formulation of several engineering alternatives to meet the WQC  choose model  collect data  calibrate model  verify model  sensitivity analysis  model run under design conditions  alter waste loads and re-run model David A. Reckhow CEE 577 #11 11

 To next lecture David A. Reckhow CEE 577 #11 12