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

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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

SLIDE 1

Lecture #11a (Distributed Sytems)

Chapra, L9 (cont.)

David A. Reckhow CEE 577 #11 1

Updated: 23 October 2017

Print version

SLIDE 2

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

David A. Reckhow CEE 577 #11 2

H B Jin Jout SD

SLIDE 3

Distributed source in PFR @SS

David A. Reckhow CEE 577 #11 3

H B Jin Jout SD 0 = − − + U dc dx kc SD

( ) ( )

c c e S k e

k x u

D k x u

= + −      

− −

1

SLIDE 4

0.5 1 1.5 2 2.5 3 2 4 6 8 10

Distance (miles) Concentration (mg/L)

David A. Reckhow CEE 577 #11 4

Increasing SD 0.9 mg/L/d 0.6 mg/L/d 0.344 mg/L/d K=0.344/d

SLIDE 5

0.5 1 1.5 2 2.5 3 3.5 4 2 4 6 8 10

Distance (miles) Concentration (mg/L)

David A. Reckhow CEE 577 #11 5

Decreasing k 0.23/d 0.344/d 0.58/d 0.88/d SD = 0.9 mg/L/d

SLIDE 6

Variable Channel Geometry

David A. Reckhow CEE 577 #11 6

H B Jin Jout SD

∆V c t J A J A rV

in c

∂ ∂ = − −

SLIDE 7

Lecture #11b (Waste Load Allocations)

Chapra, here and there

David A. Reckhow CEE 577 #11 7

Updated: 23 October 2017

SLIDE 8

Graphical Representation

 See also: Fig 1.2 from

Thomann & Mueller

David A. Reckhow CEE 577 #11 8

Miles Downstream

2 4 6 8 10 12 14 16

Dissolved Oxygen (mg/L)

1 2 3 4 5 6 7 8 9 10 11

10 20 30 40 50 60 70 80

Fishing Boating Fishing

SLIDE 9

WLA: Step by Step

 Designate a specific water use

David A. Reckhow CEE 577 #11 9

Adopt a Water Quality Criterion Determine action necessary

formulate several alternatives evaluate the alternatives

Is cost OK? No Yes

SLIDE 10

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

SLIDE 11

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

SLIDE 12

 To next lecture

David A. Reckhow CEE 577 #11 12