02-05 - Announcement Lecture notes will be posted on...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Announcement • Lecture notes will be posted on Blackboard after class.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Examples on the International Level Ex. Build up of T.D.S. in U.S. rivers because of irrigation return flow. Here's what happens: First apply water to field to grow crops: Result: Salt concentration build-up in soil to some level such that amount leaving in return flow equals the amount coming in, in the irrigation water. Flow =Qi, TDS = Ci Flow = Qp Flow = Qv Flow = Qs; TDS = Cs Cs > Ci net water loss due to evapotraspiration (assume: no salt input or loss via atmosphere) return flow underdrain or subsoil soil field irrigation H 2 O evaporation precipitation plants Qv > Qp
Background image of page 2
@ Steady State: Salt input = salt output Formulate an expression for the mass rate of salt input & output: salt input: salt output: @ steady state: So, at steady state, the salt concentration in the soil = constant Units = mass/time ; Ci (mg/L) x Qi (L/day) Qs Cs Qs Cs = Qi Ci so: Qs/Qi = Ci/Cs
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example: assume Ci = 210 mg/L (a good irrigation water) If the maximum salt concentration plants can stand is 2100 mg/L (above this level plants die because of osmotic problems) How much (%) of the water applied must be used to carry off excess salt? What if Ci = 700 ppm (still Class I irrigation water in Calif.)? Qs/Qi = 700 / 2100 = 0.33 [33% !] Qs/Qi = Ci / Cs = 210 / 2100 = 0.1 [10%]
Background image of page 4
Typical result for deterioration of water quality in a stream receiving irrigation return flow: 10 cfs (i.e. 33%) 2100 ppm (max. that will allow crops to grow) 70 + 10 = 80 cfs 875 ppm
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/13/2010 for the course CEE 3510 taught by Professor Lion during the Spring '10 term at Cornell University (Engineering School).

Page1 / 13

02-05 - Announcement Lecture notes will be posted on...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online