MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Department of Civil and Environmental Engineering
1.77 Water Quality Control
Problem Set 8
Spring 2006
Due April 25
Consider a well-mixed lake with no inflows or outflows located near Knoxville, TN (latitude
about 36 oN) having a volume of 3x106 m3 and a surface area of 20 ha. On March 1 the water
temperature is 4 oC. a) Based on the following monthly meteorological data, compute the
monthly variation in lake temperature T, equilibrium temperature Te and surface heat loss
coefficient K. b) Assuming waste heat is added at a rate of 2 MWt/ha, recompute the monthly
(heated) lake temperature Th.
Month
Mar.
Apr
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Ta
(oC)
12.6
17.0
17.5
22.9
22.1
22.9
18.7
14.6
6.8
7.0
RH
(%)
63
62
79
80
85
80
78
74
68
80
Wind
speed (m/s)
3.8
3.7
3.1
2.7
2.6
2.3
2.1
2.5
2.8
3.0
Cloud
Cover
0.59
0.58
0.70
0.66
0.77
0.70
0.63
0.50
0.52
0.77