Old MacDonald had a farm. And on that farm he had a pond. Old MacDonald (OMD) liked spending a lot of time fishing in his pond. One day a friend told him that the fish will grow twice
as big if the pond was twice as large. So. OMD decided to enlarge his pond from 2.5 ac res to
5.0 acres. Because he spent most of his time fishing and not studying the hydrologic equation
something strange happened. Can you tell? Here are some numbers to crunch
Inflow
Qu = 130.8 cubic yard per hour
Outflow
Qour = 97 m/hr
Seepage Q = 0.0055 L/minute per m' of lake area
Precipitation P = 45 inches per year per mof lake area (Account only for p falling directly
on the lake)
Evaporation E = 30 inches per year per m2 of lake area (Account only for E directly from
the lake
Irrigation I = 88 ft per day
Avg. depth h = 3 m (Assume tha t the lake describes a perfect circle).
Tasks/ Questions:
1) Scientists prefer Sl units over the footinches/acres so commonly used in the U. S.
Please convert all non SI units into metric units (Hint: use meter and day units : convert
initial numbers accordingly)
2) What is the volume of the lake before and after OMD started digging?
3) Calculate the inflow and outflow from the lake before OMD enlarged it
4) Calculate the inflow and outflow after the lake was enlarged.
5) Assume that before enlarging the lake, OMD diverted all inflows (including the amount of
rain falling onto the lake ), how long would it take for the lake to drain completely?
6) After OMD drained the lake and enlarged it, what happened to his lake?
7) How could he have avoided this o utcome?
Due: One week from today. On paper. You must show your math.