Flow rates are extremely changed by placing dams in the main flow of a river. This is very obvious because of the dramatic drop in water levels before and after the dam. In fact, the Hoover Dam in Nevada, US has a huge drop of over 700 feet from top to bottom of the dam. This stops such a great amount of water, that a lake will appear at the top of the dam, and a much smaller stream will replace the once raging river at the bottom. This loss of water at the bottom will lead to much shallower water levels and much of the previous fisheries disappear because of a lack of necessary water. Also, the top of the dam will flood the surrounding area, destroying a lot of vegetation and even depleting the oxygen supply in the water because of garbage that gets stuck at the damn, therefore starving fish of oxygen and once again destroying fisheries.
Overall Times/ Flow Rates of Makeshift River:
Control test: Time = 1:53.8, 1:25.9 seconds
Flow Rate: 0.02197 Gal/sec, 0.02910 Gal/sec
Beaver Dam: Time: 2:01.6, 2:09.2 seconds
Flow Rate: 0.02056 Gal/sec, 0.01935 Gal/sec
1" Hole Hydro: Time : 2:54.5 seconds
Flow Rate: 0.01433 Gal/sec
2 .5" Holes Hydro: Time: 2:40.9 seconds
Flow Rate: 0.01554 Gal/sec
Overall Times/ Flow Rates of Makeshift River:
Control test: Time = 1:53.8, 1:25.9 seconds
Flow Rate: 0.02197 Gal/sec, 0.02910 Gal/sec
Beaver Dam: Time: 2:01.6, 2:09.2 seconds
Flow Rate: 0.02056 Gal/sec, 0.01935 Gal/sec
1" Hole Hydro: Time : 2:54.5 seconds
Flow Rate: 0.01433 Gal/sec
2 .5" Holes Hydro: Time: 2:40.9 seconds
Flow Rate: 0.01554 Gal/sec