EES215

Lecture 10

Review of hydrologic cycle

  • Precipitation pattern: High precipitation in tropical regions; low in subtropical regions; moderate in temperate regions; low in high latitudes à related to global wind pattern
  • River formation, river profile
  • Formation of meander; alluvial fan; flood plain


Uses of water: domestic - industrial - agricultural
Comparison of water uses in different countries
Typical water use in USA: 2160 m3/person-year; 12 % for domestic use; about 3 times the world average (related to high demand for industrial and agricultural uses)

St. Lawrence River system: competing interests: flood control; beach erosion; wet lands; boating; energy production
Calculation of residence time in Great Lake system: Residence time = (total volume)/flux

Calculation contained in hydropower E = mgh
m - mass; g - gravitational attraction (9.78 m/s2); h – height

Example: Niagara Falls: h = 55 m; flow rate  6060 m3/s

E = 6060 m3/s x 1000 kg/m3 x 9.78 m/s2 x 55 m = 3.260x109 [m kg/s3 = W]

Result in Ws/s = W; for calculation of energy: Energy = Power x time

Actually, about 1/3 of the flow is diverted into the power stations near Niagara Falls.

Comparison: Ginna Power Plant : 470 MW

Uses of rivers:

  • Hydropower
  • Transport
  • Flood control
  • Irrigation