SOURCES OF WATER FOR DEVELOPMEMT. SURFACE WATERS SURFACE RUNOFF FROM SMALL WATERSHEDS STREAMS LAKES GROUND WATER WELLS SPRINGS DUGOUT PONDS. SURFACE WATER DEVELOPMENT. Advantages of Surface Water Development Very large quantities can be obtained
SOURCES OF WATER FOR DEVELOPMEMT • SURFACE WATERS • SURFACE RUNOFF FROM SMALL WATERSHEDS • STREAMS • LAKES • GROUND WATER • WELLS • SPRINGS • DUGOUT PONDS
SURFACE WATER DEVELOPMENT • Advantages of Surface Water Development • Very large quantities can be obtained • Disadvantages of Surface Water Development • More subject to drought restrictions • Lower quality water
GROUND WATER DEVELOPMENT • Advantages of Ground Water Development • More dependable during dry years • Generally better water quality • Disadvantages of Ground Water Development • Limited available quantity
CROSS-SECTION OF AN AQUIFER Non-flowing artesian well Flowing Well artesian pressure Ground Surface water table Unconfined Aquifer Artesian Aquifer
CROSS-SECTION OF AN AQUIFER Perched Water Table Spring Ground Surface Regional Water Table
DEFINITION OF GROUND WATER TERMS • ARTESIAN WELL: A well which taps an artesian aquifer where water is under pressure and will rise in the well above the top of the aquifer. • DRAWDOWN: The vertical difference between the static or non-pumping water level in a well and the water level during pumping.
WATER WELLS GROUND SURFACE STATIC WATER TABLE
WATER WELLS Q GROUND SURFACE STATIC WATER TABLE Pumping Water Level
WATER WELLS Q GROUND SURFACE STATIC WATER TABLE Drawdown Curve
DEFINITION OF GROUND WATER TERMS • SPECIFIC CAPACITY: The pumping rate divided by the drawdown in the well. (example GPM/FT). • A good way to compare wells. • A high specific capacity requires less power to obtain the same amount of water from a well, or will obtain more water for the same amount of pumping power supplied
Artesian Wells • Take water from an aquifer that is under pressure • Are not always flowing wells • Have a large radius of influence • Have low specific capacity
Power Required to Move Water • Q = Gallons/Minute • g = Water Density = 8.34 lb./Gallon • H = potential as head in feet • Horsepower = 33000 Ft-lb/Minute • 33000 / 8.34 = 3957 • Water Power = QgH Ft-lb/Minute Eq. 10.4
EXAMPLE: • Static water level in well is 15 feet below the ground surface • Well pumped at a rate of 100 GPM for 12 hours. • Water level in well at end of 12 hours is 30 feet • Drawdown = 30 - 15 = 15 feet • Specific Capacity = 100/15 = 6.67 GPM/ft
EXAMPLE: • In comparing two wells we find that one has a Specific Capacity of 10 GPM/foot of drawdown and the other has a specific capacity of 20 GPM/ft. How much more power will it take to pump 500 Gallons Per Minute from the first well than from the second well?
EXAMPLE: • The drawdown in the first well will be 500 GPM/10 GPM/foot = 50 feet. • The drawdown in the second well will be 500 GPM/20 GPM/foot = 25 feet • The difference in drawdown will be 50 - 25 = 25 feet
EXAMPLE: From Equation 10.4 on page 181 in the course text, the difference in water power will be:
Water Pumping Power Problem • Pumping Rate = 200 GPM • Static Water Level = 20 feet • Pumping Water Level = 40 feet • Pump Efficiency = 70% • Determine the power required for this well.
WATER LAW RIPARIAN DOCTRINE: Every riparian owner has equal right to water use. Only workable when the water source is not limiting. The basis for water law in the eastern US and in humid parts of the world.
WATER LAW DOCTRINE OF PRIOR APPROPRIATION: Use of water is based on historic use. Water rights can be bought and sold just like land titles. Used where water source is limited. The basis for water law in the western US and in arid parts of the world.
IOWA WATER LAW • Non-regulated uses: • Domestic household and livestock • Any beneficial use less than 5000 gallons per day • Any beneficial use of Iowa border waters. • Any existing beneficial use within municipalities as of May 15, 1957.
IOWA WATER LAW • Regulated uses (permit required) • Any use of more than 5000 gallons per day • Any discharge of surface water underground. • Any increase of municipal or industrial use of more than 3% over per-law daily peak use rate.
IOWA WATER LAW • Regulated uses (permit required) • Any water storage of 18 acre-feet or more. • Construction of a dam with 5000 acres drainage area or more. • Construction of any flood plain encroachment on any stream with 10 square miles of drainage area or more.