LAR 512 – Fall 2002
PROBLEM #11 – CALCULATING DRAINAGE &
IRRIGATION
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Solve the following drainage and irrigation questions, using
data from <http://www.barrettkays.com/downloads/kays1979book.pdf>.
- Using
the laboratory macro-porosity for the Sudbury Type Location #1 A-horizon
(page 174) and the basic method described at page 10 of <http://www.barrettkays.com/downloads/urbanforestsoils_ch5.pdf>,
determine the irrigation capacity, the amount that can be held before
runoff occurs: _____1_____ inches
- Now
using the moist antecedent infiltration graphs for the Sudbury Type
Location #1 (top of page 245, 246, and 247) calculate the average
infiltration capacity:
_____1.4_____ inches (be sure to adjust from cm to inches)
- Now
using the wet antecedent infiltration graph for the Sudbury Type Location
#1-a (bottom of page 245, 246, and 247) calculate the average infiltration
capacity: ____0.27______ inches
(be sure to adjust from cm to inches)
- Now
using the moist antecedent infiltration graphs for the Sudbury Type
Location #1 (top of page 245, 246, and 247) use the average final constant
infiltration rate as the desired irrigation rate: _____.69_____ inches/hour (be sure to
adjust from cm to inches)
- Now
using the wet antecedent infiltration graphs for the Sudbury Type Location
#1 (bottom of page 245, 246, and 247) calculate the average final constant
infiltration rate as the desired irrigation rate: ____0.14______ inches (be sure to
adjust from cm to inches)
Which of the three irrigation
capacities (answers to questions 1, 2, and 3) would be best to both maximize
the volume of irrigation on a relatively flat site and avoid runoff except
during severe wet antecedent rainstorm events?
__________ inches; what would be the best irrigation rate (answers to
questions 4 and 5) that would best fit this situation? __________ inches/hour; please explain your choices __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
- Which
of the three irrigation capacities (answers to questions 1, 2, and 3)
would be best to both maximize the volume of irrigation on a hill side
site and avoid runoff except during severe wet antecedent rainstorm
events? __________ inches; what
would be the best irrigation rate (answers to questions 4 and 5) that
would best fit this situation?
__________ inches/hour;
please explain your choices
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
- Now
use the basic method described at page 12 of <http://www.barrettkays.com/downloads/urbanforestsoils_ch5.pdf>,
and using the average wet antecedent final constant infiltration rate for
the Sudbury Type Location #1 (bottom of pages 245, 246, and 247) as the
subsoil soil permeability, calculate the drain spacing of __________ feet,
(using a water table depth of 1 feet, desired water table depth of 3 feet,
subsurface barrier depth of 5 feet, depth of proposed drain lines of 4
feet, and a drainage coefficient of 0.25 inches/hour).