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Gary R. SandsProfessor & Extension Engineer
grsands@umn.edu@UoMExtWater
for production and the environment
Controlled or ManagedDrainage Systems
Golden Rule of DrainageDrain only what is necessary for good soil conditions and
crop growth – and not a drop more
Production Environment
World Hypoxic Coastal AreasIncidents of hypoxia have increased 30-fold since 1960
Selman et al, 2008, World Resources Institute
MarFeb May Jun Jul Aug Sep Oct NovJan DecApr
DrainWatertable
Drainage
Outflow
(% change)
Nitrate Load
(% change)
Crop Yield
(% change)
-35 -34 1
Simulated conventional drainage and DWM at each site and computed change in nitrate loss.
Thorp et al., 2008
Computed fraction of cropland that is probably drained and suitable for DWM (slopes < 0.5%) using 1992 National Land Cover Data and STATSGO soils data.
Courtesy of Dan Jaynes, USDA-ARS, Ames, IA
… Water Management Zones
MgmtZone 1
MgmtZone 2
MgmtZone 3
MgmtZone 4
ELEV
INTERVAL
ZONE
Area?Area?
?
?
DWM Design Goals:
Large ZonesLess Expensive
But perhaps less effective
Small EIMore EffectiveBut smaller &
more zones ($$)
Topography can be our friend … or foe!
Image courtesy of Agri Drain Corp.
Image courtesy of Agri Drain Corp.
Image courtesy of Agri Drain Corp.
Image courtesy of Agri Drain Corp.
Image courtesy of Agri Drain Corp.
1 ft
Design with DWM in mind, so the practice can be implemented at some time
in the future….
Otherwise, the opportunity is lost forever!
No Opportunity to Manage DWM Capability
Tiling on the Coutours
ManagementZone 1
ManagementZone 2
• Each “zone” is served by a control structure.
• Think of the structure as the “outlet” for the zone.
CONTROL
ZONE 1
CONTROL
ZONE 2
CONTROL ZONE 1
CONTROL ZONE 2
CONTROL ZONE 1
CONTROL ZONE 2
Mgmt
Zone 1
Mgmt
Zone 2
Mgmt
Zone 3
Mgmt
Zone 4
Mgmt
Zone 1
Mgmt
Zone 2
Mgmt
Zone 3
Mgmt
Zone 1
Mgmt
Zone 2
2 Zones?
Mgmt
Zone 1
Mgmt
Zone 2
Mgmt
Zone 3
3 Zones?
Mgmt
Zone 1
Mgmt
Zone 2
Mgmt
Zone 3
Mgmt
Zone 4
4 Zones?
0 f
t.2
00
ft.
40
0 f
t.6
00
ft.
80
0 f
t.
To
po
gra
ph
y o
f D
rain
ag
e A
rea
0 ft. 500 ft. 1000 ft. 1500 ft. 2000 ft.
Iowa Drainage Example
53.0
54.0
55.0
90.0
OUTLET
0.5-ft contours
WM Zone = ____ ft
Number of Structures = ____Retrofit Design A
10
00
ft
1300 ft
52
53
OUTLET
0.5-ft contours
WM Zone = ____ ft
Number of Structures = ____Retrofit Design B
10
00
ft
1300 ft
56
57
58
OUTLET0.5-ft contours
WM Zone = ____ ft
Number of Structures = ____
10
00
ft
1300 ft
DWM Design
60
61
62
63
64
65
66
67
68
DWM in Summary…• DWM increases # of design considerations
– Yield, WQ, hydrology, management
• Field zoning is the major difference from conventional design
• Management becomes a consideration
• Design with DWM in mind so practice can be retrofit later!!
• Subirrigation is the next step, when irrigation may be needed & water supply is available
Drainage PublicationsUniversity of Minnesota Extension
www.DrainageOutlet.umn.edu
Questions?
Gary R. SandsProfessor, Bioproducts & Biosystems Engr.
grsands@umn.eduiMessage: grsands56@gmail.com
@UoMExtWater(612) 625-4756
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