Deep Percolation and Groundwater Level Response Following Surface Irrigation

Carlos Ochoa, Sam Fernald, Steve Guldan, Manoj Shukla

Funding sources:USDA CSREES NRI, New Mexico Agriculture Experiment Station.

Rio

Gra

nde

Irrig

atio

n di

tch

Farm scale

Valley scale

Basin scale

• USDA CSREES-funded study to determine seepage effects on Rio Grande flow in an irrigated valley in northern New Mexico (2004-2009). NMSU-Sustainable Agriculture

Science Center

• Deep percolation from irrigation can provide a fair amount of water recharge to shallow aquifers.

Time

10:00 AM 6:00 PM 2:00 AM 10:00 AM 6:00 PM

Water level (m

above sea level)

1727.0

1727.2

1727.4

1727.6

1727.8

Well 1Well 2Well 3Well 4

Irrigation

Previous study findings (2004-2007) – Deep percolation:

• A 15-62% Dp in an alfalfa field with sandy-loam soil

• A 14-42% Dp in an apple orchard with sandy-clay and clay soil

• Rapid water level response and water level rise up to 35 cm

Soil moisture sensorsAlfalfa field

• Determine deep percolation following flood irrigation in two

crop fields with different soil type.• Assess the performance of the Root Zone Water Quality Model

in simulating deep percolation.

Study objectives:

Shallow Aquifer

1 m

Deep percolation

• Characterize groundwater level fluctuations in response to

deep percolation inputs.

Experimental design:

• Two 100 m by 100 m fields

• Two soils: Fruitland sandy-loam and Werlog clay-loam

•Shallow water table (sandy-loam = 4 m and clay-loam = 2.8 m)

• Surface (flood) irrigation

• Cover crop (oats/grass mix)

• Parameters: • Irrigation depth• Soil water content• Field runoff• Water level

Sandy-loam

Clay-loam

NMSU-Sustainable Agriculture Science Center

METHODS

DP = SWCi + IRR + P - SWCfc – RO – ET

Measured and simulated deep percolation

• A daily water balance method based on field measurements

• The Root Zone Water Quality Model – Hydrology component

• Crop type• Rainfall data• Meteorological data• Soil horizons and properties• Water applied

• Deep percolation

Input Output

N

Soil moisture station

100 m

100

m

Fie

ld r

unof

f

Propeller flow meter

Flow

Water source

Driven point well

Open channel-flow meter

Slope

Field data collection – Schematic of instrumentation

Outer well

soil moisture station/well

N

Irrigation applied and field runoff

Irrigation applied

• 12 irrigation events in each field (2008-2009)

• Variable irrigation depth (4 to 22 cm)

Field runoff

• Open channel S-M flume with pressure transducer

Propeller flow meter

S-M flow meter

Soil water content and groundwater monitoring

• Vertical nests of soil moisture sensors

• Driven point wells equipped with water level loggers

• Instrumentation installed and soil repacked 15 months prior to this experiment

50 cmSoil moisture sensors

Clay loam Sandy loam

Well

RESULTS

DateDuration

(h)SWCi (cm) IRR (cm) P (cm)

SWCfc (cm) RO (cm) ET (cm) DP (cm) DP (%)

6/16/08 27.0 14.0 26.7 0 28.5 4.2 0.9 7.1 26.67/1/08 8.8 22.9 9.6 0 28.5 2.2 0.5 1.3 13.37/14/08 11.5 23.2 12.5 0 28.5 4.0 0.4 2.8 22.48/7/08 8.0 19.1 8.7 0 28.5 3.9 0.4 0.0 0.09/11/08 7.5 18.8 7.4 0 28.5 1.6 0.4 0.0 0.010/20/08 7.5 16.7 4.1 0.2 28.5 0.0 0.3 0.0 0.05/6/09 7.1 16.7 8.4 0 28.5 0.8 0.9 0.0 0.06/4/09 8.8 14.4 11.7 0.36 28.5 2.4 0.8 0.0 0.06/25/09 7.2 22.2 8.5 0 28.5 0.8 0.7 0.8 9.47/20/09 6.8 17.4 8.5 0 28.5 0.2 0.8 0.0 0.08/10/09 7.0 18.0 8.5 0 28.5 0.9 0.9 0.0 0.09/1/09 6.7 17.3 10.1 0 28.5 3.5 0.4 0.0 0.0

• Deep percolation (DP) observed in 4 out of 12 irrigation events

• DP ranged from 9 to 27 %

Fruitland sandy loam soil:

Werlog clay loam soil:

DateDuration

(h)SWCi (cm) IRR (cm) P (cm)

SWCfc (cm) RO (cm) ET (cm) DP (cm) DP (%)

6/10/08 26.5 35.0 21.1 0.0 38.2 1.4 0.9 15.6 74.16/24/08 23.0 35.1 18.7 0.0 38.2 1.7 0.7 13.1 70.17/7/08 11.5 35.8 8.5 0.0 38.2 0.9 0.4 4.9 57.68/12/08 7.0 23.4 5.9 0.0 38.2 0.0 0.4 0.0 0.09/9/08 7.6 20.8 8.1 0.0 38.2 1.1 0.5 0.0 0.0

10/28/08 7.6 18.5 4.2 0.03 38.2 0.0 0.4 0.0 0.04/29/09 9.4 24.8 12.2 0.0 38.2 0.2 0.8 0.0 0.05/21/09 8.0 27.5 9.7 0.0 38.2 0.5 0.4 0.0 0.06/15/09 7.7 27.3 9.3 0.0 38.2 0.7 0.8 0.0 0.07/13/09 7.2 17.4 8.8 0.0 38.2 0.1 1.0 0.0 0.07/27/09 7.0 18.4 8.5 0.0 38.2 1.6 0.9 0.0 0.09/2/09 7.3 14.3 10.3 0.0 38.2 0.6 0.4 0.0 0.0

• When DP present, high antecedent soil moisture observed

• DP ranged from 58 to 74 %

Field-measured (DWBM) versus simulated (RZWQM) DP:

• Regardless of soil type, preliminary simulated results with

minimum input data show a fair agreement with field-measured

based deep percolation.

Water level response: Werlog clay-loam field

• Water level rise of up to 16 cm observed following highest IRR.

IRR = 23 cm

Water level response: Fruitland sandy-loam field

• Water level rise of up to 2 cm in the midfield well following

highest IRR.

IRR = 26.7 cm

Water level response: Fruitland sandy-loam field

• In general, muted water level response (0 to 2 cm) observed

following IRR.

Conclusions• Regardless of soil type, deep percolation was only

observed during few irrigation events.

• Higher antecedent soil moisture and shallower water

table contributed to greater deep percolation and

higher water table rise in the clay loam soil.

• Fair agreement between simulated (RZWQM) and

field-measurement (DWBM) DP.

• In general, lower water level rise and longer time of

response when compared to previous study results

(Alfalfa and Apple fields).

• Water level rise of up to 8 cm in the midfield well following IRR =

23 cm.

Water level response: Werlog clay-loam field