validation of the new b2b bankless channel irrigation system model michael grabham, r. soppe, j....

Validation of the new B2B Bankless Channel Irrigation System model

Michael Grabham, R. Soppe,

J. Hornbuckle, R. Smith and S. Raine

Outline

System overview Hydraulic challenges B2B model Bay-scale comparison Whole field simulations Conclusions

System Overview

System overview

System overview

Why the system is being considered

Advantages– Labour savings– Can be automated– Machine efficiency– Expanded cropping options

Hydraulic challenges

Hydraulic challenges

Variable inflow rates Variable bay sizes Bay to bay hydraulic interaction

Time

Flo

w r

ate

Hydraulic challenges

Variable bay sizes– 60:100:40 bay ratios– Surface storage volume

accumulation– Interconnecting pipe size

selection– Drainage water minimisation

Hydraulic challenges

Hydraulic challenges

Hydraulic challenges

Hydraulic challenges

Bay to bay hydraulic interaction– Calculate the available

volumes– Calculate inflow rates– Select adequate bay

dimensions– Select adequate pipe sizes

B2B model

B2B model

Current simulation models– Single dimension– Variable inflow– Recession phase limitations– Assume free flowing drainage

B2B model

Clemmens’ (2007) surface irrigation design approach– Volume balance principles– Spreadsheet based– Simultaneously solves for

advance and inlet depth– Uses fixed inflow

B2B model

Darcy Weisbach equation

B2B model

Clemmens’ ApproachClemmens’ Approach

Darcy Weisbach equation

Bay scale comparison

B2B – Bay Scale Discharge

Errors from MeasuredwinSRFR = 65%SISCO = 65%

B2B = 18%

B2B – Bay Scale Advance and recession

B2B – Bay Scale Infiltrated depth

B2B – Bay Scale Simulation discrepancies

– Attributed to model assumptions

1. Level water surface

2. Friction ignored

3. Infiltration during recession

Field simulations

B2B – Field Scale Advance and recession

Bay 1

Bay 2

Bay 3

B2B – Field Scale

Depth

B2B – Field Scale

Inlet hydrographs

B2B – Field Scale

Inlet cumulative hydrographs

Conclusions

Novel approach taking into account bay-to-bay interaction

Enables simulation of multiple bay systems Discrepancies with known causes

Acknowledgements

CRC IF Postgraduate scholarship IAL and CRC IF Travel Fund grant CSIRO Land and Water, Griffith USQ, Toowoomba

Acknowledgements