BushTender

1
Integrating spatial and temporal information

• Craig Beverly1, Mark Eigenraam2 and Mark Hocking3
  
• 1 DPI Rutherglen
• 2 DPI Melbourne
• 3 Hocking et al.

2
Presentation Outline

• Overview
• Conceptual model
• Model components
• Conclusion
• Application / demonstration

3
Modelling Rationale

• Cause (landscape intervention) and effect
  (external cost or benefit) are separated by space
  (sometimes hundreds of kilometres) and time
  (sometimes many decades).
• The outcome of an action is exhibited elsewhere
  within the catchment
• Also, it takes time for effect to be observed
• This suggests that any assessment of the
  potential impact of landscape intervention, will
  need to be estimated (that is derived from
  models) rather than directly observed.

4
Conceptual model
5
Drivers of environmental impacts

• Climate (temporal)
• Surface cover (pasture, forestry,
  crops) (spatial)
• Soil evaporation, transpiration
• Soil condition (spatial)
• Excess(runoffrecharge)
• Groundwater (spatial)
• Discharge, baseflow

6
Simplified process
Climate
Surface cover
(assuming no change in soil moisture)
Excess
soil,slope
Recharge
Stream
7
Water excess by climate
8
Water excess by cover
9
Water excess by cover
Wheat rotation
Depth
Time (0.5 year increments)
Wheat / Lucerne
10
Soil profiles
Sandy
Duplex Clay
11
Soil / water / plant dynamics
Excess
Soil capacity
Plant wilting point
12
Water excess by soil types
13
Groundwater

• Groundwater occupies the zone of saturation.
• The water table separates the zone of saturation
  (groundwater) from the zone of aeration
  (unsaturated soil zone).
• Groundwater is found in aquifers as unconfined
  (at atmospheric pressure as surface) or
  confined (under pressure between impermeable
  layers).
• Water enters the groundwater as recharge, and is
  removed as discharge to streams, surface
  waterlogging etc.

14
Groundwater
15
Location
16
Layer 4 Bedrock
17
Layer 3 Weathered Bedrock
18
Layer 2 Deep Leads
19
Layer 1 Quaternary Alluvium
20
Groundwater
21
Layer 1 Calibration Traces
22
Model Outputs
Land management scale
Catchment scale

• Groundwater discharge (Ml)
• Stream salinity
• End-of-valley response
• Impact of pumping
• Zones of saturation (ha)

• Surface runoff (mm)
• Deep drainage (mm)
• Soil moisture content (mm)
• Water yield (mm)
• Evapotranspiration (mm)
• Sediment yield (metric tonnes/ha)
• Organic nitrogen yield (kg N/ha)
• Nitrate nitrogen yield (kg N/ha)
• Biomass (metric tonnes/ha)
• Harvested yield (metric tonnes/ha)

23
Conclusion

• The derived simulation results show good
  agreement between recharge estimates, observed
  stream flow and available experimental data using
  commonly available data sets
• Reported results suggest that this framework
  coupling one-dimensional farming system models
  can be used to assess the off-site impacts of
  land management decisions on catchment hydrology
• Incomplete information leads to poor
  understanding of catchment dynamics (eg recharge
  groundwater response)
• Current application EcoTender.

24
Demonstration
25
End of presentation
26
Response times