Local Groundwater Flow Model Addendum Guadalupe Restoration Project San Luis Obispo County October...
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Transcript of Local Groundwater Flow Model Addendum Guadalupe Restoration Project San Luis Obispo County October...
Local Groundwater Flow Model Addendum
Guadalupe Restoration ProjectSan Luis Obispo County
October 24 2002
Reasons for LGFM Revision
• Excess water entering DSA from agricultural fields to the east
• Drainage channel along eastern DSA identified
• Update layer structure to conform with new data
• Overall goals: more realistic water balance, enhance model reliability
Model Revisions
• Changed layer structure– Base of DSA revised throughout GOF
– Top of PA conforms with Worts (1951)
• Included agricultural drainage channel
• Revised recharge and soil properties for agricultural fields
• Revised calibration targets and improved model calibration
Old Layer 5 Bottom
(gray)
New Layer 5 Bottom (colored)
Old DSA Bottom (gray)
New DSA Bottom (colored)
5.4
16.5
27.5
38.5
49.5
60.5
5.4 16.5 27.5 38.5 49.5 60.5
Observed Value
Layer 1
Layer 2
Layer 3
Layer 4
Layer 5
Layer 6
Observed vs. Computed Target Values
Recalibration Statistics
Statistic LGFM 2.0 LGFM 3.0
Number of Target Water Levels 368 355
Range of Water Level Targets (ft) 54.75 54.75
Maximum Residual Water Level (ft) 9.28 3.85
Minimum Residual Water Level (ft) -5.02 -4.57
Mean Residual Water Level (ft) -0.61 -0.04
Mean of Residual Absolute Values (ft) 1.53 1.29
Standard Deviation of Residual Water Levels (ft) 1.76 1.54
Sum of Squared Residual Water Levels (ft2) 1,280 846
Standard Deviation of Residuals/Range 0.032 0.028
How Has Flow Balance Changed?
Bottom OutflowBottom Outflow
Bottom InflowBottom Inflow
Lateral OutflowLateral Outflow
Lateral InflowLateral Inflow
Outflow to RiverOutflow to River
Willows OutflowWillows Outflow
Recharge Inflow
Recharge Inflow
Evapotranspiration Outflow
Evapotranspiration Outflow
Drain Outflow Drain Outflow
Flow Balance: Old vs. NewGOF Portion of Dune Sand Aquifer
LGFM 2.0 LGFM 3.0FlowComponent gpm Percent gpm Percent
Lateralinflow
194 24.2 83 12.3
Lateraloutflow
709 88.1 593 87.3
Rechargeinflow
565 70.3 565 83.3
ET outflow 77 9.6 63 9.2
Inflowthroughbottom
44 5.5 30 4.4
Outflowthroughbottom
18 2.2 23 3.4
Total 804 100 678 100
Dune SandAquifer
Whole ModelSubregion
Within DuneSand Aquifer
All LayersWithin
Subregion
Type Percent Change Percent Change Percent Change Percent Change
Lateral inflow -84 6 -57 1
Lateral outflow -13 2 -16 2
Willows outflow No willowspresent
0 No willowspresent
No willowspresent
Inflow fromriver
No river present 33 No river present No river present
Outflow to river No river present -61 No river present No river present
Drain outflow No drain present Added inLGFM 3.0
No drain present No drain present
Recharge inflow -1 -40 0 0
ET outflow -45 -45 -18 -18
Inflow throughbottom
22 0 -32 0
Outflow throughbottom
-22 0 28 0
Net OverallChange
-23 -15 -16 1
Flow Balance: Old vs. New
Conclusions
• Model is more realistic in several ways:– layer structure– drain and river– agricultural fields– water balance
• Complies better with conceptual model