updated groundwater_to_stream_recharge unit#15
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sivasankkar
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May 4, 2026
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| bmi_unit_conv.volQ_gw_timestep_m3_per_s = 0.0; | ||
| bmi_unit_conv.catchment_area_m2 = 1.0; |
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Is there a reasoning behind initializing the area to 1?
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Good catch. The 1.0 m2 value was only a placeholder, but it could produce physically incorrect discharge if the real catchment area is not provided. I changed the default to 0.0 and added a guard so the converted m3/s output remains 0.0 unless a valid positive catchment area is available. @sivasankkar
sivasankkar
approved these changes
May 5, 2026
sivasankkar
approved these changes
May 5, 2026
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https://jira.nextgenwaterprediction.com/browse/NGWPC-10214
Issue
groundwater_to_stream_recharge was originally exposed in m (depth per timestep), while NWM expects m³/s (discharge) for qBucket, causing: Unable to convert m to m3/s
Fix
A new BMI output variable was introduced: groundwater_to_stream_recharge_m3_per_s → m³/s
Computed as:
q = depth × catchment_area / timestep
The original variable remains unchanged:
groundwater_to_stream_recharge → m
Why
Preserves LASAM native semantics (depth remains depth)
Avoids repurposing existing variables
Aligns with NWM discharge requirements (qBucket)
Maintains consistency with updates in CFE and Sac-SMA
Result
Eliminates unit conversion warning
Produces physically correct discharge output
Maintains backward compatibility and clarity
Final Mapping
Variable Meaning Units
groundwater_to_stream_recharge groundwater recharge depth m
groundwater_to_stream_recharge_m3_per_s