A Comparison of the Lumped versus Distributed Model at the Lower Mississippi River Forecast Center
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Transcript of A Comparison of the Lumped versus Distributed Model at the Lower Mississippi River Forecast Center
Eric JonesSenior Hydrologist
Lower Mississippi River Forecast Center 89th AMS Meeting
• July 2007 - Began development and implementation• Used NWS OHD Research Distributed Hydrologic Model V2.0.
• SACSMA used for rainfall-runoff• No snow model used• Rating curve method of routing
• Initially used basins 3, expanded to 7• Calibrated before implemented• Verification done on initial three basins
• Black Creek at Brooklyn, MS (BKN)• Leaf River at Collins, MS (CLS)• Emory River at Oakdale, TN (OAK)
BKN
CLS
OAK
++=
Basin Model % bias Daily RMSE Corr Coef(CMSD)
CLS Distrib 0.25 46.38 0.724Lumped -14.10 41.84 0.748
BKN Distrib 9.41 18.94 0.810Lumped 14.97 15.29 0.791
OAK Distrib -1.28 44.06 0.889Lumped -15.88 41.74 0.895
• January 2008- October 2008• Simulated Lumped vs Distributed models
• Not adjusted to stage observations
• No runtime modifications included in lumped model• Statistics on forecasts +24 hours• Used quality controlled multi-sensor precipitation est.• Mean average PE used for distributed model
• Mostly computed PE used for lumped model
BKN
Distrib Lumped
CLS
Distrib Lumped
OAK
Distrib Lumped
BKN
Distrib Lumped
CLS
Distrib Lumped
OAK
Distrib Lumped
BKN
Dist Lump
CLS OAK
Dist Lump Dist Lump
One square = 4 km2
Distrib
LumpedObs
Distrib
Lumped
Obs
One square = 4 km2
Distrib
LumpedObs
One square = 4 km2
Distrib
Lumped
Obs
Distrib
Lumped
Obs
One square = 4 km2
One square = 4 km2
Distrib
Lumped
Obs
One square = 4 km2Distrib
Lumped
Obs
Distrib
Lumped
Obs
Distrib
Lumped
Obs
Distrib
Lumped
Obs
Unadjusted routing
Adjusted routing
Observed
Forecast
Flood stage
Observed
ForecastFlood stage
• Distributed model vs lumped model • Distributed model does better in some cases• Shape of distributed hydrograph appears to be better
• Suggestions for hydrologic forecasters • Should base forecasts using data from both models