Download - 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

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

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