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