ewre99

Continental Scale River Flow Routing : 

presented by Kwabena Asante Dr David Maidment Dr Jay Famiglietti Dr Francisco Olivera Continental Scale River Flow Routing

Acknowledgements: 

Acknowledgements National Science Foundation EROS Data Center of the USGS GIS Hydro Research Group Global Hydrology Group Dissertation Committee

Outline: 

Outline General Introduction Database Construction Conceptual Basin Models Implementing the Models Comparing the Models Conclusions

Slide4: 

GIS Hydro ‘99: Digital Atlas Digital Atlas of the World Water Balance www.crwr.utexas.edu

1500 Major Drainage Basins: 

1500 Major Drainage Basins

Slide6: 

Cell-to-Cell Watershed Based Conceptual Models of a River Basin CTC HMS Source-to-Sink STS

Developing a HMS model: 

Developing a HMS model Delineate stream and watersheds Define routing parameters Calculate attributes Compute network connectivity Create and Edit Basin file Route by Muskingum Method

Developing a STS model: 

Developing a STS model Define sinks Delineate drainage basins Define sources Calculate attributes of sources Create input file for routing code Route by Diffusion Wave Method

The Congo Basin: 

The Congo Basin Area = 3.78 million km2 Mean flow = 45 000 m3/s 8 Countries

STS and HMS models of the Congo : 

STS and HMS models of the Congo Modeling Unit Size = 30’ (60 x 60 km) Number of Sources = 1378 Delineation Threshold = 1000 km2 Number of Subbasins/Reaches = 1791

Reason for the 3 day delay?: 

Reason for the 3 day delay? HMS Watershed lag time taken as the larger of (0.6 * longest flow time) and (3.5 * routing time step) 1550 out of 1791 watersheds Average watershed flow time = 1004.1 minutes Average HMS enforced lag time = 5273.8 minutes The difference = 4269.7 minutes = 2.965 days

Longitudinal Decomposability in HMS: 

Longitudinal Decomposability in HMS n = 4 n = 5 n = 6 n = 7 n = 8 reach length = 162,000 m flow velocity = 0.3 m/s muskingum K = 0.3

Slide15: 

Longitudinal Decomposability in HMS

Slide16: 

Longitudinal Decomposability in STS 2000 km 1000 km 1200 km 800 km

Slide17: 

Longitudinal Decomposability in STS

Effect of STS Modeling Unit Size: 

Effect of STS Modeling Unit Size Source size = 30’ (60 x 60 km) Source size = 10’ (20 x 20 km) Source size = 5’ (10 x 10 km)

Slide21: 

The Nile Basin Area =3.25 million km2 Mean flow = 2,500 m3/s

Slide22: 

Effect of Spatially Distributed Parameters ( Velocity & Dispersion Coefficient)

Conclusions: 

Conclusions STS model can be used to represent the hydrologic processes represented in a watershed based model STS model incorporating dispersion is longitudinally decomposable, hence the STS model is scale independent Spatially variable velocity and dispersion coefficients do make a difference and should be taken into account if variable parameter zones exist HMS imposed restrictions on parameters should be reviewed to establish a more scientific basis for imposition