1. Parallel Computation of River Basin Hydrologic Response Using DHM
Reports Environmental Hydrology Team: NCSA Alliance All-Hands meeting
May 23-25, 2001 Urbana, Illinois
Baxter E.Vieux
Daniel Weber
Fekadu G. Moreda
Henry Neeman
Zhengtao Cui
Contact:
University of Oklahoma, Norman, Oklahoma

2. Overview Objectives The Distributed Hydrologic Model
Preparing the existing model for parallel computing
Parallelization
Time of computation
Coupling the model with ARPS

3. Objectives Near term Long term
Couple atmospheric model and surface runoff model for flood forecasting
Improve computational efficiency of surface runoff model
Long term
Integrate model into EH system

4. Runoff Simulation Watershed Finite Elements Grid Cell Resolution
Rainfall
Infiltration
Runon
Runoff
Stream
Overland
Direction
Flow
Characteristics
Channel Characteristics
- Cross-Section Geometry
- Slope
- Hydraulic Roughness
* Rainfall excess
at each cell
- Soil infiltration rate
- Rainfall rate
- Runon from upslope
Grid Cell Resolution
Finite Elements
Connectivity
Watershed
Simulation
This schematic diagram shows how runoff is routed from one grid cell to the next through the drainage network defined by the topography. 1

5. Digital Watershed

6. Arc.water.fea
Forecast Location

7. Model components Time static (Preprocessing) Time Dynamic
Importing DEM
Watershed delineation
Setup specific experiment
Time Dynamic
Extraction
Simulation
Routing

8. Preparing The Model for Parallel Computing
Optimizing the existing code (rewrite in C++)
Isolate the I/O operations

9. Parallelization
MPI
Load balancing algorithm

10. Load Balancing Algorithm
Processes (Descending loads) 1 2 3 4 5 6 7 8
Basin
Proc
Processor assigned in an alternate fashion

11. Illinois River Basin, In Okllahoma and Arkansas
Illionois river
at Tahek

12. Computation based on Subbasins
Total # Subbasins =57
Max# Grid cells
12231
Min # Grid cells 54

13. Load Balancing

14. Distribution of loads (16 Processors)

15. Distribution of load (4 Processors)

16. Time of computation
9 h
5 h
3 h
1h:30min
01:00:00

17. Prototype Operational Domain
Illinois River Basin
Area: 2400km2
Resolution 30m x 30m
#Subbasins 370
7 days of monitoring
Timestep = 2sec
Prediction: better load balancing

18. Coupling DHM with ARPS
Output of ARPS (Rainfall) -> Input to the surface runoff model
Flows at subbasin and river streams are predicted
Interface to run both models from web
Visualization of results (VisAD)

19. ARPS: Rainfall prediction:01h

20. ARPS: Rainfall prediction:02h

21. ARPS: Rainfall prediction:03h

22. ARPS: Rainfall prediction:04h

23. Flow Prediction

24. Discussion