Wflow OpenStreams

A short description and selected case studies

Hydrological models wflow*

• Fully distributed

• Source maps needed:

• DEM

• Land-use [can be uniform]

• Soil [ can be uniform]

• Preparation script that performs the landscape analysis (catchment delineation etc.)

• All model parameters linked to land-use/soil maps

• Can perform state updating in real-time applications

• Written in python and pcraster

• Flexible and open

• Part of the Deltares OpenStreams Initiative (www.openstreams.nl)

Doc and source via wflow.googlecode.com

Why python/pcraster?

• Can use (parts of) exiting pcraster modules• Can use python for generic programming (command-line options,

reading XML, updating, debugger, IDE etc)• Free! (as in Speech and Beer) • Fast! If you can avoid loops and perform all operation on

vectors/matrices• Other operations can also be done in python:

• Retrieving ftp data, link to openDAP

• Data copying and cleaning

• Logging

• Plotting and analysis (similar to Matlab)

• etc.

Why another model?

• We used existing concepts and put them in a new framework• The models available balance between conceptual and physical

representation of the catchment• New data sets (DEM, RS data etc) cannot be used by many

existing models -> this framework should allow that• This models maximize the use of available (spatial) data• They Can be used in data rich and data sparse environments

Currently available

• wflow_sbm.py – Simple Bucket model (physically based) that includes lateral groundwater flow and used a exponential decay of Ksat with depth

• wflow_hbv.py – distributed version of the conceptual HBV96 model

• wflow_W3RA.py – A global hydrological model using two vegetation fractions (CSIRO)

• wflow_gr4.py – a distributed version of the gr4 model (CEMAGREF)

• wflow_routing.py – a kinematic wave based routing model (can use input from the hydrological concepts)

• wflow_wave.py – a dynamic wave model that can be run nexted in the wflow_routing model for the main rivers

• wflow_floodmap.py – a simple flood mapping routine that can be used a as step after wflow_routing of wflow_wave

Scale, grid size

Estimated grid size constraints based on the concepts in the model

•wflow_sbm.py – 5x5m to 4x4km•wflow_hbv.py – 500x500m 40x40km•wflow_W3RA.py – 10x10km to 0.5x0.5 degree•wflow_gr4.py – 500x500m 40x40km•wflow_routing.py – 5x5m to 0.5x0.5 degree •wflow_wave.py – 5x5m to 1x1km•wflow_floodmap.py – 5x5m to 1x1km

Clearly, these are very rough estimates, based on actual applications and expert judgemend, YMMV!

Applications

Typical applications of the models. Theseare estimated and the model are not specifically designed for these application. In addition, the model can also be used for other applications.

•Process hydrology – wflow_sbm, wflow_W3RA•Water resources – wflow_sbm, wflow_W3RA•Flow forecasting – wflow_hbv, wflow_gr4, wflow_sbm, wflow_routing, wflow_wave•Climate change impact – wflow_sbm, wflow_hbv, wflow_W3RA•Land use change impact – wflow_sbm, wflow_W3RA, wflow_hbv

Ok What can it do?

• Simulations of water level and discharge (for simulations or operational purposes)

• Investigate the effect of a changing environment (climate, land used, e.g. urbanisation)

• Can work on different catchment sizes

• All variables are distributed in space

• Can start simple and expand later on

Bandung

Rhine

1: Terrain analysis

1. Optional cutout part of DEM

2. Set outlet at lowest gauge and extra points (for later output) at other gauges using gauge coordinates

3. Determine river network (can use existing to burn-in if needed)

4. Determine LDD and sanitized DEM

5. Resample land-use map to DEM

1: Terrain analysis

wflow_catchment.map

wflow_dem.map

wflow_gauges.map

wflow_landuse.map

wflow_ldd.map

wflow_river.map

wflow_streamorder.map

wflow_subcatch.map

….

These maps (the model structure can be used by all models

2: Model parameters

• All parameters are linked to land-use/soil types via so called lookup tables

• Links parameters to land-use map and/or soil map

• Calibration/Verification step

Detail wflow_sbm

The processes: Interception

• Rainfall interception via Gash model → daily timesteps

The processes: The soil

• Soil accounting scheme based on TOPOG_SBM (Vertessy and Elsenbeer 1999)

• Schematic representation of the hydrologic processes modeled by Topog_SBM. Symbol definitions:

• rf, rainfall; in, infiltration; st, transfer between unsaturated and saturated zone; ie,

• infiltration excess; se, saturation excess; ex, exfiltration; of, overland flow; and sf, subsurface flow.

The processes: The soil

•Inputs to the model:

• Et + Es from the canopymodel

•Total throughfall + stemflow from the canopy model

•Determines:

•In- exfiltration

•Lateral saturated flow

•Transfer between saturated and unsaturated store

•Reduces Et + Es to an 'actual evaporation' if water stress occurs (takes rooting depth into account).

•Surface runoff via kinematic wave -> wflow_routing

The processes: The soil

• Ksat decreases exponentially in depth (M parameter)

• Transfer between unsaturated and saturated store based on K at that depth

• Infiltration can include

• sub-cell parameters for % of compacted soil.

Effect of the M parameter

Guinea

Flow from rivers needed for coastal study

Q only for one (small) station

No P and ET

Setup:• DEM and catchment from SRTM• Uniform soil, parameters estimated (soil depth from landscape)• P from TRRM, ET from re-analysis• Run for 10 years to get flows

November 30 2011

November 30 2011

Guinea

Rainfall

November 30 2011

November 30 2011

Guinea flow

Wflow_sbm for Rhine

• Description of the model at www.openstreams.nl• In short:

HBV Snowmelt

Mass wasting of snow

Gash rainfall interception

Topog_SBM soil

Soil temp for frozen soil

Kinematic wave

November 30 2011

Wflow_sbm for Rhine

• Soil decrease of Ksat with depth• Subgrid saturation depending on altitude in a cell

November 30 2011

Calibration for Rhine: http://schj.home.xs4all.nl/html/calib_report.html

• EOBS Precip and Temp -> ET derived from EOBS using Hargreaves• 1985 – 1995:

Rhein-Basel, Rheinhalle

Kalkhoven

Rockenau

Kaub

Koeln

Lobith

Raunheim

Cochem

Andernach

Maxau

Schermbeck

Menden

Hattingen

November 30 2011

November 30 2011

November 30 2011

November 30 2011

Link to delwaq (Fraction calculations)

Link to delwaq (Fraction calculations)

Thanks!

For more information:• www.openstreams.nl• Jaap.schellekens@deltares.nl