
Regionalisation
 transferring small-scale (or meso-scale)
measurements to a large scale (or basin or
regional) model
 Transferring from gauged catchments to
ungauged catchments
Calibrate model against control
catchments or long time series
 Catchment classification for regionalisation

(i) To regionalise three selected models in
three semi-arid secondary river basins
(ii) To compare the benefits and
weaknesses of the selected models in
the semi-arid environment

Flow duration curves
 Compare groups of FDCs using non-
parametric Kolmogorov-Smirnov test

Catchment characteristics
 multivariate statistical classification of
catchments based on biophysical
descriptors (discriminant analysis)
 determine relationships between biophysical
descriptors and hydrological parameters

Discriminant analysis
 Confirmed statistically differences between
Region IV and Region V

Flow duration curves
 Confirmed statistically differences between
sub-perennial and (sub-)ephemeral
catchment groups
 Did not confirm independence of
ephemeral catchment groups

Calibration: 60% CNS > 0.3

Regionalisation partially successful:
 40% CNS > 0.3
 Model performance best at 10 d

Parameter sets that performed best: slow
infiltration and percolation, moderate to
fast “overland” flow, less “baseflow”
 Mutangi

Sub-perennial catchments simulated well
 Successfully calibrated HDAM

Degraded catchments simulated poorly
 Proportion degraded land correlated to K0, fast
“overland” flow component
B72H
B72A
Calibrated in B72E, B72F, B72G
 Critical parameters were

› baseflow alpha factor
› curve number
› soil evaporation compensation
› soil available water capacity

Correlation coefficient 0.56

Correlation coefficient for calibration of
whole sub-catchment B72H: 0.51

Application to ungauged B72A

Based on
 geographical area
 spatial proximity
 shape of the flow duration curve (FDC)

SWAT regionalisation, Olifants Basin
SWAT application, Karkheh & Mzingwane
 HBV application, Mzingwane & Olifants
 HBVx application, Karkheh & Olifants

Challenge Program on Water and Food:
PN17 and PN57
 International Foundation for Science (DL)
 Echel Eau Foundation (MM)
 International Water Management
Institute (IM)
 Rand Water (MM)

Ministry of Energy, Meteorological
Organization and Agricultural Research
and Extension Organization of Iran
 Department of Environment and Water
Affairs of South Africa
 Department of Meteorological Services
and Zimbabwe National Water Authority
of Zimbabwe
