IMPACT OF INTENSIFYING IRRIGATION DEVELOPMENT AND IMPLICATIONS FOR SUSTAINABLE WATER RESOURCES MANAGEMENT IN THE WHITE VOLTA SUBBASIN - Sustainable Irrigation Development in the White Volta Sub-Basin - page 187

catchment (Figure 8.1) . The details of the catchment system parameters are
provided in Table 8.2.

8.3.4 Current accounts/Calibration

The objective of the calibration is to adjust streamflow parameters (run-off
coefficient) so as to reproduce observed streamflow readings in the
catchments. Monthly streamflow for 2005/2006 recorded at Kandiga gauging
station for the Atankwidi catchment and that recorded at Sumbrungu
gauging station for the Yarigatanga catchment were used for the calibration.
There are no streamflow recordings on the Anayari River.

In the streamflow calibration, the rainfall-runoff coefficients were estimated
from the streamflow and rainfall data for 2005/2006. Following results
validated for complete Volta Basin by Andreini et al., (2000), standard
fractions of runoff per month were used as headflows. The headflows were
enterred in the model with other data being streamflow gauges, water
demand for irrigation activities, livestock and domestic water needs for the
year 2005/2006. The initial reservoir level for Vea was obtained from the
management of the Vea dam. The rainfall-runoff coefficients were manually
adjusted for the model to produce streamflow values close to the measured
streamflow values at the gauges. The rainfall-runoff coefficients obtained
after the calibration are shown in Table 8.3.
Table 8.3 Rainfall-Runoff coefficient obtained after calibration.

Final Rainfall-Runoff Coefficient obtained from calibration

Yarigatanga
(Irrigated lands in Vea
scheme)
Catchment Area (km 2 ) 464 275 202 150
May 0.1 0.1 0.08 0.15
J une 0.15 0.15 0.2 0.25
J uly 0.2 0.2 0.24 0.33
A ugust 0.45 0.45 0.4 0.4
S eptember 0.38 0.38 0.35 0.35
October 0.25 0.25 0.25 0.25
November 0.03 0.03 0.03 0.03
December 0 0 0 0
J anuary 0 0 0 0
F ebruary 0 0 0 0
March 0 0 0 0
A pril 0 0 0 0
Average 0.130 0.130 0.129 0.147
In Table 8.3 the Yarigatanga catchment is divided into two parts (irrigated
lands in the Vea scheme and area outside the irrigation scheme) and given

Anayari Atankwidi Yarigatanga

(Area outside the
irrigated lands)