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 186

After setting up the WEAP model, it is then calibrated for the streamflow
values to mimic the recorded streamflow at the measuring gauges. The
calibrated model is then validated using the data set for 2004/2005. After a
successful calibration, the current year is modified to generate a reference
scenario upon which other scenarios can be developed. The reference scenario
adopts the natural climatic variations projected over the study time frame.
In the reference scenario, the long-term annual mean rainfall for the study
area was used for the streamflow generation. The water year method was
used to modify the streamflow and groundwater recharge to depict the
climatic conditions of the projected study period. Thereto, five climatic
conditions (very dry, dry, normal, wet and very wet) were defined with
factors that were used for generating streamflows. The determination of
these factors is discussed in a later section.
Finally future scenarios based on policies, technological development and
climate change which affect demand, supply and hydrology were built on the
reference scenario.

8.3.3 Parameterization of the study area
The schematic layout of the area in WEAP uses a Geographic Information
System (GIS) based interface. The three sub-catchments were digitised as
vector files using GIS including the streams and large reservoirs in the study
area. They are added as vector layers in WEAP to form the background.

Table 8.2 : Modelled parameters for the three catchments.

P arameters Anayari Catchment Atankwidi Catchment Yarigatanga Catchment

River/stream Anayari stream and

three tributaries

Atankwidi stream and
three tributaries

Yarigatanga stream and
three tributaries

Groundwater
s ource

Groundwater storage
and recharge

Groundwater storage Groundwater storage and

recharge and recharge

Reservoirs Three small reservoirs. Three small reservoirs. Vea dam and three small

reservoirs.

Gauging Station none Kandiga station Sumbrungu station

Demand Nodes TSW, PSW, small
reservoirs, Rural
domestic & livestock

TSW, PSW, large
irrigation, small reservoirs,
riverine water, Bolgatanga
supply, Rural domestic &
livestock.
TSW - Temporal Shallow Wells, PSW - Permanent Shallow Wells, RAD - Riverine
Alluvial Dugouts

TSW, PSW, small
reservoirs, RAD, Rural
domestic & livestock

The rivers, tributaries, groundwater source, reservoirs, gauging stations,
demand nodes, transmission and return flow links are then created for each