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 183

According to Martin (2006), groundwater contribution to streamflow is
negligible, but this may be due to the fact it was not observed at the sub-
catchment level such as Atankwidi. The contribution of groundwater to
streamflow may be observed at a larger scale such as the the sub-basin level.

8.3 M ODEL D EVELOPMENT

The WEAP model entails several steps. The first step is the
parameterization of the study area and the time frame. Next is to create the
current account which adopts the existing situation of the start year. This
forms the basis for the modelling process. It is used for the calibration of the
model to mimic the existing situation of the study area. The current account
is then validated with another set of data for a different year. An automatic
reference scenario is generated from the current account upon which
scenarios can be created. The scenarios are used to explore the impact of
‚what if situations‛ such as change in demand, policies, water supply,
climate change, alternative assumptions or policies on water availability. The
final stage is the evaluation of the scenarios with regard to water sufficiency,
demand coverage, sustainability and sensitivity of the model to uncertainty
in key variables.
This section describes the manner in which WEAP works, the model setup
and how the model is developed up till the reference scenario.

8.3.1 Overview of WEAP Model

WEAP operates on the basic principle of a water balance and is applicable
to municipal and agricultural systems, single catchments or complex
transboundary river systems. Moreover, WEAP can address a wide range of
issues, e.g., sectoral demand analyses, water conservation, water rights and
allocation priorities, groundwater and streamflow simulations, reservoir
operations, hydropower generation, pollution tracking, ecosystem
requirements, vulnerability assessments, and project benefit-cost analyses
(WEAP, 2009).
In WEAP all elements (rivers, supply sources, demand nodes, reservoirs, and
gauges) have to be created. Data can be enterred or imported into WEAP.
Demand priorities are assigned to demand nodes and supply preferences
assigned to water supply sources. The Demand Priority represents the level
of priority for allocation of constrained resources among multiple demand
sites. WEAP will attempt to supply all demand sites with highest Demand
Priority, then moving to lower priority sites until all of the demands are met