External environmental forces operating on the water resource sector are shaping the sector and the associated modelling industry. Substantial political, social and economic changes have taken place in South Africa in the past decade. These changes have been bought about by profound political change, the influence of globalisation and substantial advances in computer and communications technology (Dent, 1999). The National Water Act (NWA – Act 36 of 1998) was formed in response to these external forces and is in itself an external force driving the water resources modelling community. Albert Einstein observed ‘The significant problems we face cannot be solved at the same level of thinking that we were at when we created them.’

The NWA calls for water to be used in the most equitable, efficient and sustainable manner. This requires a multi-disciplinary understanding and approach to water use. The Department of Water and Sanitation (DWAF) has identified the need to strategically view the planning and allocation of water resources in terms of water availability, the social and economic cost and benefits, the environment and the opportunity cost in the light of international needs and priorities.

A number of challenges face the successful undertaking of a SEA, including:

• South Africa has been divided into 19 WMAs, which are each governed by a Catchment Management Agency (CMA). Each WMA will probably require an SEA, which needs to be undertaken as soon as possible. The DWAF SEA does not have the capacity to meet this challenge. It has been decided that the DWAF SEA team will document the SEA process to be undertaken and will develop tools and methodologies to assist the multi-disciplinary SEA approach, which will then be made available to the WMAs as guidelines. The CMAs will be responsible for undertaking the SEA process themselves in consultation with the DWAF SEA team using the tools and guidelines provided by the DWAF SEA.
• The challenge of the SEA is to not only provide information regarding individual disciplines (the economy, the environment and society), but rather to provide integrated information (e.g. hydro-economic, socio-economic, environmental economic information). Tools, such as models, may need to be developed to generate the required multi-disciplinary information.
• The multi-disciplinary data may be required from a number of disciplines, as well as from a number of state departments (e.g. DWAF, DOA, DEA). The systems in which the required data are stored often differ. Sometimes a number of departments have access to the same type of data; however, the quality of the data differs. In other words, a large amount of time is spent obtaining and checking the data.

The objectives of this project include to

• identify the information and data requirements for the DSS;

• review the current hydrological modelling methodology used by DWAF which includes

• identifying weaknesses in the current approach; and
• formulating a new hydrological modelling methodology to realise a strategy whereby the SEA principles and practice are put in to place to support the implementation of the NWA;

• assess the development of a SEA database, in which data/information relevant to an SEA is

• drawn from other state databases;
• generated from SEA developed tools/models; and
• generated from discussions with stakeholders, water resource managers and other government departments.

• assess the development of a hydrologically focussed scenario generator, in which the database is seamlessly integrated with the ACRU hydrological model. The scenario generator is to be developed in ArcView (a GIS package) that allows the easy generation of selected water supply and water demand scenarios that are consistent with the NWA. The focus of the hydrological modelling is the generation of water quantity information; and
• assess the types of water quality related issues that may need to be included into the hydrological modelling application (either by further developing ACRU, or by linked another hydrological model/s to the database).

Therefore, the main objective of this project is to select a suitable database structure to be used by the SEA to store the multi-disciplinary information. The second objective is to develop an application for use with the database that automatically draws off the information from the database and writes the results back to the database.

The database linked to suitable applications is seen as the Decision Support system (DSS). Thus, the DSS consists of a number of applications feeding off, and writing to, a central database. No one tool or model is thus seen as the DSS, but rather the combination of all tools with the database.

The reason for developing the DSS is that it can be handed down to WMAs with the SEA guidelines. In this way, SEAs of a high quality may be undertaken throughout the country, with guidance by the DWAF SEA team. It also allows a consistent and transparent approach to be adopted in South Africa.

The success of a specific DSS is dependent on its ability to solve the problem it is trying to address, at the scale required and the extent to which it can support the decision making process. In the context of this review the DSS will be analysed in their ability to support the SEA in its objective of developing an overall framework approach to ensure South Africa’s water resources are utilised optimally in the short and long term to the best benefit of the people and environment of South Africa.

The philosophy used in tackling this document in not how the current set of modelling tools and methodologies can service the needs of the NWA, but rather a more rounded perspective of what tools and methodologies need to be put into place in order to service the water resource use and management community in implementing the NWA.