Definitions:

• „DSSs integrate various technologies and aid in option selection […] for solving relatively large, unstructured problems“

(Mbilinyi et al. 2007)

• “[…] Computer technology solutions that can be used to support complex decision making and problem solving”

(Shim et al. 2002)

In parallel with model code developments, DSSs have been developed over the years. A DSS can be characterized as interactive software, which assists in using data and information and providing answers for decision maker on complex issues.

Traditionally, DSSs have been used within many disciplines. In some cases within water resources management, the DSS concept has evolved independently of mathematical model codes, and in other cases as simple enhancements of existing mathematical model codes with a graphical user interface and a set of post-processing tools.

The DSSs have emerged in an attempt to make model codes more usable for water authorities, by building an information technology (IT) framework, which is tailored to the requirements of the decision-making process and supports the workflow of authorities. A DSS typically encompasses additional capabilities beyond the modelling framework, including tools for data and information management, socioeconomic evaluation tools and an (interactive) communication framework for sharing and disseminating information to the public, as illustrated in Table below.

Potential functionality	Potential use
Data base and processing environment	Coordinated use of available data bases Efficient use of all existing information Data review and data quality checking Data analysis and processing Identification of cost-effective monitoring programs
Knowledge and information system	Keeping track of basin studies and initiatives Knowledge sharing among relevant stakeholders Annotated bibliographies of available relevant literature Creating reports, e.g. Basin Plans and "The State of Basin Reports" and other material promoting public accountability
Modelling analysis frameworks	Hydrologic/hydrodynamic analytical tools covering multiple river basin aspects Sector analysis of water consumption and impacts (e.g. irrigation, hydropower) Environmental analysis (wetlands, flows, land-use change, water quality, sediment loads) Adaption to e.g. climate change
Socioeconomic analysis	Identification of sustainable options acceptable to stakeholders Multi-criteria analysis for the objective comparison of alternative plans Cost-benefit analysis Benefit sharing/trading
Communication framework (e.g. public web portal)	Stakeholder involvement Proactive information sharing and networking Supporting involvement of stakeholders Consensus building and conflict resolution Training activities

IWRM at the river basin level deals with many facets of water management, from striving for water security for all purposes in a sustainable and equitable manner to being able to manage and mitigate disaster risks. This can be supported by a DSS by developing and adding generic tools, many of which water resources planners may already be acquainted with from their daily work. Examples of such tools are:

• Web publishing
• Multi criteria analysis
• Time series processing
• Simulation codes
• Geographic Information Systems (GIS)
• Scripting
• Spread sheets

(GWP 2013b)