The purpose of WRAM (Water ReAllocation Model) is to determine optimal water allocation and reallocation in terms of crop planting decisions and irrigation water requirements. As a by-product, WRAM simulates trading of water entitlements between irrigation areas, and generates water accounts for economic impact analysis. In addition, WRAM performs input-output analysis to evaluate the impact of water trading and reallocation on regional economy.

Existing and potential users of hydrologic simulation network models, i.e. IQQM and REALM water resource management models. The program is also of considerable use to environmental economists who are interested in water allocation and trading of water entitlements at the catchment scale.

WRAM is based on an economic optimisation algorithm. At its core is a powerful linear programming (LP) solver that maximises the net benefit subject to a series of land, water, capacity, and crop constraints. Basic understanding of environmental economics and hydrology, especially of natural resources allocation, crop water use, and water allocation would be useful. Generic optimisation packages such as GAMS and "What is Best?" could be used to performance similar analysis. However, these third party products cannot be deployed without incurring considerable cost. WRAM use algorithms that are as robust and sophisticated as those accessible through GAMS, and WRAM has been customarily designed for solving water allocation problems. WRAM has the additional functionality for input-output analysis.

WRAM has been applied to the 12-node and 58-node representation of the Murrumbidgee catchment. Efforts are underway to apply WRAM to the Nogoa-McKenzie catchment in Queensland.

With the advent of water reform framework instigated by the Council of Australian Governments (COAG), water trading on a temporary and permanent basis has become a prominent feature in all major irrigation areas in Australia. Hydrologic network models, although powerful in simulating entitlement-based water allocation at the catchment scale, are unable to deal with reallocation of water entitlements through trade driven by economic considerations such as crop and water price, variable production costs.

WRAM has the following features:

• Spatially explicit definition of irrigation areas (nodes)
• WRAM database support is compatible with Microsoft Access.
• Databases are geo-referenced where appropriate for integration in GIS
• Land, water, market, and rotation constraints on crops
• On-site and delivery constraints
• Robust and efficient LP solver
• Seamless integration with hydrologic network models such as IQQM and REALM
• Input-output analysis, water accounts, impact analysis
• Low cost