Joel Rahman

An integrated modelling framework for regulated river systems

Management of regulated water systems has become increasingly complex due to rapid socio-economic growth and environmental changes in river basins over recent decades. This paper introduces the Source Integrated Modelling System (IMS), and describes the individual modelling components and how they are integrated within it. It also describes the methods employed for tracking and assessment of uncertainties, as well as presenting outcomes of two case study applications. Traditionally, the mathematical tools for water resources planning and management were generally designed for sectoral applications with, for example, groundwater being modelled separately from surface water. With the increasing complexity of water resources management in the 21st century those tools are becoming outmoded. Water management organisations are increasingly looking for new generation tools that allow integration across domains to assist their decision making processes for short-term operations and long-term planning; not only to meet current needs, but those of the future as well. In response to the need for an integrated tool in the water industry in Australia, the eWater Cooperative Research Centre (CRC) has developed a new generation software package called the Source IMS. The Source IMS is an integrated modelling environment containing algorithms and approaches that allow defensible predictions of water flow and constituents from catchment sources to river outlets at the sea. It is designed and developed to provide a transparent, robust and repeatable approach to underpin a wide range of water planning and management purposes. It can be used to develop water sharing plans and underpin daily river operations, as well as be used for assessments on water quantity and quality due to changes in: i) land-use and climate; ii) demands (irrigation, urban, ecological); iii) infrastructure, such as weirs and reservoirs; iv) management rules that might be associated with these; and v) the impacts of all of the above on various ecological indices. The Source IMS integrates the existing knowledge and modelling capabilities used by different state and federal water agencies across Australia and has additional functionality required for the river system models that will underpin the next round of water sharing plans in the country. It is built in a flexible modelling environment to allow stakeholders to incorporate new scientific knowledge and modelling methods as they evolve, and is designed as a generic tool suitable for use across different jurisdictions. Due to its structure, the platform can be extended/customised for use in other countries and basins, particularly where there are boundary issues.

Making frameworks more useable: using model introspection and metadata to develop model processing tools

Abstract Several modern development environments allow executable components, such as hydrologic models, to carry metadata describing the properties and capabilities of the components. These metadata may be restricted to the names of variables, and their respective data types, or may extend to other information, such as classification of variables (e.g. input or output), numeric constraints on parameters (e.g. between 0 and 1, or greater than 0) or aliases (e.g. rainfall, also known as precipitation). Introspection in these environments allows tool developers to write programs and other components that make use of these metadata to provide generic model processing tools, while allowing model developers to take advantage of these tools without additional development effort. Typical model processing tools include model integration systems, parameter optimisers, automatic user interface generation and automated IO. One approach to implementing model introspection and metadata, used by the Interactive Component Modelling System (ICMS), is to extract information from a model when compiling a custom modelling language. An alternate approach, applied in a new modelling framework, relies on the language independent introspection provided by the .NET environment. These uses of introspection streamline model development within modelling frameworks, reducing the effort required to take advantage of other framework capabilities, such as dynamic visualisation. Introspection based systems, while introducing flexibility, defer until runtime various type checks that are typically performed by a language compiler. This introduces a performance penalty that may become significant in some circumstances.

Tarsier: a practical software framework for model development, testing and deployment

Abstract A new software framework for environmental simulation modeling is described. The framework facilitates fast, powerful model development by providing a system for implementing separate model elements as autonomous modules, which may then be tightly and flexibility integrated. The system is object-oriented, with integration of modules achieved through the sharing of common objects. Module autonomy is achieved by the use of generic messages passed between modules through shared objects. Shared objects represent concepts such as data, time, or sub-models. This facilitates effective model integration with no loss of speed as a result of the integration process. A large existing collection of modules, including IO, data representation and visualization, allows new models to be developed quickly with minimal attention to repetitive tasks. To date, the applications of the framework have been in the domains of hydrological, wildlife and ecosystem modeling. Experience has shown that the persistent merits of the framework include the data sharing/message passing approach, the generic conceptualization of modeling objects, and the body of modules assembled to date. The disadvantages are proving to be the dependence on a specific language and compiler. This hinders the utility of the framework for the broader model development community.

Tarsier and ICMS: two approaches to framework development

Modelling frameworks provide models with support components that handle tasks such as visualisation, data management and model integration. Within these broad requirements different approaches to framework development are possible. Tarsier is a modelling framework that supports the development of models in a high-level language, such as C++. This approach allows Tarsier model developers to craft object oriented solutions to large modelling problems. ICMS is a software system that supports the development of models in a custom modelling language that allows modellers with little programming experience to develop, integrate and visualise catchment models. Both frameworks provide sophisticated tools for model linking, data management, and data analysis and visualisation. By focusing on different user groups, Tarsier and ICMS have evolved into quite different environments, yet both satisfy the definition of a modelling framework. This paper concentrates on the components within each framework and the strengths and weaknesses of the different approaches.