Best Practice in Conceptual Modelling for Environmental Software Development

Conceptual modelling is used in many fields with a varying degree of formality. In environmental applications, conceptual models are used to express relationships, explore and test ideas, check inference and causality, identify knowledge and data gaps, synchronize mental models and build consensus, and to highlight key or dominant processes. Conceptual model representations range from simple box and line interaction diagrams, through interaction representations and causal models, to complicated formal representations of the relationships between actors or entities, or between states and processes. Due to their sometimes apparent simplicity, the development and use of a conceptual model is often an attractive option when tackling an environmental problem where the system is either not well understood, or where the understanding of the system is not shared amongst stakeholders. However, we have experienced many examples where conceptual modelling has failed to live up to the promises of managing complexity and aiding decision making. This paper explores the development and application of conceptual modelling to environmental problems, and identifies a range of best practices for environmental scientists and managers that include considerations of stakeholder participation, model development and representation, integration of different and disparate conceptual models, model maturation, testing, and transition to application within the problem situation

The actor - driven dynamics of decarbonization

Climate change represents an unprecedented challenge in the history of humankind. It requires not only a transformation of the present fossil-fuelled global economic system to a sustainable system based on renewable energy, but, equally important, a reorientation of the relations between nations from the present system of individual competition to a global cooperative network of interdependent entities striving to preserve a common habitable planet. Science can facilitate these transitions by analysing the conflicts of interest and inherent rigidity of perceptions that are presently hindering progress in both areas of transformation. But scientists should investigate not only the difficulties, but should also identify and highlight the most promising paths for overcoming the analysed hindrances. This is an essential pre-condition for creating the necessary incentives for effective social, economic and political action

Pricing strategies in inelastic energy markets : can we use less if we can’t extract more?

Limited supply of nonrenewable energy resources under growing energy demand creates a situation when a marginal change in the quantity supplied or demanded causes non-marginal swings in price levels. The situation is worsened by the fact that we are currently running out of cheap energy resources at the global scale while adaptation to climate change requires extra energy costs. It is often argued that technology and alternative energy will be a solution. However, alternative energy infrastructure also requires additional energy investments, which can further increase the gap between energy demand and supply. This paper presents an explorative model that demonstrates that a smooth transition from an oil-based economy to alternative energy sources is possible only if it is started well in advance while fossil resources are still abundant. Later the transition looks much more dramatic and it becomes risky to rely entirely on technological solutions. It becomes increasingly likely that in addition to technological solutions that can increase supply we will need to find ways to decrease demand and consumption. We further argue that market mechanisms can be just as powerful tools to curb demand as they have traditionally been for stimulating consumption. We observe that individuals who consume more energy resources benefit at the expense of those who consume less, effectively imposing price externalities on the latters. We suggest two transparent and flexible methods of pricing that attempt to eliminate price externalities on energy resources. Such pricing schemes stimulate less consumption and can smooth the transition to renewable energ

StellaR: A software to translate Stella models into R open-source environment

Stella is a popular system dynamics modeling tool, which helps to put together conceptual diagrams and converts them into numeric computer models. Although it can be very useful, especially in participatory modeling, it lacks the power and flexibility of a programming language. This paper presents the StellaR software which translates a Stella model into a model in R, an open source high level programming language. This allows using conceptual modeling tools provided in Stella, together with computational functionality and programming flexibility provided in R. It also opens access to powerful software libraries available in R, which is especially useful for spatial modeling

Effective engagement of stakeholders in Total Maximum Daily Load development and implementation

Total Maximum Daily Loads (TMDLs) identify the maximum amount of pollution that a water body can receive and still support its designated uses and allocates the maximum load to specific sources in the watershed. In the United States, The Clean Water Act requires public participation in the process of TMDL development. This requirement has been met through simple presentation of results at public meetings, strategic partnerships with key stakeholders, and/or to advisory committees in which stakeholders participate in critical decisions about TMDL definition and implementation. These decisions include model selection and assumptions, selection of water quality endpoints, load allocations, TMDL review, and implementation planning. In this article, we discuss the benefits and challenges of early and targeted engagement of stakeholders in TMDL development through a participatory modelling process based on our experience in Utah and Vermont

A computational study on the influence of urban morphology on wind-induced outdoor ventilation

Accurate modeling of urban wind flow is important for the assessment of the natural ventilation of the outdoor environment and therefore for outdoor air quality. Different geometrical levels of analysis can be used, ranging from regular arrays of obstacles to real and complex case studies. In order to avoid the complexity of real case studies and to obtain more generic results, regular arrays of obstacles represent a suitable level to study the relation between urban morphology and outdoor ventilation. This paper presents the first results of a numerical study with Computational Fluid Dynamics (CFD) of isothermal wind flow in generic urban configurations. Nine urban configurations are defined with regular arrays of obstacles by increasing the plan area density (from 0.1 to 0.6) and the frontal area density (from 0.02 to 0.45). By this variation, the flow structure varies from isolated obstacle flow over wake interference flow to skimming flow. Among the nine configurations defined, four test cases are selected for a preliminary study. 3D steady Reynolds-Averaged Navier-Stokes (RANS) CFD simulations are performed for the four selected configurations and the simulations are compared with experimental wind-tunnel data. An overall fairly good agreement is found between the experimental and numerical results obtained with RANS simulations. The results allow establishing some relationships between morphological and fluid dynamics parameters of urban wind flow and outdoor ventilation. It is found that the upstream building density can cause a decrease of up to the 70% of the ventilation rate in the central street. Further work will focus on extending this parametric analysis and extrapolating it to real cities