System Dynamics Modelling Approach Research Articles

Reliability Assessment of the Water Supply Systems under Uncertain Future Extreme Climate Conditions

Abstract Increase in global mean temperature and changes in rainfall amount, pattern, and distribution over the world are all indicative of climate change events. These changes alter the hydroclimatic condition of regions as well as the availability of water resources. In this study, the data generated by 14 general circulation models (GCMs) developed under the Special Report on Emissions Scenarios (SRES) A1B, A2, and B2 are downscaled and utilized to evaluate climate change impact on the hydroclimatic system of the Karaj River basin located in central Iran. The precipitation and temperature of the study region are downscaled using the change factor approach (CFA). The study analyzes future climate data, extreme changes of future climatic conditions of precipitation, and temperature. The Hydrologiska Byråns Vattenbalansavdelning (HBV) model developed by the Swedish Meteorological and Hydrological Institute (SMHI) is used to simulate streamflow under extreme climate change conditions. Two different sources of uncertainty are investigated in this study. First, the model parameters uncertainty is analyzed with the Monte Carlo procedure, and then different datasets of GCMs projection are investigated under the climate of the twentieth-century climate simulation (20C3M). Results show the GCMs projections range can almost capture the historical records during the 1980s through 2000 for the Karaj basin. By applying the HBV model, considerable range of streamflow changes in the future can be projected that will affect the operation scheme of Karaj Reservoir. In this study, the system dynamics (SD) modeling approach is used to simulate the system behavior through time in an integrated fashion and evaluate its overall reliability in supplying water. The results of this study show that the runoff will decrease in the future under the climate change impact. This will result in more than 50% decrease in reliability of the Karaj Reservoir system under the extreme conditions. As a result, this research predicts that the Karaj Reservoir system will face more than 50% decrease in its reliability under the extreme conditions. Consequently, meeting the increasing water demands would be difficult and application of demand management strategies will be unavoidable.

Forecasting the absolute and relative shortage of physicians in Japan using a system dynamics model approach.

BackgroundIn Japan, a shortage of physicians, who serve a key role in healthcare provision, has been pointed out as a major medical issue. The healthcare workforce policy planner should consider future dynamic changes in physician numbers. The purpose of this study was to propose a physician supply forecasting methodology by applying system dynamics modeling to estimate future absolute and relative numbers of physicians.MethodWe constructed a forecasting model using a system dynamics approach. Forecasting the number of physician was performed for all clinical physician and OB/GYN specialists. Moreover, we conducted evaluation of sufficiency for the number of physicians and sensitivity analysis.Result & conclusionAs a result, it was forecast that the number of physicians would increase during 2008–2030 and the shortage would resolve at 2026 for all clinical physicians. However, the shortage would not resolve for the period covered. This suggests a need for measures for reconsidering the allocation system of new entry physicians to resolve maldistribution between medical departments, in addition, for increasing the overall number of clinical physicians.

Simulating hedging rules for effective reservoir operation by using system dynamics: a case study of Dez Reservoir, Iran

Some of the most important challenges facing water managers are to increase water supply and reduce its demand. A single systematic method is needed to address both issues, such as the System Dynamics (SD) modeling approach. In this approach all the factors, parameters, and their influences on the problem are considered by causal loops and stock-flow diagrams. The multipurpose Dez Reservoir in southwestern Iran is a good case study for this approach, and we simulated 10 years under differing operation strategies to develop the most appropriate operation policy. A hydrologic time series analysis was conducted to generate simulated inflow to the reservoir, and differing policies, including hedging rules and a “goal-seeking hedge,” were applied. By using performance criteria and a new measure entitled “corrected reliability,”, the most appropriate scenarios were identified. We found that using the goal-seeking hedge in combination with water demand management offers the best chance for effectively meeting demands and minimizing supply shortages.

Analysis of performance losses of thermal power plants in Germany – A System Dynamics model approach using data from regional climate modelling

The majority of thermal power plants of more than 300 MW use river water for cooling purposes. Increasing water and air temperatures due to climate change can significantly impact the efficiency and the power production of these power plants. In this paper we analyse these impacts by modelling selected German thermal power plant units and their respective cooling systems through dynamic simulation taking into account legal thresholds for heat discharges to river water together with climate data projections (SRES scenarios A1B, A2, and B1). Possible output and efficiency reductions in the future (2011–2040 and 2041–2070) are quantified for thermal power plants with once-through (OTC) and closed-circuit (CCC) cooling systems under current legislative framework. The model validation showed that the chosen System Dynamics approach is appropriate to analyse impacts of climate change on thermal power units. The model results indicate lowest impacts for units with CCC systems: The mean trend for CCC for the A1B scenario (2011–2070) is expected to be −0.10 MW/a and −0.33 MW/a for an OTC system. On a daily basis, the power output of all considered OTC units is reduced down to 66.4% of the nominal capacity, for a single unit even down to 32%.

Evaluating the Impact of Government Policies and Regulations on M-Commerce in India: A System Dynamics Modelling Approach

Mobile Commerce (M-Commerce) is a subset of E-Commerce, which includes all E-Commerce transactions,carried out using mobile (handheld) device(s). With significant uncertainties and complexities due to evolvingbusiness and regulatory models, growth of M-Commerce is a function of appropriate and timely policyinterventions from the government(s). M-Commerce business growth is further complicated by the involvementof several interrelated stake-holders and various regulatory agencies that are part of the M-Commerceeco-system, which comprises of mobile telecom service providers, banking/financial institutions, contentfacilitators, retailers, mobile terminal industry, and end users as the major stake-holders. To understand theM-Commerce growth facilitators in India, where M-Commerce is at its infancy, system dynamics simulationmodels are developed. The simulation models are used to analyze the impact of policy and regulatoryinterventions on the growth of M-Commerce in India. These models can help policy makers in understandingthe inter-play between various independent regulatory/policy approaches and assessing their impact in a holisticmanner on the business eco-system.

Documentation for model transparency

Documentation for model transparency

Discussing feedback system thinking in relation to scenario evaluation in a balanced scorecard setup

Since the emergence of the Balanced Scorecard (BSC) at the beginning of the 1990s, literature has intensively discussed the problems of the cause-and-effect relationships, the time-delay elements between measures and perspectives and the concepts of feedback loops. This article focuses on the use of the System Dynamics Modelling approach to deal with these three problems, an approach first suggested by Forrester back in 1958. The wide scope of application of BSC as a decision-supporting instrument continues to spur the interest in BSC. We have used an actual case as inspiration on which our model construction and our simulation scenarios are based. Our findings suggest that the idea of linking BSC and System Dynamics together based on properties of the systems dynamic nature seem to be both a natural and a relevant development. Furthermore, our simulations demonstrate the ability to: (1) provide a scheme for the translation of the strategy into operational terms and at the same time (2) offer possibilities for the decision maker to be able to evaluate the plan–do–review results based on the feedbacks, specifically in a risk evaluating context.

Using System Dynamics modelling approach to develop management tools for animal production with emphasis on small ruminants

Small ruminants are important assets in several regions of the world. They account for more than half of the domesticated ruminants. Despite the growth in goat production in the world (more than 2% per year), research related to goat production is less than desired. One underused but potentially valuable approach for research on small ruminants is simulation modelling. Models of the components of small ruminant systems can enhance the financial returns and reduce negative environmental impacts. These models can be used to assess many dimensions of small ruminant production, from rumen dynamics to economic policies designed to support small ruminant production. Understanding the nutrition, production, and economic policy feedback signals and planning ahead is crucial to build a robust and integrated production activity that can be managed under different production scenarios. System Dynamics (SD) is a computer-aided modelling methodology that can be used to perform policy analysis and decision support system (DSS) applied to dynamic problems arising in complex social, managerial, economic, or ecological dynamic systems characterized by interdependence, mutual interaction, information feedback, and circular causality. SD can be used as a modelling tool to aggregate knowledge to solve different types of problems that have a limited scope to a specific location or have broad trends of applications across locations and areas of science. Important issues of broad application include the bearings of animal production in the climate change and the impacts of climate change in animal production, alternative production scenarios of animal and crop integration, associations between animal production and business (economics, marketing). The trend of increasing small ruminants in tropical and subtropical regions and an increasing pressure on tropical and subtropical livestock systems to produce food, to feed livestock, and to produce energy crops warrants the development of DSS to address issues such as what is the “real” benefits of livestock, the negative impacts livestock can have on greenhouse-gas emissions and the environment, and the effects of climate change on livestock systems.

Modeling Soft Institutional Change and the Improvement of Freshwater Governance in the Coastal Zone

Mongruel, R., J. Prou, J. Ballé-Béganton, M. Lample, A. Vanhoutte-Brunier, H. Réthoret, J. Pérez Agúndez, F. Vernier, P. Bordenave, and C. Bacher. 2011. Modeling soft institutional change and the improvement of freshwater governance in the coastal zone. Ecology and Society 16(4): 15. https://doi.org/10.5751/ES-04294-160415

Water resources planning and management based on system dynamics: a case study of Yulin city

Water security is an integral aspect of the socio-economic development in China. Nevertheless, water resources are under persistent pressures because of the growing population, heavy irrigation, climate change effects and short-term policies. Traditional management approaches narrowly focus on increasing supply and reducing demand without considering the complex interactions and feedback loops that govern water resource behaviour. Whereas these approaches may provide quick fix solutions, they often lead to unanticipated, sometimes catastrophic, delayed outcomes. Therefore, water management needs to take a holistic approach that caters to the interdependent physical (e.g. water inflows, outflows) and behavioural (e.g. decision rules, perceptions) processes in the system. Unlike reductionist approaches, System Dynamics (SD) takes a system-level view for modelling and analysing the complex structure (cause–effect relationships, feedback loops, delays) that generates the systemic behaviour. Simulating the SD model allows assessing long-term system-wide impacts, exploring leverage points and communicating results to decision makers. In this paper, we follow an SD modelling approach to examine the future of water security in Yulin City. First, we present a conceptual model for integrating water supply and demand. Based on this, we build an SD model to simulate and analyse the dynamics of water resource over time. The model output is tested to ensure that it satisfactorily replicates the historical behaviour of the system. The model is used to quantitatively assess the effectiveness of various supply/demand management options. Three scenarios are designed and examined: business-as-usual, supply management, and demand management. Results show that current management regime cannot effectively meet the future water demand. Whereas supply acquisition provides short-term benefits, it cannot cope with the growing population. A combination of conservation measures and demand-management instruments is regarded the most effective strategy for balancing supply and demand.

3.2.2 Understanding the Complex System Dynamics of Managing Water Security

AbstractIn many parts of the world, assuring reliable supplies of potable water is a serious challenge. It is not simply a matter of imposing restrictions on supply, increasing water prices, and building new dams. Effective water security strategies can only be developed when the mechanisms of supply and demand and the interactions between are fully understood. A System Dynamics (SD) modeling approach is taken to collect, analyze and merge the views of both consumers and supply managers in order to develop conceptual models which then form the basis for building quantitative models to investigate the complex dynamics. The modeling process has led to a significant increase in the understanding of the management of water security. First, the process has reinforced a number of lessons learned by SD modelers over the years, and second, the process has exposed a significant number of mis‐perceptions about water security among supply managers and consumers.

An analysis of household waste management policy using system dynamics modelling

This paper analyses the Flemish household waste management policy. Based on historical data from the period 1991-2006, literature reviews and interviews, both mathematical and descriptive relationships are derived that describe Flemish waste collection, reuse, recycling and disposal behaviour. This provides insights into how gross domestic product (GDP), population and selective collection behaviour have influenced household waste production and collection over time. These relationships are used to model the dynamic relationships underlying household waste management in Flanders by using a system dynamics (SD) modelling approach. Where most SD models in literature are conceptual and descriptive, in the present study a real-life case with both correlational and descriptive relationships was modelled for Flanders, a European region with an outstanding waste management track record. This model was used to evaluate the current Flemish household waste management policy based on the principles of the waste hierarchy, also referred as the Lansink ranking. The results show that Flemish household waste targets up to 2015 can be achieved by the current waste policy measures. It also shows the sensitivity of some key policy parameters such as prevention and reuse. Given the general nature of the model and its limited data requirements, the authors believe that the approach implemented in this model can also assist waste policy makers in other regions or countries to meet their policy targets by simulating the effect of their current and potential household waste policy measures.

A system dynamic modeling approach for evaluating municipal solid waste generation, landfill capacity and related cost management issues

As planning for sustainable municipal solid waste management has to address several inter-connected issues such as landfill capacity, environmental impacts and financial expenditure, it becomes increasingly necessary to understand the dynamic nature of their interactions. A system dynamics approach designed here attempts to address some of these issues by fitting a model framework for Newark urban region in the US, and running a forecast simulation. The dynamic system developed in this study incorporates the complexity of the waste generation and management process to some extent which is achieved through a combination of simpler sub-processes that are linked together to form a whole. The impact of decision options on the generation of waste in the city, on the remaining landfill capacity of the state, and on the economic cost or benefit actualized by different waste processing options are explored through this approach, providing valuable insights into the urban waste-management process.

Discussing Feedback System Thinking in Relation to a Balanced Scorecard, Inspired by an Actual Case

Since the emergence of the Balanced Scorecard at the beginning of the 1990s, only few articles have proposed a framework of translating BSC into an analytical numerical model. This paper addresses two research themes: (1) a discussion of the cause-and-effect modeling within the BSC and (2), how may the feedback systems thinking and causal loop reasoning be conducted within BSC. In contrast to previous literature on BSC this paper focuses on a System Dynamics Modeling approach to transform a static BSC into a dynamic and analytical closed loop management model by incorporating both time-lags and cause-and-effect schemes. Our main result shows that SDM is a relevant and possible approach for building a BSC. The SDM model adds additional benefit to the BSC by (1) providing a translation of the strategy into operational terms and (2) offering possibilities for the decision maker to simulate scenarios for planning, learning and feedback. In addition the model shows how both structural and direct action settings impact significantly on the solution paths.

Governing the teak furniture business: A global value chain system dynamic modelling approach

Javanese teak forest constitutes more than 35% of world teak forests. It provides employment and livelihood to millions of people. This paper describes the use of systems dynamics to mimic the value chain of teak from forest to final furniture market using phases of conceptual design, model specification, model evaluation and model uses. The model comprises Perhutani plantation teak, community agroforest, teak log trading, furniture manufacturing and market. From the model we observe baseline trends of teak forest and incomes to various actors participating in teak business including forest state enterprise Perhutani, local communities, brokers, manufacturers and retailers. We use the model to produce governance scenarios of fair trade and vertical integration, their impacts on actors' income and the sustainability of teak plantations.

Simulation Techniques on System Dynamics Modeling of Productioninventory Control Model

The purpose of this research is to simulate the System Dynamics modeling approach in areas related to production-inventory management. Present inventory systemis based on order rate which is proportional to the discrepancy between the desired inventory and the actual inventory and time between orders are negligible. Asymptotic growth/decline are the perplexing behavior of this type of production-inventory control model. Considering the complexities of proposed inventory control model,solution approach comprises Euler's integration algorithm to simulate under the platform of system dynamics modeling. Coding is developed in C++ platform and resultsare demonstrated in Graphics mode by considering object oriented concepts. Numerical example with graphical output is presented to show the efficacy of Euler's integration algorithm in simulation for solving real life complex problems under system dynamics environment.

Using system dynamics to model water-reallocation

Improving the efficiency of water allocation has long been recognised as a key problem for the water resources management decision-makers. However, assessing the efficacy of management decision is difficult due to the complexity and interconnectivity of water resource systems. For this reason, it is vital that robust modelling approaches are employed to deal with the feedback loops inherent in the water resource systems. Whilst many studies have applied modelling to various aspects of water resource management, little attention has been given to innovations in modelling approaches to deal with the modelling challenges associated with improving decision-making. The aim of this study is to apply a System Dynamics modelling approach to improve the efficiency of water allocation incorporating a myriad of irrigation system constraints. The system dynamic approach allows the different system components to be organised as a collection of discrete objects that incorporate data, structure and function to generate complex system behaviour. Through the application of a system dynamic approach, a robust model (named the Economical Reallocating Water Model (ERWM)) was developed which was used to examine the options of re-allocating water resources that minimize the water cost all over an irrigated agricultural area. The ERWM incorporated a wide range of complexities likely to be encountered in water resource management: surface and ground water sources, water trading between sources, system constraint such as maximum ground water pumping, rates, maximum

Closed loop supply chains – A study of US and Japanese car industries

System dynamics (SD) modeling approach is used to study the US and Japanese car industries' closed loop supply chains. The state of car recycling in the US and Japan and also end of life vehicle (ELV) regulation in Japan are reviewed. Disposal of cars that reach end of life phase in the US and Japan and export of used cars to emerging economies including potential threats to car manufacturers in these economies are examined. Relationships between reduce, reuse, recycle and disposal in the US and Japanese car markets are explored with base scenario analysis using the car consumption data and forecasts. The SD model was also subjected to extreme conditions test for structural validity. Dynamic analysis of different market scenarios for the US and Japanese reverse supply chains are also conducted. The study shows government regulations can have a significant impact on the car industries' reverse supply chains in the US and Japan.

Designing Safe Systems: Using System Dynamics to Understand Complexity

All geographical regions are subject to devastation and disruption from natural disasters. Optimizing safety requires understanding the natural and social systems involved in disasters, communicating clearly with decision makers that affect those systems, and identifying potentially effective interventions for consideration. The application of system dynamics modeling, a metatheoretical and methodological approach of systems theory, helps to accomplish all three. After a brief reference to system’s current place in hazards research and practice, the usefulness and types of systems models, including causal loop diagrams and stock and flow diagrams, are discussed. The methodological specification of system dynamics modeling is explained, along with the general modeling process. Conclusions are advanced with a discussion of the application of system dynamics modeling in hazards work and its place in designing safe systems.

Articulating Developmental Problems for Policy Intervention: A System Dynamics Modeling Approach

Developmental problems are invariably perceived as dysfunctional existing conditions that must be changed. This often removes a policy from the factors that created a problem in the first instance. Problem articulation for policy intervention as practiced in system dynamics modeling requires, on the other hand, that a problem is viewed as an internal behavioral tendency found in a system so its causes can be determined before a corrective action is initiated, which is presented in this article as an effective way to define developmental problems. To articulate a problem, a pattern representing the problem history, called a reference mode, must be constructed before developing a model that serves as a laboratory to understand the problem and create a policy design for system change. A reference mode is, however, different from a precise time history in that it represents a pattern incorporating only a slice of the history. It requires several learning cycles to construct a reference mode from time history. A learning process based on a well-known model of experiential learning is used to describe the construction of a reference mode, which is illustrated at length by revisiting the illusive problem of food security.