MON 2:30 PM Parallel Session: Environmental Decisions
Full Report: The first presentation was made by Varun Dutt on a paper titled Human Perceptions of Climate Change, co-authored by Cleotilde Gonzalez. Both are from the Dynamic Decision Making Laboratory at Carnegie Mellon University, Pittsburgh. One of the main hypotheses which guided their study was that human negligence towards issues affecting the climate system is a result of human cognitive inabilities. They argued that by failing to account for non-linearity, feedback, and delays in the way people think, it becomes difficult for people to understand the consequences of their actions for the global climate system. With the aim of advancing the investigation into human perceptions and understanding of dynamically complex problems, they built a simple interactive tool, the “Climate Change Simulator” (CCS), based on an adapted climate model from the Dynamic Integrated Climate Economy model-1992 (DICE). In a laboratory environment, they attempted to determine the effect of delay of human emission policy interventions and the variation of rates of CO2 removal on the participant’s ability to control CO2 concentrations to safer levels over a period of 100 to 200 years. They found that individuals have lesser discrepancy and bullwhip oscillation in the rapid condition than the slow condition; thus, participants learn more quickly when the system follows rapid dynamics instead of slower dynamics.
The main question that came after the presentation addressed the sources of data for calibration of the model. To answer this, Varun pointed to the Integrated Science Assessment Model (ISAM) data which was used for predicting the concentration of CO2 in the atmosphere on the two extreme IPCC emission scenarios.
The second presentation was by Hamed Nozari. He presented a paper, titled Simulation of Drainage Systems in Unsteady State Condition, Using System Dynamics, with Abdol Majid Liaghat and Majid Kholghi, both colleagues at the Department of Irrigation and Reclamation Engineering, University of Tehran. The objective of their work was to develop a model to predict the behavior of drain discharge and water table fluctuations for different drainage densities, soils, and climates. They motivated their choice of using system dynamics in developing this model by tapping into merits proclaimed by some of the finest veterans in the field - the merits of offering opportunities to “conceptualize, document, simulate and analyze models of dynamic systems.” Their presentation moved from the formulation of their problem through the causal loop diagramming to the process of converting the causal loop dynamics to a quantitative model. In the process of modeling, they began with the water balance equation formulated for unsaturated conditions. They then progressively introduced saturated conditions using the Hooghoudt’s equation (1940) to calculate the drainage outflow. Their stock and flow structures relied heavily on the system of integral or differential equations developed by Sterman (2000). The outcome was a model, the simulated data of which was statistically compared with observed data from a field in Amirkabir (Khozestan, Iran). The statistical analysis produced a good comparison between observed data and simulation results, validating the tool as reliable for predicting “water table, drainage flux, upward flux, evapotranspiration, deep percolation, infiltration, runoff, soil moisture content, and unsaturated hydraulic conductivity on the basis of variation of soil moisture content.”
The discussions that followed saw the audience very interested in knowing if the model had a spatial character. Nozari replied that the model was spatially explicit (meaning that differences resulting from spatial differences had to be input as spatial characteristics for each run changed).
Len Malczynski gave the last presentation on a paper titled System Dynamics Model of Southwestern New Mexico Hydrology to Assess Impact of the 2004 Arizona Water Settlements Act. He co-authored this paper with Amy Sun, Vince Tidwell, Geoff Klise, Will Peplinski, and Jim Brainard, all colleagues of his from the Sandia National Laboratories, Albuquerque, New Mexico. He began by presenting the background of the water situation in New Mexico, highlighting the need for collaborative solutions and multi-sectoral participation in the management of water resource issues wherever they may occur. He went on to present a water balance model of the Gila-San Francisco River Basin (Gila Basin) in southwestern New Mexico. He showed how the modeling approach behind the project moved away from the conventional attitude of compartmentalizing tasks and expertise, and instead employed an inclusive multidisciplinary, quantitative, transparent, and collaborative stakeholder-driven process to all interested parties. The outcome was a tool that addressed the information needs of stakeholders in the fields of agriculture, mining, cattle owning, the general public, and others in the Gila Basin. After presenting the results of simulations, Len showed how the model served as a bridge between different stakeholders and decision makers and the indispensable role the model plays as a decision support tool to address the impact of additional diversions under the terms of the 2004 Arizona Water Settlements Act.
A series of questions during the discussion session that followed led Len to explain the difference between a conceptual model, a quatitative model, and an application. He stated “when you add quantities to a conceptual model, it becomes a quantitative model and if you add an interface to a model, it becomes an application.” Asked if the outcome of the model in the Gila Basin could be replicated in other areas, Len explained how a similar exercise in a water-sensitive part of the world had enabled stakeholders to focus their attention on questioning the model for answers rather than attacking each other.
At the end of the session, many members of the audience utilised the sumptuous invitation of the refreshment break to mingle, chat, ask further questions, get further explanations, and exchange contacts.