A Belief Network Approach to Modeling of Environmental Change: The Methodology and Prospects for Application

In environmental management, assessments and far-reaching decisions must typically be made under very high or extreme uncertainty. The future development of the environment in interaction with societies in transition is very difficult to forecast. This is the case regardless of whether the change is introduced actively at the project or policy level, or passively through accumulated environmental deterioration or climatic change. This study presents a belief network methodology designed specifically for modeling environmental change. Belief networks contain a set of interlinked nodes. Prior probability distributions of nodes are updated with information from the rest of the network, according to transfer information in links. A link can transmit information in two directions. The existing belief network methodology was extended in several ways to meet the multiple requirements of environmental modeling. Most notably, two-layered parallel linking of nodes was allowed: the conventional probabilistic linking, and linking of outcomes of probability distributions using deterministic or logical relations. Moreover, several decision analysis techniques were included. The applicability of the methodology is discussed in reference to the following topics: knowledge acquisition, decision analytic modeling, mechanistic and process modeling, topological and spatial modeling, learning and adaptive modeling, and hybrid use

Decision Analytic Modeling of Uncertainty and Subjectivity in Water Quality Management

Quantification and reduction of uncertainty associated to decision making is one of the primary functions of modeling and monitoring targeted to assist decision making in reservoir, river, and lake water quality management. In many practical activities such as environmental impact assessment, the inference is bound to be based primarily on subjective, expert judgments, supported by empirical data and models. A bulk of analytical approaches is presently available for modeling purposes. The paper discusses selected decision analytic approaches to the handling of uncertainty associated to information available, uncertainty as a decision criterion, and as a component influencing the model structure. Computational solutions based on experience on six case studies are reviewed

Water Quality Modeling of Rivers and Lakes

Oxygen depletion, eutrophication, acidification, toxic pollution, poor hygienic state, salinity, and excess suspended matter are among the issues usually included in the concept of water quality problems. This report focuses on inland surface waters, namely on rivers, lakes, and reservoirs, to each of which the problem categories listed above are relevant. The variety of problems, the multidisciplinarity among water quality experts, the wide spectrum of societal water needs, together with the high diversity of computational approaches presently available contribute to the present situation in which applicable methodology is developing from a variety of fronts and directions, among which dynamical, partial differential equation models were taken here in focus. Transport, flow and reaction equations for shallow water bodies are reviewed for 1 and 2-dimensional cases, including an introduction to and illustration of a selection of numerical techniques. Four case studies on eutrophication modeling, and a review and discussion on the application of decision support systems on water quality management are presented thereafter

Analysis of Sardine Fisheries Management on Lake Kariba, Zimbabwe and Zambia - Structuring a Bayesian Influence Diagram Model

One of the main issues in the fisheries management of Lake Kariba is the question of how much the total effort of sardine fisheries can be increased without threatening the renewal of the stock and the economical profitability of the fisheries. This problem is subjected to uncertain natural processes and diverse and insufficient information available. A Bayesian influence diagram model was developed to analyze the decision problem. The Bayesian approach offers means for fusioning probabilistic information from different sources, and assessing the relative information value of quantities included in the model

Potential Impacts of Climatic Change on Lake and Reservoir Water Quality

Climatic change may have very diverse impacts on lakes and their water quality. This paper groups them to hydrologic, thermal, hydraulic, chemical, biochemical, and ecological ones. Their interrelations and potential changes, and their contributions to lake water quality problems, are reviewed and discussed, and checklist tables for planning, management, and impact assessment purposes are provided. Water quality problems are clustered to eutrophication, oxygen depletion, hygienic problems, salinization, acidification, toxic and cumulative substances, turbidity and suspended matter, and thermal pollution. Many of these problems may worsen due to the climatic change, yet an extreme uncertainty exists at any case specific level. Therefore, the possibility of water quality and quantity shifts due to climatic change are suggested to be integrated into contemporary planning and management in an adaptive manner, and the research and development of the impact assessment methodology are suggested to be focused on approaches that can handle extreme uncertainties. The very high uncertainty level in water quality management has obtained an additional highly uncertain component

MINE-NEC - A Game for the Analysis of Regional Water Policies in Open-Pit Lignite Mining Areas: An Improved Implementation for the NEC PC-8201A

The game MINE was developed for the analysis of regional water policies in open-pit lignite mining areas. It is implemented for a GDR test area. The purpose of the game is above all to teach decision makers and their staff in mining regions in order to get a better understanding of the complex interrelated socio-economic processes with respect t o water management in such regions. The game is designed to be played by five groups of players representing municipal and industrial water supply, agriculture, environmental protection and lignite mining. In this paper an improved BASIC version for the portable NEC PC-8201A microcomputer is introduced

Water Quality of Nitra River, Slovakia - Analysis of Organic Material Pollution

Water pollution and water quality management receives increasing attention in eastern European countries. More efficient waste water treatment is needed at the same time when the economy of those countries is not on a stable ground. Thus investigation is needed, how to set priorities and invest funds available to get optimal benefits in water quality management. In this study the role of the dischargers along Nitra river in Slovakia was analyzed based on mass balance of biochemical oxygen demand (BOD). Monthly data from 1990 were used. Because of scarce data and large uncertainties involved, a stochastic approach was taken using probability distributions in propagation of uncertainties. The river was subdivided into twelve stretches and the mass balances of each of them were closed using the BOD equation of the Streeter-Phelps model

Freshwater Management: Problems and Challenges

Water (including increasing use relative to availability, and deteriorating quality) may be one of the most severe stresses on the exponentially growing human population in the next century. Problems are becoming increasingly complex and diverse and require more and more specific knowledge from both a technical and non-technical perspective. These complexities create the need to understand and comprehend the more detailed technical components as well as broader managerial and societal issues. These non-complementary elements will increasingly demand the efficient integration of various disciplines, sectors, countries, and societies. The major challenges addressed are whether we are capable of and prepared to realize the needed integration and whether we can resolve the large amounts of existing gaps and barriers. The paper analyzes major past and desired future trends in fresh water management. There is an attempt to draw from the three main socio-economic regions: the developed world, Central and Eastern Europe (including countries of the former USSR) and the developing world. A number of issues are selected with regards to integrated freshwater management: (1) Identification, occurrence, and perception of various problems (e.g. eutrophication, acidification, global warming, salinization, groundwater contamination, eco-system degradation, land cover changes, vulnerability); (2) Current integration of methodologies; their strengths and weaknesses; Large scale projects; dams, irrigation schemes and water transfers; (3) Global urbanization; (4) Wastewater treatment and pollution control types (considering also consumption emissions); (5) Modeling and monitoring; (6) Planning and environmental impact assessment; (7) Legislation and institutions; (8) Education and public awareness; (9) Sustainable development and time preference; (10) The role of science and engineering. The past two decades showed tremendous developments in the management of water as seen from many different perspectives. In spite of these advancements there is still room for improvement. The focus of the present discussion lays mostly on the dissemination of lessons and questions which are crucial to likely future problems and desired improvements

A Belief Network Approach to Optimization and Parameter Estimation in Resource and Environmental Management Models

This study presents an approach to use Bayesian belief networks in various optimization tasks in resource and environmental management. A belief network is constructed to work parallel to a deterministic model, and it is used to update conditional probabilities associated with different components of the model. The propagation of probabilistic information occurs in two directions in the network. The divergence between prior and posterior probability distributions at model components can be used as indication on inconsistency between model structure, parameter values, and other information used. An iteration scheme was developed to force prior and posterior distributions to become equal. This removes inconsistencies between different sources of information. The scheme can be used in different optimization tasks including parameter estimation and optimization between various management alternatives. Also multiobjective optimization is possible. The approach is illustrated with two numerical examples and with a hypothetical example on cost-effective management of river water quality

Climate-driven interannual variability of water scarcity in food production potential: A global analysis

Interannual climatic and hydrologic variability has been substantial during the past decades in many regions. While climate variability and its impacts on precipitation and soil moisture have been studied intensively, less is known on subsequent implications for global food production. In this paper we quantify effects of hydroclimatic variability on global "green" and "blue" water availability and demand in global agriculture, and thus complement former studies that have focused merely on long-term averages. Moreover, we assess some options to overcome chronic or sporadic water scarcity. The analysis is based on historical climate forcing data sets over the period 1977-2006, while demography, diet composition and land use are fixed to reference conditions (year 2000). In doing so, we isolate the effect of interannual hydroclimatic variability from other factors that drive food production. We analyse the potential of food production units (FPUs) to produce a reference diet for their inhabitants (3000 kcal cap-1 day -1, with 80% vegetal food and 20% animal products). We applied the LPJmL vegetation and hydrology model to calculate the variation in green-blue water availability and the water requirements to produce that very diet. An FPU was considered water scarce if its water availability was not sufficient to produce the diet (i.e. assuming food self-sufficiency to estimate dependency on trade from elsewhere). We found that 24% of the world's population lives in chronically water-scarce FPUs (i.e. water is scarce every year), while an additional 19% live under occasional water scarcity (water is scarce in some years). Among these 2.6 billion people altogether, 55% would have to rely on international trade to reach the reference diet, while for 24% domestic trade would be enough. For the remaining 21% of the population exposed to some degree of water scarcity, local food storage and/or intermittent trade would be enough to secure the reference diet over the occasional dry years