The Tragedy of the Commons, Garrett Hardin, 1968

In this article, the author tried to conclude that the population problem cannot be solved. It means that there is no technical solution to the overpopulation problem. To proof his conclusion and to suggest possible solution, he provides examples and conceptual explanations.

The main conception about the reason of the insoluble problem is “The Tragedy of the Commons”. If there was a certain resource and it was shared to a large number of people, it is possible that the resource would be immoderately used. In other words, The Tragedy of the Commons is that the commons will be depleted and ruined when people pursuit only their goals without any agreement for using the common properties, such as pastures. This conception denies Adam Smith’s “invisible hand” which public good is automatically guaranteed as long as people pursue personal gain. From this problem, the author suggests that certain regulation or law is needed to control overbreeding. He also says that there are many problems to execute the regulations, but people should do that because their purpose is to survive and avoid the tragedy of the commons.

In sum, the author concludes that only under conditions of low-population density the commons is justifiable. He also says that the most significant thing in this problem is the necessity of abandoning the commons in breeding because there is no technical solution to the overpopulation problem.

Discussion

This article has a good approach to correct the way of solving overpopulation problem. However, I think it is possible that population would be controlled automatically without any regulation. This is because the population is not always increased. Population was dramatically grown when we see recently global population trend, but I think each nation has different era of increase/decrease in the population. As this article mentioned, people would not breed when they are suffering from economic difficulty or do not satisfy their life.

Optimal location of infiltration-based best management practices for storm water management

Perez-Pedini C, Limbrunner JF, Vogel RM (2005) “Optimal location of infiltration-based best management practices for storm water management,” JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT, 131(6) pp. 441-448

In this study, genetic algorithm is used to determine optimal places of best management practices (BMPs) in a watershed for storm water management. Especially, using hydrologic response units (HRUs) with curve number method, the impacts caused by installing infiltration-based BMPs are estimated for optimizing this multi-objective model. The result would show a Pareto frontier which is the trade-off between BMPs number and flooding in the watershed.

In the past, approaches for storm water management tended to focus on detention and retention basin and those facilities which consider storage-based BMPs. This article, however, tries to introduce infiltration approaches for the storm water management and shows the strategic integration of storage and infiltration storm water controls. Other difference with past studies is that the considered number of HRUs is much more detailed and increased in number. Another improvement in this study is the connectivity among the HRUs because multivariate regression showed failure of sufficient explanation about the influence of cell contributions at the basin outflow point in the past.

The objective of this optimization is to find the best location of installation of certain number of BMPs, which results in minimizing peak stream-flow at the watershed outlet. After making some assumption for decrease in computational time, genetic algorithm is used to solve this problem with increase in number of BMPs, the number means increasing cost as increase in BMPs install number. Then, we can get the trade-off or Pareto frontier of peak flow reduction and the BMPs cost. We can also find an interesting thing that the most results occur near major highway intersections in the study area. Another thing is that larger number of BMPs is not always inclusive of smaller BMPs solution. From some examination, the author discovered that the real optimal solution will occur when a larger BMPs solution includes all of the smaller BMP solution.

Discussion

 This article is interesting because it shows a reasonable and improved approach for optimizing the best BMPs place in a watershed. Increase in BMPs grid points and use of CN approach and connectivity among the grid point are most interesting thing in this article. An advantage of using genetic algorithm for complex calculation and the inclusion resulting from increase in number of BMPs are also interesting. However, I think the budget of placing BMPs would be different at each site because each site should have various topography and land-use. If I tried to do this research, I would add the budget variable in the optimization to provide better alternatives for the storm water management.

USE OF OPTIMIZATION MODELS IN PUBLIC-SECTOR PLANNING

BRILL ED (1979) USE OF OPTIMIZATION MODELS IN PUBLIC-SECTOR PLANNING, MANAGEMENT SCIENCE, Vol. 25, No. 5, pp. 413-422.

The purpose of optimization is to obtain ‘the answer’ and is useful for simple problem. However, in a public-sector problem, there are many problems for solving or optimizing because of a multitude of local optima and elusive elements. Because of the reason, the author maintains that the optimization for public-sector problem should play the role of generating alternatives and in facilitating their evaluation and elaboration. He also said that several models and new types of formulations should be required for the better optimization.

The author points out the limitation of using optimization model which are difficulties of considering equity or distribution of income, and which are empirical inadequacies in evaluating benefits and costs. Specifically, the article demonstrates that the incomplete multi-objective models usually show that the optimal solution in public-sector problem occurs at inferior region, not at non-inferior region. Even if the model was completely formulated, it is impossible to obtain the overall best solution.

To reduce the limitations, the author suggests several methods to make the optimization models play the important role of providing alternatives for decision makers in public-sector problems. First, ‘joint use of models’ should be used such as combining analytical and optimization models or using a tool box of models. The author also recommends us to use optimization models which generate alternatives and facilitate evaluation such as branch-and-bound method, random method, and HSJ method.

In conclusion, the solution of optimization model would be a synthesized solution resulting in their alternatives, which require unlike formulations and methods. Planners and their decision can be aided by the offered alternatives with gaining better understanding of the relationship, objectives, and constraints in public-sector problems.

Discussion

Generating alternatives from a solution in a specific optimization model is interesting because people’s thinking cannot be formulated. By offering alternatives, decision makers can refer to the alternatives and they could not always select the optimal solution, but could possibly select one of the alternatives. However, I think that the article is necessary to provide more various ways or methods to generate such alternatives, and we need to improve or invent skills generating alternatives for the future research or their application.

Use of mathematical models to generate alternative solutions to water resources planning problems

Chang, S.-Y., Brill, E.D., Jr., and Hopkins, L.D. (1982) Use of mathematical models to generate alternative solutions to water resources planning problems, WATER RESOURCES RESEARCH, VOL. 18, NO. 1, PP. 58-64, 1982

The author provides Modeling Generate Alternatives (MGA) techniques to reduce the weakness of optimization models, which do not usually give us a perfect solution about a complex problem in real world. The author argues that various alternatives from MGA should be also provided for decision makers to minimize the weakness. Introducing three kinds of methods to generate alternatives, the definition and characteristic of each method are informed and compared by applying an example of water resources planning problems.

1.      Hop, Skip, and Jump (HSJ)

‘The sum of the nonzero variables in the initial solution is minimized subject to a target constraint on the cost objective.’

2.      Ransom Generation Method

‘Maximizing the sum of several randomly selected decision variables and the number of variables selected can be arbitrarily specified or randomly determined.’

3.      Branch and Bound Screening

‘Obtaining feasible solutions within a certain limit of the objective function value’

From the analysis of a provided example, the result of HSJ method is binding with the cost constraint, and the random and BBS method’s result is little better about the cost. All the methods can generate many alternatives but BBS method can generate less number of alternatives comparing to the other methods.

We can also know that HSJ method tends to generate different number of plants in centralization, the random method tends to change the location of plants and interceptors in the similar number, and BBS tends to rearrange the certain system with making the other system constant.

In conclusion, the author argues that these three methods can be potential to help decision maker to be able to choose the best solution in a public sector problem. Though an optimization model can only contain one objective, MGA techniques make it possible to include multi-objective in the model.

Discussion

This article is interesting because it shows how to generate alternatives from an optimization model, which would be helpful for decision maker and can improve a role of optimization in public scale problem. It also provides examples the methods for generating the alternatives to easier understand us. However, I am unsatisfied with the lack of various examples because the article shows the characteristics and patterns of the models only from one example. Therefore, I would like to apply the methods into various problems to verify the characters of each method for generating alternatives.

OPTIMAL LOCATIONS OF MONITORING STATIONS IN WATER DISTRIBUTIONS SYSTEM

Lee, B.H., and Deininger, R. A., 1992, “OPTIMAL LOCATIONS OF MONITORING STATIONS IN WATER DISTRIBUTIONS SYSTEM,” JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE, Volume: 118, Issue: 1, Pages: 4-16.

Drinking-water quality should be monitored for public safety. According to the drinking-water regulation, monitor stations need to monitor the sampling frequency and the water-quality parameter. However, specific methods had not been provided for sampling in a distribution system. In this article, a method, how to install monitoring stations in a water network, and a concept of coverage were introduced.

To achieve this method, demand pattern and the flows must be known first. Then, possible locations, called nodes, should be known with the demand. The term ‘covered’ or ‘coverage’ was also used as percentage, which refers to how much demand of the total demand a node covers and which informs the degree of a representative. There is also an assumption that ‘if all the water at the sampled node came from an upstream node, then the water quality of this upstream node would also be known’.

The specific general algorithm is as following.

1. Choose one node.

2. Determine all connected nodes.

3. Calculate water fraction of the flow coming from upstream nodes.

4. In a coverage metrics, the node set to ‘1’ if the value of fraction is above a certain criteria. If it is below the criteria, the node set to zero.

5. As step 2-4, calculate them about all nodes

6. Problem formulation

7. Get result through integer programming

This article also explains that the method can solve multiple scenarios through various examples such as different direction among the node. In result of examples, the author shows the improvements and effectiveness about selecting sampling sites with combining pathway analysis, coverage matrices, and integer programming.

Discussion

This article is interesting because the method provide how to handle pathway when we have to optimize problems relative to road ways or pipes. This is also helpful for me to understand how to solve the third question of our homework. However, although the article provided 2 examples and seemed to simply solve these problems, I think that calculating all the fractions would take longer time if number of nodes increased. If there was a simple method to calculate the fractions, the author should provide the way. If there was not, I would like to study a simple method for estimating the fractions in this article.

Water-resources optimization model for Santa Barbara, California

Nishikawa, T., 1998, “Water-resources optimization model for Santa Barbara, California,” JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT-ASCE, Volume: 124, Issue: 5, Pages: 252-263.

In this article, a simulation-optimization model were performed to minimize the cost of water supply, fulfill water demand, and control saline water intrusion from near ocean in Santa Barbara area during a drought. In this model, decision variables were water conveyances from surface and ground water and hydraulic head. Sensitivity of the model was also provided about demand, carryover, head constraints, and capacity constraints.

In detail about a formulation, to fulfill minimizing the water supply cost, a linear programming was employed. The objective is subject to maximum water-supply capacity, maximum and minimum heads along the cost, limits retaining pumping distributions among producing zones, recharge distribution, and water-supply demand constraints. The decision variables were amount of water delivered from surface water, ground water, and Cachuma Reservoir carryover. Additionally, to estimate the heads from pumping pattern, the response coefficient method was employed. MODFLOW method was also used for ground-water flow model.

After select constraints, there were three kinds of scenarios. First, in Base Case which is average monthly releases, the optimization scenarios optimally reached the minimum cost with satisfying all constraints. It means that cheapest water and inland wells would be used as much as possible. In other approaches which were current and prosed monthly Gibralter distribution, the result were not better but it showed that water distribution timing is really important to minimize the cost. In addition, through sensitivity analysis we can also know that additional saving will occur if seawater intrusion is acceptable.

Discussion : This article is interesting because it shows that how to use a linear optimization method for real problems and how to set complex variables and constraints in the linear approach. However, though components of this model were quite reasonable, it would be better if there were detailed constraints and variables such as maintenance or economic trend. In case of allowance of seawater intrusion, there should be environmental impact. For further study, I would like to add additional components mentioned above or other substitutions in this study.

Summary : Water Resources Management: The Myth, The Wicked, & The Future

Reed, P. M, and Kasprzyk, J. R., 2009, “Water Resources Management: The Myth, The Wicked, & The Future,” ASCE Journal of Water Resources Planning & Management, v135, n6, pp. 411-413.

Water management science has to explore the backgrounds, legacies, and deficiencies of the problem-solving frameworks about water resource management field. The main purpose in this article is here that water management field is necessary to clarify what this field is now and has to be in the future.

The Optimality Myth

In the past years, optimization in water management field has showed a lot of limitations to resolve water resource problem, because single-criterion optimality is not fit to resolve complex water resource system environment. Climaco (2004) tried to reinforce this limitation, getting rid of using narrow scientific definition of optimality in water resource management. However, it is still difficult for analyst to define balancing technological innovation and its concomitant societal risks, using single-criterion. Therefore, hidden consequences, compromises, and hypotheses from stake holders and decision makers have to be avoided in complex public systems planning. Various approaches in modeling can also enhance decision making, and we can also avoid locality (or myopia) in water resource management.

Water: A Wicked Class of Problems

“Wicked” problem is a still challenge in water resource management when we try to resolve social value problem. First, it is hard to get exact formula, because of people’s different tastes. Second, it cannot be simply true and fault. Third, it is exclusive and not decomposable. Fourth, some of the values can be irreversible. Fifth, sometimes it is difficult to predict a range of the results or the impacts. These could be future works in a water management field.

The Future Requires Constructive Modeling

In water resource management, there are critical methodological limitations in traditional methods for many years. As water-cycle science have grown, the gap between water management and water-cycle science becomes significant. For executing successful water management modeling, diversity of hypothesis and broadly knowledge have to be provided to stakeholders, decision makers, engineers, and scientists. Moreover, by augmenting observations and estimates to social value and by build a wide range of alternatives to help water resource decision making, the gap between the water management and science have to be reduced for the future of water resource management.

a.       Why is the paper interesting or significant? This article provides conceptually what kind of myth analysts in water management have to have and what “wicked” problem is in this field and what they have to do for the future.

b.      What are the faults or limitation of this work? It is too conceptual.

c.       What is the possible work extending from this work? If this were your research, what would be your next steps to fix the work, apply ideas to other applications, or start new work from these ideas? There are no specific solutions and detailed examples about the matters. If it was my research, I try to provide some examples for reader’s understanding about problem and solution. For next research, I like to figure out how this conception can change into a methodology in detail for being able to apply real world such as constructing dams, navigations which are issue politically and economic.