Assignment 10b: NIMBY!

Pan TC, Kao JJ (2009) GA-QP Model to Optimize Sewer System Design, JOURNAL OF ENVIRONMENTAL ENGINEERING, 135(1) 17-24

Summary

Sanitary sewers aren’t rocket science. Upstream elevations must be greater than downstream elevations. The diameters of downstream pipes must be larger than their upstream counterparts. A line must be sufficiently large to carry a design flow. These are usually the main concerns, which are often accompanied by other sets of secondary limitations. If viewed at the level of an individual sewer line, its optimal design is a fairly simple problem to solve. When optimizing the sewer design for a large network, however, the process becomes exceedingly complex. In this study, the authors attempted to tackle the latter.

The problem in this article was so complex, in fact, that the authors had to break the optimization process into two separate parts: a genetic algorithm and a quadratic program. In the genetic algorithm, a set of pipe diameters for the entire system constituted a chromosome of possible solutions. These chromosomes were then passed to the quadratic program, in which the cost was optimized by modifying pipe slopes and buried depths. Optimal solutions in the quadratic program were limited by an array of constraints commonly encountered in sewer design. The result of the quadratic program was then fed back to the genetic algorithm, where the fitness of a chromosome was evaluated as the inverse of its cost (as cost increased, the fitness of a chromosome became worse, and vice versa). Upon running the GA-QP model, results were fed into an MGA function, which was used to save “good alternative” solutions which were not mathematically optimal. When applied to a case study, the authors’ method was successful in reducing the cost of a sewer design from $87 million to $10 million – a reduction of nearly 90%.

Discussion

This article was an interesting implementation of a GA, but I found two major setbacks.

First and foremost, I feel that the authors’ exclusion of particular design factors and “unquantifiable issues” would render any optimal or near-optimal solution infeasible. Geology is a major factor in any project involving cut and fill, and can cause unexpected changes in design in order to minimize costs. Although the inclusion of “unquantifiable issues” is nearly impossible in a model, I feel that the constraints posed by these issues would result in a significantly more expensive final design than what the authors advertise.

Secondly, I feel that the authors’ method is fairly limited in applicability. In order for this GA-QP scheme to be implemented, a new, large sewer network must be installed at a single point in time. New residential neighborhoods are obviously a good application, but the method offers no suggestions of improvement to existing networks, or small expansions upon such networks.

Nevertheless, I found the authors’ ideas to be interesting and worthwhile. Even if real-world constraints reject optimal and near-optimal solutions generated by the model, these solutions may encourage new approaches to design which could potentially save millions.

Assignment 10a: Brills, Brills, Brills

Brill E.D. (1979) USE OF OPTIMIZATION MODELS IN PUBLIC-SECTOR PLANNING, MANAGEMENT SCIENCE, 25

Summary

Brill’s article returns to a concept which we discussed near the beginning of this semester: “wicked” problems of the public sector, and how optimization models should be adapted when applied to these types of situations.

Brill begins his article by outlining the limitations of using optimization models. He points out how the economic efficiency objective is insufficient on two fronts: (1) it neglects to consider equity, and (2) it has empirical shortcomings associated with estimating benefits and costs. With respect to complete multiobjective models, Brill notes that in problems with several objective functions it may be “computationally impractical to generate a complete set of trade-off relationships.” He also observes that these complex problems may have “a plethora of local optima,” and that it would be impractical to have decision maker participate in the process. With incomplete models, Brill points out that the best solution may lie in the inferior region, since certain objectives are ignored.

With these shortcomings in mind, Brill suggests that “a philosophy of using optimization to aid the planning process” be adopted. This is in contrast to many current applications, in which complete “answers” are sought. Brill offers many suggestions which would streamline optimization models with the traditional “planning process.” His first set of suggestions involve the joint use of models, which he claims would enhance the capabilities of individual models. Second, and most importantly, Brill argues for the “use of optimization models to generate alternatives and facilitate evaluations.” He believes that use of optimization models in this fashion would serve as catalysts for human innovation, thereby enhancing the public-sector planning process.

Discussion

I thought this article was both soft and derivative. Its concepts and construction were nearly identical to Liebman’s article which we read at the beginning of the semester. If I had to applaud the article for one idea, I would say that its “suggestions” are an improvement over those presented by Liebman in 1976. Liebman’s “simple-minded suggestions” were extremely generic, whereas Brill’s suggestions point to specific actions which could be implemented to enhance the use of models in the planning process.

Assignment 9

Shiau JT, Wu FC (2006) Compromise programming methodology for determining instream flow under multiobjective water allocation criteria, JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, 42(5), pp. 1179-1191.

Summary

The two competing objectives at the heart of this study are the consumptive use of water and environmental concern.

The Kaoping River is a major river of Taiwan, flowing southward for 171 kilometers before discharging into the South China Sea. Water uses along the Kaoping have traditionally been agricultural, but in 1999 a diversion weir was constructed with the intent of diverting 35 cms for municipal uses. The river is also the habitat for several native species of fish. Prior to this study, minimum streamflows were set at a value of 9.5 cms.

It is now well-established that natural flow variability is essential to the well-being of a river ecosystem. In order to quantify the impact of the diversion weir, the authors examined "pre-diversion" and "post-diversion" stream data (upstream and downstream of the weir, respectively). 32 specific parameters, collectively known as Indicators of Hydrologic Alteration (IHAs), were measured for each set of stream data. Weir operations were targeted to have IHAs fall within the 25th and 75th percentile of prediversion values. Based on how closely an IHA fell to this target range, a degree of hydrologic alteration was determined. Finally, using a set of formulas constructed by the authors, an overall degree of hydrologic alteration was calculated based on the 32 individual degrees of hydrologic alteration for each IHA. Minimization of the overall degree of hydrologic alteration represented the "environmental" side of this problem.

The other two objectives of concern in this study were the minimization of agricultural water shortages and municipal water shortages. These two objectives obviously encompassed the "consumptive" side of the problem. The ultimate goal of the study was the minimization of three objectives: overall degree of hydrologic alteration, minimization of agricultural shortage, and minimization of municipal shortage.

The relationships between these objectives were fairly complex, but can be summarized fairly simply - higher streamflows are better for river ecology, but increase the risk of water shortages, and vice versa. The authors ultimately found that, with equal weight applied to natural flow variability and water supply reliability, a release rate of 26 cms from the diversion weir was optimal. The authors' solution also revealed that the status quo release rate of 9.5 cms was woefully inadequate, and only provided "a modest mitigation of hydrologic alterations."

Discussion

I found this article to be one of the most interesting of what we have read this semester. I really like the practical aspect of multi-objective programming, since in reality every complex situation has competing interests and goals. One of my main problems with the article was the way in which the overall degree of hydrologic alteration was calculated (Eqns. 2a, 2b, and 2c). With the way these equations were constructed, I felt the penalty for one IHA being of moderate or high alteration was too high. In addition, I found the equal weighting of the natural flow variability and water supply objectives in the final solution to be unrealistic. Based on traditional prioritization, it would seem more accurate to assume that municipal use would have the highest priority, agricultural use would be second, and environmental concerns would be third. A solution with this type of weighting would have been more meaningful, in my opinion.

Assignment 8

Neelakantan TR, Pundarikanthan NV (2000) “Neural network-based simulation-optimization model for reservoir operation,” JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT, 126(2) pp. 57-64

Summary

In this study, the authors employ a simulation-optimization approach to develop a model for reservoir operation. The system under examination is Chennai, India, and the surrounding reservoirs which supply its water system. In order to overcome the computational difficulty of simulation-optimization models in these types of problems, the authors incorporate a backpropagation neural network which is trained to approximate the simulation model. As for the optimization side of the model, the Hooke and Jeeves nonlinear approach is used.

Chennai is plagued by droughts on a frequent basis. Although the city receives 1300 mm (51 in) of rain per year, most of this received is during the monsoon season, which occurs between October and December. The ultimate goal of the authors' study is to reduce water deficits through optimal reservoir operation. If the erratic rain pattern makes these deficits unavoidable, the authors' secondary goal is to make the deficits less critical by providing water on a consistent basis, even though it may not completely meed demand. This process was referred to as "hedging."

Discussion

To be truthful, I wasn't able to grasp the authors' explanation of how an artificial neural network works. Nevertheless, I found their approach to be interesting, since it was able to take more complicated factors into account, such as evaporative losses and training errors related to the model. Although their approach was obviously more detailed than our homework, I found the dynamic programming approach to this problem much more enlightening. With worldwide demand continuing to grow and supplies becoming more erratic and scarce, however, a neural network approach may become more necessary in the future.

Assignment 7

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

Summary

This week's article had a very similar theme to our previous reading assignment. As indicated by the title, this study focuses on infiltration-based best management practices (BMPs), as opposed to storage-based BMPs, which we explored in last week's discussion. By infiltration-based BMPs, the authors refer to techniques "ranging from infiltration basins, rain gardens, and pervious pavements, to the use of swales and curb cuts to direct runoff from impervious surfaces to nearby pervious surfaces and depressions." The study ultimately aims to determine the optimal number and location of infiltration-based BMPs which would most effectively reduce peak runoff at a watershed outlet.

The authors selected the highly-urbanized Aberjona River watershed (near Boston) as the basis of this study. The watershed was modeled as a network of 4,533 hydrologic response units (HRUs). Each HRU was modeled as a 120m x 120m square cell and considered as a potential candidate for containing an infiltration-based BMP. Hydrologic fluxes of precipitation, infiltration, groundwater flow, and runoff were considered in each HRU. To model runoff, the NRCS curve number method was employed. Once all was said and done, the authors' model was validated and calibrated using known rainfall data from storm events in 2002 and 2003. A genetic algorithm was then used to determine the most effective locations of infiltration-based BMPs.

Because of the sheer size of the problem, the authors had to make further simplifications during the modeling process. Infiltration-based BMPs were treated as a binary decision. If this decision was a "1", the curve number on that particular HRU would be reduced by five, regardless of whether this reduction may have been less or more. Furthermore, the authors had to reduce the decision space for the genetic algorithm by narrowing down candidate HRUs. With these simplifications, the results indicated that a 20% reduction in peak flow could be achieved by implementing less than 200 BMPs. Furthermore, the authors examined the relationship between peak flow reduction and number of BMPs. Once beyond 600 BMPs, this relationship exhibited minimal reductions in peak flow.

Discussion

This article aided in my understanding of a situation which would require a genetic algorithm. Prior to reading this article, genetic algorithms seemed to be an alternative method, but not a necessary one. In this particular situation, however, I can't imagine a different technique which would yield a solution to such a highly complex problem. Even with simplifying assumptions, I personally can't comprehend a decision space of 7.0 E 168 possibilities.

I found certain aspects of this study more valuable than others. In terms of BMP distribution, I thought the authors' findings were an extension of common sense; it is obvious that industrial and commercial areas are going to be highly impermeable, so it is no surprise that the model targeted these areas as critical locations. What I did find useful, however, was the authors' examination of diminishing returns. Once 600 BMPs are in place in this particular watershed, the installation of any more is almost useless. Without this study, it would seem reasonable to assume that the installation of BMPs would have a continually beneficial effect, but this is clearly not so. This finding could save municipalities huge sums of money in the future as they move toward infiltration-based BMPs.

Overall, I feel that the authors' method could be improved by being made more general. It appears that a lot of work went into defining the Aberjona watershed with an array of specific parameters. If this process could be made more general and efficient, I believe the method would gain more recognition.

Assignment 6

Behera, P, Papa, F., Adams, B (1999) “Optimization of Regional Storm-Water Management Systems” Journal of Water Resources Planning and Management, 125(2) pp. 107-114

Summary

In 1997, Papa and Adams developed a model for optimizing detention pond geometry to minimize SWM pond costs. Decision variables in this model included storage volume, controlled release rate, and pond depth. Constraints included pollution control and runoff control.

In this article, Behera, Papa, and Adams extend their work to a system of three parallel catchments using dynamic programming. In this context, the objective function is expanded to minimize the total cost of implementing all three SWM ponds in the system. The authors define pond cost as the opportunity cost of the land occupied by the pond plus the construction and operation, maintenance, and repair (OMR) costs associated with the pond. The constraints are similarly expanded - the overall pollution control from the system prior to discharge must achieve a minimum specified level of control, and the runoff control from the system must also achieve a minimum specified level of control. Runoff and pollution control performances are defined by complex "isoquant" equations involving the runoff coefficient, rainfall event duration, rainfall event volume, and interevent time.

The authors go on to present the results of their dynamic program, and conclude the paper by discussing its benefits to land developers and municipalities. They also note that although the article only discussed a simple system of three catchments, their method is general, and may be applied to more complex urban runoff systems.

Discussion

From an economic perspective, I think the author's work is very valuable. I have always thought of detention ponds on a site-by-site basis, so the idea of analyzing several as a system struck me as creative. I can see land developers being particularly interested in this research, since the methodology reveals savings which were previously unachievable.

While their economic analysis was good, I feel that the authors overlooked a major trend in detention pond design. Today there is a large focus on seamlessly integrating detention ponds with their surrounding environment. When executed properly, the space can be used for other purposes during times of little or no storage, and oftentimes the public isn't even aware that the space is a detention facility at all. While the authors' model may yield the most economical solution, I doubt that it would be a seamless one.

The article also made me wonder how the model would change over time. While one solution may be optimal today with X number of detention ponds, future development will change the solution when more detention ponds are present in the model. Since the original detention ponds are already built to the specifications of the original solution, however, it seems that one would have to settle for a suboptimal solution when designing future development.

Assignment 5

Berry, J., Fleisher, L, Hart, W. Phillips, C. and Watson, J.-P. (2005) “Sensor Placement in Municipal Water Networks”, Journal of Water Resources Planning and Management, 131(3) pp. 237-243

Summary

Although nearly a decade has past since September 11, 2001, its impacts continue to persist today. Just as structural engineers face new challenges associated with public safety in the wake of 9/11, water resources engineers must also address similar dangers. The authors' article focuses on this subject.

Early warning systems (EWS) are the primary way in which terror threats related to water supply are addressed today. Such systems can identify both deliberate and accidental contamination of municipal water networks. The goal of the authors' research is to construct an EWS in which public protection is maximized and deployment costs are minimized. The authors turn to integer programming for a solution with the following assumptions:

1. An attack occurs at a single point in the network.
2. Total population exposure, without reference to health impacts, is examined.
3. Sensors protect downstream populations.
4. Transitions between time periods are ignored.

The preceding assumptions enable the use of integer programming - without them, the model would be too complex, and integer programming would be unreasonable.

More specifically, the authors' model is a mixed integer program. Its inputs include a given network of pipes and nodes, the probability of an attack at any given node, the population density at each node, flow patterns, and the maximum number of sensors that are deemed reasonable (or affordable). Its constraints ensure that if a node is directly attacked, it is contaminated, that a single sensor covers a pipe for flow in both directions, that contamination propagates from upstream in the absence of sensors, that there are limited number of sensors, and that there is integrality of the sensor-placement decisions.

The authors model their program using three pipe networks: two are example networks from EPANET, and the other is based on a real-world network. Each network is increasingly more populated and complex. Put simply, their results indicate that the optimal solution number varies very little with data uncertainty, and that percentages of the population at risk correlate inversely with the number of sensors put in place. The placement of sensors, however, is more susceptible to data uncertainty, a problem over which the authors muse but provide no concrete explanation. The article is then closed with four areas in which the ideas presented in the paper can be generalized and applied.

Discussion

This article served as an interesting counterpart to last week's reading. Although the mindset of the two papers was quite different, the underlying techniques were fairly similar. Overall, I see this one as an improvement over the last in that it addresses both intentional and accidental contamination schemes, both of which are consistent threats to public health.

Although the authors' effort to improve public protection is commendable, I feel that their model is too simple to be taken confidently. Terrorism is inherently random, clandestine, and uncertain. To assign a specific probability of attack at a certain location is a pure guess at best. Furthermore, attacks are often coordinated in more than one location, which violates the primary assumption of the authors' work. Addressing these two shortcomings with more complex modeling techniques would lead to significant improvements in this area of research. The authors mention techniques such as combinatorial heuristics and metaheuristics near the beginning of the article, which may be helpful in this regard.

Assignment 4

Lee, B.H. and Deininger, R.A. (1992) "Optimal Locations of Monitoring Stations in Water Distribution Systems", Journal of Environmental Engineering, 118(1) pp. 4-16.

Summary

This study stems from the mandates of the Safe Drinking Water Act, put in place by the U.S. EPA in 1974. The Act identifies specific water quality parameters which must be measured, and the frequency with which these measurements must be taken. The Act also states that water quality measurements must be representative of the entire water distribution system from which they are taken. The EPA's language is very broad and sweeping, and contains no clear explanation or suggestion of how this mandate should be met. The authors turn to integer programming for a solution.

The authors conceptualize their model with a simplified WDS of seven nodes and five demands. It is assumed that flow quantities and directions in the WDS are known. The model centers around the idea of sufficiently estimating water quality at adjacent nodes by knowing the water quality at a sampled node. For example, if 80% of the water delivered to Node B comes from Node A, it is reasonable to assume that the water quality at Node A is equivalent or superior to the measurements obtained at Node B.

The authors begin their model by first constructing a Water Fraction Matrix, W. To construct W, one node in the WDS is assumed to be the sampling node, and the fractional amount of water passing through other nodes en route to the sampling node is identified. This process is then repeated for each node, resulting in an "n x n" matrix of water fractions, where "n" is the number of nodes in the system. From W, the knowledge-carrying matrix K is constructed based upon a decided fractional criterion. If fractional values in W are above a specified value, they are rounded to 1. If below, they are rounded to 0.

From K, the integer optimization problem can be outlined. The objective function seeks to maximize the "representativeness" of the water quality measurements taken. Constraints include a limited number of sampling nodes (which can be set by the user), and a set of conditions which monitor the relationship between sampling node location and demand coverage. The authors then apply this approach to more complicated systems in Flint, MI and Cheshire, CT, demonstrating significant coverage improvements over current monitoring systems.

Discussion

I found this article to be an interesting application of integer programming, although I am curious to know what was done to optimize water quality measurement between 1974 and 1992, when this article was written. The article doesn't give much insight into existing practices at the time, but it is obvious that the introduction of integer programming to this problem provided a significant step forward toward optimization.

Although the authors account for many of the complexities of a WDS, I feel their approach is held back by its simplifications. Reducing a WDS to less than 5 flow/demand patterns, arbitrary selection of a "coverage criterion", and crude rounding in the "knowledge-carrying" matrix are some of the major generalizations which I feel would lead to smaller coverage percentages than advertised in the authors' examples. Furthermore, even if optimization yields 60% coverage of the WDS, there is still 40% of the system which is consistently unmonitored. Although the authors' solution may have the best relationship between coverage and cost effectiveness, I feel it needs to be supplemented by another system to account for these unmonitored areas, whether it be randomized or more sophisticated.

Assignment 3

Garrett Hardin, "The Tragedy of the Commons," Science, 162(1968):1243-1248.

Summary

Written in 1968, "The Tragedy of the Commons" is cited by many as Garrett Hardin's most influential work. Hardin focuses on the idea that individuals left to their own self-interests will ultimately deplete common resources and hurt the common good, even if such consequences are clearly not their intention.

Hardin illustrates this notion with a hypothetical cattle pasture. In this pasture, Hardin asserts that rational herdsmen would seek to maximize individual gain. According to Hardin, this end would be achieved by placing more cattle on the pasture, thereby increasing individual revenue. The negative component of this situation comes from the fact that more cattle on the land would lead to overgrazing. Since the land is common, however, the loss of overgrazing would be distributed among all herdsmen using the pasture. Thus, in the case of the commons, individual gain will always outweigh collective loss. Hardin asserts that this pattern continues until a common resource is completely obliterated, paradoxically making any type of individual gain an impossibility.

Hardin relates this metaphor to the "population problem," stating that the commons and unabated population growth are completely incompatible schemes. Hardin claims that the population problem has no technical solution, and that society must necessarily abandon the commons in breeding in order to avoid "ruin to all." Hardin observes how the commons have historically been abandoned in other aspects of human life, such as private property and waste disposal. Human breeding, Hardin claims, is simply an extension of this historical trend that must be regulated in order to preserve other freedoms that we currently enjoy.

Discussion

Although I find Hardin's perspective interesting, I also find it equally disturbing. First and foremost, I feel that Hardin ignores other factors that are at play when it comes to population growth, especially in highly developed nations. In Hardin's commons scheme, bringing a child into the world is a gain of +1 for the family of the child, and a loss of somewhere between 0 and -1 due to the dispersion of the child's needs and consumption throughout the world. What Hardin ignores is the direct economic burden that having a child places on a family. Recent estimates place the cost of raising a child from birth through age 17 to be somewhere between $250,000 and $300,000 in the United States. It would seem that this enormous cost would play a large role in deciding whether or not to have a child - and it does. In lesser developed nations, where these resources are often not available, children perish at rates several times higher than those in developed countries. These two realities are effective natural regulators of unabated population growth which Hardin completely ignores.

Second, I could never see Hardin's vision being successfully implemented in any free democratic nation, regardless of the circumstances. Regulation of human life in this manner has serious implications. What if the regulation of procreation was unsuccessful? Would you then judge which living people on earth were worthy of keeping their right to live? Human history has been marred by many dark periods surrounding these types of issues, which is why I believe the free world has collectively agreed that the right to live and procreate are inalienable natural rights.

In brief, I find Hardin's foresight valuable, but I strongly disagree with the conclusions he draws from his visions. Although he claims there is no technical solution, humans must continue to persevere with innovation. If we are ultimately unsuccessful in our technological advances, we must face the ugly doomsday of natural selection. Any attempt at regulating population growth beforehand, however, would be uglier.

Assignment 2

Atwood, D and S. Gorelick (1985) “Hydraulic Gradient Control for Groundwater Contaminant Removal”, Journal of Hydrology, 76(1-2), pp. 85-106

Summary

The Rocky Mountain Arsenal was a United States military facility that operated between 1942 and 1992. Its main purpose was to manufacture chemical weapons in support of the United States' involvement in World War II. Due to improper disposals, however, the site has been plagued by environmental issues (specifically groundwater contamination) ever since its inception. Cleanup efforts over the decades eventually led to the official establishment of the Rocky Mountain Arsenal National Wildlife Refuge in 2004. Cleanup is scheduled to be complete in 2011.

Atwood and Gorelick's article was written in the mid 1980s. By this time, the environmental impact of the Rocky Mountain Arsenal had been fully realized, and scientists were attempting to determine the most effective and efficient method of groundwater contaminant cleanup.

In their article, the authors document a hypothetical test of groundwater remediation at the Rocky Mountain Arsenal site. The method is broken into two distinct stages. In Stage I, the "[groundwater] contaminant transport is simulated through time using an assumed velocity field." This simulation yields an approximate contaminant boundary over time. In Stage II, the results of Stage I are integrated with linear programming to "select the wells and determine the pumping/recharge schedules that most effectively stop the migration of the plume by controlling the hydraulic gradient during cleanup."

Without first breaking the problem into two parts, this problem could not be analyzed in a linear fashion. Stage I yields an "expected geometry" of the contaminant boundary - a simplification which Stage II would be unable to function without. Given the expected geometry, the authors' linear program is capable of finding the optimal operation of wells around the site within a 16-year "management period". In the case of this particular problem, optimal operation is defined by the minimal amount of pumping/recharge required of wells which would sufficiently maintain the hydraulic gradient requirements outlined by the groundwater flow model from Stage I. In addition, the authors ran two iterations of the linear program: one "global", which accounted for the entire planning horizon, and another "sequential", in which the most optimal course of action was selected based on the current status of the system.

Discussion

I found this article to be both interesting and significant. Because the applicability of theory was so clear in this particular study, I found myself interested throughout the entire article. The authors did an excellent job of not delving too much into the background behind their linear program, but rather focusing on the approach to the problem and analysis of results. I found the authors' work significant simply by the nature of the issue they chose to tackle - any work involving the improvement of public health is inherently significant. In addition, shaving years of time off of the remediation effort is a major contribution which would have not happened without the authors' linear programming contribution.

Future work in this area will likely focus on combining the authors' two-stage process into one. Because Stage I of this process yields an approximate plume boundary location over time, the results of Stage II will only be as certain as the approximation of Stage I, regardless of how well the linear program is constructed. If these two stages could somehow be combined, a more accurate result would likely be obtained, and the process of modeling would likely be expedited. Nevertheless, I give the authors a lot of credit for the creativity of their approach, and I do not feel that the errors of these approximations take away from the significance of their findings.

NOTE

Additional information for this post was obtained from the following source:
http://www.rma.army.mil/site/sitefrm.html

Assignment 1

Liebman, Jon (1976) "Some simple-minded observations on the role of optimization in public systems decision making" Interfaces 6(4) pp. 102-108

Summary

In this article, Liebman examines the effectiveness of applying private-sector modeling and optimization techniques to "state and local decisions." Liebman colloquially refers to these problems as "wicked." Unlike private-sector issues, in which problems are often clearly defined and decisions unanimously agreed upon, public-sector issues are consistently marred by conflicting goals and individual biases. Liebman ultimately concludes that using private modeling techniques for public issues is like using an old tool for a new trick, and that the application of these modeling methods must be modified in order for them to be effective. He argues that only humans can resolve the complexity of "wicked" problems, and that models should be limited to assisting humans in the exploration of alternatives. Liebman then makes four "simple-minded suggestions," which are paraphrased below:

1. "Modeling is thinking made public." Models inherently "develop and transfer understanding" from an analyst to a decision-maker. Decision-makers should be more involved in the model making process in order to increase their depth of understanding surrounding their subject of interest.
2. "A model is not unique." Decision-makers often see the narrow view of one model's results. Seeing multiple, diverse models will lead to more informed decisions.
3. "The model is the message." Analysts gain greater understanding from more complex models, but the public loses out. Models should be kept as simple as possible without sacrificing integrity.
4. "Reinventing the wheel is not always bad." The use of a generic model gives the analyst no "feel" or understanding of its conclusions. Although time-consuming, a tailored model will usually be more accurate and provide more insight to an analyst.

Discussion

I personally found this paper more interesting than significant. Although he admittedly provides no answers in the article, the questions and concepts Liebman raises are interesting to ponder. Even with the factor of conflicting goals taken out of the picture, public issues are still staggeringly complex - modeling a balance sheet at a small company is obviously an easier task than optimizing traffic flow in a city like Houston or Los Angeles. Nevertheless, Liebman does an excellent job of proving public "wickedness" to be the crux of issues. When comparing the urban firefighting and river basin quality cases, Liebman shows that is it the nature of issues, not their technical complexity, that determines the success or failure of traditional modeling techniques.

I found Liebman's four "suggestions" to be an extension of common sense, which is probably why he called them "simple-minded." To me, Liebman's four suggestions can be boiled down even further:

1. If you're involved with making your model, you will understand more.
2. Seeing more points of view leads to a better decision.
3. Keep it simple, stupid.
4. Specialized models will be more accurate and understandable than generic ones.

Despite the shortcomings of his suggestions, I found Liebman's idea of using modeling for suggestions to be insightful. A possible implementation of this concept would involve two systems, one with a traditional-decision model and the other using Liebman's model-suggestion technique, and comparing the performance of the two. Unfortunately public systems are not "amenable to experimentation," which would make such comparison difficult. Other future work based on Liebman's idea could involve improving models and their suggested alternatives based on the traditional behavior of competing parties and other social inputs. If this were my research, I would work to improve the four "suggestions" Liebman provided and begin developing a controlled experiment (similar to the aforementioned one) to analyze their effectiveness. As they stand, Liebman's concepts and suggestions are very broad, and could be applied to almost any public scenario. I feel specificity, such as a modeling approach for river basin quality management, would lead to more rapid and measureable progress in the application of his ideas.

Ulibarri, Carlos, Harry Seely, and David Willis (1998) "Farm Profitability and BUREC Water Subsidies: An LP Look at a Region" Contemporary Economic Policy Vol. XVI pp. 442-451

Summary

At the heart of this article is the United States Bureau of Reclamation (BUREC) "irrigation assistance" policy. The policy has a long political history, but boils down to the fact that "irrigators are accountable to the Treasury for repaying BUREC construction costs." Construction costs stem from federal irrigation projects such as the Central Valley Project, which supplies 2 trillion gallons of water per year and serves as the lifeblood of agriculture in central California. The government is then paid back over a period of time based on the amount of water that irrigators use. If irrigators are unable to repay the government for irrigated water which they have used, the deficit is subsidized by an increase in the cost of electrical power which is provided by the federal government. In effect, the burden of cost is passed to anyone using federal power, even if they are not involved in agriculture. Due to a quirk in federal legislation, the US Treasury is also a source of water subsidy - although irrigators are required to repay the Treasury for the cost of construction, interest on irrigation-related capital costs is ignored, thus leaving the Treasury out to dry on multi-million dollar repayment plans that span the course of decades. The paper aims to formalize "...the cost relationship between power rates and irrigation water" by constructing a linear programming model which "estimates the change in farm profitability" from elimination of these costly subsidies. The results of the model indicate such action would result in a $4.58 million annual redistribution of irrigator profit to federal power users and the US Treasury.

Discussion

This article is significant in its findings. Although the final results show a $4.58 million annual redistribution of profit, the authors also note that such losses would not represent "significant regional impacts on growers," especially if taken in stride with more efficient irrigation and other water-saving techniques. With a US Treasury irrigation debt of $137 million in 1996, the authors feel that the results of the model illuminate a necessary course of action.

I feel that the authors did a poor job of explaining their model in the paper, which is probably why my explanation here is not very deep, either. There are some generalized mathematical formulas contained in Part III of the work, but they give the reader little insight. A clearer explanation of the model would give the final findings more validity.

Since the availability of water is very dynamic over time, future work in this area might relate to the restructuring of irrigation subsidy policy. Greater scarcity of the resource over time will translate to costlier projects which irrigators will have less of a chance of paying back. In the end, policy must be flexible over time as conditions change in order to create the most equitable situation for everyone involved.

Assignment 0

Dr. Zechman, classmates of CVEN 665, and everyone else out there:

My name is Ian Hudson. I am originally from northwest Houston, and I have been studying at Texas A&M University since 2004. I completed my undergraduate degree in Civil Engineering in December 2008, and am now pursuing a Masters of Engineering in Civil Engineering with a focus on Water Resources Engineering.

I am enrolled in Water Resources Systems Analysis because of my dual interests in water resources and technology. At the most fundamental level, my passion for water resources derives from the benefit it serves to society. Many other professions, especially in engineering and science, can raise political questions and discord, but the good deed of managing life's most vital resource is virtually unquestionable. My appreciation for technology is a reflection of my place in the last pre-internet generation. Although I do remember life without the internet, I was luckily born late enough such that my environment has always consisted of rapidly-evolving technology. Because of these two factors, I feel that my peers and I possess a unique combination of appreciation and skill that will be absent in later generations.

By the end of this semester, I hope to have an understanding of a programming language with which I have little or no prior experience. My undergraduate education at Texas A&M gave me a thorough understanding of MATLAB, which is a perfect tool in certain situations, but I would like to be familiar with other options for instances in which they would be more appropriate.

Critical Thinking

According to the English philosopher Francis Bacon, critical thinking is defined as a "...desire to seek, patience to doubt, fondness to meditate, slowness to assert, readiness to consider, carefulness to dispose and set in order; and hatred for every kind of imposture." One quote can obviously not encompass the concept of critical thinking, but Bacon's interpretation is a good start.

What strikes me as most true in Bacon's quote is a "patience to seek". In order to think critically upon a subject, one must have a measurable interest in the matter, as the mind will always naturally gravitate toward the subjects which it finds most interesting. Foreign language is an excellent example. Learning a language requires an enormous synthesis of information, word roots, relationships to other languages, and so on. If a student with no interest in learning Spanish is placed in a Spanish classroom, he or she may have sufficient performance, but will not ever critically think in the way that is necessary to master a language. On the other hand, a student whose goal is to become fluent in Spanish will inevitably immerse themselves in the subject and thereby notice more relationships, patterns, and nuances. The student with an interest in Spanish may not be as intelligent as the first, but due to the critical thinking which is spawned by their drive, the interested student will ultimately become a more proficient Spanish speaker.

I also agree with Bacon's emphasis on the time that critical thinking takes - "patience," "slowness," and "carefulness" are the three virtues which tie into this theme. By almost any definition, critical thinking cannot take place within a short period of time. In many cases, a person will devote their life to a subject, thus making their critical thinking process a culmination of lifelong knowledge. In a way, critical thinking is a continually dynamic process with no "beginning" or "end", so long as the conditions and information which influence one's complex web of critical thought are changing.

In the end, the breadth of critical thought is too great to be covered in one book, much less one blog entry. I am interested to see the thoughts of others!

Sources
http://www.criticalthinking.org/ (homepage)
http://en.wikipedia.org/wiki/Francis_Bacon