Category: Research

Principal Investigator: Edward M. Perdue (Georgia Institute of Technology)
Principal Investigator: J. Helmut Reuter (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1969-07-01; Completion Date: 1971-12-31;
Keywords:
Description:

The rivers of southeast Georgia are rich in dark brown organic matter which resembles soil fulvic acids both in appearance and in chemical characteristics. The Satilla River system, draining out of the coastal plain, was sampled from the headwaters downstream to the freshwater-salt water interface. River water organic matter, obtained by freeze-drying the river water samples, was fractionated by gel permeation chromatography (GPC) into three molecular weight fractions. Both the unfractionated river water organic matter and the GPC fractions were characterized by chemical analysis of acidic functional groups (total acidity, carboxyl groups, and phenolic hydroxyl groups). The material was found to be highly acidic, with total acidity ranging from 11.3 to 16.6 meq/g. Carboxyl groups (6.9 to 10.7 meq/g.) accounted for much of the total acidity. The material was characterized by IR and NMR spectroscopy. The spectra are comparable to those of soil fulvic acids, but are distinctly different from the spectra of humic acids. The unfractionated material was hydrolyzed and the hydrolyzate was analyzed for amino acids. From the amino acid content, the percent nitrogen in river water organic matter was calculated to be less than one percent, which is in good agreement with values reported for soil fulvic acids (Schnitzer and Skinner, 1968).

Technical Report

Principal Investigator: Duane W. Hill (Georgia Institute of Technology)
Principal Investigator: Eugene A. Laurent (Georgia Institute of Technology)
Principal Investigator: L. Douglas James (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1969-10-01; Completion Date: 1971-09-30;
Keywords:

Description:

The goal of flood plain management is to reduce the adverse effects of flood events by modifying human activity on the flood plain. Formulation of an effective combination of incentives and controls requires an understanding of the particular people involved, of the reasons motivating flood plain settlement, of perceptions of and attitudes toward the hazard, and of the kinds of communication likely to dissuade further encroachment.

The foundation for this study is an analysis of the various levels of decision making affecting flood plain settlement from the viewpoints of the individuals seeking a residential location, the individuals engaged in land development and construction activity, and individuals charged with forming and implementing public flood control policy at various levels of government. A conceptual model is presented of factors influencing how individuals select a residential location, react to flood experiences, and pressure for government help.

Flood plains (defined by the 50-year event) in the Peachtree Creek watershed in metropolitan Atlanta, Georgia, contain 1831 homes predominately occupied by middle to upper income white owners. A randomly selected, geographically stratified sample of 175 residents was chosen, and information was collected from 135 of these in a 200-question structured interview. Responses and associations among responses are tabulated and analyzed. One of the most important findings was that 43 percent of those interviewed knew of the hazard before they moved in. Furthermore, 89 percent said that they expected at least one flood in the next 50 years and 61 percent expected at least eleven. The area had had five floods severe enough to inflict major damage in the seven years before the interview. Respondents reported a median damage of $400, and some gave figures as high as $10,000. Despite this record, 63 percent say they have no doubts that they would still move into the same home knowing what they now know about the hazard. Only 15 percent are seriously considering moving away. Of those who say they expect to be flooded at least once every five years, 54 percent say they would still definitely move into the same house and 27 percent say they definitely would not. When expectations also included damages in the order of magnitude of $500 per flood, the percentages were 34 percent would and 40 percent would not.

The results of the study have a number of implications with respect to making flood plain management policy. When a large body of people are quite willing to endure floods every few years to enjoy the other advantages of living in an area, a policy that automatically prohibits them from doing so would be critically reviewed. The argument is particularly strong for plains subject to shallow flooding. Such events do relatively little damage to properly constructed homes and pose only a minor threat to life and health. The study points out basic differences between the type of people who knowingly risk flood hazards and the type who move onto flood unaware of the danger and discusses the implications of these terms of differences in the information that people in the two groups must be supplied to influence their location decisions.

Technical Report

Principal Investigator: John J. Heise ()

Sponsor: GWRI
Start Date: 1967-10-01; Completion Date: 1971-06-30;
Keywords:

Description:

The cyclic nature of concentration and chemical forms of transition metal ions in resevoir waters as the seasons progress has been dileneated. Stratifications of metal concentrations with depth profiles have been followed. This report seeks to confirm the changes in concentration of iron and manganese through the year as temperature, acidity and activity of biota change. Particular attention has been paid to determination of differences in concentrations of certain valence states of manganese and iron by use of electron spin resonance (ESR) absorption and atomic absorption (AA) techniques. ESR was used to determine the concentration of the divalent valence state of manganese (Mn++) and to compare it to the total concentration of manganese as determined by AA.

The results showed that there are significant differences between the amount of manganese found by the two techniques at any one sampling site depth profile. A proportional increase in the Mn++ form of manganese at all the sampling sites was correlated with a progression in season through summer. Proportionally higher Mn++ concentrations were found to occur at lower depths in the hypolimnion compared to the surface epilimnion.

The metal iron was found to be unsuitable for ESR analysis because of its complexion into organic and mineral forms that do not allow valence state ESR analysis.

However, some solid natural mineral deposits from Lake Allatoona which yielded complex ESR spectra were found. The ESR spectra of the metallic deposits suggest that they are made up of some ferro-manganese complex.

Principal Investigator: Charng Ning Chen (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1970-11-01; Completion Date: 1970-11-01;
Keywords:
Description:

The mechanics of the process by which a sediment particle is removed from a stream bed was investigated. An idealized model, consisting of a one-inch diameter sphere protruding through a flat plate, a sphere-supporting base, and two equal height sphere-restraining pins aligned perpendicular to the flow direction, was used to simulate the condition of a cohesionless particle lying on a stream bed. By means of this model, the statistical variables of the angle of repose, the protrusion condition, and the approach velocity distribution became controllable at deterministic values.

In spite of the replacement of most of the statistical variables by the deterministic variables, initial motion of the particle is a fluctuating phenomenon which must be described in probabilistic terms because the fluid-dynamic force is fluctuating in nature. The transition from a stationary state to the removal of the spherical particle was found to be gradual rather than instantaneous. The transition is characterized by the random rocking motion of the sphere. The initial stage of the transition is defined as the condition at which the cumulative per cent time of contact between the sphere and the base is 95 per cent. The final stage is defined as the condition at which the sphere would be rolled over definitely. The condition of initial stage is established by equating the static weight-restoring moment to a moment level which exceeds the fluctuating fluid-driving moment 95 percent of the time. The final stage is established by equating an additional impulsive moment to the difference of the driving moment and the restoring moment as used in establishing the initial stage. The flow condition associated with the transition is expressed in terms of the mean velocity at the height of the protruding sphere. The effect of nonuniform velocity distribution is accounted for by the use of a momentum correction coefficient.

The fluid-dynamic moments and forces were determined experimentally in air flow with both uniform and non-uniform approach velocity profiles. Since the transitional stage is associated with the balance of moments, a method has been developed using the weight-restoring moment at the transitional stage as a gauge to measure the unknown fluid-driving moment. The corresponding fluid-driving force pattern was then determined through a set of three algebraic equations defining the equilibrium of moments due to the driving force and the restoring force. Experimental results indicated that the ratio of the coefficient of lift to drag decreased from approximately 1.6 to 0.4 as the ratio of the protrusion height to the sphere diameter increased from 25 per cent to 100 per cent. Also, the resultant fluid driving force could be considered as passing through the centroid of the sphere for protrusion height equal to or less than 75 per cent of the sphere diameter.

Technical Report

Principal Investigator: William W. Hines (Georgia Institute of Technology)
Principal Investigator: John E. Knight (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1968-07-01; Completion Date: 1970-06-30;
Keywords:

Description:
The management and control of a region’s water quality are known to be greatly influenced by prevailing social, political, and economic conditions. Research into how these conditions and attitudes relate over time to result in water quality control has been inadequate to date. The main objective of this research has been to illustrate how these prevailing conditions and attitudes interrelate in an information feedback and control system to produce traditional modes of system response. Included are such considerations as the level of water standards legislation, public awareness to pollution concentrations, enforcement effort by an administrative agency, and ecological deterioration due to excessive pollution concentration levels.

More specifically, the research attempted to (1) identify and quantify some controlling feedback loops in the complex system which encompasses water quality control and response in a basin, and (2) test the generalized model under a wide range of policies and parameters to illustrate system response and sensitivity to these changes. Utilizing the understanding of the system structure and its response patterns, directions for effective policy formulations can be suggested and tested. The methodology and philosophy of Industrial Dynamics was utilized to model this high order, multi-loop, non-linear feedback system. The DYNAMO simulation language was used to program this model for digital computer simulation, testing, and experimentation.

Initial emphasis in the modeling phase was placed on isolation of important system variables and identification of their relative magnitudes, periods, and phasing in historically polluted watersheds. The understanding of the relationships between these social, political, and economic factors led to the postulation and testing of interrelated feedback loops thought responsible for identified modes of behavior. Following refinement of the model, different policies and parameters were tested to determine their overall effect on total system response.

The results of the research include a systematic analysis of important feedback loops within the total complex system identified. General response patterns of water quality crises are shown to be embedded in the system structure proposed. Within the complex structure, feedback loops were found to have greater importance in system behavior than did relationships between variables in feedback loops. In addition, gaining an understanding of when and how various loops gain dominance of the system was then found to be necessary for understanding system response. For example, the non-linear public awareness to perceived water pollution concentration levels created different response according to the loop’s ability to direct the system for an extended time.

In summary, the study conclusions demonstrate that water quality management and control is deeply embedded in a complex, information feedback system involving social, political and economic pressures and forces. Furthermore, the complex system response was shown to be highly insensitive to many parameter changes and also very unintuitive in behavior. However, some critical points do exist, and through programs directed at these points, significant changes occur in system response.

The results of the study would be applicable to high level, governmental planning agencies since effective understanding of the interactions creating historical, pollution-control response patterns would lead to more effective development of future control policies and programs. Specifically, the research provides some in sight into the total system response time as conditions of public awareness, enforcement effort, and legislative commitments change over time.

Technical Report

Principal Investigator: William E. Gates (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1965-05-03; Completion Date: 1969-06-30;
Keywords:

Description:

The problem of dynamic oxygen balances obtained under a variety of oxygenation and deoxygenation conditions was studied. Both laboratory studies using batch reactors and field studies using natural streams were conducted during the course of the project. It was determined that the Streeter-Phelps expression for the mathematical description of oxygen sag curves was inaccurate due to the inclusion of the first order expression for describing substrate utilization by bacteria. The Monod Equations were determined to be most appropriate for defining bacterial substrate utilization and protozoa bacterial utiliization. The nature of substrate utilization as determined by the COD test was found to be dependent on the time frame for sampling. The shorter the time frame, the greater the variances and apparent inconsistencies in the data. This situation was not totally resolved, but, probable explanations were developed. Techniques for determining the Monod Equation constants using batch reactor data and data obtained under continuous dilution in a natural stream were developed. In general, the results of the study indicate that the use of a laboratory system to evaluate the impact of alternative methods of water resource management on the oxygen resources of the receiving stream is an appropriate course of action.