Category: Research

Principal Investigator: Peter E. Sturrock (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1984-08-01; Completion Date: 1985-08-01;
Keywords: Electrochemical Detection, HPLC, Carbamates, Triazines, 2,4-Dinitroaniline Herbicides.

Description:
The research summarized in this report investigated the application of a new electrochemical detector to the high-performance liquid chromatographic analysis of water for three classes of organic pollutants: carbamate pesticides, 2, 4-dinitroaniline herbicides, and triuine pesticides. The detector is a computer-controlled device capable of being programmed to operate in many modes. Rapid-sweep square-wave voltammetry, the preferred mode of operation where applicable, was applied successfully to the triazine pesticides. For these compounds, the detector is more sensitive than a uv detector, and the swept mode of operation is useful in resolving components not separated completely by the chromatographic column. For the 2, 4-dinitroaniline herbicides, the rapid-sweep square-wave voltammetric mode was also successful. However, no clear advantage over the uv detector is evident. For the carbamate pesticides, the swept mode of operation is not suitable because of the slow kinetics for the electron-transfer reactions. However, a DC mode of operation, with extreme potential pulses for electrode cleaning, was very effective. Several of the carbamates detected in this study have not been detected by electrochemical means before. The limits of detection are much superior to those reported for uv detectors or other electrochemical detectors.

Principal Investigator: Adel Shirmohammadi (University of Maryland)
Principal Investigator: Flavio da Silva (The University of Georgia)
Principal Investigator: Daniel L. Thomas (University of Georgia)
Principal Investigator: E. Dale Threadgill (The University of Georgia)

Sponsor: GWRI
Start Date: 1984-09-01; Completion Date: 1985-08-01;
Keywords: Georgia Flatwoods, irrigation, drainage, subirrigation, water table, models, water use, system design, soil hydraulic properties

Description:

This project was conducted on the SEA-MAR farm located in Pierce County, Georgia on Pelham loamy sand soil. The study area included 40 hectares of land under a drainage-subirrigation system of which 38 hectares were in blueberries, 1 hectare in corn and the remaining 1 hectare in soybeans. The system installation included two different drain spacings of 15.3 and 20 m for comparison purposes. Two types of water table management systems were used. They were an open ditch and a closed system network. Seventeen punch-tape water level recorders were used to measure the water level in the soil profile at midfield (on tiles and midway between the tiles), at the open ditch and closed system control structures (one for each), and in an undrained-nonirrigated section of the farm. A punch-tape rainfall recorder was also used to measure rainfall at the site.

Experimental results showed that using inappropriate design criteria or mismanagement can lead to poor performance of the system. Excessive drainage at the early part of the growing season coupled with slow subirrigation phase due to deep drain tiles (tiles were located too deep in less permeable material) resulted in poor performance of the system in the corn field. This led to crop stress. Proper management of the system in the blueberry field resulted in favorable soil water conditions and excellent crop growth.

DRAINMOD, a water management model for shallow water table conditions, was used to simulate the system performance for the conditions of Flatwoods soils. Simulation results indicated that a drain spacing of 18-20 m is appropriate for combined drainage-subirrigation systems for soils similar to those in Pierce County, Georgia. However, more research is required to develop appropriate design guides for other soil types in the Georgia Flatwoods region.

Overall findings showed that a combined drainage-subirrigation system is an appropriate water management scheme to be used in the Flatwoods of south Georgia. A preliminary economic analysis led us to believe that this system, if properly designed, can save up to $144/ha/yr and $129/ha/yr when compared to center pivot/drainage and traveling gun/drainage systems, respectively.

An initial evaluation of the water resources requirement for drainage-subirrigation systems indicated that more water is needed to achieve the same useable application amount than for other systems (center pivot/drainage and traveling gun/drainage). Hopefully, continued research can provide improved management practices and increase the water use efficiency of drainage-subirrigation systems.

Principal Investigator: Joe B. Birch (The University of Georgia)
Principal Investigator: James L. Cooley (University of Georgia)

Sponsor: GWRI
Start Date: 1980-11-01; Completion Date: 1983-05-01;
Keywords: Biomass, flood adapted, floodplain, forest, hydroperiod, moisture limited, oxygen limited, production, subsidy-stress.

Description:
Floodplain forest biomass production followed a bimodal gradient from the wettest to driest sites. The wettest sites were continually flooded and supported a bicultural water tupelo-baldcypress forest that was highly adapted through an extensive water-root system to constant flooding and periodic flushing by riverine floods. The wood production (6379 kg/ha/yr) of this forest was among the highest of the floodplain forests studied. The next wettest site was flooded much of the year, had waterlogged soil for much of the rest of the year, and had a drained soil surface for extended periods. This tupelo-baldcypress, root oxygen limited, forest did not have a water-root system and had the lowest biomass production (3553 kg/ha/yr) of any of the forests studied. The sites that were flooded during some portion of the year but well drained during most of the growing season while maintaining a relatively available soil moisture level were the most productive (6883 kg/ha/yr) floodplain forests. The forest that was only slightly flooded each year by the highest floods had a much lower biomass production (4623 kg/ha/yr) than the heavily flooded and well drained forest. Sites subjected to intermediate levels of flooding and well drained soils had an intermediate level of biomass production (an average of 5240 kg/ha/yr). The upland hardwood, moisture limited forest that is no longer flooded had a low biomass production (3677 kg/ha/yr) similar to that of the waterlogged soil, tupe10-baldcypress forest.

Principal Investigator: Augustine O. Esogbue (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1979-10-01; Completion Date: 1982-12-31;
Keywords: Nonpoint source water pollution, best management practices, public

Description:
Agencies designated to implement the Clean Water Act of Public Law. PS 72-500, Section 208 often encounter difficulties associated with the management of systems consisting of complex interactions of soft and imprecisely stated phenomena. Two such major areas in this implementation process concern the use of the publics in water resources plan formulation and the use of the so called best management strategies in the control of nonpoint source water pollution. The quantitative analysis of these systems as well as the development of quantitatively based models for measuring their effectiveness is the subject of the inquiry whose results are reported here.

The central thesis of our work is that because of the presence of soft imprecise variables, any quantification efforts should invoke the tools of fuzzy set theory. To prove this point, the goals of State Planning Industries particularly relative to Erosion and Sedimentation Control were reviewed and the problems inhibiting compliance highlighted. The essentially fuzzy variabIes and phrases were syphoned out and a plan to minimize the fuzziness developed.

The use of the publics in water resources planning was next considered leading to the development of a working definition of their effectiveness. A fuzzy multi-level hierarchical model which provides a pessimistic as well as an optimistic measure of this effectiveness was then developed and validated using the Water Resources Advisory Group of the Atlanta Regional Commission as the leitmotif. Various fuzzy clustering algorithms were developed to group the field data. This model was also used to analyze the contributions of various hypothesized variables (factors) on the total system effectiveness of public participants and planners.

A comprehensive list of BMPs in use in the State of Georgia as well as in the nation was developed and a statistical analysis of their effectiveness performed. Effectiveness was approached both from the system and cost effectiveness perspectives. The total effectiveness of BMPs as a control approach for nonpoint source pollution was assessed using a modification of the fuzzy multilevel model. As in the public participation effectiveness measurement, the contributions of each design principle to total system and cost effectiveness were determined. A statistical analysis of the importance and effectiveness of each BMP was also performed leading to a ranking of these BMPs, structural and nonstructural, in terms of their effectiveness. Their policy implications are obvious.

Principal Investigator: David L. Cochran (The University of Georgia)
Principal Investigator: Jerry L. Chesness (The University of Georgia)

Sponsor: GWRI
Start Date: 1981-04-01; Completion Date: 1982-06-30;
Keywords: Irrigation, crop water requirements, simulation modeling

Description:

A number of techniques are available for predicting irrigation water demands. However, many are applicable only to arid and semiarid climates where the probability of rainfall during the growing season is low. The rapid increase in irrigated acreage in the southeastern region of the U.S. dictates the need to develop methodologies suitable for humid climates.

A continuous simulation model was developed for predicting seasonal irrigation water requirements of crops. The model was derived by writing water balance equations for successive soil zones in an irrigated soil profile. The quantity of water infiltrating the uppermost zone was the difference between daily precipitation and runoff (according to the SCS equation for runoff volume). Zonal water volumes exceeding field capacity were passed into the next lower zone. Irrigation was called for whenever calculated soil water removal increased soil water tension to a preset level in the profile.

Input data to drive the model are: (1) historical or synthetic daily precipitation and pan evaporation values, (2) crop canopy growth factors; (3) soil water tension-content relationships, (4) irrigation water management depth and level (tension) and (5) SCS runoff curve number.

Daily measured values of soil water tension and irrigation amounts for nine crop (corn and soybeans) seasons were obtained from Dr. James Hook, Assistant Professor, Agronomy Department, Coastal Plains Experiment Station, Tifton, Georgia. Predicted seasonal irrigation water requirements averaged within 11.2% of measured values for eight of the crop seasons.

Principal Investigator: Ronald M. North (University of Georgia)
Principal Investigator: Jackie Sellers (University of Georgia)

Sponsor: GWRI
Start Date: 1978-10-01; Completion Date: 1982-08-01;
Keywords: financing, cost sharing, revenue sharing, *benefit pricing

Description:
Historical aspects of Federal/non-federal sharing of water resources costs were reviewed for projects and programs. The theoretical basis for these sharing arrangements were explored and the authors suggest that the only theoretically sustainable purpose for cost sharing is that of effecting changes in economic distribution or equity — not efficiency. The alternative cost sharing policies proposed in 1975, 1976, 1977 and 1978 were described and evaluated with respect to anticipated changes in shares of cost burdens should certain options be adopted. These evaluations were done in detail for flood damage reduction in the south Atlantic Gulf region. General estimates of cost sharing in Georgia were developed from available State budget data. All cost sharing and financing proposals emanating from Federal and state sources, in common, support or accede to a decreasing Federal financial and cost burden offset by increasing state assumption of both financing and cost burdens – some of which would be recovered from beneficiaries through user charges.

Principal Investigator: Joseph P. Gould (Georgia Institute of Technology)
Principal Investigator: Byung R. Kim (Georgia Institute of Technology)
Principal Investigator: Michael A. Rollor (Georgia Institute of Technology)
Principal Investigator: Wendall H. Cross (Georgia Institute of Technology)
Principal Investigator: Makram T. Suidan (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1978-11-01; Completion Date: 1982-09-01;
Keywords: carbon, granular activated carbon, regeneration, solvent regeneration, adsorption
Description:
he in situ solvent regeneration of activated carbon by means of organic solvent extraction has been suggested as an economically attractive alternative to thermal regeneration. Therefore, an experimental investigation was performed in order to identify, characterize, and evaluate the important physical-chemical aspects of the solvent regeneration process. Four adsorbates of varying molecular weights and size were employed along with five commercially available activated carbons in a series of continuous flow column studies in order to evaluate the effects of molecular size, regeneration temperature, solvent type and activated carbon characteristics on regeneration efficiency. In addition, the reuse of non-recovered (contaminated) solvent and the corresponding effect upon the economic feasibility of the regeneration process were examined. From the extensive experimental investigations, it was concluded that the important aspects of the solvent regeneration process include:

1) the physical and chemical characteristics of the adsorbent, particularly the pore size distribution and energy of adsorption associated with the activated carbon

2) the degree of solubility of the adsorbate in the organic solvent

3) the miscibility of the organic solvent in water

4) the temperature at which the regeneration is performed.

In addition, the economic feasibility of the process was determined to be directly related to costs incurred for energy requirements and to the recoverability of valuable adsorbates for subsequent reuse in the industrial process.

Principal Investigator: George Roy Elmore, Jr. (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1972-05-01; Completion Date: 1972-05-01;
Keywords:

Description:
Responsibilities of the states for management of their water resources have been increasing rapidly in the view of the public and under the requirements of Federal programs. The State of Georgia has been among those governments in states with abundant water resources which have given minimum attention to water resources management. As a result the organization of the State’s executive branch has been inadequate to meet many current demands for management. The issue by issue response of the State has proven unsatisfactory to those who desire more comprehensive and coordinated water resources management. The organizational structure of resources management agencies in Georgia has appeared to impede progress toward better coordination and more comprehensive management. Therefore many concerned citizens have viewed reorganization as a necessary step toward improved State programs. However there has been disagreement over the appropriate form of organizational structure and over the significance of organizational structure in achieving better water resources management. The objectives of this research are to identify effects of organizational structure of the executive branch of Georgia state government on its functional programs of water resources management so that a more objective assessment of the importance of organizational structure can be made.

The natural resources organization structure of Georgia has been compared to that of five other states with the aid of a research model developed from classical public administration theory. An outline of an ideal state water resources program was developed and applied to Georgia’s state and Federal water resources programs. This information was used to test hypotheses about the effect of organizational structure on water resources programs.

It was found that, although the power of the available techniques of analysis and the available data were not sufficient to define organizational structure as cause and program as effect, the structural forms recommended by classical public administration theory were regularly associated with more highly developed programs. Existing and potential shortcomings of Georgia’s water resources programs which appear to be related to organization are interagency conflict, ineffective leadership from the governor, difficulty in adapting to change, and the omission of programs for water resources planning, flood protection, dam safety, and water rights. Possibilities for improvement of Georgia’s organization suggested by the organization of other states are discussed.

Principal Investigator: William C. Little (Georgia Institute of Technology)
Principal Investigator: Paul G. Mayer (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1972-05-01; Completion Date: 1972-05-01;
Keywords:
Description:

The objective of this study was to systematically investigate the effects of sediment gradation on channel armoring. The primary variable was gradation of the sediment material. A geometric mean diameter of 1.00 millimeter was used for all sediments with geometric standard deviations, ago, of 1.12, 1.50, 2.00, 2.50, and 3.00. These mixtures of crushed quartz were placed in a recirculating flume with a sediment bed 1.97 feet wide, 40.0 feet long, and approximately 0.15 foot deep.
Arbitrarily selected flows, to purposely induce armoring, were kept constant throughout each experiment. Bed slope was initially set at 0.002. Depth of flow was held constant throughout each experimental run by a sluice gate. The armoring process was considered to be stable when the final
sediment transport rate was not more than one percent of the initial transport rate. The surface layer of particles was then removed by the wax method and the distribution of the armored particles determined. An empirical equation was developed through dimensional analysis relating the sediment properties of the original and armored distributions to the flow properties, when the sediment bed had become stable because of the armoring process.
The equation is

[3 -I 0.353u*c = 0.908 v(s-l)g dgo ° go (1)

where dga and dgo are geometric mean diameters of the armored and original sediment mixtures, respectively, σgo is the geometric standard deviation of the original sediment mixture, u* is the bed shear velocity defined by u* = gRS where g is the acceleration of gravity, R is the hydraulic radius and S is the slope of the energy grade line, ν is the kinematic viscosity of the water, and s is the specific gravity of the sediment (2.65). From the equation, for the given flow conditions and original sediment properties in a channel, the geometric mean diameter of the armored material, dga, can be calculated. The armored diameter calculated from this equation is applicable only if the channel would armor.

Another criterion was developed to determine, for the given sediment and flow properties, if the sediment bed could armor. If the calculated geometric mean diameter of the armored surface material was between the d05 and d95 (that size for which 5 and 95 percent, respectively, by weight is finer) size of the original material, the original bed material would armor for those flow conditions.

With the broadly graded materials, σgo >= 2.00, where channel armoring occurred, the bed degraded uniformly in depth along the length of the bed. However, for uniform materials, σgo < 1.50, little or no armoring could be induced, and the bed did not degrade uniformly in depth but degraded more at the beginning of the reach and less at the outlet end resulting in a reduced bed slope.

Dunes formed initially and as they moved off, armoring was immediately observable. Armoring of the surface had no significant change on the average bed shear stress throughout the armoring process.
After an armor coat had developed, a very low sediment transport rate continued for long periods of time. This transport was by local scour of fine material around larger particles. Fine material could be observed hiding in the wake or zone of separation of the large partides. Turbulence caused shifting of the zone of separation and sporadic movement of fine material. The results of this study were compared with the calculated armored distributions by a method developed by Gessler. The geometric mean diameters calculated by Gessler’s method were consistently lower than the measured values of this study and differed from 3.5 to 29.0 percent with an average difference of approximately 20 percent.

Principal Investigator: Alfred W. Hoadley (Georgia Institute of Technology)
Principal Investigator: Mark A. McClanahan (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1970-12-01; Completion Date: 1972-06-30;
Keywords:

Description:
Seasonal limnological changes in the vicinity of a major (1200 acres) recreational facility on Lake Sidney Lanier, Georgia were studied from November, 1970 to November 1971. During the study period only the beginning phases of construction occurred (clearing and grading land, road construction and utility installation). Parameters measured included: temperature, dissolved oxygen, pH, Secchi disk transparency and iron and nitrate concentrations. A positive heterograde oxygen profile with the maximum in the metalimnion developed during summer stratification. This type oxygen profile was found both around the construction site and in the open lake. Occurrence of this type of profile at both 10 cations indicates that the lake water contained the nutrients necessary for the production of oxygen rather than their being washed into the lake from the construction site. The only detectable influence of the construction activity at the site on lake water quality was siltation of some of the bays near where large areas of land had been cleared and the soil disturbed. Analysis of the available data indicates that the part of Lake Lanier studied could be classified as mesotrophic. However, it could be caused to become eutrophic in a rather short period of time if the influent waters are allowed to be degraded by man-made wastes.