Category: Research Sponsored by GWRI

Principal Investigator: George A. Brook (University of Georgia)
Principal Investigator: Chin-Hong Sun (The University of Georgia)

Sponsor: GWRI
Start Date: 1985-08-01; Completion Date: 1985-08-01;
Keywords: Modelling, Simulation, Georgia, Hydrology, Lower Coastal Plain, Watershed, Ground Water, Streamflow

Description:
Overland flow to streams is rare in the Lower Coastal Plain watersheds of Georgia. As a result, commonly-used watershed hydrologic simulation models can not be used to predict streamflow accurately. Therefore, a distributed watershed hydrologic simulation model, named COASTAL, has been developed specifically for the Lower Coastal Plain regions of Georgia, Florida, and South Carolina. A basic assumption of the model, which can be run on a personal computer, is that all streamflow results from ground water discharge into stream channels. COASTAL was developed by combining surface and ground water simulation models. In modelling, the watershed is divided into rectangular grid elements. Input data for each grid element can be obtained easily from topographic maps, soil surveys, aerial photographs and generalized published tables. At least one year of measured daily streamflow data is needed to calibrate the model. Outputs from the model include daily stream discharge, a water budget, and average daily ground water level for each grid element within the watershed.

The model has been tested using data for the Hurricane Creek watershed of Georgia. Correlation coefficients between simulated and measured streamflow were in the range 0.8 to 0.9. Work is presently underway to improve COASTAL by installing an automatic calibration module.

Principal Investigator: M. M. Aral (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1984-08-01; Completion Date: 1985-08-01;
Keywords: Ground water seepage, *Finite element method, Multilayer aquifers, Aquifer management

Description:
In order to effectively monitor and manage aquifers subjected to artificial recharge as well as increased pumping demands, it becomes necessary to analyse their hydrodynamic response. Several mathematical/numerical models are developed earlier to accomplish this purpose in a regional scale for single layer aquifers. In the present study a regional two-dimensional flow analysis is formulated using finite element techniques for multilayer aquifers. The advantages of using finite element analysis for aquifer analysis become evident when attempting to model irregular boundaries and variable inputs such as recharge, pumping and field properties in multilayer systems. Numerical solutions are also presented, which when compared with known analytical solutions show the accuracy levels expected and also some limitations of the model. This study is a preliminary step toward the ultimate goal of predicting and monitoring water quality and quantity in a multilayer aquifer system.

Principal Investigator: Gian S. Ghuman (Savannah State College)

Sponsor: GWRI
Start Date: 1984-08-01; Completion Date: 1985-08-01;
Keywords: groundwater, contamination, leaching, sludge, water quality

Description:

A study was conducted on the City of Savannah’s Water Pollution Control Plant to determine the efficiency of wastewater treatment in the removal of heavy metals. Four periodic samples of influent water, effluent water and sewage sludge were collected in October, December, 84 and March, June, 85 and were analyzed for the concentrations of Mn, Zn, Cd, Cu, Ni and Cr. The concentrations of dissolved heavy metals were slightly greater in the treated effluent water than in the influent water. Separation of sludge was effective in the overall removal of heavy metals from the wastewater. The activated sludge component of effluent water had high concentrations of heavy metals and must be fully removed to minimize the heavy metal content in the discharged water. Among the heavy metals, the total concentrations of Zn, Cu and Ni in the effluent water (both the aqueous and the sludge phases) were decreased, which indicated a material balance of zero for these metals when removal in the separated sludge is considered. On the other hand, the total concentrations of Mn, Cd and Cr were increased in the effluent water as compared to the influent water and it may be possibly due to the influent water samples collected from the outlet in the plant not being truly representative of the material, going in for treatment. A leaching study in PVC columns packed with sludge ash (pH 10.4) was conducted using de-ionized water, lagoon water, and acetic acid 5000 ppm (pH 5.0) as the leaching solutions. All leachates contained very low amounts of heavy metals and the incineration of limed sewage sludge into ash appears to be an efficient method of disposal. High concentrations of heavy metals as insoluble oxides in the sludge ash may prove to be a commercial source in the future for chemical separation.

Principal Investigator: James E. Kundell (The University of Georgia)
Principal Investigator: S. Wesley Woolf (The University of Georgia)

Sponsor: GWRI
Start Date: 1984-07-01; Completion Date: 1985-06-01;
Keywords: coastal marshes, drainage, erosion, estuaries, flood control, forest management, Georgia, land use, law, marshes, salt marshes, soils, urban runoff, vegetation, water management, waterfowl, wetlands.

Description:
Georgia is experiencing “Sunbelt” population growth and expansions in agricultural and forestry production resulting in increased pressure to convert wetlands to other uses. An analysis was undertaken of data generated by the Fish & Wildlife Service’s National Wetland Inventory, Georgia Department of Natural Resources’ Landsat land use study, and Soil Conservation Service’s National Resources Inventory. Wetland acreage, distribution, types, and trends were identified for Georgia. A review of case law and statutory law was conducted and wetland management activities of federal, state, and local governments were determined. Alternative management strategies were identified for Georgia.

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.