VTechWorks Repository :: Browsing by Author "Shanholtz, Vernon O."

Browsing by Author "Shanholtz, Vernon O."

Now showing 1 - 20 of 36

Agricultural engineering: application of a parametric model to simulate flows from an urban watershed
Harris, J. A.; Shanholtz, Vernon O. (Virginia Agricultural Experiment Station, 1975-11)
Past studies using parametric watershed models for simulating the hydrology of agricultural watersheds have been proven effective. They can also be used when studying watersheds containing significant urban influence
Agricultural engineering: hydrologic and water quality modeling of surface water discharges from mining operations
Herricks, Edwin E.; Shanholtz, Vernon O.; Contractor, Dinshaw N. (Virginia Agricultural Experiment Station, 1975-01)
Studies were undertaken to develop methods whereby a better understanding of the impact of mining on drainage from a specific area could be achieved.
Agricultural engineering: hydrologic response units based on characteristics of the soil-vegetative complex within a drainage basin
Li, E. A.; Shanholtz, Vernon O.; Contractor D. N.; Carr, J. C. (Virginia Agricultural Experiment Station, 1975-12)
A model in this paper was developed to predict precipitation excess. It predicts excess by hydrologic response units using a hydrologic model. The model simulates excess precipitation with infiltration equations.
Agricultural land use : effects on the chemical quality of runoff
Smolen, M. D.; Shanholtz, Vernon O. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1980)
This research is the first phase of the Blackstone Environmental Quality Program, a study to distinguish the water quality effects of agricultural practices. Th is research focused on changes in runoff quaIity when land is put under cultivation. The data will be used in later phases of the program to evaluate chemical transport models. The three study watersheds, located in Virginia's southern Piedmont, had not been under cultivation for 30 years. During the research, two of the watersheds were put into agricultural production while the third was left uncultivated and used as a control. A grab sampling program was maintained on two watersheds for the full five-year period of study. Continuous streamflow gaging was maintained for the last four years. During the final three years, sampling and flow gaging were also maintained on a third watershed. For those three years, grab sampling was supplemented by automatic samplers for stormflow sample collection. Samples were analyzed .for nitrate, ammonium, and total Kjeldahl nitrogen, orthophosphate and total phosphorus, bicarbonate alkalinity, pH, and specific conductance. Clear differences in streamflow characteristics were noted between the treated and the control watersheds. More surface runoff was observed in the treated watersheds than in the control, suggesting that increased surface runoff may have resulted from the cropping activity. All three watersheds exceeded the phosphorus criterion proposed by the Environmental Protection Agency, and a two-to-threefold increase in total phosphorus concentration was attributed to agricultural land use without employment of conservation practices. A twofold increase in total nitrogen concentration also was noted. Soluble inorganic nitrogen was present at a low concentration in the control watershed, but accounted for 20-30 percent of all nitrogen exported from the treated watersheds. The presence of nitrate nitrogen in the agricultural watersheds was the characteristic most attributable to agricultural activity. The research showed that serious enrichment problems could occur in Piedmont lakes or impoundments if the predominant land use of a watershed were agricultural cropping and if conservation practices were not employed.
Auxiliary Procedures for the AGNPS Model in Urban Fringe Watersheds
Yagow, Eugene R. (Virginia Tech, 1997-02-28)
The Agricultural Nonpoint Source model (AGNPS) is a single-event grid-based model used for simulating runoff, sediment and nutrients from agricultural areas. This study involved using geographic information system (GIS) spatial data and functionality to improve the spatial and temporal assignment of parameter values for the AGNPS 5.0 model and incorporated methods for representing urban fringe land uses and their nonpoint source (NPS) pollution contributions in model inputs. Auxiliary procedures for modeling with AGNPS were developed both for enhancing input into the model and for enhancing modeled output. On an event basis, one procedure automated the creation of complex-formatted AGNPS 5.0 model input files using GIS as a spatial data manager. One pair of alternative procedures were developed to automate the assignment of parameter values on an event basis. One procedure used typical average annual parameter values, and the second assigned parameter values using adaptations of existing time-dependent relationships. On a monthly basis, a sequencing procedure was created to perform multiple runs with the model for a list of storms while updating parameters for each event and aggregating monthly modeled spatial output. Another pair of alternative procedures were developed to facilitate the simulation of monthly output from AGNPS modeled events. The first of these aggregated event output for all storms in each month, while the second supplemented the aggregated output with baseflow and septic system loads. The study area was the 6,500 ha urbanizing Bull Run watershed in northern Virginia, which was modeled as 14,621 cells. Databases were assembled and 109 selected storm events within a 16-year period were modeled using the above procedures. Event data were added together, where necessary, to correspond with observed data from composite-sampled intervals. Output from the two event parameterization procedures were compared with monitored loads calculated for 89 composite periods, while output from the two monthly simulation procedures were compared with monthly monitored data for 23 complete months. The monitored-modeled comparisons were considered inconclusive. Evidence strongly suggested that the rainfall records from a rain gauge outside the watershed did not correspond well with monitored runoff. The average runoff produced with the AGNPS model from the 109 selected storms amounted to 40.7% of rainfall, consistent with the calculated long-term average of 38% for the Bull Run watershed. A nonpoint source pollution index was developed to utilize monthly modeled total nitrogen, total phosphorus, and suspended sediment. Individual rating curves were developed to separately transform loads and concentrations of each pollutant into sub-index values. The maximum sub-index from each parameter was added together and averaged for the index. The index was calculated at the watershed outlet from monitored data, and in a spatially-distributed fashion along all streams from simulated output.
A case study of irrigation water management at Kaudulla irrigation scheme and development of water management alternatives for the dry zone of Sri Lanka
Goonasekere, Kapila G. A. (Virginia Polytechnic Institute and State University, 1985)
A case study was conducted at the Kaudulla irrigation system in the city zone of Sri Lanka. The principal objective of the study was to perform a comprehensive evaluation of the system in operation with primary focus on identifying major constraints to effective irrigation management through a multi-disciplinary research approach. Inadequate control facilities and neglected maintenance of the channel system were the major problems affecting irrigation management. Other constraints identified were the lack of motivation among management personnel and insufficient funds available for maintenance, which were dependent on constraints external to the system, namely the national economic and political environment. The delicate economic status of a majority of the farmers, grassroot level political environment and the economic vicissitudes of the entire country have resulted in the formation of vicious economic cycles that have contributed to a breakdown in the institutions essential for an engineering system to function effectively. Irrigation management alter:aat:ives were developed on the basis of generating motivational incentives to the management personnel and financial resources to sustain the technical capability of the engineering system to effectively distribute the irrigation water. Techniques for integrating these aspects into new community organizations in addition to existing organizational framework were outlined. These procedures should assist in eliminating the major constraints to effective utilization and management of irrigation water.
A Comparative Study of the Total Maximum Daily Load (TMDL) Program and Process in Virginia and Kansas: Possible Outcomes and Effects upon Stakeholders
Miller-McClellan, Jennifer Lynn (Virginia Tech, 2003-04-29)
As population increases, the number of water bodies meeting water quality standards tends to decrease. The 1972 Clean Water Act (CWA) addresses the issues of point and nonpoint source pollution by requiring states to compose lists of waters that do not meet water quality standards and develop Total Maximum Daily Loads (TMDL) for those waters. This requirement of the CWA remained inactive until EPA and states suffered lawsuits from environmental groups and concerned citizens. The result prompted a flurry to develop TMDLs in compliance with consent decrees. A variety of methods and models serve as tools to calculate existing loads, load reductions and allocations. The purpose of this study is threefold 1) to examine two methods of TMDL development, Flow Duration (FD) used in Kansas and Hydrologic Simulation Program-Fortran (HSPF) used in Virginia; 2) to compare results of both methods in the same watershed of Virginia; and, 3) to evaluate stakeholder involvement in the TMDL process. A variety of stakeholders such as agencies, towns and industry, agribusiness, and concerned citizen/environmentalists are faced with meeting TMDL reductions and allocations. It is important that the TMDL process and implications are understood by all stakeholders.
Comparison of two hydrological models on a Virginia Piedmont watershed
Fu, Youtong (Virginia Tech, 1994-12-05)
KINEROS and PSRM-QUAL:J two distributed parameter event-based hydrologic models, were applied to Foster Creek Watershed, Louisa County, Virginia. The simulations of the two models were conducted using published data and a ten year database from the Foster Creek Watershed, Louisa County, Virginia. Data management and analysis was supported through the use of PC-VirGIS, a DOS based GIS package developed by the Information Support Systems Laboratory, Virginia Tech. The performance of the two models were based on the criteria established to compare the simulated and recorded peak discharge rates , total runoff volumes and time to peak. Goodness of fit criteria were based on graphic comparison relative error, model efficiency, linear regression, hypothesis testing and variance. Based on these measurements, the simulated results by both models were acceptable. KINEROS generally made better predictions of peak discharge rate and time to peak. Hydrograph shapes also generally matched the recorded sequence more closely. PSRM-QUAL simulated the total runoff volume slightly better than KINEROS. The sensitivity of KINER OS and PSRM-QUAL to the model input parameters was evaluated. For KINEROS, peak discharge rate and runoff volume were very sensitive to changes in rainfall amount, saturated hydraulic conductivity and effective capillary drive. For PSRM-QUAL, peak discharge rate and total runoff volume were very sensitive to changes in SCS CN, initial abstraction coefficient and rainfall amount.
A computer simulation model for predicting pesticide losses from agricultural lands
Kenimer, Ann Lee (Virginia Tech, 1987-08-05)
A field scale model for predicting the surface losses of pesticides (Pesticide Losses In Erosion and Runoff Simulator, PLIERS) was developed. PLIERS accounts for pesticide losses by degradation and volatilization, the washoff of pesticides from plant canopy and surface residue, the adsorption and desorption of pesticides to and from soil particles, and the movement of pesticides in the dissolved and adsorbed phases. Hydrologic data are generated by the comprehensive watershed model, FESHM; which contains an extended sediment detachment and transport algorithm. PLIERS uses first order rate equations to describe degradation and volatilization, and pesticide washoff. The adsorption of pesticides to individual particle size classes is estimated using the Freundlich equation. Movement of atrazine and 2,4-D in runoff and sediment was measured on twelve field plots under simulated rainfall. The plots were treated with conventional or no-tillage in combination with one of three residue levels (0, 750, and 1500 kg/ha). Runoff and sediment losses were found to increase with decreasing residue cover for both tillage systems. No-till reduced sediment loss and total runoff volume by 98 and 92 percent, respectively, compared to conventional tillage. Concentrations of atrazine and 2,4-D ir1 runoff and sediment were greater from the no-till plots than from the conventional plots but the total losses were less. Both pesticides were carried predominately in the dissolved phase. Averaged over all plots, the atrazine losses were 2.9 percent of applied amount for conventional tillage and 0.3 percent for no-tillage. The corresponding values for 2,4-D were 0.3 percent and 0.02 percent. PLIERS was validated using data from the rainfall simulator field plot studies. Agreement between predicted and observed data was very good for dissolved pesticide losses and satisfactory for adsorbed pesticide losses. In addition, the effects of tillage type and residue level were reflected in PLIERS predictions. PLIERS shows great potential as a flexible planning tool since it could be used with any comprehensive hydrologic model and is able to predict the losses of pesticides under various field conditions.
Computer system for the reduction and analysis of soil moisture data
Shanholtz, Vernon O. (Water Resources Research Center, Virginia Polytechnic Institute, 1968)
The quantitative evaluation of soil moisture through extended periods is a basic requirement in areas of research related to engineering, agriculture, and the life sciences. Invariably, it involves the processing and analysis of thousands of measurements. These are most often taken with nuclear soil moisture monitoring equipment. It is the purpose of this report to present a system of computer programs, written in Fortran IV for the IBM 7040/1401 system, but readily convertible to other systems, designed specifically to expedite the reduction and analysis of soil moisture data. The system contains 3 unique and independent programs or sections. The first section consists of a reduction of the basic field data, the second section is a coding, summary and plotting routine, and the third section is an analysis of variance routine. These separations allow for a more general approach in the reduction procedure. Data are collected in the field, key punched from the field sheets, and processed in exactly the same order as they are obtained....
Crop selection, tillage practices, and chemical and nutrient applications in two regions of the Chesapeake Bay Watershed
Bosch, Darrell J.; Shanholtz, Vernon O. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1992-11)
The objectives of this study were to obtain information on crop selection, tillage, and nutrient and chemical use on cropland having varying sediment loading and leaching potential. Additional objectives were the determination of economic, attitudinal, and demographic factors related to these agricultural practices. The study was carried out in Virginia in three counties of the Northern Neck region (Lancaster, Northumberland, and Westmoreland) and in Rockingham County. In each area, a stratified random sample of 120 sites with varying leaching and sediment loading potential was drawn from the Virginia Geographic Information System (VirGIS) database of cropland. Information on cultural practices on the sites as well as other farm and farmer characteristics was obtained through personal interviews with farm operators. Survey responses indicate that farmers are concerned about the effects of pollution on water quality-particularly drinking water. However, farmers tend not to see actions on their own farms as contributing to water quality damage. Most farmers do not agree that runoff and leaching of nutrients and chemicals from their farms contribute to water quality problems. When asked about the sampled sites on their farms, farmers generally responded that the potential for water quality damage caused by leaching and erosion was low. Their assessment of potential damage did not increase significantly on sites with high leaching or sediment loading potential. In the Northern Neck, farmers generally apply nitrogen and phosphorus at close to recommended rates. In Rockingham County, nitrogen is applied at below recommended rates, while phosphorus is overapplied due to heavy manure applications. Farmers' tillage practices, crop rotations, and nutrient and pesticide application rates generally do not vary according to site leaching and sediment loading potential. Thus, sites with higher leaching and/or sediment loading potential are likely to contribute a disproportionate share of potential loadings to groundwater and surface water. Further research is needed to determine whether targeting nonpoint pollution control to sites with higher leaching and sediment loading potential is a cost-effective way to achieve water quality protection goals.
The development of an evaluation method for best management practices on agricultural lands
Stavros, Robert William (Virginia Polytechnic Institute and State University, 1987)
To help local, rural planners make decisions on which Best Management Practices (BMPs) are most appropriate for the control of Non-Point Sources of Pollution (NPSP) within their jurisdiction, a method is developed for unbiased site-specific evaluation of BMPs appropriateness. An appropriate BMP is functional, practical and cost effective. The method developed is a rational method suitable for the general evaluation of agricultural BMPs to control NPSP in rural watersheds. The method is functional, practical, and cost effective because it uses existing data and personnel wherever and whenever possible. Unlike other NPSP modeling methods, this method lends itself to the selective application of BMPs throughout the watershed based on its actual land use and physical composition. This means, BMP's can be applied to the entire watershed uniformly or applied to a subset of the watershed based on selection criteria such as field slope, soil type, or existing cover crop. In addition, a combination of selection criteria can be used, and a combination of BMPs. This flexibility in selecting various BMPs and BMP combinations, allows planners to pose many different schemes for controlling NPSP within the watershed. The results of the schemes can be compared to determine which scheme is the most appropriate for use within the specific watershed. The method developed relies heavily on the United States Department of Agriculture's Soil Conservation Service's (SCS) Universal Soil Loss Equation (USLE) and uses data already being collected by the SCS and the Agricultural Stabilization and Conservation Service (ASCS). The method does require the creation of Hydrologic Response Units (HRUs) comprised of unique combinations or soil type and land use areas. To demonstrate the method's ability to select an effective BMPs for a watershed, a series of BMP scenarios were evaluated. The BMP scenarios were divided into three categories: a uniform application of a BMP throughout the watershed; a selective application of a BMP throughout the watershed and; the selective application of a set of BMP's throughout the watershed. Using a series of trial runs, the benefits of using the method were demonstrated. For example, similar results were obtained using a cropping BMP of "Corn, grain, soybean and cover" throughout the sample, and a ''no-till" BMP on 3 percent of the sample. This type of information was used by economic modelers to help target precious BMP implementation dollars. As an indirect result of the method's HRU development, it was possible to test the independence of each of the USLE factors within the Nansemond/Chuckatuck watershed. The results of the Duncan's Multiple Range Test shows an interdependence between the "soil type and the cover", "overland flow versus cover", and "overland flow versus soil type".
Development of an inexpensive computer vision system for grading oyster meats
Awa, Teck Wah (Virginia Tech, 1988-05-05)
The objective of this study was to develop an inexpensive automated device for grading raw oyster meats. The automation technique chosen was digital imaging. Typically, a computer vision system contains a microcomputer and a digital camera. An inexpensive digital camera connected to a personal computer was used to measure the projected area of the oyster meats. Physical characteristics of the oyster meats were important in designing a computer vision grading system and the necessary data were not found in the literature. Selected physical characteristics of oyster meats, including the projected area, weight, height, and volume were measured by independent methods. The digital image areas were found to be highly correlated to oyster meat volumes and weights. Currently oysters are marketed on the basis of volume. The results from this study indicated that the relationship between the oyster meat area as measured by computer vision and volume can be used as a grading criterion. The oysters ranged in volume from 3.5 cm³ to 19.4 cm³ A three dimensional image was not required because the height was not important. Tests showed that the system was consistent and successfully graded 5 oysters per second. The system was calibrated, and the prediction equation was validated with an estimated measurement error of ± 3.04 cm³ at a 95% confidence level. The development of automated graders using digital imaging techniques could help improve the quality and consistency of the graded oyster meats.
The effect of distance between artificial drainage facilities and disposal trenches on the movement of biological and chemical pollutants from septic tank effluent
Stewart, Larry Wayne (Virginia Polytechnic Institute and State University, 1982)
A field study was conducted at a residence in Chesapeake, Virginia to determine the effect of setback distances from a drainage ditch on the disposal of septic tank effluent. The study was done from September 1979 to August 1981. The soil used is the Tomotley series belonging to the fine-loamy, mixed, thermic family of Typic Ochraquults. Four prototype trenches were installed at 1.5, 3, 6 and 21 m from the edge of a drainage ditch which was 1.5 m deep. The trenches were pressure dosed equally with 2.4 to 4 cm per day. Replicated nests of sampling wells at depths 90, 150 and 300 cm were placed with distance from the trenches. Continuous stage recorders were positioned 4.5, 29.1 and 60 m from the ditch to monitor water table behavior. Groundwater analysis included fecal coliforms, the NH₄, NO₃, NO₂, Na, Ca, Mg, Cl and PO₄ ions, pH and EC. Ammonium concentrations in the soil beneath the trenches indicated nonuniform effluent infiltration yet more uniform than with conventional gravity flow distribution. High sodium absorption ratios of the septic tank effluent ranging from 18 to 45 did not significantly reduce infiltration rates as no ponding of effluent in the trenches was observed. The existing land surface was sloped greater than the water table gradient resulting in decreasing unsaturated depths with closeness to the ditch. The mean distances between the trench bottom and the water table were 64 cm at 3 m, 80.1 at 6 m and 90.4 cm at 21 m. The accumulation of fecal coliforms, NH₄, P, Cl and total salts (EC) in the groundwaters at 120 to 150 cm depth was inversely proportional to the mean distances from the trench bottoms to the water table. The lack of denitrification occurring underneath the trench with the most extensive unsaturated zone suggests NO₃ may accumulate under disposal systems that have mean unsaturated depths of ≥ 90 cm. Effluent movement was mainly lateral and in the upper zone of the water table with limited vertical movement below the water table surface. An equation applying D-F theory to infinitely deep soil was developed to describe flow for the given drainage system and for the inclusion of standard size drain fields. The current practical setback distance of 21 m is considered counterproductive for effluent treatment for some situations.
Effects of tillage system, crop residue level, and fertilizer application technique on losses of phosphorus and pesticides from agricultural lands
Mostaghimi, Saied; Shanholtz, Vernon O.; Dillaha, Theo A. III; Kenimer, Ann Lee, 1964-; Ross, Burton Blake; Younos, Tamim M. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1987-09)
A rainfall simulator was used to study the effectiveness of three best management practices - no-till, residue level and fertilizer application technique - for reducing sediment, phosphorus, and pesticide losses from agricultural lands. Simulated rainfall was applied to 12 experimental field plots, each 0.01 ha in size. The plots were divided into conventional and no-till systems. During phase I, the effectiveness of two fertilizer application methods - subsurface injection and surface application - were investigated for the two tillage systems. In phase II, three crop residue levels - 0, 750, and 1500 kg/ha - were studied within each tillage system. Granular fertilizer was applied at the rate 46 kg/ha. Atrazine and 2,4-D were applied at the rates of 2.24 and 0.56 kg/ha active ingredient, respectively. Fertilizer and herbicides were applied 24 to 48 hours before the start of rain simulation. Water samples were collected from the base of each plot and analyzed for sediment, nutrient, and pesticide content. No-till was found to be very effective in reducing runoff and sediment losses. No-till with high residue level produced the greatest reductions in runoff and sediment losses, and the highest reduction for both runoff and sediment occurred with no-till and 1500 kg/ha crop residue level. No-till reduced sediment loss by 98% and total runoff volume by 92%. The injection fertilization method reduced 0-P losses by 39% for no-till and 35% for conventional tillage. Reductions in T-P losses due to no-till practice were 89% and 91 % for surface and injection fertilizer application methods, respectively, compared to the conventional system. Averaged across all fertilizer treatments, an equivalent of 0.9% and 8.9% of the total-P fertilizer applied to the plots was lost from no-till and conventional tillage plots, respectively. Concentrations of atrazine and 2,4-0 in runoff and sediment were greater from the no-till plots than from the conventional plots, but total losses were less. Water was the major carrier for both herbicides, although the concentration of 2,4-D in sediment was higher than that of water. Averaged over all plots, the atrazine losses were 2.9% of the applied amount for conventional tillage and 0.3% for no-till. The corresponding values for 2,4-0 were 0.3% and 0.02%.
Factors affecting water quality from strip-mined sites
Connell, J. F.; Contractor, Dinshaw N.; Shanholtz, Vernon O. (Water Resources Research Center, Virginia Polytechnic Institute and State University, 1976)
This project analyzed the parameters that influence the quality of water from strip-mined sites. An instrumented watershed near Beckley, W. Va., provided data on precipitation, stream flow, and water quaIity, both before and during mining operations. This data was analyzed to derive linear relationships between a water-quality parameter and such variables as temperature, current and antecedent precipitation, and the extent of the area disturbed by mining. Mathematical formulae representing sulfate and calcium concentration, alkalinity, turbidity, conductance, and discharge were used in the study. A correlation analysis also was made among the various water-quality parameters. A formula for each water-quality parameter was derived for each of three different conditions: (1) before mining; (2) during mining for the disturbed area alone, and (3) during mining for the entire watershed. The coefficients in the formulae then were refined for minimum error. As is reported in the findings, the coefficients indicate that temperature is not an important water-quality consideration except in the case of alkalinity. The coefficients of the antecedent precipitation terms indicate that, in most cases, surface runoff is the basic mechanism by which the substances affecting water quality are conveyed from the disturbed area into a receiving stream. The findings provide data that can be used in the future for predicting water-quality impacts from strip mining operations at particular sites in the study area.
Groundwater levels as affected by swine waste lagoons in high water table soils
Bucklew, Oscar Thomas (Virginia Tech, 1976-07-09)
The popularity of anaerobic lagoons for use with confinement swine operations in Southeast Virginia has been increasing in recent years. These lagoons are not difficult to build and maintain and have served as a feasible method of waste disposal in the region. This area typically has a high water table with sandy loam soils. There has been concern by state officials that these units could possibly cause contamination of groundwater in the surrounding area due to infiltration from the lagoons to the water table. The deep aquifer in this area is a good potable source of water. Its low concentrations of minerals make it feasible for both private and industrial use. This study was initiated to evaluate the possibility of a pollution hazard from anaerobic lagoons.
Hydrologic aspects of no-tillage versus conventional tillage systems for corn production
Shanholtz, Vernon O.; Lillard, James H. (Water Resources Research Center, Virginia Polytechnic Institute, 1968)
For many years one of the goals of tillage research at Virginia Polytechnic Institute has been to develop a system which (a) reduces the amount of tillage required, (b) maintains an open-sail structure conducive to good rainfall intake and storage, and ( c) makes more beneficial use of the residues of preceding crops for minimizing evaporation, soil erosion and runoff losses. From these investigations evolved the no-tillage system. With this system the crop is planted directly into a chemically killed sod or crop residue with no prior mechanical seedbed preparation, thereby utilizing vegetation from the preceding crop for surface mulch.
Impact of best management practices on water quality in the Nomini Creek Watershed
Sims, Christopher N. (Virginia Tech, 1996)
The Nomini Creek Watershed project was initiated in 1985 as Virginia's action in dealing with the water quality problems of the Chesapeake Bay. Nomini Creek was selected because it was an agricultural watershed with few best management practices in place at the beginning of the study and was a representative watershed for the Coastal Plain of Virginia. The watershed is located in Westmoreland County, Virginia. The goal of the project was to provide data needed to quantify the water quality impacts of cropland BMP implementation in a watershed with a complex landuse. The data collected during the project included landuse, hydrologic, water quality, soils, and geographical data. The goal of this study was to conduct a detailed analysis of the data collected from the Nomini Creek watershed in order to evaluate the effectiveness of a system of BMPs on the quality of surface water. The specific objectives of this study were: 1) to compile the landuse data and determine if any significant changes in cropping practices occurred during the study period, 2) determine if any changes occurred in the monthly rainfall, and runoff values over the study period, and 3) determine if any changes occurred in the monthly total suspended solids, nitrogen, and phosphorous loadings from the watershed over the study period. The analysis indicated no significant change in the rainfall and runoff amounts over the study period. The BMPs implemented during the study target surface runoff. Sediment bound nutrients such as ammonium and total kjeldahl nitrogen reduced during the study period and soluble nutrients such as ortho-phosphorous and total phosphorous increased during the study period.
An integrated modular watershed planning model applied to the Upper South River watershed, Waynesboro, Virginia
Steger, Charles W. (Virginia Tech, 1978-07-01)
The problems associated with urban development and its resultant effects on environmental quality present increasingly complex decisions for elected and technical officials. Current approaches to modeling often result in the development of models which are too complex to be understood and require such long time periods to be modified that by the time the model is operational the problem has changed. A modular modeling framework is proposed which considers land use, runoff, and water quality and connects these factors to a budgetary function. In addition, the modular configuration facilitates the process of modifying components of the model in response to a changing problem environment. In order to test the feasibility of the proposed modeling approach, the model is applied to the Upper South River watershed, Waynesboro, Virginia. The following three alternative development plans are evaluated: 1. To permit no additional population growth and preserve the area for agriculture and recreation. 2. To permit concentrated development in the form of two new communities each with a population of three thousand persons. 3. To increase the population by three thousands persons but to allow development to continue to follow the existing pattern of urban sprawl. The study concludes by stating that if zoning ordinances and comprehensive plans focus on consolidating development within the framework of existing water and sewer networks, the cost of providing the sewer network for Alternative 2 will be ten million dollars less than Alternative 3 for the same increase in population.

Browsing by Author "Shanholtz, Vernon O."

Results Per Page

Sort Options