This study was designed to investigate the indicator bacterial densities in runoff from urban and rural sources and to compare these densities with the densities in both raw and secondary-treated, unchlorinated sewage effluents. Analysis was performed on a total of 42 samples, 22 of which were taken at the urban and the rural sites and correlated with storm flow. The remaining 20 samples were taken, 5 at each of the 4 sites, in order to establish respective baseline densities for total coliform, fecal coliform, and fecal streptococcus. Results indicated that mean values for total coliforms and fecal coliforms during dry flow were within Virginia State standards for urban runoff, but exceeded those two standards 100 percent and 91.9 percent of the time, respectively, during storm flow conditions. Mean values for total coliforms and fecal coliforms during dry flow at the rural site exceeded Virginia State standards 100 percent and 75 percent of the time, respectively. During storm flow the standards for both of these indicators were exceeded 100 percent of the time. It was also determined that the increase in densities typically lagged behind flow increases and maintained this lag while returning to baseline values. Finally, the FC/FS ratio as originally proposed by Geldreich was statistically supported as being valid for use in the identification of fecal pollution sources. Individual ratios were less than 0.7 at the urban watershed for 80% of the dry flow samples and 64.6 percent of the storm flow samples. For the rural site, FC/FS ratios were less than 0.7 for 25 percent of the dry flow samples and 81.8 percent of the wet flow samples. Samples of raw and secondary treated sewage exhibited ratios above 4.0, 40 percent, and 25 percent of the time respectively. / Master of Science

Major excursions in the position of the South Pacific Convergence Zone (SPCZ) and/or changes in its intensity are thought to drive tropical cyclone (TC) and precipitation variability across much of the central South Pacific. A lack of conventional sites typically used for multimillennial proxy reconstructions has limited efforts to extend observational rainfall/TC data sets and our ability to fully assess the risks posed to central Pacific islands by future changes in fresh water availability or the frequency of storm landfalls. Here we use the sedimentary record of Apu Bay, offshore the island of Tahaa, French Polynesia, to explore the relationship between SPCZ position/intensity and tropical cyclone overwash, resolved at decadal time scales, since 3200years B.P. Changes in orbital precession and Pacific sea surface temperatures best explain evidence for a coordinated pattern of rainfall variability at Tahaa and across the Pacific over the late Holocene. Our companion record of tropical cyclone activity from Tahaa suggests major storm activity was higher between 2600-1500years B.P., when decadal scale SPCZ variability may also have been stronger. A transition to lower storm frequency and a shift or expansion of the SPCZ toward French Polynesia around 1000years B.P. may have prompted Polynesian migration into the central Pacific.

No description available.

No description available.

The primary objective of this study is to investigate the runoff and quality variations exhibited on a medium-sized, agricultural catchment, dominated by a chalk and clay geology: the River Wallington, Hampshire, southern England. Emphasis has been focused on storm-based responses, particularly quality variations, monitored at two locations between October 1981 and May 1983. Quality parameters monitored include nitrate-nitrogen, phosphate, potassium, pH, chloride, sodium, suspended, volatile and dissolved solids, conductivity, temperature and dissolved oxygen. Stable rainfall and runoff conditions were observed with mean daily flows 0.2 m^3/s. Bankfall discharges of 10.0 m^3/s are exceeded at least once a year. Soil moisture status and antecedent catchment conditions are important factors in modelling observed runoff. Storm-based rainfall-runoff responses are adequately modelled using unit hydrograph techniques on seasonally divided data, with observed peak discharges estimated to within 10% and time to peak flows to within 2 hours. Definition of effective precipitation is a prime control on the performance of this prediction, particularly during the summer when more variable antecedent conditions occur. Loss of surface water as recharge to the Chalk aquifer complicates summer modelling. Rock and soil type are the major controls on surface water quality variations, which show stable responses during the study period. The influence of the Chalk maintains high pH, T.D.S., S.E.C. and NO_3-N concentrations, with long-term trends in the Chalk groundwater showing rising NO_3-N and Cl concentrations. Baseflow concentrations show minor dilution with higher discharges while stormflow concentrations show a wide range of behavioural responses with increasing flows, including dilution, concentration, flushing, between sample variability, and stable concentrations. The goodness-of-fit shown by bivariate concentration-discharge models used to describe the data are generally poor, indicating the importance of controls other than discharge in determining runoff quality. Mean storm concentrations show little change from the mean baseflow concentrations with orders of magnitude during storms typically: T.D.S. > V.S. > S.S. > Cl > Na > NO_3-N > D.O. > K > PO_4. The negligible concentration changes result in an increase in loads transferred during storms. The magnitude of increase depends on storm discharges but is typically double for solutes and fifty-fold for particulates. Storms are therefore important mechanisms of material transfer. (D72033/87)

No description available.

Thesis (M.-.)--Washington State University, May 2007. / Includes bibliographical references (p. 171-192).

Thesis (M.S.)--University of Montana, 2006. / Mode of access: Internet. Title from title screen. Description based on contents viewed Feb. 13, 2007. Includes bibliographical references (p. 118-121).

Thesis (Ph. D.)--Ohio State University, 1982. / Includes bibliographical references (leaves 121-124). Available online via OhioLINK's ETD Center

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 76-82). Also available on the World Wide Web.