Thesis (M.Sc.)--College of William and Mary. / Includes bibliographical references.

No description available.

A study was undertaken to evaluate the effectiveness of alum coagulation, permanganate and chlorine dioxide preoxidation, and powdered activated carbon pretreatment for the removal of trihalomethane (THM) precursors from the Po River, the Ni River and the Ni River Reservoir waters in eastern Virginia. The effects of temperature and storage were also studied. Samples were collected on two occasions and were analyzed for total organic carbon (TOC), THM-formation potential (THMFP), color, UV-absorbance and pH. Samples were then treated in a manner similar to that ina typical water treatment plant by bench-scale jar tests and reanalyzed for TOC, THMFP, color and UV-absorbance. The results indicate that the THMFPs of both Po and Ni River waters were high. Alum coagulation at pH 6.0 reduced TOC by as much as 48 percent while THMFP reductions averaged 63 percent. Permanganate preoxidation at dosages as high as 2.0 mg/L reduced THM precursors by less than 14 percent. Powdered activated carbon at 10 to 20 mg/L reduced THM precursors by less than four percent. Application of 2 mg/L chlorine dioxide reduced THM<-precursors by eight percent over what could be achieved by alum coagulation alone. A major conclusion was that treatment of the Po River by conventional measures to meet existing and future drinking water standards for THMs would be difficult, if not impossible. / Master of Science

In hydrological and hydraulic modelling, river geometry is a crucial input data. Recent investigations have been looking at methods to improve the description of cross sections extracted by DEM derived by satellite images. SRTM derived DEM are often lacking precise information as the sensors cannot detect the submerged river parts, but, on the other hand, it is available on a global scale which makes it very attractive and useful, especially in data scarce regions. This study aims at applying the so called “slope break” method to improve river cross section geometry extracted from SRTM DEM. The report is divided into three parts: a) The making of a Matlab-code to improve cross sections geometry extracted by satellite derived DEM; b) an application of the code to real cross-sections from the river Po in Italy and c) hydraulic simulations with and without SRTM modified cross sections to test the performance of the method, in collaboration with senior colleagues. The Matlab successfully performs the slope break point and finds, when appropriate, the approximated lowest point zmin of the cross section below the water surface. The comparison of the river geometry of the modified SRTM cross sections versus LiDAR available cross sections show the good performance of the method in improving the river geometry description. This code can simplify the work and improve many SRTM river cross sections in an effective way. The hydraulic simulations performed with and without the modified cross sections show how the modified SRTM model improves when compared to LiDAR results