A hydrogeologic investigation was completed of the alluvial aquifer near the Osceola County Rural Water System (OCRWS) H-Series well-field, located in Osceola County, Iowa. The primary purpose of the investigation was to quantify drought resiliency benefits of engineered systems on a well-field scale through the use of a groundwater model. Specifically, a groundwater flow model was developed for the OCRWS H-Series well-field to quantify groundwater withdrawal and storage benefits of: • One rock riffle structure placed within the well-field • Two rock riffle structures placed within the well-field • An excavated, historic river channel system combined with one rock riffle structure The objective of these engineered systems is to increase the groundwater storage within the aquifer. Riffles and channel systems provide additional groundwater storage during periods of normal or above normal precipitation by raising the stage of the river. This additional storage, reflected in groundwater heads, is then available to maintain water production during a drought. Groundwater model results showed that all three of the engineered systems quantified substantially improved groundwater storage and induced recharge during the drought simulations. While each system was shown to influence the aquifer, benefits to groundwater storage and induced recharge from the two riffle system was shown to provide the greatest amount of drought resiliency benefit. Through the use of a cost-benefit analysis, the two riffle system was also shown to be the most cost-effective method in this study in terms of achieving additional groundwater storage and induced recharge to the aquifer.

New pedologic, carbon isotope and phytolith analyses along with stratigraphic correlations to nearby archaeological sites record the spatial and temporal distribution of past vegetation patterns in the Sac Valley Archaeological District of southwest Missouri. Radiocarbon ages obtained from a soil core along Bear Creek, CB5, are related to those from Hajic et al. (1998, 2000) indicating that the CB5 location contains correlative middle Rodgers Shelter submember deposits. This relationship also indicates that sedimentation was approximately two times greater at the CB5 locality than at the Big Eddy (23CE426) archaeological site providing much higher temporal resolution for the alluvial history as well as the vegetation proxies during the early to middle Holocene. Most midcontinent climate proxy records include indications of an early Holocene warm period when prairie replaced forests, then a cooler period in which trees dominated the landscape, followed by a warmer middle Holocene period when prairie vegetation was dominant. However, the CB5 δ13C profile of mixed C3/C4 vegetation indicates either that the vegetation at this location was not as sensitive to climate change or that this location was buffered from other influences, e.g. fires, which were critical to the expansion of prairie vegetation. On the other hand, the phytolith assemblages at CB5 indicate that there were periods with abundant C4 grasses even though the δ13C values indicate a dominance of C3 vegetation. This indicates that in the mixed forest/prairie ecotone interpretations of past vegetation from either carbon isotopes or phytolith assemblages alone may not accurately reflect patterns of vegetation. A new core, DDY-KR2, was obtained from the Big Eddy (23CE426) archaeological site and a finer resolution of δ13C values at Big Eddy increased the detail about alluvial activity and revealed subtle changes in the vegetation. The vegetation types suggested by the δ13C values for DDY-KR2 are reflected in the phytolith assemblages validating their usefulness in reconstructing local vegetation history.

No description available.

Thesis (Ph. D. - Civil Engineering)--University of Arizona. / Includes bibliographical references (leaves 98-102).

Thesis (M.S.)--University of Nevada, Reno, 2007. / "May, 2007." Includes bibliographical references (leaves 40-42). Online version available on the World Wide Web.

Thesis (M.S.)--Texas State University-San Marcos, 2008. / Vita. Appendices: leaves 34-54. Includes bibliographical references (leaves 31-33). Also available on microfilm.

Thesis (Ph. D.)--University of Southern California, 1997. / Includes bibliographical references (leaves 219-229).

Alluvial fan construction within British Columbia was dependant upon temporary conditions resulting from deglaciation; there is no significant fan aggradation at present. Five study areas were selected from the semi-arid sections of the Fraser, Thompson, Bonaparte, South Thompson and Similkameen valleys. The Tertiary and Quaternary geo-morphic histories of these areas are similar in many respects--most significantly, one or more phases of Pleistocene glaciation were followed by fluvial and lacustrine aggradation--but vary regarding the amount of subsequent downcutting by major rivers. This ranges from several hundred feet in the Fraser and Thompson valleys to a few feet or none in the Similkameen and Bonaparte valleys. Stratigraphic evidence from the Fraser Valley indicates that fan building commenced soon after the valley floor became ice-free, probably whilst glacial conditions persisted in tributary basins. It continued during aggradation by major rivers and for sometime afterwards. In the Thompson and South Thompson valleys fans were most recently built upon degradational river terraces. The occurrence of Mazama volcanic ash within fans indicates that construction continued until after 6,600 years B.P. Fans were built during a phase of landscape readjustment from predominantly glacial to predominantly fluvial conditions. They resulted from the secondary deposition of glacial drift and locally weathered material by streams and mudflows. Fan composition was dependant upon the nature of the available material and upon the character of the parent basin. For example, the widespread occurrence of glacio-lacustrine silt in the Thompson Valley gave rise to fans composed of silty mudflow gravels. Generally, small, steep basins produced mudflows whereas larger basins had more constantly flowing streams which deposited fluvial gravels. Fan aggradation declined as the drift supply was exhausted; deposition of material derived by current weathering was insufficient to maintain the growth of the fans. After deposition ceased many fans were dissected as a result of local base-level lowering controlled by degradation of major rivers and/or fan-head trenching initiated as the debris supply declined. Fan-head trenching is best developed in the South Thompson Valley; base-level dissection predominates in the Fraser and Thompson Valleys. Where fan building persisted during degradation, multilevel fans were constructed. Statistical correlations among morphometric parameters describing fans and related basins indicate that basin characteristics exerted an influence upon fan geometry through the nature of the fan building stream. There relationships vary regionally, possibly reflecting lithologic, climatic and geomorphic contrasts. British Columbia fans are steeper and display a greater variation of morphometric relationships than fans of the arid American Southwest. Fans resulting from deglaciation are distinguished by use of the prefix "para-glacial". / Arts, Faculty of / Geography, Department of / Graduate

Sand boil formation due to underseepage is a potential failure mechanism for levees in the Lower Mississippi River Valley. Sand boils were identified in the Buck Chute study area in the 1990s during high water events and during the 2009 Flood. The site is unique due to the presence of point bar and abandoned channel deposits. To understand the role of these alluvial deposits on sand boil formation at the site, a geologic investigation of the subsurface was conducted. Using shallow geophysics, cone penetrometer tests (CPT), borings, and a geographic information system (GIS), it was concluded that the thin blanket associated with point bar deposits, abandoned channel deposits causing a blocked seepage path, and head differential changes caused by the Muddy Bayou Control Structure were the controls of sand boil formation at Buck Chute.

Fish assemblages from 54 oxbow lakes in the Mississippi Alluvial Valley were sampled to identify relationships among environmental variables and fish biodiversity in floodplain lake ecosystems. Environmental variables deterministic over fish biodiversity showed a hierarchical organization and were classified as primary or secondary depending on if one variable was considered to govern another. Primary variables included depth, surface area, surrounding land use, and degree of lake-river interconnectedness. Secondary variables included suites of water quality and primary productivity variables. Maximum depth and percentage of agricultural land surrounding lakes showed strongest relationships with other ecosystem components, significantly influencing water quality, primary productivity, and fish biodiversity. I found contrasting results regarding effect of lake-river interconnectedness on fish biodiversity, but maintain that connectivity is nonetheless an important floodplain lake ecosystem component and suggest that floodplain lake management efforts focus on depth, percentage of agricultural land, and restoration of connectivity.