Master of Science, University of Toledo, 2023, Geology

Coastal terrestrial-aquatic interfaces (TAIs), although occupying a small portion of the Earth's surface, have a significant impact on global biogeochemical cycles. These regions are experiencing rapid changes such as sea-level rise, variable precipitation patterns, and storm surge events which lead to varying saturation and salt concentration in the root zone. These changes disrupt the equilibrium between plants and their surrounding physicochemical conditions, causing plant stress and forest decline. Despite the critical nature of these ecosystems, our understanding and predictive abilities remain limited due to a lack of mechanistic data and inadequate tools for quantification and prediction. This study provides a hydrogeophysical approach to estimate the amount of saturation and salt concentration in the soil during and after a saturation event, thus, guiding future research efforts that explore the response of ecosystems to changing hydrologic disturbance patterns. Subsurface heterogeneity limits the use of in situ measurements to quantify subsurface flow during flooding due to the spatial discontinuity in the measured data. However, geophysical methods, including time-lapse electrical resistivity tomography (ERT) and Induced Polarization (IP), are increasingly used to monitor soil hydrological processes due to their high spatial resolution capabilities. This study combines background ERT, ground penetrating radar (GPR), time-lapse ERT, soil characterization, and numerical flow modeling developed using an Advanced Terrestrial Simulator (ATS) code to quantify the infiltration pathways and describe the hydrological dynamics during a simulated flooding experiment. Combining the ERI and GPR results with soil core data revealed the stratigraphic heterogeneity at the experimental site with a silty clay layer from 1 – 2 m between an overlying loamy topsoil and an underlying saturated silty sand. This silty clay layer could restrict deep infiltration. During the simul (open full item for complete abstract)

Committee: Kennedy Doro (Committee Chair); Xingyuan Chen (Committee Member); James Martin-Hayden (Committee Member) Subjects: Geology; Geophysics; Hydrology

Master of Science, The Ohio State University, 2021, Earth Sciences

Log jams are natural features in mountain streams that promote stream-groundwater interactions, or hyporheic exchange, through a variety of mechanisms. Log jams alter gradients in hydraulic head, increase the area available for exchange by creating backwater areas, and lead to the formation of branching channels and bars that drive additional exchange. Here, I numerically simulated stream-groundwater interactions for two constructed flume systems—one without jams and one with a series of three jams—to understand the effects of interacting jam and channel structures on hyporheic exchange. Jams increased stream-groundwater connectivity, or decreased the turnover length that stream water travels before it enters the hyporheic zone, by an order of magnitude and drove long flow paths that connected multiple jams and channel threads. The increased turnover of stream water through the bed was due mainly to the increase in the average hyporheic exchange rate, though the wetted surface area available for exchange also increased slightly. Jams with larger volumes had longer hyporheic residence times and path lengths that exhibited multiple scales of exchange. Additionally, the longest flow paths connecting multiple jams occurred in the reach with multiple channel branches. These findings suggest that large gains in hydrologic connectivity can be achieved by promoting in-stream wood accumulation and the natural formation of both jams and branching channels.

Committee: Audrey Sawyer (Advisor); Michael Durand (Committee Member); Joachim Moortgat (Committee Member) Subjects: Geomorphology; Hydrologic Sciences; Hydrology

Master of Science (MS), Bowling Green State University, 2020, Geology

Understanding how wildfires affect watershed hydrology is a vital aspect in the protection of water resources and mitigation of flooding risks in fire-prone regions. The 2013 Rim Fire, for example, burned ~21.5% of the Tuolumne River Watershed that supplies San Francisco, California, USA with 85% and 17% of its water and electricity, respectively. The goal of this study was to develop Soil and Water Assessment Tool (SWAT) models to evaluate and better understand the impacts of the 2013 fire on the hydrology of the Tuolumne Watershed. Two SWAT models were developed, with Model 1 based on pre-fire, 2011 land cover data and Model 2 based on post-fire, 2016 land cover data. After calibration, both models performed well in daily discharge estimation, yielding R2 and Nash-Sutcliffe Efficiency (NSE) values ranging from 0.69-0.98 and 0.60-0.98, respectively when comparing to discharges observed at three United States Geological Survey (USGS) gaging stations. Our modeling results from two burned sub-basins show the Rim Fire could drastically increase the magnitude of peak flows, potentially leading to severer flooding events and damages. Our results also show fire-induced increase in surface runoff, with 90, 84, and 124% estimated for sub-basins burned at low, moderate, and high severity, respectively. Fire's impact on base flow, however, seemed negligible. Our water-budget analysis and cross-model comparison, furthermore, indicate necessity to account for fire-induced land condition changes while developing watershed hydrologic models. Across the entire Tuolumne watershed, it is estimated that evapotranspiration rates decreased by 27%, lateral flow increased by 64%, and return flow decreased by 28% due to the fire. Within burned areas of the watershed, an average higher discharge of 139 mega m3 yr-1, flashier response to precipitation events, a maximum of 45% more surface runoff (2017), and a total of 2 m less evapotranspiration were calculated during the post-fire pe (open full item for complete abstract)

Committee: Ganming Liu PhD (Advisor); Peter Gorsevski PhD (Committee Member); Anita Simic-Milas PhD (Committee Member) Subjects: Hydrology; Water Resource Management

Master of Arts, The Ohio State University, 2019, Geography

The goal of this research is to develop a new proxy record sensitive to water availability in the tropical Andes, where climate change threatens glacial reserves of water stored as ice. As such, this study constitutes the first investigation into the radial growth of the newly described tropical tree species, Polylepis Rodolfo-vasquezii. In the dry season of 2017, a sample set of cores were extracted from a P. rodolfo-vasquezii montane forest in the Cordillera Huaytapallana in the central Peruvian Andes. Standard dendrochronological techniques were applied to the samples to produce a 77 year-long annually resolved chronology, from 1940 to 2016. Correlation analysis between tree ring widths and station data as well as regional anomalies and reveal that P. rodolfo-vasquezii is sensitive to wet season precipitation and discharge from the nearby Shullcas River. The strongest relationship with the tree rings was late wet season discharge. Based on these correlations, the first-ever monthly and seasonal discharge reconstructions were produced for the Shullcas River. The calibration-verification statistics for each model indicate that there are varying degrees of predictive skill in the reconstructions produced. The optimal reconstruction was for the average of April-May discharge. This work provides evidence that Polylepis rodolfo-vasquezii is a useful species for dendrochronological research and highlights its relationship to moisture in the Cordillera Huaytapallana.

Committee: Bryan Mark PhD (Advisor); Alvaro Montenegro PhD (Committee Member); Ellen Mosley-Thompson PhD (Committee Member) Subjects: Environmental Science; Geography; Hydrologic Sciences; Paleoclimate Science

Master of Arts, The Ohio State University, 2015, Geography

The following thesis investigates glacier recession, climate change, and water resources, specifically glacier melt and groundwater contributions to surface water discharge in the Shullcas River watershed in 2014, near the city of Huancayo, Peru. The Shullcas River watershed is a glacierized mountainous region of the Central Andes that has experienced rapid rates of glacier recession over the past 25-30 years (Lopez-Moreno et al, 2012). My interests are particular to the intersection of human and natural systems, and using the conceptual framework developed by socio-hydrologists I argue that the Shullcas River watershed is a profoundly coupled human-water system (Carey et al., 2014; Swyngedouw, 2009). Using a mixed methods approach to research during eight weeks of fieldwork, I conducted synoptic scale hydrochemical sampling while carrying out ten semi-structured interviews with a diverse set of water users from the region. As a result of this investigation we now have a synoptic snapshot of the Shullcas River watershed as it relates to the Huaytapallana glacier melt water contribution to surface water discharge in the Shullcas River. Using the Hydrochemical Basin Characterization Method for a single dry season in 2014, the glacier melt contribution to stream flow is estimated to be between 8.9-16.6% of the Shullcas River discharge upstream from pump stations for local agricultural canals and the drinking water supply for the city of Huancayo, Peru. The interviews reveal that many participants noted changes in the hydrologic cycle in recent years. Participants observed that precipitation is more variable and there have been observed reductions in the water levels of tributaries and the Shullcas River during both the rainy and dry seasons. The interviews also show participants' experiences of climate change within the context of glacier recession, specifically through the use of narrative and memories of particular life events near or related to the Huaytapallana gla (open full item for complete abstract)

Committee: Bryan Mark (Advisor); Kendra McSweeney (Committee Member) Subjects: Geography

MCP, University of Cincinnati, 2002, Design, Architecture, Art, and Planning : Community Planning

Urbanization and land use change is inevitable in many watersheds. The way urbanization has been occurring till now it has been observed that the hydrologic characteristics of watershed are adversely affected in terms of ground water recharge, water pollution and storm water drainage. Urbanization leads to creation of impervious surfaces, which causes an increase in the storm water runoff volume. Runoff has traditionally been viewed as a nuisance, and a major contributor to the environmental degradation to waterways. Careful physical planning is required to minimize the disturbance caused by runoff on urbanizing watersheds. For this, planners need a vision to foresee the hydrologic impacts of land use change. A need was felt to develop a hydrologic model in a GIS platform for modeling hydrologic processes and computer simulation of catchment behavior of watershed, which would aid in relating storm water runoff to the land use change. In this research project, the TR-55 Model, one of the simpler hydrologic model that does not require extensive data inputs has been used. It employs simple, straightforward yet sophisticated techniques for runoff estimation using Curve Number method of the Soil Conservation Service and is well suited for planners, water resource professionals and decision-makers. The results from modeling suggested that urban sprawl is a major contributor to storm water runoff in the region. There are some local as well as state organizations in Cincinnati working on storm water management program but after studying their primary goals, it was observed that neither of them concentrates on curbing the adverse effects of runoff discharges into water bodies. To plan effectively to protect the watershed and other natural features, it is essential to assess the impact of different land use types in the watershed region on the runoff volume. This thesis acts a guide for planners to use hydrologic modeling in estimating runoff in urbanized and urbanizing water (open full item for complete abstract)

Committee: Dr. Carla Chifos (Advisor) Subjects: Urban and Regional Planning

Master of Environmental Science, Miami University, 2010, Environmental Sciences

This study quantifies relationships between hydrologic and sediment loading estimates, generated using the AnnAGNPS watershed model, and indices of physical habitat quality (PHQ) in headwater streams within mixed land use headwatersheds of Southwest Ohio. Loading estimates were generated to stream reaches for which PHQ assessments were carried out in the field. Indices of PHQ utilized include the index of Relative Bed Stability (RBS) and the Qualitative Habitat Evaluation Index/Headwater Habitat Evaluation Index (QHEI/HHEI). Both RBS and QHEI/HHEI were found to be negatively correlated with sediment loads from hill-slopes. While RBS was found to be positively correlated with surface runoff and negatively correlated with interflow, the relationships between QHEI/HHEI and hydrologic loading were more complex. These results suggest that quantitative prediction of in-stream PHQ based on modeled loading estimates may prove to be useful for informing decision making with regard to restoration and maintenance of biotic integrity in low order streams.

Committee: William Renwick PhD (Committee Chair); Christopher Nietch PhD (Advisor); Andrew Miller PhD (Committee Member) Subjects: Agricultural Engineering; Agriculture; Aquatic Sciences; Environmental Engineering; Environmental Management; Environmental Science; Environmental Studies; Freshwater Ecology; Geographic Information Science; Geomorphology; Hydrologic Sciences; Hydrology; Natural Reso