Master of Science / Department of Civil Engineering / David R. Steward / A one-dimensional model was developed to study the flow of groundwater in the sloping Ogallala Aquifer at a steady state during predevelopment condition. The sloping base was approximated using a stepping base model. GIS applications were applied during data collection and preparation, and later during interpretation of model results. Analytical and numerical methods were employed in the development of this model which was used to try to understand long-term water balance in the study region. The conservation of mass was achieved by balancing groundwater input, output, and storage; this led to understanding the interactions of groundwater and surface water in the predevelopment conditions. The study resulted in identification of where natural discharge from groundwater to surface water occurred, and the quantity of these flows was obtained. The Ogallala Aquifer is thick in the south western part of Kansas, this region had an average saturated thickness of 100m during predevelopment conditions. The model found that groundwater flowed at a discharge per width of approximately 17 m[superscript]2/d in this region. The aquifer thickness tends to gradually decrease from west to east and from south to north. The northern part had an average saturated thickness of 40m during predevelopment conditions; the model found that groundwater flowed at a discharge per width of approximately 3 m[superscript]2/d in this region. It was also found that groundwater leaves the Ogallala Aquifer on the eastern side with discharge per width between 0-3 m[superscript]2/d. The discharge from groundwater to surface water was summed over contributing areas to river basins. The discharge to streams necessary to satisfy long-term conservation of mass computed by the model showed that Cimarron River has total baseflow of about 5.5 m[superscript]3/s; this was found to be almost 100% of the total streamflow recorded during predevelopment conditions. The Arkansas River was found to have total baseflow of about 0.97 m[superscript]3/s, which is approximately 14.3% of the total streamflow recorded during predevelopment conditions. The Smoky Hill River was found to have total baseflow of about 1.7 m[superscript]3/s, which is approximately 73.9% of the total streamflow recorded during predevelopment conditions. The Solomon River was found to have total baseflow of about 0.95 m[superscript]3/s, which is approximately 41.1% of the total streamflow recorded during predevelopment conditions. The Saline River was found to have total baseflow of about 0.25 m[superscript]3/s, which is approximately 62.5% of the total streamflow recorded during predevelopment conditions. The Republican and Pawnee River was found to have total baseflow of about 0.38 m[superscript]3/s and 0.22 m[superscript]3/s, which is approximately 18.5% and 12.6% of the total streamflow in the predevelopment conditions respectively. The model was found to be always within -16 to +12 meters between observed values and the model results, with an average value of 0.15m and a root mean square error of 1.98m. Results from this study can be used to advance this study to the next level by making a transient model that could be used as a predictive tool for groundwater response to water use in the study region.

Master of Science / Department of Geology / Saugata Datta / More than 75 million people in the Bengal Delta of eastern India and Bangladesh are exposed to drinking water with dangerously high arsenic (As) concentrations; the worst case of environmental poisoning in human history. Despite recognition of dangers posed to chronic exposure to drinking water with elevated As, its biogeochemical cycle is inadequately constrained in groundwater flow systems due to its complex redox chemistry and microbially-mediated transformations. Arsenic concentrations in Bengal Delta sediments are comparable to global averages, but its highly heterogeneous spatial distribution (on scales of meters to kilometers) in sediments and groundwaters is poorly understood. Though many research efforts have targeted understanding this heterogeneity in Bangladesh, less work has been done in eastern India. Murshidabad (23°56.355‘N, 88°16.156‘E), an eastern district in West Bengal, India, where groundwaters are highly As-affected (~4000 μg/l), was chosen as our study area. Research objectives were: (1) characterize sediment cores (mineralogically, geochemically) and groundwaters (hydrochemically, isotopically) in areas with contrasting As concentrations—west (low-As) and east (high-As) of river Bhagirathi, a major distributary of Ganges flowing through the heart of Murshidabad; (2) describe and understand the extent of spatial variability, laterally and vertically, of dissolved As concentrations in shallow (< 60 m) aquifers, comparing sediment core chemistry to water chemistry; (3) identify source(s) of aquifer recharge and (4) role(s) of inorganic carbon within the aquifer to understand the bioavailability and mobilization of As from sediments to groundwaters. Mineralogical differences between high-As (grey) and low-As (orange-brown) sediments, were the presence of greater amounts of micas, Fe- and Mg-rich clays, amphiboles, carbonates, and apatite in high-As sediments; these were virtually absent from low-As sediments. In high-As areas, As was associated with amorphous and poorly-crystalline Fe-oxyhydroxide phases and labile (specifically-sorbed) phases, especially where Fe(II):Fe[subscript]T was high in the sediments. High-As groundwaters had high As(III):As[subscript]T, iron, bicarbonate, phosphate, and ammonium, and low concentrations of chloride and sulfate. Dry season precipitation was probably the main source of aquifer recharge; lighter values of [superscript]13C in dissolved inorganic carbon resulted from oxidation of natural organic matter. This study points to an idea that both microbially-mediated oxidation-reduction and competitive ion-exchange processes occurring in shallow aquifers of Murshidabad drive As mobilization and sequestration by aquifer sediments.

Doctor of Philosophy / Department of Agronomy / Gerard J. Kluitenberg / The Parsons soil has a sharp increase in clay content from the upper teens in the A horizon to the mid fifties in the Bt horizon. The high clay content continues to the parent material resulting in 1.5 m of dense, slowly permeable subsoil over shale residuum. This project was designed to better understand soil-water management needs of this soil. The main objective was to determine a comprehensive hydrologic balance for the claypan soil. Specific objectives were a) to determine effect of tillage management on select water balance components including water storage and evaporation, b) to quantify relationship between soil water status and crop variables such as emergence and yield, and c) to verify balance findings with predictions from a mechanistic model, specifically HYDRUS 1-D. The study utilized three replicates of an ongoing project in Labette County, Kansas in which till and no-till plots had been maintained in a sorghum [Sorghum bicolor (L.) Moench] – soybean [Glycine max (L.) Merr.] rotation since 1995. Both crops are grown each year in a randomized complete block design. The sorghum plots were equipped with Time Domain Reflectometry (TDR) probes to measure A horizon water content and neutron access tubes for measurement of water throughout the profile. Precipitation, evaporation, and perched water depth were determined at the field scale. Drainage was estimated as negligible after performing hydraulic conductivity measurements on the clayey subsoil. Runoff was determined as the residual in this water balance. Cumulative differences in the hydrologic balances as a result of tillage management were found to be minimal over an entire growing season. However, tillage treatment differences were seen in early season evaporation, surface water content, and the resulting residual runoff values. The chisel-disk treatments had greater evaporation leading to reduced runoff when compared with no-till. There was interaction between tillage treatment and time for surface water content measurements. No effect of tillage treatment was found for whole-profile water content. Crop variables were unaffected by tillage other than the first days emergence, and first days tillering being greater for chisel-disk treatments. No correlation between stored water and crop variables could be found. All aspects of field measurement were well supported by the predictions of the HYDRUS 1-D model.

Master of Science / Department of Biological & Agricultural Engineering / Kyle R. Douglas-Mankin / The Great Plains once encompassed 160 million hectares of grassland in the central United States. In the last several decades, conversion of grassland to urban and agricultural production areas has caused significant increases in runoff and erosion. Past attempts to slow this hydrologic system degradation have shown success, but climate change could once again significantly alter the hydrology. The Intergovernmental Panel on Climate Change (IPCC) studies the state of knowledge pertaining to climate change. The IPCC has developed four possible future scenarios (A1, A2, B1 and B2). The output temperature and precipitation data for Northeast Kansas from fifteen A2 General Circulation Models (GCMs) were analyzed in this study. This analysis showed that future temperature increases are consistent among the GCMs. On the other hand, precipitation projections varied greatly among GCMs both on annual and monthly scales. It is clear that the results of a hydrologic study will vary depending on which GCM is used to generate future climate data. To overcome this difficulty, a way to take all GCMs into account in a hydrologic analysis is needed. Separate methods were used to develop three groups of scenarios from the output of fifteen A2 GCMs. Using a stochastic weather generator, WINDS, monthly adjustments for future temperature and precipitation were applied to actual statistics from the 1961 – 1990 to generate 105 years of data for each climate scenario. The SWAT model was used to simulate watershed processes for each scenario. The streamflow output was analyzed with the Indicators of Hydrologic Alteration program, which calculated multiple hydrologic indices that were then compared back to a baseline scenario. This analysis showed that large changes in projected annual precipitation caused significant hydrologic alteration. Similar alterations were obtained using scenarios with minimal annual precipitation change. This was accomplished with seasonal shifts in precipitation, or by significantly increasing annual temperature. One scenario showing an increase in spring precipitation accompanied by a decrease in summer precipitation caused an increase in both flood and drought events for the study area. The results of this study show that climate change has the potential to alter hydrologic regimes in Northeast Kansas.

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Eric A. Bernard / This study is an integration of GIS, the Arc Hydro data model and tools, and hydrologic models to solve land use planning issues in the Little Kitten Creek watershed, Riley County, Kansas. Every day designers plan and design in watersheds. These designs alter the land use cover and change the hydrologic regime. Generally the design and development process does not consider upstream/downstream impacts on water quality and quantity. As a result development often increases flooding and water pollution. With the advent of the geodatabase, and the Arc Hydro geodatabase data model, designers have a flexible new tool for rapid simulation of a watershed. Arc Hydro allows the incorporation of traditional hydrologic data into linked modeling software together enabling users a “one-stop” approach for assimilating and modeling water resource systems. Once hydrologic data is in the Arc Hydro format it can be incorporated into assessment models, such as the Map to Map model. This case study assessed the floodplain analysis capabilities of the Map to Map model in the Little Kitten Creek (HUC 14) watershed. Steps to accomplish this goal were: data collection (digital and field surveys) and processing, geodatabase construction, linking the geodatabase with hydrologic modeling programs and, analysis of land uses within the watershed using the Map to Map model with the intent to produce flood maps based on land use changes.