Date of Award
Master of Science in Biological and Environmental Sciences (MSBES)
Environmental and Earth Sciences
Southern Rhode Island experiences annual seasonal population spikes during the summer months. During that period, the 2012 Rhode Island Water Resource Board Strategic Plan reported inadequate water supply to meet the average and peak seasonal demand in the Southern Region (RIWRB, 2012). The region is characterized by predominantly mixed land use with areas of residential use interspersed within agricultural fields and mixed forests. The region is also an important summer tourist destination which increases water demand for many aquifers. In general, New England’s watersheds are expected to see an increase in frequency and magnitude of extreme flow events i.e., droughts due to hotter, drier summers, and floods during warmer, wetter winters (Hayhoe et al., 2008). Overall, these factors lead to increasing concerns over future water availability in the region.
Hydrological models can effectively predict the effects of land use and climate change on water resources. They are important tools used to simulate water quantity and quality through integrated approaches (Trolle et al. 2012, Devia et al. 2015, Tan et al. 2020). These models serve as powerful decision support tools (DSTs) as they provide important information to many questions related to water shed management and natural resources (Schoumans et al. 2009, Francesconi et al. 2016). Loose coupling between the hydrologic and groundwater models allows for the prediction of the surface water processes but also groundwater flow and water exchange between the streams and the aquifer (Guzman et al., 2015). Examples of models which can be coupled include the Soil and Water Assessment Tool (SWAT) and MODFLOW. The coupling between these models permits SWAT to simulate surface conditions and stream and channel processes, while MODFLOW simulates groundwater responses to surface conditions.
The objective of this Thesis is to assess historical drought conditions within the Chipuxet watershed using a calibrated SWAT model. Climate change scenarios are also assessed using the Soil Moisture Deficit Index (SMDI), Evapo-Transpiration Deficit Index (ETDI), and Indicators of Hydrologic Alterations (IHA). Furthermore, this thesis will outline the parameterization methodology for loosely coupling SWAT with MODFLOW. The work is organized in two chapters:
Chapter 1. Manuscript (formatted to be submitted to Agriculture by MDPI) - The objective of this chapter is to outline the calibrated SWAT model and to assess the drought conditions of historical and climate change scenarios through multiple drought indicators and indices.
Chapter 2. Manuscript (formatted to be submitted to Water by MDPI) The objective of this chapter is to outline the parameterization necessary for loosely coupling a SWAT model of drought conditions with MODFLOW.
Results of drought assessment indicates that water stress in both, low emission (RCP4.5) and high emission (RCP8.5) scenarios will increase compared to historical data. SMDI and ETDI statistics shows that RCP8.5 scenarios will result in more severe deficits. Furthermore, IHA calculations show that all climate scenarios have more zero flow days and more lengthy low flow durations.
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Tulungen, Christian Pieter, "A Loosely Coupled Surface and Groundwater Model to Assess Drought in the Chipuxet Watershed, Rhode Island" (2023). Open Access Master's Theses. Paper 2446.