Impact of Changing Climate on Water Resources in the Western Lake Erie Basin Using SWAT
Abstract
Water quality impairment in the Great Lakes Region has become a major concern for the scientific community. With increasing high intensity short duration precipitation events and rise in temperatures, there is the need to determine the impacts of a changing climate on water resources in the Great Lakes region. This is especially so in the Western Lake Erie Basin (WLEB); Lake Erie is prone to toxic harmful algal blooms due to climate variations and large nutrient and sediment inflows from the surrounding, primarily agricultural lands. The aim of this study was to determine the implications of future climate conditions on water quality and quantity in WLEB in the near, mid, and late 21st century. In this study, climate datasets from GCMs (General Circulation Models) under CMIP-5 (Coupled Model Intercomparison Project-5) were corrected for bias and used in a hydrologic model (SWAT) to quantify the sediment and nutrient loadings from the WLEB. The application of stochastic weather generators to correct the bias was evaluated against conventional bias correction methods. The results of this study showed that Stochastic Weather Generators (SWGs), including CLIGEN and LARS-WG have great potential in simulating long-term climate using a limited length of observed data. Additionally, a reliable future climate dataset (2006-2099) for sixteen ground-based climate stations within WLEB was created by correcting the bias in existing climate projections. This dataset will be made available to the public for climate change studies. The climate projections showed the potential for more frequent precipitation, and that the magnitudes of annual precipitation and one-day maximum precipitation could increase drastically, consistent with existing literature. Under such influence of erratic precipitation and increasing temperatures, simulations from SWAT projected that subsurface hydrology of the system could change considerably along with surface hydrology; tile flow could increase by up to a maximum of 67% and nutrients including soluble phosphorus via tile drains could decrease by as low as 60% but overall soluble phosphorus yield in the tile-drained agriculturally dominated watershed could increase by up to 26% or decrease by 60% towards the end of 21st century based on distribution of precipitation outputs from different climate models and radiative forcing. Using a suite of climate models, as opposed to an ensemble, provided a reliable band of confidence for watershed water quality responses in the face of climate change. The results from this study will provide valuable information, data, and tools that can be used to evaluate and recommended best management practices (BMPs) and inform policy-making in the WLEB in the face of a changing climate. Further studies are needed to translate the methodology and approach to the entire WLEB to mitigate the issues related to water quality that can result under projected climate conditions.
Degree
Ph.D.
Advisors
Gitau, Purdue University.
Subject Area
Water Resource Management
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