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Analysis of Coastal Georgia Ecosystem Stressors using GIS Integrated Remotely Sensed Imagery and Modeling: A Pilot Study for the Lower Altamaha River Basin


PI: Dr. Mustafa M. Aral (School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA)

Support: Georgia Sea Grant College Program and the School of Civil & Environmental Engineering (Georgia Institute of Technology)

Timeframe: 03/2000 - ongoing

Project Overview:
The focus of this project is the development of the state-of-art methods to analyze and evaluate the hydrologic and hydrogeologic characteristics of watersheds. The Lower Altamaha River Basin in south Georgia was selected as the pilot study area. The objective is to develop GIS-integrated watershed modeling software for the basin.

Progress:
Readers are referred to the excellent website for this project:
http://www.ce.gatech.edu/Research/MESL/research/altamaha/index.htm

Excerpt from final report (see below):

        "In this study, a hybrid surface/subsurface flow and transport model is developed that blends the powerful distributed parameter models with relatively simpler lumped parameter models. The proposed hybrid model solves the channel flow and saturated groundwater flow domains in continuous time using fully distributed physics-based formulations. This system is supported with the overland flow and unsaturated groundwater flow that uses lumped parameter descriptions in discrete time. This hybrid formulation decreases the computational requirements associated with overland and unsaturated zone domains in a large scale continuous watershed modeling task but still allows a representative description of the watershed flow processes.
        In the proposed model, a one-dimensional channel flow model is dynamically coupled with a two-dimensional vertically-averaged groundwater flow model along the river bed. As an alternative to the commonly applied iterative solution technique, a so-called simultaneous solution procedure is developed to provide a better understanding to the coupled flow problem. This new methodology is based on the principle of solving the two flow domains within a single matrix structure in a simultaneous manner. The method eliminates the iterative scheme that is otherwise required to obtain the convergence of the solution and provides a faster solution.
        In addition to the flow model, a coupled contaminant transport model is also developed to simulate the migration of contaminants between surface and subsurface domains. Based on its flow counterpart, the contaminant transport model dynamically couples a onedimensional channel transport model with a two-dimensional vertically-averaged groundwater transport model. The coupling is performed at the river bed interface via advective and dispersive transport mechanisms. A modified extension of the proposed simultaneous solution procedure is also implemented to solve the coupled contaminant transport problem. The dynamic coupling provides the much needed understanding for the continuity of contaminants in strongly interacting surface/subsurface systems such as a river and an unconfined aquifer.
        The coupled flow and transport models are finally applied to the lower Altamaha watershed in southern Georgia. The flow model is used to perform simulations of hydrologic and hydraulic conditions along the river and in the dynamically linked surfacial aquifer. The model predicted the flood patterns including the magnitude of peaks and their arrival times with sufficient accuracy. Under the given flow conditions, the transport model is then implemented to test alternative contaminant transport patterns both in the river and within the aquifer."

Reports and Publications:

The March 2004 final report for Georgia Sea Grant is especially detailed. This is a large PDF.
Surface and Subsurface Flow and Contaminant Transport Modeling in the Lower Altamaha Watershed
Orhan Gunduz and Mustafa M. Aral


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This page was updated June 27, 2014