Have a Question?
Ask the Graduate
College at our new
Doctoral Dissertation Announcement
Candidate: Richard H. Becker
Doctor of Philosophy
Title: Remote Sensing Studies for the Assessment of Geohazards: Toxic Algal Blooms in the Lower Great Lakes and Land Subsidence in the Nile Delta
Dr. Mohamed Sultan, Chair
Dr. Carla Koretsky
Dr. William Sauck
Dr. Barry Lesht
Dr. Joseph Atkinson
Date: Thursday, June 12, 2008 1:00 p.m. – 3:00 p.m.
1122 Rood Hall
Remote sensing techniques provide valuable tools for assessing a wide variety of environmental phenomena. They have been used for monitoring and assessment of various types of geologic and environmental hazards occurring on land, in air, or in oceans. I present results from two studies, the first of which examines algal blooms in the Great Lakes; the second measures subsidence in the Nile Delta.
In the first study, methodologies to investigate the extent and distribution (temporally and spatially) of algal blooms in Lake Erie and Lake Ontario are studied. Millions of people in the U.S and Canada rely on the Great Lakes for drinking water, food, work, and recreation. Toxic algal blooms present a hazard to the substantial number of communities that draw water from the Great Lakes. Visible and infra red MODIS satellite data are used to map the extent of algal blooms in these lakes. Existing algorithms to retrieve chlorophyll concentrations are successfully tested against in situ measurements from sampling cruises. Algorithms are developed to identify the potentially toxic cyanobacterial blooms.
The second study examines subsidence in the Nile Delta. The modern Nile Delta, the major agricultural production area for Egypt, is formed from sediments supplied by at least 10 distinct distributary channels throughout the Holocene. With an average elevation of a meter or so above sea level and with a predicted rise in sea level of 1.8-5.9 mm/year, the subsidence of the northern 30 km of the delta is a topic of major concern to the Egyptian population and government. Ongoing subsidence rates in the northeastern Nile Delta are measured using persistent scatterer radar interferometry techniques. The highest rates (~8 mm/yr; twice average Holocene rates) correlate with the distribution of the youngest deposition, with older depositional centers subsiding at slower rates of 2-6 mm/yr. Results are interpreted to indicate that: (1) modern subsidence in the Delta is heavily influenced by the compaction of the most recent sediments, and (2) the highly threatened areas are at the terminus of the Damietta, where the most recent deposition has occurred.