The Mississippi River Delta Basin and Why We Are Failing to Save Its Wetlands

University of New Orleans ScholarWorks@UNO University of New Orleans Theses and Dissertations Dissertations and Theses 8-8-2007 The Mississippi River Delta Basin and Why We are Failing to Save its Wetlands Lon Boudreaux Jr. University of New Orleans Follow this and additional works at: https://scholarworks.uno.edu/td Recommended Citation Boudreaux, Lon Jr., "The Mississippi River Delta Basin and Why We are Failing to Save its Wetlands" (2007). University of New Orleans Theses and Dissertations. 564. https://scholarworks.uno.edu/td/564 This Thesis is protected by copyright and/or related rights. It has been brought to you by ScholarWorks@UNO with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights- holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Thesis has been accepted for inclusion in University of New Orleans Theses and Dissertations by an authorized administrator of ScholarWorks@UNO. For more information, please contact [email protected]. The Mississippi River Delta Basin and Why We Are Failing to Save Its Wetlands A Thesis Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirements for the degree of Master of Science in Urban Studies By Lon J. Boudreaux Jr. B.S. Our Lady of Holy Cross College, 1992 M.S. University of New Orleans, 2007 August, 2007 Table of Contents Abstract.............................................................................................................................. iii Chapter 1..............................................................................................................................1 Introduction..............................................................................................................1 Chapter 2............................................................................................................................17 Chapter 3............................................................................................................................25 Chapter 4............................................................................................................................38 Bibliography ......................................................................................................................46 Glossary .............................................................................................................................49 Vita.....................................................................................................................................50 ii Abstract Every thousand years or so, when the Mississippi River’s sediment load lengthened and blocked the River’s route to the Gulf of Mexico, the mother stream changed course completely, finding a shorter route to the sea. Then, it built a new delta, thus spreading the gift of land creation along a wide coastline and creating the bayou region of Louisiana. However, this ancient, natural process was gradually halted by the arrival of man who settled across the River’s natural floodplain (delta) and constructed levees and other structures to control the great Mississippi River. Since the 1930s, the Mississippi River Delta Basin and the coast of Louisiana have been literally losing ground. The decline of this environment is now affecting, and will continue to affect, our nation’s economy, infrastructure, culture, and safety. Moreover, efforts to fix this problem are not working. My research and this thesis will address the issue of how plans without action have appeased Louisianans while the nation looses vital wetlands daily. Keywords: Introduction to the Mississippi River Delta Basin The Mississippi River Deltaic Plain Landforms Deltaic Evolution and Process Mississippi River Delta Lobes The problem the Mississippi River Delta Basin and its people is facing Why Louisiana and the nation ignore the problem The plans that have failed to fix the problem Why using the river to fix the problem has failed iii Chapter 1 Introduction to the Mississippi River Delta Basin Being a Plaquemines Parish resident and having grown up hunting and fishing in the wetlands of the Mississippi River Delta Basin (Southeast Plaquemines Parish), I can attest to the problem at hand. My father, known to east Plaquemines parish residents as “Sonny the marsh man,” and I have hunted, trapped, and fished all our lives in these wetlands. We now see hundred acre lakes where once only small two acre duck ponds with shoreline blinds existed. These shorelines have continuously receded over the past 20 years. Thirty-foot-wide canals we fished are now 130 feet wide. Areas where we once trapped alligators are no longer habitat for the freshwater reptiles due to saltwater intrusion. Post hurricane Katrina, this area is no longer protected by the Breton Island chain and is now mostly open water extending into the Gulf of Mexico. These are just a few examples of my experience of the decline of Louisiana’s wetlands that I have witnessed in my 41 years. Historically, the Mississippi River has had a great effect on the land formation of coastal Louisiana. The entire coastal area is the result of sediment deposits following the latest rise in sea level about 5,000 years ago. Each Mississippi River Deltaic cycle was started by a gradual capture (take over) of the Mississippi River by a natural channel which created a shorter route to the Gulf of Mexico. The abandonment of the previous delta lobe resulted in the cutting off of the fresh water supply and sediment to the lobe.1 As a result, an area would undergo compaction, subsidence, and erosion. The previous delta lobe would begin to retreat as the gulf advanced, 1 C.R. Kolb and J. R. Van Lopik, “Geology of the Mississippi river deltaic plain , Southeastern Louisiana.” U.S. Army Corps of Engineers Waterways Experiment Station: Vicksburg, Mississippi, 1958. 1 creating lakes, bays, and sounds. Meanwhile, a new delta lobe would start an advance toward the gulf. Over the past 5,000 years this delta-building process has caused the coastline of south Louisiana to advance toward the Gulf of Mexico, forming the present coastal plain. The Mississippi River The major drainage in the Central United States and one of the major rivers of the world, the Mississippi River, which extends from Cairo, Illinois to the Gulf of Mexico, some 700 miles, has created a distinct channel through its course in southeast Louisiana. Changes in its depocenter (site of active sedimentation deposits) during the last 2,000 years have created a series of different delta lobes and sediments.2 Progradation (building process causing shoreline migration into the basin) of the present and former Mississippi River courses and deltas helped mold the recent alluvial valley and deltaic plain of southeastern Louisiana. Each time the Mississippi River has built a major delta lobe seaward, that course has subsequently been abandoned in favor of a shorter, more direct route to the sea. These meander belt changes in the Alluvial Valley and accompanying shifts in centers of deposition have caused the variety and distribution of deltaic sediments along the coast of southeastern Louisiana. Marine transgression caused by compaction and subsidence of deltaic sediments begins after a delta lobe is abandoned. Nevertheless, the net result between the advancing deltas and the encroaching sea generally has been an overall increase in the size of the 2C.R. Kolb and J.R. Van Lopik, “Depositional Environmental of The Mississippi River Deltaic Plain-Southeastern Louisiana.” Edited by M. L. Shirley and J. A. Ragsdale, 1966: 17-62. 2 recent coastal plain.3 However, within the last few decades, coastal land loss has accelerated due to chemical and physical erosion as well as the restriction of sediment supply to these areas. The term “delta” is derived from the ∆-shaped (triangle shaped) land form of the lower Nile Valley, originally described by Herodotus (Greek historian, “Father of History”). In current geological literature, however, the term describes any coastal accumulation of river-derived sediments located at, or immediately adjacent to, the source of the stream.4 Because of the tectonically induced drainage systems of continental land masses, major deltas form on the trailing edge of the continents. Deltaic facies (characteristically deposited rock mass), therefore, generally account for a large percentage of the sedimentary rocks on passive continental margins.5 The Mississippi Deltaic Plain is one of the world’s best examples. Rocks of deltaic and closely related facies account for the bulk of the Mesozoic (66 to 245 million years ago) and Cenozoic (65 million years ago to present time) stratigraphic column of the gulf coast basin. The present drainage basin of the Mississippi covers and drains 41% of the continental United States. At present, the Mississippi River delivers about 500 million tons of sediment to the Gulf Coast each year. This load consists of approximately 20 percent fine and very fine sand, and 80 percent silt and clay. The fine grained load of the Mississippi has been instrumental in building a very shallow delta front which, in turn, greatly attenuates the incoming waves. As a consequence, the nearshore wave energy at the Mississippi Delta distributaries is much less than

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