Mississippi Flood of 2011 Remote Sensing Observations of Thematic Change & Geomorphological Causes Preventing Flooding Catastrophes in an Ancient Alluvial Floodplain
“Mississippi River basin is s practically 75% of the United States. Magnitude that such a landmass’ drainage basin gets a last seasonal deluge from the frozen snow packs is a serious hydrology contributing factors annually a foreboding harbinger to natural floodplain geomorphological phenomena. What must be annual agony for public official, farmer and floodplain citizen alike , take heed as you watch these Time lapse animated gif dramatically replaying the months of snow, rain, sleet, thunderstorms accumulations. Amazing technological slideshow revealing snowpack waters contribution to a climactic 2011 Spring Thaw. An annual occurrence albeit a natural battle between the basin vs long ago l found bedrock. The spring floods throughout time are a rebirth of soil. Humanity just gets in the way. Please enjoy these two snow features prior to enjoining the paper. Thank you for taking it in. Please leave a comment or better still your knowledgeable advice.”
Figs.1-2) Right click, choose open hyperlink from the drop down context menu to view the animated recreation of all seasonal snow/water weather activities Midwest Mississippi River Basin’s snow season activity to view the rapid snowmelt . Animation credit: National Operational Hydrologic Remote Sensing Center
Historical snow-pack melt (fig.2) with unseasonable tornado activity (fig.3) brought a disastrous Mississippi spring flood season. Severe weather conditions heightened Mississippi flood plain potential for historic flooding. Earthen levees in Missouri were exploded to prevent the city of Cairo, Illinois from being inundated due to the resulting storm runoff. Historical previous flood scenarios studied, prompted environmental hazard management experts from the USGS, Army Corps of Engineers to advise Governors in Illinois, Missouri, Tennessee, Arkansas, Mississippi and Louisiana to prepare their citizenry for the worst. Ultimately the federal government named eleven counties along the Mississippi River FED Disaster Areas following findings by USGS Vicksburg District officials. Environmental hazard management operations were ordered by governors in the delta states of Illinois, Arkansas, Tennessee, Mississippi and Louisiana
man-made environmental hazard management practice in the USGS Vicksburg District averted historic potential flooding disaster in the Louisiana state Mississippi flood plain area. Potential damage in the millions was averted using the clearly carved history of the river’s paths mapped over time. Previous alluvial floodplain geomorphology studies over time detailed exactly the potential and ultimate path the floodwaters’ took. Intricate hand drawn USGS floodplain mapping performed in 1944 were extremely accurate prediction mechanism. Humanity coexists on the floodplain. River floods regain and retreat from which land the river decides to flood in spite of man-made controls. 2011 flood season required man-made flood control structures to be opened which allowed the Mississippi River to take its natural floodplain course. Remote sensing captured the events dramatically. Remote sensing studies thru detailed monitoring of such events over temporal studies conducted from satellite platforms are an invaluable tool in floodplain management. Mid latitude cyclone patterns exacerbated increased hydrology tables during spring thaw. Glacial sculpted landscape demonstrated the typical floodplain activities expected of an ancient river basin covering a huge geographic space. Purpose of the s
Study Purpose is to chronological track natural floodplain activities exhibited by the watershed during the Great Flood of 2011. (FIG.1)
ANCIENT FLOOD PLAIN GEOMORPHOLOGY
Mississippi River has its origins in the glaciers that once covered the upper Midwest and Canada. Mississippi River h headwaters gin in Clearwater County Minnesota. Lake Itasca is a glacially formed lake 1479 feet above sea-level. Total area covered by the Mississippi River basin extends from the Appalachian Mountains to the Rocky Mounts. Mississippi River basin covers more than 1,245,000 square miles. 32 U.S. states and two Canadian provinces watersheds drain into the basin. Mississippi River Basin’s watershed total land catchment includes 40% of the landmass of the continental US. The Mississippi River is 2530 miles long. Mississippi River is the 4th largest by area and 10th longest river system in the world. (Saucier, 1994)
Mississippi River Valley is underlain by a plate rift that developed perpendicular to the larger Gulf of Mexico rift. The Mississippi embayment forming the basin depression is an ancient aulacogen that dates back to the breakup of the ancient continent, Rodinia. Extreme earthquakes in the early 19th century occurred in the ancient rift. Southern Oklahoma Aulacogen, which has been studied thru its Wichita Mountains exposure dates to an Eocambrian rift system formed as a product of intercontinental rifting during the breakup of Pannotia.
Aulacogens are a failed arm of a triple junction in a plate tectonics rift system. A triple junction beneath the continental plate of the previous super continent initiated a three-way breakup of the continental plate. As the continent’s subsequent mass broke away, that movement developed one of three spreading ridges. One ridge just failed. It just stopped spreading. Eventually the rift formation creates a grabben system within the land mass. (ASLAN, 1998)
Global study of the same geomorphology on other continents finds many major rivers begin along the failed arm of a triple junction, In this case the massive amounts of sediment from glacial advance and retreats of ice ages such as the Wisconsin Age filled the depression’s linear basin forming sedimentary rock. Approximately 208 million years ago the Mississippi River Valley formed along a failed arm of a triple junction where, currently Northern and Southern hemisphere occupants once were one land mass. North and South America separated into the two Americas leaving the triple fault.
Large glacial lakes were formed as the glaciers retreated–the largest of the glacial lakes, Lake Agassiz, was formed as the Des Moines Lobe of the glacier retreated some 12,000 years ago and the drainage of this approximately 320,000 square kilometer lake may be responsible for the formation of the Upper Mississippi River Valley–the rivers were responsible for draining the large amounts of water from the melting glaciers. Alternating broad and narrow reaches of present river floodplains reflect the nature of the slowly sloping elevation of Paleozoic rock channels cut by river flows from ancient glacial lakes in Iowa, Canada and Wisconsin. River flow reaches created eroded the sedimentary soft sandstone left in the rifts River side bluffs cut down to erosion resistant rock leaving a narrow at times straighter river. (Hamar, 2005)
Missouri and Mississippi River confluence is the beginning of Lower Impounded Reach of the Mississippi Floodplain. Unlike the Upper Impounded Reach of the Mississippi River the flood plain is wide and meandering creating an ancient alluvial floodplain which has left meander scars and oxbow lakes in the river basin floor. Braided streams formed tributaries and stream systems which act as the watershed. Braided streams combined to form the central channel. Centuries of water flow scars left by water seeking the path of least resistance remain visible in the satellite images of the study area. (FIG.4) (Theiling, River Geomorphology and Flood Plain Habitats, 1998)
ENVIRONMENTAL HAZARD STUDY
2011 Mississippi Floods set new record flood stages within the USGS Vicksburg District. Memphis, Vicksburg, Greenville and Natchez communities within the district prepared for the worst. Oxbow lakes are numerous in this area of the alluvial floodplain.
Braided stream channel flows meander scars detail ancient alluvial Mississippi floodplain. (FIG.4) Many sediment closings have formed lakes of various shapes and sizes. Greenville, MS. is located on the eastern bank of Lake Ferguson, an oxbow lake (FIG.5) left by one such old channel in the ancient Mississippi floodplain Greenville was likewise affected by the potential of flooding. River Hydrological studies in the geomorphology floodplain areas portended peak river flow at Vicksburg of 2,340,000 cubic feet per second (66,000 m3/s).(FIG.5) Levels which exceeded flood levels of the Great Mississippi Flood of 1927 2,278,000 cu ft/s (64,500 m3/s) by 1,500 m3 per second 2011 floods also exceeded the 1937 flood’s 2,080,000 cu ft/s (59,000). ( (NOAA N. , 2011)
USGS monitoring potential risk assessment supported opening the floodways. The combination of water from the floodways and from the Old River Control Structure just upriver of Morganza pouring into the Atchafalaya basin flood a large swath of mostly farmland and undeveloped land. Stream flow of the 2011 floods would have flooded those areas as well as greatly damaged the large river harbor areas in New Orleans and Baton Rouge, LA. Morganza floodways opening diverted 300,000 cubic feet per second of water from the Mississippi River. (FIG. 6) Choosing not opening the spillway, flood water would have only partially flowed in the natural flood basin of the Atchafalaya River. River bank flooding pressure generated from the excess flow of water would have cause levees to fail along the river from Morganza to Plaquemines Parish, LA inundating Baton Rouge. Further down river the Bonnet Carre Spillway structure in Norco were also opened further diverting flood water from the Mississippi River entering into Lake Pontchartrain threatening the below sea level basin New Orleans sits within. USGA flood mitigation measures spared the Greater Metropolitan New Orleans area estimates of 25 feet of floodwaters, according to by the Army Corps of Engineers. (Fig.6) (NOAA, 2011)
Animation above provides a thermal imagery data view of thunderstorms spawned April’s tornadoes exacerbating Mississippi Flooding. Cloud height and extent 10.6 miles into the atmosphere NASA’s TRMM satellite, Image credit: NASA/SSAI, Hal Pierce Characteristic
mid-latitude cyclone activity patterns produced regional rainfall greatly increasing runoff in water saturated watershed areas in the Mississippi River basin. Accumulated precipitation falling on these saturated areas rapidly flowed into the snow-pack melt swollen waterways. Tributaries were in flood stage throughout most of the entire basin from April 23 remaining flooded thru most of June. Basin study areas affected heavily were Missouri, Illinois, Arkansas, Tennessee, Mississippi, and Louisiana.
Fourteen day rainfall totals exceeded normal by 800% of normal across mid-Mississippi River valleys. Precipitation was captured at 20 inches in various areas. Study area along the Landsat row 37 and 38 recorded record flood crests on the lower Mississippi River. Arkansas City and Greenville rivers crested May 16, Greenville, May 17, Vicksburg May 19 and Natchez May 19, 2011. Lower basin Mississippi Portal region of the delta remained in flood stage from 37 ft. to up to 61.9 ft. through June. Natchez was in flood crest inundation until June 22. Second largest river basin in the delta basin area is the Yazoo River Basin east of the main channels on the periphery of the alluvial flood plain meander fields of the Mississippi River. Back water flooding occurred along the Yazoo River inundating farmlands. Record river crest levels at Vicksburg and Natchez and was pushed near record level at Arkansas City and Greenville. Back water flooding along the Yazoo River reached near record levels at Belzoni and Yazoo City. River levels crested in mid-May, with most points not falling below flood stage until the first and second weeks of June.
Opening the Old River Control Structure sent twice the cubic volume of Mississippi flood water into the Atchafalaya River basin. Floodwater observations upriver in the USGS Vicksburg district reveal the flooding potential these measures averted. (Fig, 5) Floodplain management averted serious flood damage. Flooding would not have over-topped lower elevation Morganza floodway, but Mississippi and Louisiana experienced little levee failure downriver due to overall velocity of cubic water flow reduction. Baton Rouge escaped inundation because of the opening. (Fig.6) Property damages struck 350 residences destroyed, 1440 damaged.6 businesses were destroyed and 34 damaged. Emergency declarations evacuated 2000 residences. Roadways and many of its tributaries in the Delta Basin region were closed due to flooding across the thruway… River barge and boat transport was delayed or curtailed based upon size and urgency boat. One citizen of Vicksburg drowned attempted to wade through flood waters.
REMOTE SENSING METHODOLOGY
Appropriate thematic study of geographical phenomena require a before and after data set. Landsat TM 5 data was acquired representing pre flood study area hydrologic activity from the months of February, April, May and June of 2011 covering the majority of the Great Flood of 2011. Imagery as close to the flood crest levels recorded were obtained.
Qualitative and quantitative analysis was performed using ERDAS Imagine.
Imagery was downloaded from Landsat TM 5 for the study are including row 24 path 38, 37 and 39 containing band 1-7. Thermal band layer was not used. Qualitative imagery was constructed from bands 1-6. Quantitative data utilized the Landsat bands recommended by USGS for wetland study; bands 4,3,2 in RGB gun load. Numerous incredible interesting imagery processing tasks were performed. Interest in this area was heighten with each new view from as many different processes as could be obtained with the limits of the software and the imagery. Majority of the imagery was qualitatively assessed. Both data types are important in an emergency situation.
Quantitative study is easily understood Decision makers who are not trained remote sensors rely on technocrats to provide easily understood data to make decisions quickly in emergencies. Disasters most often limit access to the affected geography. Flooding indeed usually prohibits access to areas where the worst flooding has occurred. Remote sensing gives a fast and relatively inexpensive process for emergency management to make decisions. Citizenry depends on the relief those decisions provide. In an emergency situation it is up to the analyst to provide easily understood data.
Data quantified in this study is just such data. Qualitative data provides a bird eye view that is easily understood. Flood situations are graphically depicted. Majority of that imagery was not quantitatively studied. It is provided in this study to demonstrate just hoe educational remote sensing imagery can be in emergency management Qualitative analysis from two stages of the flooding gives community planners more time to react. Geographical imagery insights into affected areas are invaluable to emergency management success. Such information lays a roadmap for deployment when communities are facing impending inundation. Quantitative imagery studies undertaken for this study greatly support the qualitative studies.
For qualitative study, areas of interest subset images were taken from row 24 region images. Geographically, that is the area below Memphis, Tennessee and above the Morganza spillway. Images were layer stacked utilizing bands 4, 3, 2. AOIs (Areas of Interest) were then processed using unsupervised classification methods. Five classes were utilized to isolate the areas before the flood and areas affected during the flood. Exact meters of flood inundation found were quantitatively taken by comparing the number of pixel classified as standing and overflowing existing water bodies between the two periods.( Feb Pixels in Water Class 1 = 3279480 x 30 meter resolution =98384400. June Pixels Water Class 1 = 3859799 x 30 meters = 11573970 -9838440 = and increase in Water Class meter water coverage of 1735530)
Water Class 2 in June imagery represents tributary and existing water body overflow flooding. Cropland and urban standing water detailed 8549781 pixels which equal 256493430 meters of flood inundation. The images follow with their attribute tables. The first two images are the subset chipped AOI (Area of Interest) prior to the unsupervised classification. Subsets were stretched to unsigned 8 bit and recorded as thematic data for processing. Land cover seasonal differences are apparent. Histogram equalizing and co-variance stretching was performed to compensate between the two-time periods.
HISTO RED GREEN BLUE OPACITY CLASS
0 0 0 0
65535 0 0 1
-1524094721 0.65 0.16 0.16
-1524094721 0.65 0.16 0.16
-1524094721 0.65 0.16 0.16
-1524094721 0.65 0.16 0.16 1
Land SAT TM Bands 432 from Feb., 2011 and June, 20
IG. 5) Composite False Color band 5-4-3 Landsat 5 Layer-stack utilizing ERDAS 10 processed photo of oxbow Lake Ferguson adjacent to Greenville, Mississippi, 2011 May Flood Crest which would have inundated the rural micropolitan area were not Missouri levees exploded and flood spillway opened.( USGS EARTH EXPLORER LANDSAT 5 TM Imagery