Richard Campanella, a geographer and professor from New Orleans, will be delivering a speech at the “Paradoxes of Peace and Water” forum in September 2018 at Augsburg University. He has kindly granted us permission to publish the article provided below. This piece effectively portrays the dangers, intricacies, and contradictions involved in managing water and land in New Orleans. Campanella possesses a keen understanding of the interconnectedness between land and water in this deltaic city, which currently sits at sea level and is therefore extremely susceptible to the impacts of climate change and sea level rise.

This article was originally published in the ‘Cityscapes’ column by the author in the New Orleans Times-Picayune on February 2015, and is reproduced here with permission.

-Patrick Nunnally, Editor.

Eleven individuals were severely injured, and four adjacent homes, plus the nearby house, were significantly reduced to rubble. A ranch house in a tranquil neighborhood of Metairie, located a mile away from Transcontinental Drive, suddenly exploded in a powerful fireball, causing damage to 20 neighboring buildings and shattering windows. This incident occurred on an early September morning in 1975.

Technicians from Co. Service Gas Louisiana and authorities from Jefferson Parish are investigating the smoldering ruins to determine the proximate cause of a broken gas line. The residents of Metairie are unnerved and wonder about the amounts of time bombs they may be living in, as reported by “Times-Picayune”.

It was discovered that soil subsidence was to blame, as the quantity and intensity of the explosions indicated a deeper reason, one that exceeded poor craftsmanship or unfortunate coincidence.

A spark from an electrical source or a cigarette lighter was sufficient to set off a massive fire. Gas gathered in pockets beneath the foundation or rose into the attics as the pipes broke and leaked gas. The concrete foundations of the slab tilted and buckled as a result of the settling of the former swampland, which had been recently drained, leading to the distortion of the buried gas lines.

Amid a flurry of parish lawsuits and finger-pointing, officials eventually require the foundations to be set on a grid of sturdier pilings driven deeper into the earth below the most level superficial sinkage, in order to accommodate the shifting designed hook-ups and prevent bending of the “goose neck”.

The piles stabilized the bases, and the adaptable connections put a stop to the gas line cracks.

In the central-western section of Metairie, which had a particularly thick layer of ancient marsh peat, the broken gas lines did not release the deadly gas that oxidizes organic matter, but one researcher argued that it was due to the introduction of air and the removal of water following the rotting of this organic material. Despite this, the sinkage continued, causing the integration of tree stumps, leaves, and grass into the coffee-like mud, affecting the streets, driveways, and gardens.

The artificial draining of Lake Pontchartrain, located south of the city, has created a geophysical hazard that affects all areas within the lesser and greater extents of the protected levee. This remains a larger problem, and serves as a frightening symptom. We should be grateful that modern building codes have effectively solved this issue, as the extreme example of soil subsidence can cause houses to explode, posing a significant public health hazard.

Having knowledge of the occurrence and risks associated with soil subsidence requires an understanding of the geology specific to our locality.

The five elements that make up our underlying land are organic matter and water, which are composed of sand, silt, and clay particles. These particles were mostly created by the Mississippi River, which regularly overflows its banks and changes its course, over a period of 5,000 to 7,200 years.

The river deposits the largest quantities of coarsest sediments in its distributaries, while dispersing smaller quantities of finer clay and silts particles in the lower marshes and backswamp areas, closest to its highest channels.

When the waterlogged soils in the area were drained out through manmade drainage systems, the groundwater level was lowered, causing the organic matter and water in the soil to shrink. As a result, most of the dried organic matter was preserved, and the runoff accumulated in the fringes of the West Bank and the areas of Broadmoor, Gentilly, Lakeview, and Metairie in East Orleans. Today, these spots in the metro area are the lowest, although they are still slightly above sea level.

Elsewhere, in prehistoric times, when the Mississippi River would jump channels, a new building would form while the old deltaic “lobe” subsided. The first subsidence started when the river no longer spread fresh water and sediment onto its deltaic landscape.

The earth gradually stabilized in their absence, but they were inherently advantageous, and those past catastrophic floods, undoubtedly, posed a threat to human beings. Inhabitants constructed man-made embankments along the lower Mississippi to avert seasonal inundation from the 1700s until the 1900s.

The majority of our modern soil subsidence is not attributable to the installation of drainage systems within the New Orleans metro area, but rather to the levees along the river.

In the 1890s, Albert Baldwin Wood, an engineer, developed a highly efficient system that dramatically increased the capacity and speed of debris removal. Wood patented his new system, which primarily pushed water from Pontchartrain Lake and surrounding bodies of water into the outfall canals through a series of underground pipes and gutters. This sophisticated system allowed for the direct runoff of water through pumping stations in New Orleans.

In the following years, the fundamental blueprint, along with significant alterations like the placement of pumping stations, was duplicated in neighboring parishes and expanded into the eastern part of New Orleans during the 1910s and 1920s.

The effect of municipal urban drainage on geography was nothing short of revolutionary. In 1909, George Washington Cable stated, “When is it now where the surface is ten feet or more from the ground and the soil is saturated to a level of half and two feet, but the salubrity that could not be achieved is there.” The forest swamp curtains are completely gone, covering miles with homes and gardens that are dry and drained.

New Orleanians moved en masse from their historic high ground by the river into new auto-friendly subdivisions on former swamps to the east and west, eliminating worries about longer topography.

The ground subsided, and the finely grained particles settled into those hollows. Additional gaps emerged, subsequently oxidizing the natural material and creating air pockets within the soil while eliminating undesirable marsh water. However, a significant issue arose.

A 1913 article in the Times-Picayune pondered the drainage of the city, which was caused by the settling of the old St. Louis cathedral wall that occurred a few days ago. The impact upon the cityscape was first noticed by architects, who are now concerned about two questions in New Orleans: will all the old downtown buildings experience similar breaks in their walls, and will it necessitate their reconstruction?

Why were those spots the lowest to begin with? In East Orleans, New Orleans, and parts of Metairie, the water level was 12 to 6 feet, which was closest to the surface, hence why those spots were the lowest. The same applies to Gentilly and Lakeview, where the water level was 8 to 5 feet. Additionally, in Broadmoor, the water level was 6 to 3 feet. Roughly half of the metropolis was below sea level, with the sea level sinking below the surface of the land by one-third. This metropolis, which originally lay above sea level, saw one-third of its surface land sink below the sea level by the 1930s.

The fact that the sea level is rising indisputably makes it a potentially deadly matter. When we measure the relative sea level, it roughly doubles the absolute rate of land sinkage, which is the worst news. It is alarming that humans are sinking with it, and the fact that we used it to be nearly 100 percent above sea level is bad news. On the positive side, it is good news that 50 percent of our metropolitan area remains above sea level.

When Hurricane Katrina hit, the landscapes, which were populated many years ago, have generally been washed off the next day. These landscapes have not subsided or been drained, and a similar surge came upon them like the surge caused by Hurricane Katrina. This surge poured swiftly and deeply into many areas because they had become bowl-shaped due to the accumulation of soil subsidence, and the levees ruptured.

The Katrina flood, instead of being drained, remained on top of well-established communities for several weeks. Some individuals lost their lives due to the unexpected consequences of wetland drainage and ground sinking.

It is not feasible for water and soils to “reinflate” in urban areas, while the problem of soil subsidence has no true solution.

It is beneficial to restore a certain level of water content in the soil, as it is key to slowing the future sinkage of interest in the rain, bioswales, ponds retention, surfaces porous through possible as runoff stormwater much as retain or absorb.

It is indeed possible to reverse erosion and subsidence further through coastal restoration techniques such as the beneficial use of dredged sediments and the beneficial use of sediment siphons, as well as river diversions. This is imperative for undrained and undeveloped areas along the lower Mississippi River.

In order to create a pleasant dining experience and stabilize the house, it seems that there is a need for a security job in this town. Antoine’s restaurant has been consistently successful in business since the same year. The local industry offers services such as shoring and supplying operators for pit-sand, including structures to counteract the effects of subsidence. Although we cannot completely solve the problem of urban soil subsidence, we can effectively address the symptoms by building above-grade pilings and piers to prevent water from entering our yard.

We can also acknowledge that topography matters, and that our higher ground is a valuable resource which ought to host higher populations.

Before constructing fresh embankments or developing and urbanizing more wetlands, in this deltaic plain, we can gain knowledge from the past events—and the geographical aspects—such as the devastating blasts in Metairie during the 1970s—by contemplating extensively and profoundly.