Floods Collide with Sprawl in Louisiana’s Amite River Basin

Introduction

Before daybreak on the morning of August 12th, 2016, I was driving my wife to catch an early flight from Baton Rouge’s airport. Before heading out, I’d checked the airline’s website and the local weather radar. The airline optimistically proclaimed an anticipated on-time departure, but the radar showed heavy rains. Nonetheless, I was hopeful for a smooth connection, since the aircraft had arrived the night before. As we drove, rain pelted our car, and we inched through city streets filled with water from curb to curb. Leaving the surface streets for the elevated and well-drained interstate, we were able to arrive at the airport in ample time, and the flight made its departure through the continuing downpour. On my return trip, I detoured off the main surface streets to slightly higher terrain to avoid the prospect of flooding my low-clearance auto. This was obviously a big-rain event, but street flooding is all too common in Louisiana’s capital city, and I continued my day more or less as planned. Others were not so fortunate.

As the day progressed, rain continued, and forecasters intensified their warnings of impending river flooding. More than eleven inches fell on Baton Rouge that day and over a five-day period, numerous rain gauges in the region captured more than twenty inches. One weather station collected thirty inches. This copious amount of water, some 7 trillion gallons, overwhelmed the Amite River and its major tributary the Comite, which flow through the city’s eastern and southeastern suburbs.

The Amite drains a relatively small basin with only 1,280 square miles. Its headwaters are some 300 to 400 feet above sea level in southern Mississippi. In normal situations it follows a modest gradient, slicing through the so-called “grand canyon” of Louisiana at Fluker’s Bluff and meanders across the gently undulating landscape---forming a portion of the East Baton Rouge and Livingston Parish border---and converges with the Comite. South of the merger, the Amite passes across the Mississippi River floodplain toward Lake Maurepas, which feeds into the sea-level Lake Pontchartrain. With extremely slight gradient on this lower course, the Amite slows, spreads, and following heavy rains tends to cause backwater flooding across the suburbs in Ascension Parish.

With the extreme precipitation of mid-August 2016, the Amite reached a record crest of 46.2 feet---nearly five feet above its 1983 high---and it overtopped levees in Ascension Parish (Figure 1). In this tiny basin, floods can rise swiftly, especially when there are dramatic downpours. At Denham Springs, the river rose from a threatening thirty-five feet at midnight on August 13 to over forty-six feet twenty-four hours later. Even residents who regularly see high water were caught unprepared for the scope of this tragic flood and had to evacuate their homes as water rose quickly.

Additionally, many residents who had never experienced flooding before had the rivers slip into their homes under the cover of darkness with little warning (Figure 2). Once aware of the imminent danger, many families faced a second challenge: retreating to safety.

Evacuation routes, in many cases, were inundated, stranding people on tiny neighborhood islands in the midst of the rising flood (Figure 3). A flotilla of boat owners, of which there are many in the fishing-crazy Sportsman’s Paradise, responded.

This so-called volunteer “Cajun Navy” worked day and night, along with professional emergency responders, to rescue thousands of stranded families (Figure 4). News accounts were replete with countless tales of harrowing escapes and courageous courtesy extended to neighbors and strangers alike (Advocate 2016).

FLOODS ARE NO STRANGERS

The August 2016 floods were the result of a truly exceptional precipitation event that produced terrifying conditions for residents, but this region has a noteworthy history of recent flooding. High water is a regular visitor to the Amite River basin (Figure 5). Since 1973, the river has risen more than a foot above flood stage thirty-four times---twice in one year on several occasions. Most notably, in early April 1983, torrential rains fell across the Florida parishes in southeast Louisiana. Over the course of two days, more than ten inches of precipitation pelted the upper reaches of the Amite River basin. The runoff from this extended downpour filled the river beyond its capacity, and the Amite crested at a record height of 41.5 feet, a benchmark that stood until 2016. The high water caused unprecedented flooding in recently developed suburbs in Baton Rouge, Denham Springs, and downstream in Ascension Parish. Damage to property and infrastructure exceeded $171 million (Emmer 1985).

As they embarked on recovery from this flood, local governments took steps to avoid a repeat catastrophe. Authorities launched efforts to improve the flow of water under a major interstate bridge that had been a choke point, and officials began planning a major diversion channel on the upper Comite to reroute excess flow to the Mississippi River. Yet, only two years after the record flood, local floodplain manager and geographer Rod Emmer pointed out that floods were a common feature of this small river basin. He recounted that there had been four major floods between 1972 and 1983 (Figure 5). He reported that the population of the Baton Rouge capital region had grown significantly in that decade and that urban land uses had more than tripled---much of it in the impacted Amite River basin (Figure 6). And, he asserted that much of the financial losses and personal suffering could have been avoided if the parishes had implemented a rational flood-reduction program (Emmer 1985). His main point echoes the argument that there are no natural disasters. That is, extreme natural events occur, but tragic outcomes to society are the result of accumulated human decisions. Gilbert White put it succinctly in 1945: “floods are acts of god, flood losses are largely acts of man” (White 1945, 2).

Baton Rouge is no exception to these broader relationships between nature and society. There has been a well-established pattern that has seen more businesses and residences built in flood-prone suburban areas, which has placed more people and property at greater risk in recent decades. From Chicago to San Antonio, geographers have chronicled the encroachment on floodplains and the increased incidence of suburban flooding. A combination of building in low areas that had been avoided for decades and the increased runoff produced by covering the land surface factor in to increased risk. Levee building in some places has contributed to the expansive development guided by a false sense of security. In addition, scholars are directing our attention to the accentuated risk in urban areas driven by climate change (Leichenko and Solecki 2013).

In Louisiana, residential expansion had pushed out of the old core of Baton Rouge towards the Amite River between the end of World War II and the late 1980s (Figure 6), and spilled over into adjacent Ascension and Livingston parishes especially after 1980. In the years after the 1983 flood, population growth and suburban development continued to sprawl across the Amite basin. Livingston and Ascension parishes saw their populations double between 1980 and 2010, while the much larger East Baton Rouge Parish added more than 70,000 residents during that time span (U.S. Census 2016). Housing and commercial development grew along with the number of residents. Shopping centers and schools added to the land uses that shed rainfall, as did more miles of roads. The capital metropolitan region spread across the Amite River basin, exposing more people and property to risk that might have been averted had the communities heeded the 1985 advice of floodplain manager Emmer.

Fast forward to mid-August 2016. Massive rains forced the Amite River well above the 1983 mark. Early estimates placed the number of damaged homes at 135,000 (Gallo 2016; Table 1). In the community of Central, 80 percent of its residences were impacted. To rebuild, Louisiana has requested $4 billion in disaster relief (Edwards 2016). All aspects of the 2016 event eclipsed the record-setting 1983 tragedy, and once again prompted calls for better protection for residents and businesses. While there is a tendency to declare this a natural disaster due to the exceptional rainfall, the consequences of expansive suburban development across the flood-prone region put people and property in harm’s way.

Meteorologists have characterized the August 2016 downpour as a 1000-year event---or a storm that has a 0.1 percent chance of happening each year---but floods have been a common feature of this basin since the 1983 benchmark (Figures 5 and 7). Storms in spring 2016 drove the Amite River up to over thirty-nine feet. Rain from Hurricane Gustav in 2008 pushed the river above thirty-six feet and Tropical Storm Allison dumped some twenty inches of rainfall that caused the river to top thirty-eight feet in 2001. The local river-basin authority identified nineteen significant floods between 1961 and 1995. As I was preparing this article in early December 2016, some gauges in the region received more than six inches of rain, pushing the river up from 11.5 feet on December 3 to about 16.5 feet on December 6---but well below flood stage (USGS 2016). In January 2017, nearly five inches of rain fell and briefly pushed the river above flood stage. There will be flooding again in this basin.

PLANNING FOR FLOODS, BUT PERMITTING DEVELOPMENT

Certainly steps have been taken to mitigate flood impacts, but there is a fundamental conflict in urban flood management that is all too obvious in the Amite River basin. The impulse to permit suburban development and promote economic growth can override a more basic and essential consideration: public safety. While there have been steps taken to plan for floods, flood damages have continued due to suburban sprawl on flood-prone locations. There is limited safe space above the reach of common flood stages in the Baton Rouge metropolitan region, and neighborhoods, shopping centers, public facilities, and schools have spread across the low-lying landscapes.

Back in 1985, Rod Emmer pointed out that the primary causes for flooding were obstructions to flow, increased runoff from impervious surfaces associated with development, and encroachment of development into flood-prone territory (Emmer 1985). Even before the 1983 flood, steps had been taken to lessen the backwater flooding due to low gradient and a meandering channel. The Corps of Engineers dug a diversion canal along the lower Amite to speed flow through the troublesome lower course. The idea of diverting excess discharge reappeared after the 1983 flood. Planning for a Comite River diversion canal began moving toward the goal of redirecting a portion of the flow from the upper Comite directly across the landscape to the Mississippi River. Voters in tax-adverse Louisiana even approved a millage---a tax equivalent to one-tenth of a cent per dollar income---to fund the project in 2000, and renewed that revenue stream in 2010. The diversion canal, which might have lowered the 2016 flood a few feet, has seen a modest amount of construction, but the basin authority has not been able to secure sufficient funding, and the project remains incomplete and far from providing any protection (Amite River Basin Commission 2013).

A major study about the choke point caused by the I-12 highway bridge over the river led to modifications to ease the passage of water beneath the spans. Yet, the installation of new concrete barriers between the lanes of the interstate highway to prevent accidents in recent years gave rise to accusations, following the most recent event, that they inhibited flow and aggravated flood conditions. There was also discussion of constructing a reservoir on the upper Amite to capture and store excess runoff, but the reservoir idea has fallen by the wayside due to its high estimated costs and limited benefits. So despite some progress, structural flood-protection projects have languished.

There are also “nonstructural” options to mitigate flood risk in the region. The National Flood Insurance Program, created by Congress in 1968, offers homeowners access to subsidized insurance against flood damages and local communities have participated in this program. Yet, it did not deter people from building in flood zones, or rebuilding after floods. In the community of Central, perched between the Comite and Amite rivers, some 75 percent of the urban territory is within the designated 100-year floodplain (City of Central 2016) and 90 percent of the homes there suffered damage. Yet, only about 20 percent of the Central homeowners had flood insurance (Allen 2016).

For some homeowners, insurance is a relatively inexpensive way to recover from the all-too-frequent floods. For other homebuyers, it is a cost that might push a desirable residence out of financial reach. A study by University of New Orleans researchers documented that 52 percent of policyholders in the community of Greenwell Springs had filed repeat flood claims between 1995 and 2009. The Natural Resources Defense Council has mapped repeat flood-insurance claims nationally, and the Amite River basin stands out in its map as a region with a high rate of repeat claims (Moore 2016). A review of FEMA repeat flood claims by Christopher Flavelle in Bloomberg View shows the Amite River basin as part of a swath of repeat flood claims in coastal Louisiana (Flavelle 2016). Additionally, each of the three parishes affected by flooding in the Amite River basin had policies that called for homeowners who suffered major damage to rebuild one foot above the record flood in high-hazard zones. This is a strong and sensible approach to limit repeat damages, even though it did not restrict building in flood-prone areas in the first place. Financial institutions were willing to lend to homebuyers who buy flood-insurance policies in the higher-risk areas. In the wake of the 2016 floods, each parish waived the requirement that homeowners would need to rebuild a foot above the record flood (Hardy 2016). Parish governments took this step to encourage homeowners to return quickly and to minimize short-term rebuilding costs. Also, the state’s projected budget for recovery places a priority on rebuilding in place and only allocates a small share of the requested funds to mitigation.

In most areas of society we appreciate records. Yet, local policymakers in the Amite basin have decided to reject the most recent benchmark as an outlier, too rare to be used as the basis for ensuring safety for their constituents. Furthermore, it is common for communities to challenge the flood zones mapped by FEMA. Commonly, they request a reduction in the size of the area designated as high-risk flood zones. Indeed, Central submitted a formal request to reduce the territory in the 100-year floodplain well before the August event, and it gained FEMA approval about a month before the deluge. The change enabled some homeowners to drop flood insurance required by their mortgage lenders and lowered the rates for others (Allen 2016).

Tragically, some homeowners terminated their policies between the release of the new maps and the flood. Among them, some residents suffered damage that will not be covered (Allen 2016). By rejecting the most recent flood as the new benchmark, local leaders not only allow homeowners to rebuild in place and to remain in harm’s way, but encourage it. Flood insurance does the same. In the long term, this storm, and the flood-causing spring 2016 rains, will not be factored into floodplain maps for years to come. The sensible policy to require building one foot above the record flood provides protection in proven flood areas in the interim before flood-zone maps are updated. That will not happen. Decisions to allow quick return for those directly impacted and to restore local tax bases eclipsed safety. This course of action reinforces the tendency to attribute disaster to nature and absolves local decision makers. It also dismisses the more extreme weather that will accompany a changing climate and make events of this sort more common.

RECOVERY

We tend to measure flooding in terms of recovery costs and lives lost. The former was substantial in this event and fortunately the latter was modest, even though unquestionably tragic. The state has requested $4 billion in recovery dollars and thirteen individuals did not survive the flood. Yet there are many additional costs that are not fully measured by normal tabulations. In the days immediately after the storm, over 5,000 people sought shelter in local emergency facilities (Figure 8). By mid- October, some 2,400 households remained in temporary shelter (hotels or motels), and that number declined to 1,700 families by late November (Louisiana GOHSEP 2016; FEMA 2016). As of late November 2016, 153,000 families or individuals had requested FEMA assistance and over 21,000 families applied for home-repair assistance. FEMA provided aid to over 86,000 survivors (FEMA 2016). These numbers only begin to reflect the magnitude of the event on lives and businesses in the region. Those in temporary shelter seldom had normal kitchen facilities and encountered higher costs for meals, and often additional miles to commute to work.

Families who were directly impacted, and their circle of family and friends, endured countless hours in sweltering conditions hauling damaged household items to the curb, gutting houses, volunteering to help clean up churches and schools, and taking in and feeding the displaced---for months in many cases (Figure 9). They dealt with innumerable disruptions to daily routines. Schools that were not damaged hosted students from flooded campuses, and parents and their children had to contend with irregular schedules and extraordinary traffic.

Local businesses had to lay off some workers as they repaired their facilities (Figure 10), while some national chains were able to put staff to work at other stores---but often necessitating extra commuting time for those employees. Countless volunteers from beyond the immediate vicinity lent a hand through various service and faith-based organizations (Figure 8). The hours of personal repair work and volunteer labor are not adequately incorporated into the customary tabulations. While recipients of this generous aid are grateful, it needs to be pointed out that those who have decided to rebuild in place, and the national flood insurance program supports this option, will remain in areas that have recently flooded. Many of those who bore the biggest costs, continue to face the greatest risk and repeat expenses.

Another way to measure the flood impact is to look at the number of houses affected in 2016 compared to 1983. Some 50,000 houses (Table 1) suffered major damage in the most-recent storm (Gallo 2016). Early reports revealed shocking statics: approximately a third of the houses in Ascension Parish and about 75 percent in Livingston Parish took on water. In 1983, only 5,400 endured serious damage. The floodwaters were lower in 1983 and not all damaged properties were in designated high-risk zones, but development enlarged the number of homes at risk in the thirty-plus years between the storms. The fact that nearly ten times the number of homes had major damage---and many more experienced some impact---is testimony that it was not just the high water that created the catastrophe. Development decisions were very much involved. Each house, big-box store, parking lot, and mile of newly paved roadway sheds additional water. Every culvert, bridge, and structure can act to back up raging floods---adding to the height of the water. Land-use changes alter flood risk, but the formal flood-zone maps seldom keep pace with development and changing land uses--- although local maps were recently updated.

Most of the more than 2 million cubic yards of curbside debris had been carted away by the end of 2016, eliminating the most obvious evidence of damages (Figure 11). Stores in a major shopping center in Livingston Parish had rushed to reopen in time for the holiday shopping season (Figure 10). Numerous schools across the region were striving to be open for the spring semester. Within six months, there was some semblance of normal in the Amite River basin, although home and business repairs will continue for months to come. Yet, the more fundamental question remains unanswered: is the region better prepared for the next big rain?