Dr. Carol Wilson is an ecogeomorphologist. Even though that word is a mouthful, what Carol spends her days doing is much more accessible and important than you might think. She studies river systems - how they move, how they build and feed wetlands, and how they can be both life-giving and destructive forces.
Carol has been a professor at LSU for four years now. She recently returned from a research trip to the Ganges-Brahmaputra delta on the Indian subcontinent. Carol studies both the Ganges-Brahmaputra delta and the Mississippi river delta. Both areas have levee systems that impact the local populations in different ways. During her visits to southern Bangladesh, Carol works with other researchers to understand and hopefully mitigate the impact of cyclones and other severe storms on the Ganges-Brahmaputra delta system and the people who rely on it, many of whom are desperately in need of better ways to cope with natural disasters.
Carol’s interest in marshes began when she pursued her master’s degree in New Orleans, where she studied wetland erosion in Louisiana. She wanted to understand why and how the marsh shorelines were eroding and what was happening to all of their organic and inorganic material.
College of Science: Can you tell us a bit more about your research?
Dr. Wilson: My research centers on quantifying the processes that shape our wetlands, specifically how biology, geology and water interact to create and maintain functioning landscapes. Deltas are a particular type of wetland that form as rivers empty their water and sediment into another body of water, such as an ocean. It is very important that we understand deltas because they are areas where lots of people live. Deltas also contain a lot of natural resources, including fisheries as well as oil and gas infrastructure, especially here in the Mississippi Delta.
The Ganges-Brahmaputra Delta a river delta in the Bengal region of the Indian subcontinent is probably one of the most densely populated river deltas in the world. This region is very vulnerable to things like sea level rise, storms and flooding from major river events during the monsoon season.
Part of my work is understanding the natural dynamics of the Ganges-Brahmaputra Delta, particularly where sediment is going in the system. I’m trying to answer questions such as, is there enough sediment in the system to be able to build up land at a pace that is sustainable with sea-level rise and other deltaic processes? We are also looking at elevation changes and subsidence in this area. Subsidence is a natural lowering of the land surface.
We are also going into areas where people are living in the Ganges-Brahmaputra Delta to see how humans have changed the landscape. In Louisiana, levees are a familiar sight. We have leveed our lands in an attempt to prevent our rivers from flooding our lands and our fields. People have done the same thing in Bangladesh. There have been repercussions. For example, most of the land in the Ganges-Brahmaputra Delta is now lower in elevation, where natural sediment is not building up those landscapes. This potentially puts people living in this area at risk.
College of Science: What is a delta and how sediment is involved?
Dr. Wilson: A delta is the area where a river is discharging into an ocean basin. Rivers carry loads of sediment from upland areas such as mountains. Ultimately, they build new landscapes right at the ocean.
Rivers have been doing this over the last ten thousand years or so. We see that almost all rivers, if there’s enough sediment load, create deltas. The problem is that humans have altered rivers’ sediment loads with the construction of dams further upstream. Dams divert or stop the natural flow of sediment down the river. We’ve also put levees up on our lower delta plains to prevent flooding. Unfortunately, this has created an imbalance. Land surfaces that are naturally lowering have no new sediment coming in to compensate for the land loss.
A river’s path isn’t naturally static. Rivers are very dynamic systems. A river moves around over time, creating the quintessential delta shape. Sometimes a river undergoes a process called avulsion where it will skip and move and start building into another location.
The movement of rivers across a landscape can also produce a cut off. A meander loop in a river can get cut off over time as the river moves. There are several places where we can see this naturally. For example, False River in Louisiana, which is a lake presently, used to be a very large meander bend in the Mississippi River that naturally got cut off a few hundred years ago.
College of Science: What do you find most exciting about your fieldwork?
Dr. Wilson: Right now we have two projects that are bringing together many different types of scientists from both the United States and Bangladesh, including geologists, engineers, hydrologists and sociologists. These different types of researchers don’t often get to work together. We’re bringing them all together on a collaborative project to understand the natural dynamics of the Ganges-Brahmaputra delta system, be it how the river is migrating, how salinity is impacting where people are living or how human migration is being impacted by either salinity stress or storm surge risk. It’s really exciting to be on the ground right now as part of this team, working to understand how sustainable the Ganges-Brahmaputra delta is and what practices might make it more sustainable for people living in the area.
College of Science: What are the challenges of living in the Ganges-Brahmaputra Delta?
Dr. Wilson: Southern Bangladesh, particularly coastal Bangladesh, is a very rural landscape. It’s impoverished compared to developing nations. On our coasts in the U.S., we have houses built of very sturdy wooden construction, brick and mortar. Many people in areas of coastal Bangladesh have thatched houses made of local timber. If they’re lucky their roof is made of corrugated aluminum. If they’re very, very lucky they are able to afford bricks. But most of the building materials are not cyclone-proof. As such, most residents are not prepared to withstand cyclone winds. Thankfully in recent decades there has been a real push to build cyclone shelters within these rural communities, which has reduced the number of casualties during storm events.
Fresh and clean drinking water is also a limited resource in the area. So it’s really important for locals to have a drinking water source that can be maintained throughout the year and not get contaminated or polluted. Arsenic is a common water contaminant in the area, a problem that our team is trying to hep address. We are conducting research to try to understand which areas are contaminated with arsenic, why, and what residents could do about it.
For example, residents may be able to access clean water located deep underground. However, this water is difficult and expensive to access, being located more than 300 feet under the land surface. A better solution may be sustainable rainwater harvesting. This is something the locals are actively pursuing, but we are investigating whether we can help improve their rainwater harvesting practices and how they contain those harvests so that their clean water doesn’t become contaminated by flooding during a cyclone, for example.
College of Science: Outside of your own team, who do you work with in the field?
Dr. Wilson: We are actively collaborating with several institutions on the ground in Bangladesh. So we have several partners associated with Dhaka University, Khulna University, the Bangladesh Water Development Board and the Bangladesh government, including people in their forestry department their Institute of Water Modelling.
Synergy between all of these different organizations is really important to what we do. But we also just want to work together. Our work in the Ganges-Brahmaputra Delta is not a matter of coming in, collecting information and walking away. The whole point is to learn about their delta system so that we can help develop best practices for sustainability and resilience that might be implemented by local scientists and residents. The locals involved also know their system better than we do, so having them involved is extremely important. Ultimately the goal is to create a more sustainable delta society.