When it comes to policy questions regarding land use, sometimes a little science is required to evaluate the effects on the land and the costs for developers.
For Dr. Melissa Kenney and her colleagues, their research on the Mississippi River Delta will help influence future state-planned land development in the region through its examination of options that are cost-effective and environmentally conscious.
“The Mississippi River Delta is a really critical ecosystem and social system, and for the U.S. there’s a massive amount of commerce that goes through it,” said Kenney, an assistant research professor in Environmental Decision Analysis at the University of Maryland. “It helps to support a robust fishery, and a number of people have lived there for many generations.”
“Since the 1930s, the Mississippi delta has lost about 4900 kilometers of land- that’s larger than the size of Rhode Island,” said Kenney. While land is compacted naturally, oil and gas production and levies along the riverbanks are starving the river of sediments.
Dr. Benjamin Hobbs, a professor in geography and environmental engineering at Johns Hopkins University and colleague of Kenney’s, said their research will help policymakers make more informed decisions in regard to how they should build on their limited land.
“You look at different engineering designs- some cost more than others, some are more desirable, some have fewer environmental effects,” said Hobbs. “No solution is most reliable, and cheaper, and environmentally friendly.”
For the project, Kenney said that the researchers combined three different models, including an engineering model examining diversion projects ranging in size from shallow to deep and narrow to wide, a land building model given the diversion of water and sediment for a particular diversion project and the economic model.
“When you need to build land and maintain a certain amount of water for navigation purposes, you have to increase your sediment ratio to water if you want to expand land building,” said Kenney.
“It turns out that if you do have small projects, you’re taking sediment from higher in the water column, and there’s just a lot less sediment in the water column,” said Hobbs. “You need sand in order to build land.”
“Even though a deep diversion is more expensive per unit of water, it’s cheaper per unit of sand and unit of land,” said Hobbs.
Further, it showed that a construction portfolio aimed for large values of land should include at least one deep diversion project in order to build large amounts of land and maintain sufficient water in the main channel of the Mississippi River for navigation purposes.
Awarded the 2013 WRR Editors’ Choice Award, Kenney said that their research paper could help create the general bounding conditions for land development options in the Mississippi River delta, but to make land diversion decisions, decision makers would have to consider additional information to evaluate all of the individual project choices.
“When we have regions like that where good science could help inform the decisions we are making, it seems our responsibility as scientists to engage and help answer some of those policy questions when we have the knowledge or tools that could help influence those policy decisions,” said Kenney.
“To me, it’s a lot more important to do [research into] things that would have direct relevance to some of our societal challenges because there’s so many opportunities where really good science could make a lot of difference,” said Kenney.