Sand dunes threatening to bury the runway required stabilization using native vegetation. Root structure analysis identified species combinations that anchor sand while tolerating salt spray and drought.
The problem of moving sand
Thandwe Airport is the gateway to Ngapali Beach, one of Myanmar's premier coastal destinations. Its location, however, presents a persistent engineering challenge: moving sand. Coastal dunes are dynamic systems, shaped by the constant force of wind, a process known as aeolian transport. While dunes form a natural barrier against storm surges, their mobility means they can encroach on infrastructure. At Thandwe, this meant loose sand from the coastal dunes threatened to migrate onto the runway and taxiways, posing a significant safety risk to aircraft during takeoff and landing.
Traditional engineering solutions, like concrete walls, are expensive and can disrupt the natural coastal processes, sometimes worsening erosion elsewhere. Instead, a bio-engineering approach was used. This method relies on the specific properties of native plants to create a living, self-sustaining barrier. The goal was to halt the sand's advance by establishing a dense cover of vegetation whose root systems could bind the loose sand particles together, effectively anchoring the dune in place. This required a careful scientific analysis of which local plants could perform this function while surviving the harsh coastal environment.
A botanical solution
The success of dune stabilization depends on selecting plants adapted to the foredune environment—an area defined by salt spray and intense sun and constant sand burial. Two important pioneer species native to the tropical coasts of Asia are prime candidates for this work: Ipomoea pes-caprae and Spinifex littoreus.
Ipomoea pes-caprae, commonly called beach morning glory or railroad vine, is a fast-growing perennial. It sends out long, creeping runners, or stolons, that can exceed 30 feet, creating a vast surface network that covers the sand. Below the surface, it develops a deep taproot system that firmly anchors it. Its distinctive two-lobed leaves give it another common name: goat's foot vine. This plant is exceptionally hardy, able to tolerate direct salt spray and soil with minimal nutrients.
Spinifex littoreus, or beach spinifex, is a perennial grass that forms dense, tough mats across the dunes. Its stems, called culms, grow 40 to 80 centimeters long, trapping windblown sand. A remarkable adaptation of Spinifex littoreus is its response to being buried by sand. The burial stimulates the plant to grow more vigorously, extending its stolons and producing more adventitious roots from its nodes. This cycle of sand deposition and responsive growth is precisely what builds and stabilizes a dune over time. A detailed analysis of these species' root structures—their depth, density, and tensile strength—allows engineers to create an optimal planting combination that locks the sand in place and protects the important airport infrastructure just beyond the dunes.
💡Fun Facts
The scientific name *Ipomoea pes-caprae* means "goat's foot morning glory," referring to the shape of its leaves which are notched to resemble the hoofprint of a goat.
The female *Spinifex littoreus* grass produces large, spiky seed heads that detach from the plant and are rolled along the beach by the wind, dispersing their seeds.
The underground root network of dune vegetation is the most important part for stabilization. The roots of some dune grasses, like Sea Oats, can grow to a depth of 40 feet (about 12 meters) to find water and anchor the sand.
Sand burial stimulates *Spinifex littoreus* to extend its runners by over 40% and produce more roots, allowing it to thrive in the dynamic dune environment.
The dune stabilization project is part of the airport's operational infrastructure and is not open for public tours. It can be viewed from the airport perimeter and during takeoff or landing.
Admission
Not applicable.
Accessibility
The terrain is sandy and uneven, characteristic of coastal dunes. Access is restricted as it is an active airfield.