Where have the sand dunes gone?

VISAKHAPATNAM: It may not be long before the golden sand dunes, that accentuate the beauty of any beach, vanish from the physical map of the Port City. With incessant human intervention and construction activities, the sand loss from the beaches and disappearance of natural sand dunes or sand hillocks is taking place at a rapid rate in areas stretching from the Coastal Battery and RK Beach to Tenneti Park as well as Rushikonda.
Studies related to coastal sand dune ecology show it's a serious ecological threat, affecting the flora, fauna and residents living close to the beaches. In the city, deposition of boulders and sand from dredging activity is leading to creation of artificial beaches' as the natural dunes have stopped forming due to unusually alarming rates of sand erosion.
Typically, sand erosion and accretion are natural processes. Erosion happens due to the waves coming perpendicular to the shore while accretion or deposition takes place due to the southern current that moves parallel to the shore. But the construction of the outer harbour near the Dolphin's Nose Hill is obstructing the natural process of sand deposition, say experts, pointing out that the various human activities and new construction near the shore are only aggravating the problem.
Emphasising on the need for restoration of beaches and checking further erosion, Aparna Sunrampudi, a scholar at the environmental sciences department of Andhra University, who has been conducting a research on Coastal sand dune ecology and conservation of biodiversity' over the last four years, said, "Dunes act as natural barriers against winds. Without sand dunes, the impact of storms and cyclones like Hudhud will be felt more strongly, especially in localities near the beaches. The leeward dunes that sit behind the fore dunes and are usually located around 12 feet from the shore, are biodiversity hotspots housing several varieties of flora and fauna. In Vizag, we have observed around 90 varieties of flora, many of which are of considerable medicinal value. With dunes vanishing, the rich biodiversity too is slowly getting affected."
Another problem with the vanishing sand dunes is the enhanced risk of salt water mingling with ground water or salinity ingress. Environment activist and founder-president of Mother Earth Environment Consciousness Society (Meecons) S Ravi Kanth Reddy said, "The dunes help maintain aquifers by preventing intrusion of marine saline water into fresh water as they maintain a sensitive demarcation between the sea water and fresh water. But now, with the dunes depleting and sand eroding, saline water is entering into the ground water and causing problems, especially for residential areas extending from Coastal Battery to RK Beach."
Prof M Jagannadha Rao of the department of geology at Andhra University averred, "The rocky beaches of Vizag used to protect the coast naturally but sand accretion is being obstructed by the outer harbour and increasing port activities. During dredging also, the sand gets dumped at some other place, which is not required instead of in the RK Beach submarine area, where there's no rocky subsurface and the damage is extensive. This continuous loss of sand is creating changes in coastal geomorphology, which is bound to affect buildings in the vicinity of the beach in the near future."
Experts point out that in the given scenario, restoration of the dunes is extremely important. "Natural dunes take more than five years to come up again with the accumulation of sand. Therefore, concrete perpendicular sea walls to trap the sand and sand binders are required to arrest further erosion at the earliest," stated Prof Rao.
"It's also essential to allow certain vegetation to grow in the hinterland behind the leeward dune zone that act as sand binders and foster sand accumulation. These species include Ipomea Pes Caprae and Spinifex Littoreus," added Sunrampudi.