In coastal areas besides dynamics that occur, there are also natural processes that can actually be utilized by the surrounding population. One of them is sand dune. Sand dune is a natural laboratory in the form of sand dunes formed by the wind carrying sand. Not all coastal areas have this natural laboratory, one of the beaches that has is Parangtritis beach, Yogyakarta, Indonesia. The process of formation begins with sand spewed by Merapi volcano when it erupts which then settles. After being deposited on the shore a very strong wind from the Indian Ocean distributes this sand back to the north. Then formed a natural embankment which we know as sand dune or sand dune.
Sand that has reached the edge of the sea is not piled up at the mouth of the river but spread left and right as wide as 50-60 Km. Starting from ParangTritis Beach in the south of Jogja, Samas Beach, to Congot beach in the west. In Parangtritis there are about 190 sand dune formations, consisting of 70 types of barchan, 80 longitudinal, 30 parabolic and 10 combs. Each of these forms has different ways and factors controlling formation. The shape of the parabolic and comb is affected by vegetation which cuts the direction of the wind so that the wind speed behind the vegetation is less. Sand dune on Parangtritis beach has a barchan type. Barchan is a crescent-shaped sand dune with a steep slip face. Barchan is usually separated from each other and not fused. This type of sandbanks is formed if the amount of sand transported is limited or not too much. In some instances, Barchan can turn into a transverse shape with the direction of the wing perpendicular to the direction of the wind.
Sand dune has a function, among others, as a local aquifer in the form of fresh ground water, as a buffer from sea water interventions, seasonal plant media, tsunami wave dampers, and as a natural laboratory. Of course the potential that can be directly felt by the community is as a new tourist attraction the existence of sand boarding.
Sand dune is disturbed by the cover of shrimp pine vegetation as a misunderstanding from the relevant agencies which assesses the sand dune as a critical land so it needs to be reforested. In fact, the presence of vegetation will actually reduce the wind speed so that the sand material becomes retained so that it causes sedimentation in certain areas. In addition, the construction of illegal houses around the area of sandbanks makes sand become retained. As a solution, zoning can be made between the area maintained for the sand dune process and the area that is allowed for cultivation or settlement.