Print Email Facebook Twitter Rehabilitation of the Mayabeque Beach: Determination of the main causes of erosion and proposal of several solutions Title Rehabilitation of the Mayabeque Beach: Determination of the main causes of erosion and proposal of several solutions Author Van den Hengel, D. Poot, J.G. Theunissen, R.P.G.J. Kluyver, T.M. Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 2004-06-01 Abstract In this report the beach erosion problem at the Village of Mayabeque, located 60 km south of Havana at the South coast of Cuba will be investigated. Mayabeque is a small local holiday village. 20 houses are permanently inhabited and in the summer the population goes up to 3000, mostly Cuban people all spending there holidays here. Mayabeque suffers from an average coast regression of 1.1 meter per year. The main objective of this project is the rehabilitation of the Mayabeque Beach. Therefore an investigation to the causes of erosion needs to be made and after that solutions will be proposed. The first step in the research was gathering relevant information. Information on bathymetry, wind, waves etc. was collected. Furthermore the influence of nearby rivers, the neighbouring mangrove coasts and the Coral reefs in the gulf of Batabano has been investigated. With all this data a qualitative analyses was made to identify the probable causes of erosion. The following circumstances were identified as possible causes of erosion: An increase in the frequency and intensity of storms (thus an increase of offshore transport), global sea level rise, a dominant long shore transport and the construction of houses on the dune. All these possible causes have been integrated in a complete erosion theory. The principal idea is that sand from the beach and dune is transported to the foreshore and then moved out of the area by long shore transport. Both long shore and cross-shore transport have been calculated, using the CERC formula and Unibest CL+ for long shore transport and the convolution method and Sbeach in combination with BMAP for cross-shore transport. It appeared to be difficult to combine the results from both gradients in order to simulate the history of erosion. Mainly qualitative insights were gained. The results though do prove that the developed theory is a good description of the history of erosion at Mayabeque Beach. With this theory in mind three concepts are presented for the rehabilitation of the Mayabeque beach. These concepts are: nourishment, nourishment with groins and nourishment with offshore breakwaters. Every concept contains several alternatives. With the help of a Multi Criteria Analysis one alternative from every concept was chosen to be designed. These alternatives are: Beach nourishment, groin field with nourishment and multiple offshore breakwaters in combination with nourishment. After designing these alternatives a multi criteria analysis was performed again and it was found that the groin field with nourishment was the best solution. After an optimization a cost reduction of 30 % was achieved and this alternative ultimately arrived to the following dimensions: The groin field exists of four groins with a distance of 500 m between them and with a length of 133 meters each, with a crest height of 1,5 meter above mean sea level and a crest width of 5,04 meter. Each groin has an armour layer, filter layer and care. At both sides at the toe a filter is placed. The armour layer exist of quarry stone with a Dn50 of 0,63 m, the filter layer of armour stone with a Dn50 of 0,32 m and the core exists of quarry run with a Dn50 of 0,16 m. The filters at the toe are made up of three layers. Each layer has a width of 20 cm. In downward direction these layers have a Dn50 of respectively 108 mm, 18 mm and 3 mm. The slope of the groin is 1:1 and of the head 1:23. The average width of the beach nourishment is 30.2 meter with a total volume of 428800 m3. The construction of the whole alternative will claim about 24 weeks and the costs of this project are calculated at 1.4 million dollar. Due to the groin field with nourishment the beach will be stable and after a storm accretion will return to equilibrium situation. Erosion is present at the down drift side (at the mangroves) of the groin in the west but due to the initial placement of the nourishment in the form of the equilibrium profile the erosion will be less. It is realized this solution still is expensive and that it will take time for Melena del Sur to raise funds. Therefore a cheap initial solution is presented, which can be used to cover the time until sufficient funds for the definitive solution have been found. This cheap initial solution involves a redistribution of the available stones presently situated in seawalls and groins in an orderly sequence of berm breakwaters. Subject erosionbeach erosionMayabequerehabilitationnourishmentbreakwaters To reference this document use: http://resolver.tudelft.nl/uuid:84f36232-2020-41bd-a811-75abf7004200 Coordinates 22.671444, -82.142024 Source Master Project Report Part of collection Student theses Document type student report Rights (c) 2004 Van den Hengel, D.Poot, J.G.Theunissen, R.P.G.J.Kluyver, T.M. Files PDF Project_groep_CF27_-_2004.pdf 77.49 MB Close viewer /islandora/object/uuid:84f36232-2020-41bd-a811-75abf7004200/datastream/OBJ/view