RBI maps Pangandaran area (Bakosurtanal sheet 1308-232)
Land use of Pangandaran and surrounding area is divided into several types of utilization such as settlement area, garden area and rice field, forest area, coastal area, and conservation area. The settlements area (in the figure marked by pink) are mostly scattered near the beaches in the southern part of the research area because the beaches in the study area are a developing tourism area. Besides near the beach, there are also some scattered settlements in the north to northeast which is a hilly area that is covered by a lot of vegetation (in the figure marked by green). In the north-northwest part of the research area which is a hilly area widely used for irrigated rice fields, fields, or plantation areas (in the figure marked by yellow). Coastal areas located in the southern part of the study area where much exploited as tourist area, ports citizens and fishponds. In the southern part (headland) is a research area and there is a conservation area or a nature reserve that is protected forest and has steep cliffs.
The potential of disaster in the Pangandaran area are Tsunami, Earthquake, Flood, and Landslide.
Based on the research, Potential tsunami Pangandaran on the highest position compared to tsunami potential in other coastal areas in West Java. Based on the history of the largest tsunami disaster that ever occurred in the area of Pangandaran occurred on July 16th, 2006. Disaster that happened at the time it can not be predicted accurately if seen the history and study of experts. But in geology there is the term paleotsunami. Paleotsunami is an ancient tsunami or tsunami that occurred in old time. Paleotsunami research is a study to find out tsunami that have occurred in the past based on geological evidence. The evidence is generally in the form of tsunami sand deposits.
The tsunami sand deposits have distinctive features that can be distinguished from other sand deposits. These deposits are often found to cover the old soil layer. Generally, the tsunami sand deposits show the appearance of the structure of grain size fining upward gradually. In one tsunami deposit, this structure can be seen more than one. This structure is a clue to many waves that struck when the tsunami occurred.
The results of paleotsunami research can also be used as a reference in the preparation of spatial coastal areas that observe the potential of tsunami disaster. This is done by understanding the distribution of ancient tsunami deposits. Generally, pangandaran beach prone to tsunami disaster. This is happen because the two regions are both in earthquake prone zones as a result of subduction between the Indo-Australian ocean plate and the Eurasian continental plate. The interaction of the two plates continues from the first to the present and in the future. Thus, earthquakes can still occur again at any time, as well as tsunami.
The first deposition which is located at a depth of 10-20 cm from the surface was predicted to be a tsunami deposit on 1921. The thickness of this deposit reaches up to 4 cm. For comparison on July 2006, the thickness sand deposit of tsunami in the Pangandaran area reaches up to 11 cm. Besides its thickness, the tsunami deposit are very similar to the tsunami sediment in July 2006 that consists of only one layer of black sand. This sand resembles the sand beaches in the area Pangandaran. The grain size of the sand is well sorted from bottom to top and contains quartz, iron ore, and sand-shell fragments. This layer can not be found in every possible place because some has been lost eroded erosion after precipitation.
The second tsunami sediment layer is at a depth of 2 m below the surface. The thickness of this layer reaches up to 15 cm, black slightly brown color. In the sand contains soil chunks. These chunks are probably the result of scouring by tsunami waves which are then deposited with the sand they carry. This layer although quite thick, but looks not continuous. What is interesting about this second layer of tsunami sediment is that it is flanked by layers of green clay deposits at the bottom and a layer of brown clay on the top. The boundary of the tsunami sediment layer with both layers of clay is very firm. The green clay at the bottom may be deposited in the lagoon environment, while the brown clay on top of it containing a little sand may be deposited on land.
The environmental change from pre-tsunami lagoons to land after tsunami sand was deposited indicates that the earthquake that occurred at the time besides generated tsunami waves, was also accompanied by lifting of land. This indicates that the earthquake that occurred at that time is likely to be a powerful earthquake.
Tsunami hazard risk map of Pangandaran area
Flood in Pangandaran making activities and partly paralyzed residents to evacuate. Floods occurred in Pangandaran itself largely caused by:
- Natural events such as rainfall over long periods.
- Bad handling of garbage, until then the source of drains clogged.
- In the area very less water infiltration. So facilitate flood disaster happen.
- Conditions of land covered with cement, paving or asphalt, so that can’t be infiltrate water.
- Construction of settlements where vacant land is converted into street of building, parking area, so there’s no infiltration of rain water.
- Flash floods
The following are some of Pangandaran areas that are flooded disaster:
- Bojongtempel, Babakan Village
This area is flood subscription, if the flood is large enough then the people be ordered to evacuate to a highest area, many people who fled to friends or siblings who are not affected by floods, floods in this area often reaches to the adult chest even in the north more deeply . One of the people said the water rises even though the rain has stopped, this is probably the water from the mountainous areas in the northern part of Pangandaran.
- Bojongjati, Pananjung Village
No different with the Babakan Village that is close to the flow of cikidang river make the most of Bojongjati areas flooded.
Wilayah ini biasanya tergenang diseluruh bagian jika dilanda hujan, sebuah wilayah kecil ditengah persawahan desa pananjung dan purbahayu yang dihuni puluhan kepala keluarga ini dipastikan tergenang, bahkan jalan yang menghubungkan wilayah pananjung dengan purbahayu lumpuh.
The area is usually flooded in all part if rain, a small area in the middle of paddy field in Pananjung and Purbahayu village which is occupied by dozens head of family is sure to be flooded, even the roads that connect region with Pananjung with Purbahayu paralyzed.
- Cijoho a, Parigi District
Cijoho was once flash floods causing paralysis of the main route Parigi-Cigugur, people who will going to Cigugur must take an alternative route via Cintaratu to then exit in Cibenda if going to Pangandaran or otherwise. Until this news was sent no casualties fell, although there is one house that almost eroded the flow of water but the residents of the house has been successfully evacuated.
The front area of the Kalipucang market that has become a subscription to floods, heavy rains and overflowing river citanduy make this area continues to be flooded when the rainy season comes.
In addition to floods, landslide disaster is also common in Pangandaran area. Areas that have occurred landslides are: Langkaplancar District, Padaherang District, and Cijulang District. The average occurrence of this landslide is caused by the occurrence of soil erosion to leave only rocks, and no infiltration water when rainy in area.