SUMBER SEDIMEN DAN PERKEMBANGAN SEDIMENTASI RECENT DI PERAIRAN PANTAI SEMAT, JEPARA

Abstract

The aim of the research was to identify the composition and source of base sediment in waters of Semat coast, and also to predict the development of sedimentation process. Field survey method was used in order to identify sediment distribution. To predict the sedimentation development was used granulometri and fades analized. The result showed that litogenic sediment in the research area was about 20 % - 71 %, carbonate material was about 19 % - 76 %, and organic material was about 2 % - 5 %. Such a thing indicated that onland process was the dominant material supply for sedimenation process at the seashore. In general the course sand was distributed at near coastline and become fine in offshore direction. At the near mangrove, the sediment consisted of fine grain material. This condition was easy to understand because the mangrove can reduce wave attack, and also as source of organic material. The source of carbonate material was predicted come from corals debris in surounding area. The result also showed that in Semat coast have been occurred accretion process. The data indicated that the process will be continue, especially in around of the Bunder River estuary. Penelitian ini bertujuan untuk mengetahui komposisi penyusun dan sumber sedimen material dasar di perairan Pantai Swat, sekaligus memprediksi perkembangan proses sedimentasi yang terjadi. Metode survey lapangan digunakan dalam menentukan distribusi sedimen. Sedangkan perkiraam perkembangan sedimentasi digunakan metode analisa granulometri dan analisa fasies sedimenter. Basil penelitian menunjukan bahwa sedimen lithogenik di daerah ini berkisar antara 20 % - 71 %, material karbonat 19 % - 76 % dan matrerial organik 2 % - 5 %. Hal ini menindikasikan bahwa proses onland sangat dominan dalam suplai material bagi proses sedimentasi di tepi pantai. Secara mama material berukuran pasir terdistribusi di dekat garis pantai, dan semakin jauh ke arah laut ukuran sedimen semakin halus. Pada daerah dekat mangrove hampir seinua sedimen berukurtan halus. Hal ini mudah dipahami karena keberadaan mangrove dapat berperan dalam memperkeeil energi gelombang, disamping juga sebagai sumber sedimen organik. Material karbonat yang ditemukan diduga kerns sebagai basil hancuran koral di daerah sekitamya. Basil penelitian juga menunjukan bahwa telah terjadi proses akresi di daerah penelitian. Data yang ads mengindikasikan bahwa proses sedimentasi masih terus akan bcrlangsung terutama di sekitar muara Sungai Bundm.