The Influence of Sedimentation to The Morfology Change of Serang River Estuary at The National Strategic Area Yogyakarta International Airport (Ksn Yia)

Abstrak. Bandara Internasional Yogyakarta terletak di Kawasan Strategis Nasional, Kabupaten Kulon Progo. Daerah ini secara geologis merupakan daerah dataran rendah yang diapit oleh Sungai Bogowonto dan Sungai Serang yang menyebabkan banjir tahunan pada musim hujan. Sistem pengendalian banjir dikembangkan untuk menjaga kinerja bandara. Penetapan Kawasan Strategis Nasional juga menyebabkan perubahan tata guna lahan di sekitarnya yang dapat mempengaruhi perubahan morfologi sungai. Perubahan morfologi di kedua sungai tersebut telah diidentifikasi berdasarkan pengamatan di lapangan. Berdasarkan pengamatan tersebut dapat diketahui bahwa peningkatan laju sedimentasi merupakan parameter terpenting yang dapat mengubah morfologi kedua sungai tersebut. Pengaruh perubahan morfologi di muara sungai Serang telah dipelajari dengan menggunakan software DELFT3D, sedimentasi di muara sungai Serang telah disimulasikan dengan beberapa skenario antara lain pada saat monsun barat dan monsun timur. Hasil pemodelan menunjukkan bahwa tebal sedimentasi di muara Serang pada kondisi eksisting adalah 3,5 m pada musim barat dengan luas 0,063 ha dan 4,0 m pada musim timur dengan luas 0,437 ha. Kata-kata Kunci: Morfologi, muara, Delft3D Abstract. The Yogyakarta International Airport has located in the National Strategic Area, Kulon Progo regency. This area is geologically a low-lying area flanked by the Bogowonto River and the Serang River which causes annual flooding in the rainy season. A flood control system was developed to maintain airport performance. The determination of the National Strategic Area has also led to changes in the surrounding land use which can affect changes in the morphology of the rivers. The morphological changes in the two rivers have been identified based on field observations. Based on this observation, it can be seen that the increase in sedimentation rate is the most important parameter that can change the morphology of the two rivers. The effect of morphological changes in the Serang river estuary has been studied using DELFT3D software, the sedimentation in the Serang river estuary has been simulated with several scenarios, including during the west monsoon and east monsoon. The modeling results show that the sedimentation thickness in the Serang estuary under existing conditions is 3.5 m in the west season with an area of ​​0.063 ha and 4.0 m in the east monsoon with an area of ​​0.437 ha. Keywords: Morphology, estuary, Delft3D