Suprapto Dibyosaputro
Department of Environmental Geography, Faculty of Geography, Universitas Gadjah Mada

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PENGARUH MORFODINAMIKA PANTAI GLAGAH, KABUPATEN KULONPROGO, DAERAH ISTIMEWA YOGYAKARTA TERHADAP KESELAMATAN PENGUNJUNG PANTAI

Jurnal Bumi Indonesia Volume 1, Nomor 3, Tahun 2012
Publisher : Fakultas Geografi UGM

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Abstract

Pantai Glagah terletak di Kec. Temon, Kulonprogo, yang merupakan tujuan wisatautama di Kulonprogo. Daerah penelitian meliputi daratan yang dibatasi pasang tertinggi dansurut terendah. Penelitian ini bertujuan untuk (1)mengetahui arah dan kecepatan pergeseranmorfologi tanjung dan teluk Pantai Glagah pada musim penghujan, (2)menentukan lokasibahaya arus retas berdasarkan pergeseran tersebut.Metode yang digunakan adalah survey dengan mengamati dan mengukurkarakteristik angin, gelombang, dan arus sepanjang pantai, serta mengukur jarak antara garisbasis di darat yang telah ditetapkan dengan garis pantai pada setiap tanggal pengukuran. Datahasil pengukuran dan perhitungan dianalisis secara deskriptif dengan tabel, grafik, dan petamorfodinamika pantai sehingga diketahui jarak pergeseran morfologi tanjung dan telukpantai.Berdasarkan hasil analisis, diketahui bahwa morfologi tanjung dan teluk PantaiGlagah mengalami pergeseran ke arah Timur sejauh 9,83-14,78 meter dalam sebulan. Lokasibahaya arus retas berasosiasi dengan morfologi teluk pantai, sehingga lokasi terjadinya arusretas mengalami pergereran yang serupa.Kata kunci : pergeseran morfologi tanjung dan teluk pantai

TINGKAT KERUSAKAN LAHAN AKIBAT PENAMBANGAN BATUGAMPING DAN PRIORITAS REKLAMASI LAHAN DESA PACAREJO KAB GUNUNGKIDUL DIY

Jurnal Bumi Indonesia Volume 1, Nomor 3, Tahun 2012
Publisher : Fakultas Geografi UGM

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Abstract

Tujuan dari penelitian ini adalah mengkaji pengaruh aktivitas penambangan rakyat terhadap kondisi sosial ekonomi masyarakat di lokasi penambangan, menganalisis tingkat kerusakan lahan akibat penambangan rakyat dan menentukan daerah prioritas reklamasi lahan dan upaya pengendalian lingkungan yang ditimbulkan oleh aktivitas penambangan rakyat Metode yang digunakan dalam penelitian ini adalah survey lapangan dengan pengukuran sampel data dengan teknik purposive sampling. Penilaian atau pengharkatan didasarkan pada skor terendah dan tertinggi untuk menentukan tingkat kerusakan lahan. Untuk mengetahui pengaruh penambangan terhadap sosial ekonomi penambang digunakan quisioner. Prioritas reklamasi lahan didasarkan nilai tingkat kerusakan lahan dan luas area penambangan Hasil penelitian menunjukkan bahwa terdapat 8 lokasi penambangan batugamping di Desa Pacarejo. Hasil pengukuran menunjukkan bahwa tingkat kerusakan lahan di lokasi tambang terdiri atas tingkat kerusakan lahan sedang dan tingkat kerusakan lahan berat.Kata kunci: kerusakan lahan, penambangan, reklamasi lahan

Inventarisasi Data Ungkungan Fisik Daerah Rencana Kawasan Wisata Jimbaran-Kedonganan Bali

Forum Geografi Vol 7, No 1 (1993): July 1993
Publisher : Universitas Muhammadiyah Surakarta

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Abstract

Daerah Jimbaran dan Kedonganan adalah merupakan salah satu daerah yang direncanakan untuk kawasan pariwisata pantai Pulau Bali. Tujuan penelitian ini adalah mengadakan inventarisasi data lingkungan fisik daerah tersebut yang meliputi iklim, geomorfologi, tanah, hidrologi, dan oceanografi. Adapun metode penelitian yang digunakan adalah metode observasi yakni pengamatan, pengukuran dan pencatatan terhadap aspek-aspek tersebut baik langsung di lapangan maupun di laboratorium. Hasil penelitian menunjukan babwa wilayaj Jimbaran dan Kedonganan sebagian besar mempunyai potensi lingkungan fisik yang baik sebagai kawasan wisata pantai. Subu rata-rata adalah 27.05° C dengan subu tertinggi terjadi pada Bulan Oktober yakni 29° C dan suhu terendah pada bulan Agustus yakni 26° C. Hujan rata-rata setahun adalah 1240 mm dengan bulan-bulan basah antara Desember hingga April, sedang bulan-bulan lainnya adalah bulan kering. Secara geomorfologis daerah penelitian merupakan teluk dimana dari tempat ini dapat melihat panorama alam yang indah yakni terbenamnya matahari di waktu sore. Daerah ini juga merupakan bagian Ieher dari suatu tombolo. Sebelah selatan daerah penelitian berbatasan dengan cliff dari batu gamping yang menambah keindahan panorama alami. Kedalaman air tanah bervariasi antara 4-7.65 meter dengan tebal air tanah antara 0.65-1.00 meter. Potensi air tanah sebesar 5.913.600 mm3, dengan pH air di beberapa daerah 7 karena adanya intrusi air taut. Potensi tersebut tidak mencukupi untuk kebutuhan air untuk keperluan hotel-hotel di wilayah ini sebingga harus menambah air dari luar kawasan tersebut. Wilayah teluk Jimbaran-Kedonganan ini mempunyai tinggi gelombang antara 0.25-1.60 meter, frekuensi gelombang antara 10-15 buah gelombang per menit, lebar gisk antara 75-100 meter, dengan kemiringan gisk 5-7. Di dalam teluk Jimbaran Kedonganan ini terdapat adanya teluk dan tanjung yang kecil yang letaknya selalu berpindah-pindah. Hal ini berbahaya bagi perenang di laut karena arus balik kuat (rip cureent) ke arah laut berpindah-pindah tempat pada periode waktu tertentu.

Morphometry Characteristics of Riverbed Sediment Grains as Basic Indicator Management of River Valley Environment (Case Study of Bogowonto River, Central Java)

Forum Geografi Vol 29, No 2 (2015): December 2015
Publisher : Universitas Muhammadiyah Surakarta

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Abstract

This research aims to propose the usage of riverbed sediment grains roundness/flatness as basic indicator of river valley management. It is based on the evaluation of anomalous morphometry condition of sediment grains and valley condition along the river as one indicator of the stability of the riverbank of the river valley. This stability express the physical condition of the river valleys. In this paper, we provide methodological explanation as well as a case study in Bogowonto River. Analysis of the morphometry of sediment grain on riverbed from upstream to downstream as well as the relationship between the distance of the upstream and morphometry of sediment grains along Bogowonto River were conducted. Finally, we evaluated the anomalous condition as indicator of different environmental condition of the riverbank. We conducted three stages survey processes: preparation, fieldwork, and post-fieldwork. The preparation phase includes site selection, depiction of the main river channel of Bogowonto River, and the determination of the sample location. The distance between each sampling site was 5 km along Bogowonto River. The results show that there is anomalous morphometry of sediment grains found in the study area. The reason is that the channel of the segment of the river flowing over rocky riverbed of breccia along the 7.5 km, with hard and sharps edge grained of rock particles. This is accompanied by landslide the occurrence in the upper segment of the river. This is why the value of roundness and flatness indexes are changed significantly become lower value than the previous segment. This condition can be implemented to be used as indicator to basic management of landslide along a certain segment which indicated by the changing in roundness and flatness index values of the sediment grains. 

A concept of Surveying and Mapping Vulnerability and Flood Hazard (with Hydro-Geomorphological Approach)

Forum Geografi Vol 12, No 1 (1998)
Publisher : Forum Geografi

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Abstract

The general event of natural process phenomena on lowland areas is flood as an effect of the overtooping stream water over natural levees and inundate the area of surrounding the river. Most of the lowland surround the rivers is used by man for settlements, agriculture land, high way, and other activities to support their life intensively. Therefore flood is not only the physical phenomena but also a socio – economic phenomena. One of the way to understand the spatial distribution of flood prone areas an be done by means of survey and mapping of the flood susceptibility and hazard using an hydro- geomorphological approach. The fluvial landform units on the lowlands reflect the effet of the geomorphological and hydrological processes in the past. Therefore those phenomena can be applied to explain the recent flood characteristics such as inundation  area, depth and flood duration, as well as flood frequencies and sources of floods. This explanation can be used as the starting point of the existing information which an be used as a basic survey and mapping of the flood suspectibility and hazard. The exiting of the interaction between man and natural event (flood) information, can also be applied as a fundament to define the hazard levels of every landform units own flood susceptibility levels.

Lahar at Kali Konto after the 2014 Eruption of Kelud Volcano, East Java: Impacts and Risk

Forum Geografi Vol 29, No 1 (2015): Forum Geografi
Publisher : Forum Geografi

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Abstract

Five days after the Kelud Volcano eruption of 13 February 2014, lahar occurred in several channels of the Volcano. Rainfall with intensity of 26 mm/hour mobilized pyroclastic material from the upper slopes of Kelud Volcano down the channel during 3.5 hour. Using this eruption as a case study, the aims of this paper are (1) to study the geomorphic impact of lahars and (2) to study future hazards and risks due to the potential of lahar source material and lahar repose area. To reach these two goals, we use both primary and secondary data. The primary data comprises an integration of remote sensing, GIS approach, and fieldwork control, in order to investigate the geomorphic impacts of lahars. Secondary data were collected through interviews and statistical approach in villages, in order to determine their perception to the risk of lahar. Morphogenic processes such as riverbank erosion, channel-widening and riverbed downcutting took an important role in generating the impact of lahar in Kali Konto. The medial and distal areas were affected more largely affected than the proximal area. This major impacts have been river widening and buried crop field inside of the channel. This result allowed us to provide recommendation to population living along those areas at risk, in order to be prepared against the eventuality of potentially large and destructive lahars.

Morphometry Characteristics of Riverbed Sediment Grains as Basic Indicator Management of River Valley Environment (Case Study of Bogowonto River, Central Java)

Forum Geografi Vol 29, No 2 (2015): Forum Geografi
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Original Source | Check in Google Scholar | Full PDF (588.875 KB)

Abstract

This research aims to propose the usage of riverbed sediment grains roundness/flatness as basic indicator of river valley management. It is based on the evaluation of anomalous morphometry condition of sediment grains and valley condition along the river as one indicator of the stability of the riverbank of the river valley. This stability express the physical condition of the river valleys. In this paper, we provide methodological explanation as well as a case study in Bogowonto River. Analysis of the morphometry of sediment grain on riverbed from upstream to downstream as well as the relationship between the distance of the upstream and morphometry of sediment grains along Bogowonto River were conducted. Finally, we evaluated the anomalous condition as indicator of different environmental condition of the riverbank. We conducted three stages survey processes: preparation, fieldwork, and post-fieldwork. The preparation phase includes site selection, depiction of the main river channel of Bogowonto River, and the determination of the sample location. The distance between each sampling site was 5 km along Bogowonto River. The results show that there is anomalous morphometry of sediment grains found in the study area. The reason is that the channel of the segment of the river flowing over rocky riverbed of breccia along the 7.5 km, with hard and sharps edge grained of rock particles. This is accompanied by landslide the occurrence in the upper segment of the river. This is why the value of roundness and flatness indexes are changed significantly become lower value than the previous segment. This condition can be implemented to be used as indicator to basic management of landslide along a certain segment which indicated by the changing in roundness and flatness index values of the sediment grains. 

Landform Control On Settlement Distribution Pattern in Progo Delta, Indonesia

Indonesian Journal of Geography Vol 47, No 2 (2015): Indonesian Journal of Geography
Publisher : Faculty of Geography, Universitas Gadjah Mada

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Abstract

Landform is part of the Earth ‘s surface whose characteristics affect resources and geomorphological hazard, and therefore, affect humans in determining their choices in building settlements. This research aims to : ( 1 ) analyze landforms control on settlement distribution pattern in abandoned Progo Delta, and ( 2 ) analyze the factors that influence humas in choicing their residental locations. Landform control on the settlement distribution was analyzed from produced geomorphological and settlement maps and overlay them. The influence factors were analyzed from the results of in-depth interviews conducted in each village in the study area. The results show that the settlement in the study area is distributed in a dispersed pattern, following the presence of abandoned delta’s natural levees. The influencing factors include flat topography that implies a good accessibility, soil fertility that defines land capability in sustaining their life, water resource availability, and security from disasters especially floods.

LONGSORLAHAN DI DAERAH KECAMATAN SAMIGALUH, KABUPATEN KULON PROGO, DAERAH ISTIMEWA YOGYAKARTA

Majalah Geografi Indonesia Vol 16, No 2 (2002): September 2002
Publisher : Fakultas Geografi, Universitas Gadjah Mada

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Abstract

ABSTRAK Penelitian ini dilakukan di daerah Kecamatan Samigaluh dan sekitarnya, Kabupaten Kulon Progo, Daerah Istimewa Yogyakarta, dengan tujuan untuk mempelajari, mengklasifikasi, dan memetakan daerah penelitin ke dalam peta geomorfologi dan peta unit medan, mempelajari daerah-daerah potensial terjadi longsor lahan dan menyusun peta bahaya longsor lahan, serta mengevaluasi longsor lahan setiap unit medan. Berbagai data yang dikumpulkan meliputi curah hujan, kemiringan lereng, jenis batuan, kedalaman pelapukan batuan, banyaknya dinding terjal, tebal solum tanah, tekstur dan permeabilitas tanah, penggunaan lahan dan kerapatan vegetasi penutup. Metode yang digunakan adalah metode survey dengan teknik pengambilan sampel secara berstrata, dengan unit medan sebagai unit analisisnya. Unit medan diperoleh dengan menumpang-susunkan peta-peta geomorfologi, lereng, dan penggunaan lahan. Penentuan kelas bahaya longsor lahan menggunakan teknik pengharkatan terhadap masing-masing parameter medan, dan kemudian menjumlahkannya untuk masing-masing parameter medan tersebut. Selanjutnya dari jumlah harkat tersebut digunakan sebagai dasar untuk penentuan tingkat bahaya longsorlahan pada setiap unit medan, yang akhirnya disusun peta bahaya longsorlahan. Hasil penelitian menunjukkan bahwa daerah penelitian dapat dikelompokkan ke dalam 32 unit medan. Hasil analisis tingkat bahaya longsorlahan yaitu kelas II (tingkat bahaya rendah) sebanyak 5 unit medan yang didominasi oleh kompleks dataran alluvial dan teras sungai dan perbukitan solusional berbatu gamping koral; kelas III (tingkat bahaya longsorlahan sedang) sebanyak 6 unit medan pada sebagian unit medan kompleks dataran alluvial dan teras sungai dan unit medan dari bentuklahan perbukitan solusional berbatugamping. Kelas IV (tingkat bahaya longsorlahan tinggi) terdiri dari 14 unit medan pada pegunungan denudasional dan berbatuan breksi dan perbukitan denudasional berbatuan tuff. Tingkat bahaya longsorlahan sangat tinggi (Kelas V) sejumlah 5 unit medan yaitu pada pegunungan denudasional berbatuan breksi, dan perbukiyan denudasional berbatuan tuff. Unit-unit medan yang mempunyai klas bahaya longsorlahan tinggi (Kelas IV) dan sangat tinggi (Kelas V) terjadi pada unit medan dengan kemiringan lereng (8-25%), terjal (20-40%) dan sangat terjal (<40%), kedalaman pelapukan batuan/tanah dalam hingga sangat dalam (>100cm). Penggunaan lahan tegalan, kebun campuran, dan permukiman, serta sebagian kecil sawah yang pengolahannya dilakukan dengan cara penterasan.

Dampak Perubahan Penggunaan Lahan terhadap Perubahan Runoff di Daerah Aliran Sungai (DAS) Bedog Yogyakarta

Majalah Geografi Indonesia Vol 27, No 2 (2013): September 2013
Publisher : Fakultas Geografi, Universitas Gadjah Mada

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Abstract

ABSTRAK DAS Bedog merupakan salah satu DAS di Yogyakarta yang daerah aliran sungainya mengalami proses pengembangan wilayah perkotaan. Proses perkembangan wilayah perkotaan di DAS Bedog ini terjadi dalam kurun waktu 10 tahun terakhir. Parameter dari adanya proses pengembangan wilayah perkotaan di DAS Bedog adalah terjadinya peningkatan peningkatan tipe penggunaan lahan “permukiman”, yang semula sebesar 15,29% di tahun 2004 menjadi 16,94% tahun 2008 dan 17,72% pada tahun 2010 atau meningkat sebesar 0,4% per tahun.Tujuan utama dari penelitian ini adalah menganalisis dampak perubahan penggunaan lahan terhadap perubahan runoff dan merumuskan simulasi/skenario penggunaan lahan dalam menurunkan runoff di DAS Bedog menggunakan metode Curve Number-USSCS (CN-USSCS). Berdasarkan perhitungan metode CN-USSCS pada tahun 2004, 2008 dan 2010, akibat dampak dari perubahan penggunaan lahan menghasilkan ketebalan runoff sebesar 1.353,0 mm (66% dari jumlah hujan/tahun), 1.277,2 mm (55,5% dari jumlah hujan/tahun), dan 1.536,4 mm (57,6% dari jumlah hujan/tahun). Penggunaan lahan “permukiman” dan “lahan kosong” berkontribusi terbesar dalam peningkatan ketebalan runoff di DAS Bedog, dikarenakan memiliki nilai CN yang tinggi dan berarea luas.Validasi terhadap metode CN-USSCS menggunakan uji statistik, T-test dihasilkan nilai T-test sebesar 0,00 dan 0,092 dibawah nilai T-tabel sebesar 1,67 dan 1,71 serta nilai koefisien determinasi (R2) diatas 0,5 yang berarti metode CN-USSCS dapat diterapkan di DAS Bedog untuk memprediksi ketebalan runoff.Hasil rumusan skenario perubahan penggunaan lahan di DAS Bedog bahwa perubahan penggunaan lahan untuk 6 tahun ke depan (tahun 2016) mengalami perubahan ketebalan runoff sebesar 4% dari tahun 2010 (skenario 1). Penurunan ketebalan runoff di DAS Bedog dapat dilakukan dengan peningkatan luasan hutan berupa kebun campuran dan tumbuhan perdu (semak belukar) di daerah Bantul sebesar > 50% dari luas DAS Bedog (skenario 4). ABSTRACT Bedog watershed is one of the watersheds in the area of Yogyakarta through the process of urban development. The process of urban development in the Bedog watershed this happened in the past 10 years. The parameters of the process of urban development in the Bedog watershed is the increase in land use "settlement" from 15,29% (2004) to  16,94% (2008) and 17,72% in 2010 or an increase of 0.4% per year.The main objective of this research is is to analyze the impact of land use change on runoff and formulate of the simulation / scenarios of land use in reducing runoff in the Bedog watershed using the Curve Number -USSCS (CN-USSCS). Based on the calculation of CN-USSCS in 2004, 2008 and 2010, due to the impact of changes in land use resulted runoff of 1353.0 mm (66% of the amount of rain / year), 1277.2 mm (55.5% of the amount of rain / year), and 1536, 4 mm (57.6% of the amount of rain / year). Settlement and Bareland contributed to the greatest increase in runoff in the Bedog watershed, due to having a high value of CN and has a large area.Validation of the methods of CN-USSCS using statistical test, T-test produced values of 0.00 and 0.092 below the T-table values of 1.67 and 1.71, and the coefficient of determination (R2) above 0.5, which means CN-USSCS method can be applied in the Bedog watershed to predict the runoff.The results of the formulation of land use change scenarios in Bedog watershed that the change in land use for the next 6 years ( 2016) to change the runoff by 4% from the 2010 (scenario 1). Decrease runoff in the Bedog watershed to do with the increase in forest area in the form of mixed garden and herba plants (shrubs) in Bantul for >50% of the total Bedog watershed (scenario 4).