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"ABSTRAKTanah longsor sebagai gejala alam merupakan salah satu penyebab yang bisa merusak hutan lindung pada kawasan Taman Nasional gunung Gede-Pangrango (Tamnas GEPANG).Sehingga sangat relevan, suatu penelitian untuk menentukan teknik mengidentifikasi lokasi tanah longsor potensial, agar bisa diambil sikap yang tepat.Tanah longsor berkait erat dengan stabilitas lingkungan alami. Stabilitas lingkungan alami terpengaruh oleh beberapa aspek gejala atau fenomena alami. Maka untuk mengidentifikasi potensi lokasi tanah longsor, perlu diungkap lebih dahulu gejala-gejala alami yang mempengaruhi stabilitas lingkungan.Untuk itu dikembangkan konsep Potensi Kerapuhan Lingkungan Alami (PKLA), yaitu himpunan dalam kesatuan ruang dari kekuatan, sifat, dan keadaan gejala alam yang secara potensial mempunyai daya merusak terhadap lingkungan hidup.Ada empat variabel yang secara potensial mempengaruhi stabilitas lingkungan, yaitu keterjalan lereng (XI), intensitas hujan (X2), tekstur tanah (X3), dan tutupan vegetasi (X4).Da1am rangka menelaah bahwa PKLA merupakan indikator lokasi tanah longsor potensial, dilakukan dengan pendekatan ilmu lingkungan. Pendekatan yang dikembangkan dari kombinasi pendekatan ekologi dengan pendekatan geografi ini, bertumpu pada prinsip interdisiplin, prinsip spatial, serta prinsip orientasi kedepan.Prinsip interdisiplin mengakomodasikan konsep-konsep yang ada pada geografi fisik, geologi, geomorfologi, ilmu tanah, ekologi, dan klimatologi.Prinsip spatial atau prinsip ruang menghendaki digunakannya peta sebagai alat analisis.Prinsip orientasi kedepan menghendaki dilakukannya peramalan wilayah (regional forecasting).Nilai PKLA (pkla) atau nilai kumulatifnya dihitung dengan menggunakan teori himpunan (set theory), yang aplikasinya menggunakan diagram Venn. Dengan teknik tumpang tindih {super impose), nilai-nilai PKLA (pkla) secara hierarkis dikembangkan dari PKLA (pkla) berdimensi satu, menjadi PKLA (pkla) berdimensi dua, lalu meningkat menjadi PKLA (pkla) berdimensi tiga, dan terakhir menjadi PKLA (pkla) berdimensi empat. Dari proses ini akan diperoleh jumlah konstribusi PKLA (pkla) elemen dari masing-masing dimensi terhadap pembentukan PKLA universe. Di samping itu dapat pula dihitung bobot konstribusi relatif pkla masing-masing himpunan bagian (sub-das). Ternyata hanya sub-das yang mempunyai bobot konstribusi surplus yang mempunyai potensi tanah longsor.Tanmnas GEPANG yang terbentuk oleh 40 sub-das, ternyata 26 sub-das diantaranya, mempunyai potensi tanah longsor; sepuluh sub-das mempunyai potensi tanah longsor tinggi, dua belas sub-das nempunyai potensi tanah longsor menengah, empat sub-das mempunyai potensi tanah longsor rendah.Potensi tanah longsor bisa menjadi faktual atau menjadi kenyataan bila rezim hujan menunjukkan sifatnya yang ekstrim. Ini bisa terjadi pada bulan-bulan Desember atau Januari yaitu pada saat terjadi hujan maksimum. Dan lebih besar kemungkinannya untuk terjadi pada bulan-bulan Maret atau April yaitu pada saat hujan maksimum sekunder.Namun ada fakta lingkungan yang menarik, yaitu pada tempat-tempat di mana hujan menunjukkan peranan kuat untuk menjadikan massa tanah tidak stabil yang di satu pihak memungkinkan terjadinya longsoran,maka peranan tutupan vegetasi di tempat itu dalam menjaga kestabilan massa tanah, yang di pihak lain mencegah terjadinya longsoran juga kuat.Ini menunjukkan bahwa lingkungan alami pada hakekatnya selalu menjaga keseimbanganya sendiri.Dalam hal ini sikap mendasar yang perlu diambil adalah minimal menjaga keseimbangan yang ada.Namun lebih bijaksana bila keseirrbangan itu diubah dengan kecenderungan peranan tutupan vegetasi sebagai faktor yang menjaga kestabilan massa tanah diperkuat fungsinya. Ini berarti bahwa. wi.layah hutan lindung perlu diperluas, terutama pada sub-das - sub-das yang mempunyai potensi tanah longsor tinggi.

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ABSTRACT

Potential Natural Environment Fragility As An Indicator For Potential Landslide Location:The case of Mount Gede-Pangrango National ParkAs a natural phenomenon, landslide is one of the causes which is capable of damaging the protected forest in the area of Mount Gede-Pangrango National Park {Tamnas GEPANG). It is so relevant that a research should be conducted for discover a technique of identifying the potential landslide location in order to be to take correct measures.

Landslide is closely related to natural environment stability. Several indicative aspects or natural phenomena influence the natural environment stability. Therefore, in order to identify potential landslide location, it is necessary to reveal the national-phenomena, which influence the environment stability.

Therefore, a concept of Potential Natural Environment Fragility - (PNEF), whish is a system of power, character, and a state of natural phenomena having potentially damaging force against environment, is developed.

There are four variables viz.; slope steepness (X1), rainfall intensity (X2), soil texture (X3), and vegetation covering (X4).

In analyzing that PNEF is used as an indicator for potential landslide location, an approach using environmental science is conducted. The approach, which is developed from ecological a geography cal approach, is based-on interdisciplinary principles, spatial principle, and future-oriented principle.

The interdisciplinary principle constitutes concepts prevailing in physical geography, geology, geomorphology, pedology, ecology and climatology.

The spatial principle needs the use of maps as means of analysis. The future-oriented principle calls for regional forecasting complementation.

M EE' value or its cumulative value is calculated by using a set theory whose application uses Venn's Diagram- By employing superimpose technique, the PNEF values are hierarchically developed from PNEF of one dimension to PNEF of two dimension, then increased to PNEF of three dimension, and finally to PNEF of four dimension.

From this process, total contribution of elemental PNEF from respective dimension to the formation of universal PNE will be obtained. Apart from that, the relative contribution quality of PNEF from each sub catchments area can be calculated. It appears that only sub-catchments area having the surplus contribution quality- has landslide potential.

GEPANG National Park comprising 40-sub catchments area, 26 out of with have landslide potential. The have high landslide potential; the other twelve have medium, and the other four low landslide potential.

The landslide potential may turn into reality when rainfall shows its extreme characteristics. Under the circumstances it can hap pen in the month of December or January when the rainfall reaches its peak. And more likely, it can take place in the month of March or April at the time when the rainfall is at its secondary maxi nun.

Nevertheless, there is an-interesting environmental feature, that at places where on the hand rainfall plays an important role in forming unstable mass of land, landslide is likely occur, but on the other hand the vegetation covering at the identical places keeps the stability of the mass of land and thus prevents landslide-probability.

This shows that natural environment, properly speaking, always keeps its own equilibrium.

For this reason, a fundamental attitude towards this particular case necessarily to be taken is at least to keep the existing equilibrium.

However, it will be recommendable if the equilibrium is altered to an inclination that the role of vegetation covering as a functional factor which preserves-the land mass stability is stimulated.

Consequently, it means that protected forest areas should be enlarged, especially in the catchments areas which have high landslide potential."

"Penggunaan lahan pada suatu daerah tangkapan air (DTA) memiliki pengaruh terhadap kualitas suatu perairan. Sumber air dari suatu perairan dapat berasal dari mata air yang terdapat di dalamnya dan dari masukan air sungai atau limpasan air permukaan serta air hujan yang mengalir di lahan sekitar perairan tersebut. Daerah tangkapan air adalah suatu daerah yang mengalirkan air ke Situ Gintung. Masyarakat yang tinggal di sekitar Situ Gintung memanfaatkannya untuk perikanan, pertanian dan sarana wisata. Dalam jangka waktu 20 tahun, yaitu tahun 1999, 2004, 2009, 2014, 2019, Situ Gintung mengalami perubahan kualitas perairan secara fisik dapat diketahui melalui kandungan materi yang mengubah warna air tersebut. Perubahan tersebut salah satunya dipengaruhi oleh erosi dan sedimentasi. Untuk mengetahui besarnya laju erosi pada suatu lahan digunakan pemodelan USLE (Universal Soil Loss Equation). Hasil penelitian menunjukkan terdapat empat tingkat erosi di DTA Situ Gintung, yaitu normal, ringan, sedang, berat. Sebaran erosi yang terjadi di DTA Situ Gintung mengikuti pola lereng. Laju erosi normal terbesar sebesar 178,13 ton/ha/tahun pada tahun 2019 dan terkecil sebesar 58,43 ton/ha/tahun pada tahun 2014. Tingkat erosi ringan terbesar sebesar 1410,63 ton/ha/tahun pada tahun 2019 dan terkecil sebesar 706,13 ton/ha/tahun pada tahun 2014. Tingkat erosi sedang tertinggi adalah 2.831,84 ton/ha /tahun pada tahun 2009 dan yang terkecil sebesar 1710,71 ton/ha/tahun pada tahun 2014. Laju erosi berat terbesar adalah 4782,74 ton/ha/tahun pada tahun 2009 dan terkecil adalah 2.312,31 ton/ha/tahun pada tahun 2019.

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Changes in land use in a sub-watershed have an effect on the quality of a waters. Sources of water from a waters can come from springs contained in it and from river water input or runoff surface water and rain water that flows in the land around these waters. Pesanggrahan Sub-watershed is a sub-watershed that flows water to Situ Gintung. People who live around Situ Gintung use it for fisheries, agriculture and tourist facilities. Within a period of 20 years, namely 1999, 2004, 2009, 2014, 2019, Situ Gintung experienced a change in the quality of the physical waters, namely changes in the number of suspended solids entering the waters. The amount of the TSS value in a waters is influenced by soil material which is eroded by water passing through a land area. To determine the amount of the erosion rate on a land, USLE (Universal Soil Loss Equation) modeling is used. The results showed that changes in the land cover of the Situ Gintung catchment had an effect which was directly proportional to the rate of erosion in the Situ Gintung catchment area. The distribution of erosion that occurs in the Situ Gintung catchment follows the slope pattern. The largest normal erosion rate was 178,13 ton/ha/year in 2019 and the smallest was 58,43 ton/ha/year in 2014. The largest light erosion rate was 1410,63 ton/ha/year in 2019 and the smallest was 706,13 ton/ha/year in 2014. The highest moderate erosion rate was 2.831,84 tonnes / ha / year in 2009 and the smallest was 1710,71 ton/ha/year in 2014. The highest rate of heavy erosion was 4782,74 ton/ha/year in 2009 and the smallest was 2.312,31 ton/ha/year in 2019"

"[ ABSTRAK Sedimentasi saat ini merupakan dampak dari permasalahan lingkungan yangdapat menyebabkan kerugian pada ekosistem, perikanan, dan saluran irigasi yangbiasa sering ditemui pada daerah agrikultur atau perkotaan. Sedimentasi dapat terjadisecara alamiah ataupun terjadi karena ulah manusia. Secara global, dilaporkan setiaptahun,jumlah volume permukaan tanah yang ter-erosi mencapai angka 60 milyarton,24 milyar ton diantaranya ditemukan di muara laut dan tercatat hamper 25 milyarton sedimentasi berasal dari daerah agrikultur. Melalui skripsi ini, penulis mencobamencari nilai sediment delivery ratio (SDR), yaitu perbandingan antara erosi yangterjadi dengan nilai potensialnya menggunakan metode Universal Soil Loss Equation(USLE). Pada skripsi ini, daerah yang menjadi fokus penelitian adalah daerah JatiKramat, yang merupakan daerah aliran sungai yang bisa menimbulkan masalahsedimentasi.

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ABSTRACT Sedimentation nowadays becomes an environment impact that harming the

ecosystem, fisheries, or irrigation that can be found in the agricultural land or urban

land use. The sedimentation can happened by the natural process and can be

accelerated by the human activities. From the global point of view, it is reported that

each year, erosion of surface soil from river basins amounts to 60 billion tons,

resulting in 24 billion tons of sediment flux to the oceans in the world and almost 25

billion tons of soil lost from agricultural land. Through this thesis, author try to find

the sediment delivery ratio (SDR) with comparing the sediment yield and erosion

potential estimated using Universal Soil Loss Equation (USLE) method. The focused

objected study area in this thesis is Jati Kramat watershed, which believes this

watershed has a settle water infrastructure that able to transport sediment due to

erosion potential.;Sedimentation nowadays becomes an environment impact that harming the

ecosystem, fisheries, or irrigation that can be found in the agricultural land or urban

land use. The sedimentation can happened by the natural process and can be

accelerated by the human activities. From the global point of view, it is reported that

each year, erosion of surface soil from river basins amounts to 60 billion tons,

resulting in 24 billion tons of sediment flux to the oceans in the world and almost 25

billion tons of soil lost from agricultural land. Through this thesis, author try to find

the sediment delivery ratio (SDR) with comparing the sediment yield and erosion

potential estimated using Universal Soil Loss Equation (USLE) method. The focused

objected study area in this thesis is Jati Kramat watershed, which believes this

watershed has a settle water infrastructure that able to transport sediment due to

erosion potential.;Sedimentation nowadays becomes an environment impact that harming the

ecosystem, fisheries, or irrigation that can be found in the agricultural land or urban

land use. The sedimentation can happened by the natural process and can be

accelerated by the human activities. From the global point of view, it is reported that

each year, erosion of surface soil from river basins amounts to 60 billion tons,

resulting in 24 billion tons of sediment flux to the oceans in the world and almost 25

billion tons of soil lost from agricultural land. Through this thesis, author try to find

the sediment delivery ratio (SDR) with comparing the sediment yield and erosion

potential estimated using Universal Soil Loss Equation (USLE) method. The focused

objected study area in this thesis is Jati Kramat watershed, which believes this

watershed has a settle water infrastructure that able to transport sediment due to

erosion potential., Sedimentation nowadays becomes an environment impact that harming the

ecosystem, fisheries, or irrigation that can be found in the agricultural land or urban

land use. The sedimentation can happened by the natural process and can be

accelerated by the human activities. From the global point of view, it is reported that

each year, erosion of surface soil from river basins amounts to 60 billion tons,

resulting in 24 billion tons of sediment flux to the oceans in the world and almost 25

billion tons of soil lost from agricultural land. Through this thesis, author try to find

the sediment delivery ratio (SDR) with comparing the sediment yield and erosion

potential estimated using Universal Soil Loss Equation (USLE) method. The focused

objected study area in this thesis is Jati Kramat watershed, which believes this

watershed has a settle water infrastructure that able to transport sediment due to

erosion potential.]"