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"ABSTRAKIsu terbesar di abad ini adalah tentang berubahan iklim dan pemanasanglobal. Efek dari perubahan iklim adalah perubahan dari musim yangbiasanya menjadi tidak terprediksi dengan baik di dunia, diamana biasterjadi kondisi ekstrim seperti hujan yang sangat lebat maupun kekeringanyang panjang, kondisi ini sangat berpengaruh terhadap muka air tanah.Untuk mendapatkan dan mngetahui secara baik fase secara fisika dari nilaikohesi dari tanah dan kestabilan terhadap lereng akibat dari infiltrasi airdan naiknya muka air tanah maka dibuatlah model untuk mendapatkannilai kemanan berdasarkan variasi nilai kohesi dan kemiringanmenggunakan model numeric Flac 3D. Dan hasil digambarkan dalamfariasi angka keamaan berdasarkan total kohesi dan variasi kemiringandalam kondisi tidak jenuh.

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Abstract Recently, one of the biggest challenges in this century is climate change andglobal warming. The climate change effect has changed that condition fromthe regular season to be unpredictable season on the word, where the moreextreme conditions such as heavy rain falls and droughts. So To find outand well understanding the physical phases of value of cohesion of soil andslope stability due to water infiltration and rising water table we make theseveral models to fine FoS due to variation of cohesion and variation ofinclination by using software Flac3d. And the result illustrated some ofFoS in variation of total cohesion and variation of inclination angle forunsaturated condition."

"Air tanah merupakan sumber daya yang sangat penting. Pengukuran dan analisis mengenai kedalaman air tanah diperlukan untuk mengetahui ketersediaan air tanah di suatu daerah. Penelitian ini membahas mengenai fluktuasi permukaan air tanah tahun 2013-2014 dan perubahan fluktuasi permukaan air tanah tahun 1991-1992 sampai 2013-2014 di Daerah Aliran Ci Leungsi Hulu, Jawa Barat. Data fluktuasi diperoleh dari pengukuran langsung di lapangan. Data fluktuasi tersebut kemudian dikaitkan dengan curah hujan, ketinggian, lereng, jenis batuan, dan penggunaan tanah. Hasil analisis menunjukkan bahwa fluktuasi permukaan air tanah tahun 2013-2014 secara temporal memiliki hubungan yang kuat dengan curah hujan dan secara spasial dipengaruhi oleh ketinggian, lereng, karakteristik batuan, dan penggunaan tanah. Disamping itu, hasil analisis menunjukkan bahwa selama tahun 1991-1992 sampai 2013-2014 telah terjadi perubahan fluktuasi permukaan air tanah sebesar 0,82 m dimana perubahan itu disebabkan oleh penambahan persentase pemukiman.

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Groundwater is an important resource. Measurement and analysis of water table is required to determine the availability of groundwater. This study discusses about water table fluctuation in 2013-2014 and the changes of water table fluctuation in 1991-1992 until 2013-2014 in upstream area of Ci Leungsi Watershed, West Java. Water table fluctuation data used comes from the field survey. Water table fluctuation data that correlates with rainfall, altitude, slope, characteristic of rock, and landuse. From analysis result showed that the water table fluctuation in 2013-2014 have a strong relationship with rainfall, temporally and spatially influenced by the altitude, slope, characteristic of rock, and landuse. Besides that, from analysis result showed that in 1991-1992 until 2013-2014 have occurred changes water table fluctuation by 0,82 meter where that change was caused by addition of a percentage of settlements."

"This book provides experiences from studies on agricultural water management under climate change as references for agriculture and irrigation planners, decision makers, researchers and students. Chapters 2 and 3 provide an overview of global assessment of climate change impacts and water requirement for future agriculture. Chapters 4-7 provide analyses of crop water requirements in four case studies in developing countries. Chapters 8 and 9 are studies of irrigation management under sea-level rise in Vietnam's Mekong Delta. Chapters 10-12 discuss examples of adaptation alternatives such as water-saving techniques and groundwater exploitation, and related policy settings. The last chapter links the dominant approach of uncertainty presented in the climate change discourse with policy discussions on climate adaptation strategies."

"This study presents a unique way to utilize the existing literature to explain the success of treaties in managing hydrologic stress. Literature-derived core concepts are summarized as seven treaty mechanisms categories (specificity, uncertainty management, enforcement, communications, flexibility, integrativeness, and scale) and are hypothesized as important for shaping the institutional resiliency of a treaty. Treaty design is shown to have a relevant and important role in shaping basin management so that nations may better achieve their goals in a changing climate."

"[The book explores the geo-chemical, physical, social and economic impacts of climate change on water supplies. It contains examples and case studies from a wide range of countries, and addresses the need to promote sustainable water use across the world., The book explores the geo-chemical, physical, social and economic impacts of climate change on water supplies. It contains examples and case studies from a wide range of countries, and addresses the need to promote sustainable water use across the world.]"

"Penelitian sebelumnya telah menunjukkan bahwa curah hujan dan gempa bumi adalah dua mekanisme utama yang memicu tanah longsor (Keefer, 1984; Schuster et al, 1996;. Crosta, 2004). Untuk tanah longsor disebabkan gempa, banyak telah dilakukan penelitian mendalam tentang identifikasi dan deskripsi tanah longsor coseismal, terutama yang disebabkan oleh gempa bumi bencana ( Keefer, 1984; Harpa et al, 1991;. Jibson et al, 1994;. Harpa dan Jibson, 1996; Khazai dan Sitar, 2004). Pada Rabu,September 30, 2009, jam 5:16, sebuah gempa 7,6 Mw melanda pantai barat Sumatera, yang menyebabkan tanah longsor bidang di tiga desa di Kanagarian Tandikat dan menelan korban jiwa 360 orang. Penelitian ini mengkaji metode perkiraan untuk menentukan pengaruh infiltrasi pada stabilitas lereng dari dua lapisan dan akibat gempa. Ada dua pendekatan: 1.Analisa matematika dengan kondisi jenuh menggunakan model Hijau-Ampt, 2.Analisa numerik dengan kondisi jenuh menggunakan. Hasilnya adalah perpindahan akibat meningkatnya variasi kohesi, Dalam kondisi hujan lebih besar dari kapasitas infiltrasi, hal ini ditunjukkan oleh respon yang lebih besar sebelum hujan dan setelah hujan, dan perpindahan pada bagian lereng lebih besar dari bagian datar. Hal ini berarti variasi kohesi yang disimulasikan infiltrasi air hujan pada tiga kondisi, menyebabkan amplifikasi lokal, hal ini lebih berbahaya karena keberadaan air. Yang paling berisiko tanah longsor jika ada air tanah di lapisan batuan yang memisahkan pasir karena akan berisiko karena bidang tanah longsor mengikuti aliran air tanah.

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Previous studies have shown that rainfall and earthquakes are two main mechanisms that trigger landslides (Keefer, 1984; Schuster et al., 1996; Crosta, 2004). For earthquake induced landslides, many studies have been concerned with the identification and description of coseismal landslides, particularly those caused by catastrophic earthquakes (see, for example, Keefer, 1984; Harp et al., 1991; Jibson et al., 1994; Harp and Jibson, 1996; Khazai and Sitar, 2004). On Wednesday September 30, 2009,at 5:16 p.m., an Mw 7.6 earthquake struck the west coast of Sumatra that caused landslides fields in three villages in Kanagarian Tandikat a lost life of about360 victims.

This study examines an approximate method for determining the influence of infiltration on the stability of the two superficial layers of slope. There are two approaches: mathematical 1.Analyse unsaturated conditions with the Green- Ampt model, 2.Numerical analysis of saturated conditions using the program FLAC 3D.

The result is displacement increased as the variation of cohesion In the condition when the rain greater than capacity infiltration showed a greater response conditions before the rain After the rain, and the displacement at the slope section greater than flat section. its means variation of cohesion which is simulated rainwater infiltration at all three conditions, causes amplification of the amplification local, is more dangerous because of the presence of water. Who is most at risk of landslides if there is groundwater in the rock which separates the sand it would be risky because the field of landslides following the flow of groundwater."

"Severe droughts, damaging floods and mass migration, climate change is becoming a focal point for security and conflict research and a challenge for the world’s governance structures. But how severe are the security risks and conflict potentials of climate change? Could global warming trigger a sequence of events leading to economic decline, social unrest and political instability? What are the causal relationships between resource scarcity and violent conflict? This book brings together international experts to explore these questions using in-depth case studies from around the world. Furthermore, the authors discuss strategies, institutions and cooperative approaches to stabilize the climate-society interaction."

"This book explores the implications of urbanization and climate change for peri-urban water security in South Asia. Focusing on four locations in the region, namely Kathmandu (Nepal), Khulna (Bangladesh), and Hyderabad and Gurgaon (India), the book describes how climate change and urbanization shape peri-urban water security. The research documents the socio-technical mediation of water insecurity, describing both technological and institutional adaptive responses. In describing adaptation, the focus is both on planned and autonomous adaptation. The book further documents the differential vulnerabilities of peri-urban communities, describing the factors that disadvantage certain men, women, and groups of people as compared to others. With a focus on peri-urban contexts, the book bridges an important gap in current studies of adaptation and vulnerability to the impacts of climate change that tend to focus on purely agrarian or urban contexts. It thus contributes to the emerging body of work on peri-urban issues as well as to the literature on vulnerability and adaptation. The research presented is interdisciplinary in nature, employing a wide range of research tools and methods across the natural and social sciences."

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Bendungan Raknamo merupakan tipe bendungan zonal urugan random batu dengan inti tegak, dilengkapi dengan instrumentasi tekanan air pori berupa pisometer. Tekanan air pori menjadi salah satu parameter penting dalam evaluasi stabiltas lereng bendungan, terutama pada bendungan urugan. Penentuan besaran tekanan air pori dapat dilakukan dengan menggunakan pemodelan numerik, hitungan dan bacaan aktual menggunakan instrumentasi pisometer. Instrumentasi pengukur tekanan air pori dipasang pada saat pelaksanaan konstruksi, mulai dibaca dari awal pemasangannya sampai dengan tahapan operasi bendungan. Jika dibandingkan, nilai tekanan air pori pada tahapan desain berbeda dengan kondisi saat operasi, baik pada kondisi pembebanan normal (tanpa gempa) serta pembebanan menggunakan koefisien gempa pseudostatic pada kondisi muka air normal pada el. +104,00 m. Tekanan air pori saat operasi lebih tinggi dibandingkan perkiraan tekanan air pori tahapan desain. Rasio tekanan air pori yang terukur dari awal konstruksisampai dengan Februari 2021 rata-rata dibawah 0,2.

Dalam studi ini membahas bagaimana tekanan air pori pada bendungan urugan zonal terbentuk dan mempengaruhi stabiltas lereng bendungan.

 

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Raknamo dam is zonal fill dam with clay core, equipped with some pisometeer to monitoring pore water pressure. Pore ​​water pressure is one of the important parameters in evaluating dam slope stability. Measurement of pore water pressure can be carried out using a numerical model, calculations and actual readings using instrumentation such as piezometer. The piezometer was installed at the time of construction, starting to be read from the beginning of installation up to the dam operation stage (recent years). When compared, the value of pore water pressure at the design stage is different from the conditions during operation, both under normal loading conditions (without earthquakes) and loading using earthquake coefficient pseudostatic at normal water level conditions at el. +104.00 m. The pore water pressure at operation is higher than the design stage pore pressure estimate. The pore water pressure ratio measured from the start of construction to February 2021 is on average below 0.2.

This study discusses how the pore water pressure in the zonal fill dam is formed and influence the slope stability of the dam.

 

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