Characterization of Monsoonal Rainfall in the Sudano-Sahelian Zone of Northwestern Nigeria

Wavelet transform has been underutilized in characterization of rainfall (Real Onset Dates and Real Cessation Dates) in the study area. This study aims at the characterization of monsoonal rainfall. Daily rainfall data of four stations for the period 1981-2018 were collected from Nigerian Meteorological Agency. The Intra-seasonal Rainfall Monitoring Index (IRMI) was generated and used in determining the RODs and RCDs. The Mann–Kendall test was used to detect trends of the rainfall characteristics. Wavelet transform was used in modelling RODs and RCDs. Findings revealed that RODs vary between stations. There is low (0.3 Spearman’s Rank r) correlation between latitudes and Early Cessations (ECs) of rains. The Morlet wavelet analysis revealed that from 1999 to 2018, there were more of EOs and NOs especially in Kano station. We conclude that from 1981 to 2018 there has been a minimal increase in the retreat dates of rainfall in the study area.

Influence of Physical Environmental Factors on The Rising Insecurity in Northwestern Nigeria

Northern part of Nigeria has witnessed a widespread security challenges in recent years, in most cases armed conflicts. Boko Haram's insurgency in the Northeast, herdsmen militancy in North-central, while in the Northwest, banditry has become the major security concern. Millions of people have been displaced, some were dead as a result. There are efforts by concerned entities, less attention was given to physical environmental. Environmental psychology has shown that the physical environment is responsible for behavior or crime; therefore, this study identifies the environmental factors that are influencing the increase of insecurity activities in the Northwestern states of Nigeria. Data was collected using focus group discussions, observations, interviews and review of related existing literature. System theory was used to show the interdependence of the factors by identifying and categorizing them into internal and external factors (artificial and natural). The internal factors include; Urbanization and Poor Environmental Design/Planning, Territorial encroachment, Urban poverty among others. While the external factors are; Climate, Topography and Vegetation, Natural resources and etc. The study discusses their effects on increasing insecurity in the region and concluded that both internal and external factors have significant effects on the increasing banditry in Northwestern part of the country and need to be viewed as a system and be treated holistically. Finally made some recommendation on the way forward.

Integrasi Metode Resistivitas, Seismik Refraksi, Geologi Berbasis Geospasial untuk Identifikasi Potensi Longsor di Srimartani, Yogyakarta

Kabupaten Bantul merupakan salah satu kabupaten yang berpotensi terjadi tanah longsor, tepatnya di daerah Srimartani, Kecamatan Piyungan. Penelitian ini dilakukan dengan tujuan untuk mendapatkan data dan informasi mengenai parameter metode geofisika daerah longsor dan mengetahui dugaan zona potensi longsor. Metode yang digunakan dalam penelitian ini adalah survei lokasi, akuisisi metode seismik refraksi, akuisisi metode resistivitas, dan pemetaan foto udara (geospasial). Dari penampang bawah permukaan seismik refraksi metode hagiwara didapatkan bahwa lapisan lapuk pada daerah riset berupa soil dan pasir tuffan dikarenakan memiliki sifat permeable dan bidang gelincirnya yang bersifat impermeable. Pada penampang bawah metode seismik refraksi lapisan pertama yaitu soil dengan kecepatan V1 sekitar 313.8 m/s – 461.6 m/s dan lapisan kedua yaitu pasir dengan kecepatan V2 sekitar 459 m/s – 1567 m/s. Sementara penampang bawah permukaan metode resistivitas konfigurasi dipole – dipole didapatkan lapisan lapuk tersebut memiliki nilai resitivitas yang kecil dikarenakan lapisan tersebut bersifat lunak sehingga ada kemungkinan lapisan tersebut dalam kondisi basah. Pada penampang resistivitas memiliki nilai 126 ohm.m hingga lebih dari 301 ohm.m, daerah tersebut diperkirakan terdapat batuan breksi batuapung dari formasi semilir yang diduga sebagai bidang gelincir. Dari segi geologi, daerah penelitian sangat rentan terjadi tanah longsor dikarenakan kondisi lereng searah dengan kondisi struktur regional di daerah penelitian yaitu barat-timur, didukung oleh kondisi batuan yang ada berupa breksi batuapung dan tuff yang sangat rawan terjadi longsor. Dengan adanya penelitian ini, diharapkan dapat menambah pengetahuan mengenai antisipasi masyarakat dalam meminimalisir dampak yang ditimbulkan dari adanya tanah longsor. Bantul Regency is one of the districts that have the potential for landslides to occur, precisely in the Srimartani area, Piyungan District. This research was conducted with the aim of obtaining data and information about the parameters of the geophysical method of landslide areas and knowing the alleged landslide potential zone. The methods used in this research are site survey, seismic refraction acquisition method, resistivity method acquisition, and aerial photography (geospatial) mapping. From the subsurface seismic refraction of the Hagiwara method, it was found that the weathered layer in the research area was soil and sand due to its permeable properties and impermeable slip plane. . In the lower section of the seismic refraction method, the first layer is soil with a V1 velocity of around 313.8 m/s – 461.6 m/s and the second layer is sand with a V2 velocity of about 459 m/s – 1567 m/s. While the subsurface resistivity method of the dipole - dipole configuration found that the weathered layer has a small resistivity value because the layer is soft so there is a possibility that the layer is in a wet conditionIn the cross section resistivity has a value of 126 ohm.m to more than 301 ohm.m, the area is estimated to contain pumice breccia from the breccia formation which is thought to be a slip plane. In terms of geology, the research area is very susceptible to landslides because the slope conditions are in line with the regional structural conditions in the research area, namely west-east, supported by the existing rock conditions in the form of pumice breccia and tuff which are very prone to landslides. With this research, it is hoped that it can increase knowledge about community anticipation in minimizing the impact of landslides.

Electrical Resistivity and Geotechnical Attributes and The Dynamics of Foundation Vulnerability

This research evaluates the significance of geotechnical and Electrical Resistivity methods in studying structural integrity as fundamental factors that may account for failure in a typical sedimentary environment of Ukpenu Primary School, Ekpoma, Edo State, Nigeria. Two methods were used in this study such as the Electrical Resistivity approach involving the use of Lateral Horizontal Profiling (LHP), 2D Electrical Resistivity Tomography (ERT), and Vertical Electrical Sounding (VES) techniques. While geotechnical method involved the collection of soil samples from the study locations for the characterization of the soil properties that are very vital to foundation studies. Nine VES were carried out using Schlumberger array with current electrode spacing varying from 1 to 40 m, with 2-D ERT using Dipole-Dipole electrode array with inter-station separation of 5 m and an expansion factor varied from 1 to 5 while LHP involve Wenner array with an electrode spacing of 5 m interval and was used to determine the vulnerability factors for the building sustainability. The VES interpretation results were used to determine the second-order parameters for the determination of vulnerability. The results obtained from the two methods review that both are very fundamental to foundation dynamics. However, electrical attributes were found to give better information in terms of depth, lateral extent, layer stratification, and nature of materials which make it an indispensable tool over geotechnical attributes whose depth of investigation is up to a maximum of 5 m which poses great limitation in the evaluation of structural integrity, against stress, and strain occasion by geodynamic activities that often result into fracture, crack, highly weathered formation that usually goes beyond the shallow depth of investigation. Therefore, it can be stated that resistivity attributes account for 90% of the major contributing factors that affect foundation vulnerability.

Application of Electrical Resistivity Method to Site Characterisation for Construction Purposes at Institute of Agriculture Research and Training Moor Plantation Ibadan

This research was carried out within Institute of Agriculture Research and Training Moor Plantation Ibadan, Southwestern Nigeria, with the aim to ascertain suitability of the proposed site for building construction and usage. The geophysical investigation involved three electrical resistivity techniques; Vertical Electrical Sounding (VES) using the Schlumberger configuration, 2D ERT and 2-D electrical imaging using Dipole-dipole electrode configuration. Two traverses were established E–W direction cutting across geologic strike with a distance of 80 m and of varying inter-traverse spacing. Eight (8) VES stations were occupied covering the entire study area for layer stratification and geoelectric parameters. The results were qualitatively and quantitatively interpreted and are presented as sounding curves and geoelectric sections. The 2-D imaging gave information on the subsurface characteristic in the area with generally low apparent resistivity indicating low competence material. The results obtained from the VES delineate three geoelectric units which comprise of the topsoil, weathered layer and fresh basement. The results from the VES were used to determine the second order parameters. The entire results correlate well with one another showing that all the techniques used were complemented. This study has further justified the need for geophysical site investigation as pre-condition before any construction to avoid problems of differential settlement. In determining of foundation material, topography elevation, clay content and the depth of weak zones should be put into consideration, since the depth of the weak zone is appreciably high.

Sedimentation Rate Analysis in Dock C PT. Petrokimia Gresik, Indonesia

Dock C is one of the supporting facilities at PT. Petrokimia Gresik which functions as loading and unloading goods from ships to land and vice versa. Another benefit of the jetty is that it can significantly increase the company's production capacity. Dock C PT. Petrokimia Gresik. In the treatment of sedimentation in port it is necessary to analyze the current pattern and sedimentation rate early, because this is the first step to predict the amount of sedimentation contained in the port in a certain period of time. Several ways can be done to minimize the rate of sedimentation, one of which is the layout of Dock C to reduce the frequency of dredging. This study compares the sedimentation volume at the existing condition jetty and two alternative jetty that occur due to currents and waves, while modeling is done using Mike 21. The results of the existing jetty modeling show the sedimentation volume for 12 months was 20641.68 m3. Whereas the sedimentation volume from alternative jetty 1 and 2 produced for 12 months was 11293.56 m3 and 7426.2 m3. Modifications to the layout of the jetty provided were able to reduce the rate of sedimentation in Dock C, with the most optimal sedimentation volume for 12 months at 13215.48 m3

Klasifikasi Tutupan Lahan Peta Rupabumi Indonesia dalam Identifikasi Kesesuaian Kawasan Permukiman di Kalimantan Tengah

Berdasarkan Katalog Unsur Geografis Indonesia (KUGI), Peta Topografi Indonesia (RBI) memiliki 6 kategori unsur dengan 152 unsur klasifikasi tutupan lahan. Oleh karena itu, untuk keperluan analisis kesesuaian penggunaan lahan, klasifikasi tutupan lahan RBI perlu disederhanakan. Penelitian ini bertujuan untuk menyederhanakan klasifikasi kategori unsur tutupan lahan RBI dan menganalisis kesesuaian kawasan pemukiman berdasarkan variabel tutupan lahan dan penggunaan lahan. Studi kasus klasifikasi tutupan lahan dan kesesuaian penggunaan lahan untuk pemukiman telah dilakukan di Provinsi Kalimantan Tengah. Hasilnya, klasifikasi tutupan lahan Provinsi Kalimantan Tengah dikelompokkan menjadi 15 kategori. Sebagian besar tutupan lahan di Kalimantan Tengah adalah hutan dengan luas mencapai 65%. Sementara itu, kesesuaian kawasan permukiman berdasarkan variabel tutupan lahan dan penggunaan lahan menyebar mengikuti sebaran spasial semak belukar dan lahan gundul seluas 16% Kalimantan Tengah. Based on th Indonesian Geographical Feature Catalogue (KUGI), the Indonesian Topographic Map (RBI) has 6 feature categories with 152 land cover classification features. Therefore, for land-use suitability analysis purposes, the RBI land cover classification needs to be simplified. This study aims to simplify the classification of RBI's land cover element categories and analyze the suitability of residential areas based on land cover and land-use variables. A case study of land cover classification and land-use suitability for settlements was conducted for the Central Kalimantan province. As a result, the land cover classifications of Central Kalimantan Province are grouped into 15 categories. Most of the land cover in Central Kalimantan is the forest with covering 65% of the area. Meanwhile, the suitability of residential areas based on land cover and land use variables spread following the spatial distribution of shrubland and bare land covering 16% of Central Kalimantan.

Efektivitas Komposit Material Overburden Batubara, Zeolit, dan Arang Aktif Tempurung Kelapa Sebagai Adsorben Besi dalam Air Asam Tambang

Abstrak: Penelitian ini mempelajari penyerapan Fe dari air asam tambang yang berasal dari lokasi penambangan batubara. Adsorben yang digunakan dalam penelitian ini yaitu kombinasi antara claystone, zeolit, dan arang aktif tempurung kelapa. Adsorben tersebut harus diaktivasi terlebih dahulu untuk membersihkan pengotor di permukaannya sehingga luas permukaannya meningkat. Aktivasi claystone dilakukan dengan 3M NaOH, zeolit dengan 3M HCl, dan arang tempurung kelapa dengan 4M HCl. Komposit dibuat dengan mencampurkan ketiga adsorben dengan perbandingan (Claystone[C]: Zeolit[Z]: Arang aktif[A]) = 25:25:50. Hasil uji luas permukaan menunjukkan bahwa komposit memiliki luas permukaan 62,44 m2/g. Adsorpsi dilakukan dengan sistem batch menggunakan alat hot plate stirer pada variasi waktu kontak 30, 60, 90, 120, dan 150 menit. Berdasarkan hasil uji adsorpsi, 7,5 gram komposit mampu menurunkan konsentrasi Fe dengan efektivitas 99,61% dan kapasitas adsorpsi 0,432 mg/g pada waktu kontak 30 menit. Kata Kunci: adsorpsi, komposit, efektivitas, kapasitas Abstract: This research studied adsorption iron (Fe) from acid mine drainage in coal mining. Adsorbent used in this research is the combination of activated claystone, activated zeolite, and ativated carbon from coconut shell. The adsorbents need to be activated to remove the impurities from its surface and improved its surface area. Claystone was activated using 3M NaOH, 3M HCl for zeolite, and 4M HCl for coconut shell. Composite was made by mixing claystone, zeolite, and coconut shell with 3 ratio (claystone [C], zeolite [Z], activated carbon [A]) = 25:25:50. The result of surface area analyzer showed that the surface area of composite was 62,44 m2/g. Adsorption with batch system was carried out using hot plate stirer on 30,60, 90, 120, and 150 minutes of contact time. Adsorption result showed that 7,5 gram of composite succeded decreasing iron metal concentration with 99,61% effectiveness and 0,432 mg/g adsorption capacity on 30 minutes of contact time. Keywords: adsorption, composite, efectiveness, capacity

Indikasi Potensi Gas Hidrat Sebagai Sumber Energi Nonkonvensional di Wilayah Maritim Indonesia

Abstrak: Gas hidrat merupakan sumber energi nonkonvesional yang kuantitasnya hampir dua kali lebih banyak apabila dibandingkan dengan energi yang bersumber dari fosil. Oleh karena itu, penulis memiliki tujuan untuk mengembangkan potensi gas hidrat tersebut dan mengindikasikan potensi persebaran serta pembentukannya di Indonesia. Metode penelitian yang digunakan yaitu studi pustaka yang bersumber dari literatur seperti jurnal, artikel, dan buku. Berdasarkan penelitian ini, potensi cadangan gas hidrat di Indonesia dapat ditemukan di wilayah perairan Indonesia terutama perairan laut dalam seperti di Cekungan Busur Muka Simeulue, Sumatera dan Selat Makassar. Selain itu, potensi tersebut juga didukung oleh adanya kegiatan tektonik yang terjadi Indonesia. Metode geofisika seismik, BSR (Bottom Stimulating Reflector) dan analisa AVO merupakan beberapa metode yang digunakan untuk mengindikasikan adanya keberadaan potensi gas hidrat di suatu daerah. Gas hidrat dapat menjadi substitusi bagi bahan bakar fosil dan berpotensi masuk tahap eksplorasi dan eksploitasi, sehingga dibutuhkan studi lanjutan agar dapat diproduksi secara komersial. Kata Kunci: bottom stimulating reflector (BSR), gas hidrat, Indonesia, laut dalam, seismik Abstract: Gas hydrate is a non-conventional energy source, which is almost twice as large as fossil energy sources. Therefore, the authors want to develop gas hydrate potential and indicate the potential for its distribution and formation in Indonesia. The research method used is literature study sourced from literature such as journals, articles and books. Based on this research, the potential gas hydrate reserves in Indonesia is found in Indonesian territorial waters, especially deep sea waters such as the Simeulue Forearc Basin, Sumatra and the Makassar Strait. In addition, this potential is supported by tectonic activity occurs in Indonesia. Seismic geophysical methods, BSR (Bottom Stimulating Reflector) and AVO analysis are some of the methods used to indicate presence gas hydrate potential in area. Gas hydrate can be substitute fossil fuels and has the potential enter the exploration and exploitation stage, so further studies needed so that it can be produced commercially. Keywords: bottom stimulating reflector (BSR), deep sea, gas hydrate, Indonesia, seismic

Estimasi Tingkat Bahaya Erosi dengan Menggunakan Metode USLE Pada Daerah Aliran Sungai (DAS) Amandit

Abstrak: Erosi tanah menjadi semakin meningkat setiap tahun yang disebabkan oleh terjadinya peningkatan kerusakan lahan. Daerah Aliran Sungai (DAS) Amandit mengalami kerusakan lahan yang ditandai dengan luasnya lahan kritis pada DAS tersebut yang akan berpengaruh pada tingginya tingkat bahaya erosi pada DAS tersebut. Penelitian ini bertujuan untuk menganalisis tingkat bahaya erosi yang terjadi pada Daerah Aliran Sungai (DAS) Amandit. Penelitian ini menggunakan peta bentuklahan sebagai dasar pengambilan sampel. Jumlah sampel dalam penelitian ini adalah 18 buah sampel. Analisa data yang digunakan adalah berdasarkan Metode Universal Soil Loss Equation (USLE) yang digunakan untuk mengetahui tingkat bahaya erosi yang terjadi pada wilayah penelitian. Hasil penelitian menunjukkan tingkat bahaya erosi yang terjadi di Daerah Aliran Sungai (DAS) Amandit termasuk dalam klasifikasi berat-sangat berat. Tingkat bahaya erosi yang paling tinggi adalah 1276.535 ton/ha/tahun. Faktor yang dominan yang mengakibatkan tingkat bahaya erosi pada Daerah Aliran Sungai (DAS) Amandit termasuk dalam klasifikasi berat-sangat berat adalah kemiringan lereng, nilai erodibilitas yang tinggi, dan tutupan lahan. Kata Kunci: Tingkat Bahaya Erosi (TBE), Bentuklahan, USLE, DAS Amandit Abstract: Soil erosion is increasing every year due to increased land degradation. The Amandit Watershed has suffered damage which affects critical land in the watershed which will affect the level of erosion hazard in the watershed. This study aims to analyze the level of erosion that occurs in the Amandit Watershed. This study uses a landform map as a basis for sampling. The number of samples in this study were 18 samples. The data analysis used is based on the Universal Soil Loss Equation (USLE) method which is used to see the level of erosion hazard that occurs in the study area. The results showed that the level of erosion that occurred in the Amandit Watershed was classified as heavy-very heavy. The highest level of erosion was 1276.535 ton/ha/year. The dominant factors resulting in the level of erosion in the watershed (DAS) included in the weight-very weight classification are the slope of the slope, high erodibility values and land cover. Keywords: Erosion Hazard Level, Landform, USLE, Amandit Watershed