Regional stress alignments in the Kutai Basin,East Kalimantan,Indonesia: a contribution from a borehole breakout study

Borehole breakout data from 134 wells located within the Kutai Basin region, East Kalimantan were analyzed to determine the present day regional horizontal stress alignments. The data were extracted from various types of dipmeter logs. The study reveals that the majority of the data give a coherent picture of breakout orientation. The mean azimuths for the entire-unweighted, ellipticity-weighted and magnitude-weighted data sets are preferentially aligned in the regional-mean direction of 48.9° N or 128.9° N. Most of the data have a low dispersion value (So) and the ranking of reliability in Zoback’s classification is ‘A’. There is no significant azimuth variation with depth. These relatively consistent alignments of breakout azimuths indicate that the maximum regional stress direction in the study area is NW–SE. This regional-mean of breakout azimuths deviates from the axis of the anticlinorium trends and from the strike of the thrust–fault patterns in the region. It is believed that these structural patterns are influenced by reactivation of weak zones related to sediment loading (structural inversion).     

Groundwater exploration and evaluation by using geophysical interpretation (case study: Al Qantara East, North Western Sinai, Egypt)

Different geophysical tools such as geoelectric, gravity, and magnetic have been applied to detect groundwater potentiality and structural elements, which controlled a geometry of the groundwater aquifers in the study area. Nineteen vertical electrical soundings measured using ABEM SAS 4000 equipment through Schlumberger configuration of AB/2 ranged from 1.5 to 1,000 m; the quantitative interpretation was carried out using manual and analytical techniques. The results of quantitative interpretation used to construct six geoelectrical cross-sections indicate that the subsurface sequence of the study area consists of seven geoelectrical units. These units are Quaternary sand sheet and sand dunes, Quaternary aquifer, marly limestone, clay, sandy clay, clay with sandstone intercalation, and deep Nubian sandstone aquifer. The isopach map of the Quaternary aquifer exhibits thickness of the Quaternary aquifer that increased at the northern and southern part (50 m) and decreased at the eastern and western part (5 m), and the depth of the aquifer increased at the northern part (40 m) and decreased at the central part to 6 m. The isoresistivity map of the aquifer shows a high resistivity at the northern part but the southern part reveals low resistivity according to the lithology. The water salinity increases in the direction of groundwater flow from 500 to 10,500 mg/l. The low water salinity is due to direct recharge from El-Sheikh Zayed Canal, which supplied fresh water to this area. Sixty-five gravity stations were measured using Auto-Grav gravity meter; different gravity corrections were applied on raw data. The corrected gravity values were plotted to represent a Bouguer anomaly map; the residual gravity anomaly map was used for delineation of the fault elements. The area was dissected by different fault elements of trends NW–SE, NE–SW, and E–W. In addition, 65 ground magnetic stations were measured at the same sites of gravity stations. The results of magnetic interpretation indicate that the depth of the basement is shallow at the western and southern parts of the area (4,500 m), but the central part exhibits greater depth of 7,900 m.

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الملخص العربي   طرق جيوفيزيقية مختلفة مثل الكهربية الأرضية, التناقلية الأرضية والمغناطيسية الأرضية تم تطبيقها لتحديد إمكانية تواجد المياه الجوفية والتراكيب الجيولوجية التي تتحكم في إبعاد وهندسة الخزان الجوفي في منطقة الدراسة. تسعة عشر جسة كهربية عمودية تم قياسها باستخدام جهاز من شركة (ِ ABEM) ساس 4000 من خلال تشكيل شلمبرجير بمسافة بين القطبين أب /2 تبدأ من 1.5 متر حتى 1000 متر, التفسير الكمي تم علي البيانات باستخدام التفسير اليدوي والتحليلي. نتائج التفسير الكمي تم استخدامها لتشييد ست قطاعات جيوكهربية والتي أوضحت أن التتابع التحت سطحي لمنطقة الدراسة يتكون من سبعة وحدات جيوكهربية. هذه الوحدات هي صفائح من الرمال والكثبان الرملية للعصر الرباعي, الخزان الجوفي الرباعي, حجر جيري مارلي, طفلة, طفله رمليه, طفله متداخلة مع الرمل والخزان الجوفي النوبي. خريطة السمك للخزان الجوفي الرباعي تظهر أن سمك الخزان الجوفي الرباعي يزيد عند شمال وجنوب منطقة الدراسة (50 متر) ويقل عند الجزء الشرقي والغربي (5 متر). وعمق هذا الخزان الجوفي الرباعي يزيد عند الجزء الشمالي (40 متر) وينقص عمق الخزان الرباعي عمد وسط المنطقة (6 متر). خريطة المقاومة الحقيقية للخزان الجوفي الرباعي تبين أن المقاومة تزيد عند الجزء الشمالي وتقل المقاومة عند الجزء الجنوبي من منطقة الدراسة بناءا علي التكوين الصخري للطبقات. ملوحة المياه الجوفية تزيد في اتجاه سريان المياه من 500 مليجرام/لتر إلي 10500 مليجرام/لتر. نقص الملوحة المياه ناتج عن التسرب المباشر من قناة الشيخ زايد والتي تعتبر مصدر المياه العزبة في منطقة الدراسة. خمس وستون محطة تثاقيلية أرضية تم قياسها باستخدام اوتو-جرافميتر, العديد من تصحيحات الجاذبية الأرضية نم تطبيقها علي البيانات الأصلية. قراءات الجاذبية الأرضية المصححة تم رسمها علي خريطة لتمثل شاذات البوجير وتم استخدام خريطة الشاذات المحلية لتجديد التراكيب الجيولوجية (الفوالق). حيت أوضحت الدراسة أن المنطقة تأثرت بعده فوالق باتجاهات مختلفة مثل شمال غرب- جنوب شرق, شمال شرق-جنوب غرب وشرق-غرب. نتيجة تفسير بيانات المغناطيسية الأرضية أظهرت أن عمق ضجور القاعدة تكون ضحلة عند الجزء الغربي والجنوبي (4500 متر) وتكون ضجور القاعدة عميقة (7900 متر) عند الجزء الأوسط من منطقة الدراسة.

     

Probabilistic and spatial liquefaction analysis using CPT data: a case study for Alameda County site

Soil liquefaction is one of the major concerns causing damage to the structures in saturated sand deposits during earthquakes. Simplified methods for the assessment of liquefaction potential rely on the limit states that are generally established with built-in conservatism and a great deal of subjectivity. Well-known SPT- and CPT-based methods are widely used in the design practice for this purpose due to their simplicity and reasonable predictive capability. However, these methods do not account for various sources of uncertainties explicitly. Moreover, evaluations are made only at the locations of test results and are generalized for the whole region, which may not give accurate results where spatial variation of soil properties is significant. The present study focuses on the probabilistic evaluation of liquefaction potential of Alameda County site, California, considering spatial variation of soil indices related to CPT soundings. A stochastic soil model is adopted for this purpose using random field theory and principles of geostatistics by developing 2D exponential correlation functions. It has been observed that the probability of liquefaction is significantly underestimated as much as 34 %, if the spatial dependence of soil indices is not considered. Further, the effect of spatial variation is more prominent in low-level earthquakes compared to the high-level earthquakes, showing a 41.5 % deviation for magnitude 8.1 and a 60.5 % deviation for magnitude 5.0 earthquake at a depth of 10 m.     

Forest fire risk estimation in a typical temperate forest in Northeastern China using the Canadian forest fire weather index: case study in autumn 2019 and 2020

Natural Hazards - China's forest cover has increased by approximately 10% as a result of sustainable forest management since the late 1970s. The forest ecosystem area affected by fire is...     

Landslide susceptibility mapping and factor effect analysis using frequency ratio in a catchment scale: a case study from Garuwa sub-basin,East Nepal

For assessing landslide susceptibility, the spatial distribution of landslides in the field is essential. The landslide inventory map is prepared on the basis of historical information of individual landslide events from different sources such as previously published reports, satellite imageries, aerial photographs and interview with local inhabitants. Then, the distribution of landslides in the study area is verified with field surveys. However, the selection of contributing factors for modelling landslide susceptibility is an inhibit task. The previous studies show that the factors are chosen as per availability of data. This paper documents the landslide susceptibility mapping in the Garuwa sub-basin, East Nepal using frequency ratio method. Nine different contributing factors are considered: slope aspect, slope angle, slope shape, relative relief, geology, distance from faults, land use, distance from drainage and annual rainfall. To analyse the effect of contributing factors, the landslide susceptibility index maps are generated four times using (a) topographical factors and geological factors, (b) topographical factors, geological factors and land use, (c) topographical factors, geological factors, land use and drainage and (d) all nine causative factors. By comparing with the pre-existing landslides, the fourth case (considering all nine causative factors) yields the best success rate accuracy, i.e. 81.19 %, which is then used to produce the final landslide susceptibility zonation map. Then, the final landslide susceptibility map is validated through chi-square test. The standard chi-square value with 3 degrees of freedom at the 0.001 significance level is 16.3, whereas the calculated chi-square value is 7,125.79. Since the calculated chi-square value is greater than the standard chi-square value, it can be concluded that the landslide susceptibility map is considered as statistically significant. Moreover, the results show that the predicted susceptibility levels are found to be in good agreement with the past landslide occurrences.     

Pliocene Intrusions in the Gunung Bijih (Ertsberg) Mining District,Irian Jaya,Indonesia: Petrography and Mineral Chemistry

At least 16 Pliocene hypabyssal intrusions crop out within the Gunung Bijih (Ertsberg) Mining District in Irian Jaya (western New Guinea), Indonesia. Several Cu-Au ore deposits are associated spatially and genetically with these young hypabyssal intrusions. Approximately 188 mt of Cu-Au skarn ore has been delineated or produced from the district. Most of these skarns are associated with a quartz monzonite to quartz monzodiorite stock (the Ertsberg Intrusion). The Grasberg Complex, a series of nested intrusions, hosts a supergiant porphyry copper deposit containing ～9.8 mt of Cu-Au ore.

Textural and mineralogical differences among the intrusions are largely the result of crystallization at different crustal levels. The intrusions were emplaced at ≤ 2 km depth into deformed sedimentary rocks that originally were deposited on the northern margin of the Australian continent. Emplacement of at least one intrusion was controlled by cross-cutting NW- and NE-trending fault sets. Intrusions within the Gunung Bijih District can be divided into a “high-K” group of latites, trachydacites, and trachytes, and a “low-K” group of medium- to high-K andesites and dacites.

The high-K group of intrusions is volumetrically more important (at current levels of exposure), containing the two largest igneous bodies in the district: the Ertsberg Intrusion and the Grasberg Complex. The Ertsberg Intrusion is a single intrusion with an estimated volume of 10 to 20 km³. The Grasberg Complex, which has an outcrop area comparable to that of the Ertsberg, consists of a series of small (≤4 km³) intrusions. All other intrusions in the study area appear to be ≤1 km³ in volume.

The Ertsberg Intrusion is equigranular, with only a few phenocrysts and a generally coarser grain size than the other intrusions. In contrast to most district intrusions, the Ertsberg contains only trace amounts of amphibole. Despite its large (for the district) volume, the Ertsberg is relatively homogeneous in terms of mineral content and mineral compositions. These observations, along with the occurrence of near end-member magnetite in the Ertsberg, suggest that this intrusion was emplaced in the shallow (≤2 km) crust as a single pulse of crystal-poor magma, which then cooled slowly. At this depth, the dissolved H₂O content of the magma remained too low to stabilize amphibole throughout crystallization. Coexisting titanite, diop-side, magnetite, and quartz, with no ilmenite, suggests oxygen fugacity in the Ertsberg was at least one log unit above the nickel-nickel oxide (NNO) buffer.

Other intrusions in the district, including those in the Grasberg Complex, are porphyritic, containing 40% to 60% phenocrysts in fine-grained (usually ≤10 μm) groundmass. These intrusions commonly contain 5% to 20% amphibole or pseudomorphs of alteration minerals after amphibole. These intrusions crystallized phenocrysts at depth (10-15 km?) where increased confining pressure allowed dissolved H₂O contents to build up enough to stabilize amphibole. Strongly zoned plagioclase phenocrysts in low-K intrusions indicate that low-K intrusions reached H₂O saturation early in their crystallization history, and that low-K magmas crystallized with higher dissolved H₂O contents than did porphyritic high-K magmas. None of the porphyritic intrusions contain mineral assemblages indicative of oxygen fugacity, but the lack of orthopyroxene in these intrusions may indicate oxygen fugacities greater than the minimum estimated for the Ertsberg Intrusion.     

Hazard assessment of underwater landslide-generated tsunamis: a case study in the Padang region, Indonesia

Submarine landslides can generate local tsunamis with high run-ups, posing a hazard to human lives and coastal facilities. Both ancient (giant Storegga slide off Norwegian coast, 8200 B. P.) and recent (Papua New Guinea, 1998) events show high potential danger of tsunamigenic landslides and the importance of mitigation efforts. This contribution presents newly discovered landslides 70 km off Padang (Western Sumatra, Indonesia) based on recent bathymetry measurements. This highly populated city with over 750,000 inhabitants exhibits high tsunami vulnerability due to its very low elevation. We model tsunamis that might have been induced by the detected landslide events. Estimations of run-up heights extrapolated from offshore tsunami amplitudes for Padang and other locations in the northern Mentawai fore-arc basin yield maximum values of about 3 m. We also provide a systematic parametric study of landslide-induced tsunamis, which allows us to distinguish potentially dangerous scenarios for Padang. Inside the fore-arc basin, scenarios involving volumes of 0.5–25 km³ could endanger Padang. Apart from slide volume, the hazard distribution mainly depends on three landslide parameters: distance to Padang, water depth in the generation region, and slide direction.     

Provenance analysis as a key to orogenic exhumation: a case study from the East Carpathians (Romania)

Provenance analysis of the sediments from foredeep basins is crucial in understanding the contemporaneous orogenic exhumation processes. We report in this paper complex sediment provenance analysis using sandstone petrography and mudstone geochemistry, combined with magnetic susceptibility of the Upper Miocene to Pliocene deposits from Focşani foredeep basin (Romania). Data show a change of source area between 5 and 6 Ma, from an active volcanic arc towards a recycled orogenic belt, concurrent with an important increase of accumulation rate. This change was triggered by exhumation and erosion of the outer nappes from East Carpathians.     

Combined particle swarm optimization and linear discriminant analysis for landslide image classification: application to a case study in Taiwan

In Taiwan many reservoirs are constructed in mountain areas. Unfortunately, several earthquakes shook the soil, and typhoons brought a huge amount of water to the reservoir zone. In the past studies, remote-sensing image data were used to effectively monitor the landslide near reservoirs. In recent years, linear discriminant analysis (LDA) has become a well-known method for image classification. However, there are few studies to optimize the linear classification function. While the ancillary information has been adopted easily by new methodologies, the ancillary information must be examined by a landslide image classification system. To explore the effects of optimization on the LDA equations, three approaches were compared: (a) conventional LDA; (b) combined discrete rough sets and LDA (DRS + LDA), which identify the core factors and the corresponding thresholds of landslide occurrence; and (c) combined particle swam optimization algorithm and LDA (PSO + LDA), which optimizes the parameters of LDA equation to attain the best classification outcomes. The above methods were applied to a reservoir region in Taiwan, and the following classification results were obtained. The application of DRS + LDA in our case study reduced the number of ancillary attributes from 14 to 5, and resulted in an accuracy rate of 0.83. On the other hand, the application of PSO + LDA resulted in the same accuracy rate as that of DRS + LDA, whereas the accuracy rate of conventional LDA was found to be 0.78.     

Slope stability analysis on a regional scale using GIS: a case study from Dhading,Nepal

A spatially distributed physically based slope stability model combined with a hydrological model is presented and applied to a 350-km² area located in Dhading district, Nepal. Land slide safety factor maps are generated for five cases, including three steady state conditions assuming either completely dry soils, half saturated soils, or fully saturated soils, and two quasi-dynamic conditions, i.e. soil wetness resulting from storm events with, respectively a 2 or 25-year return period. For the quasi-dynamic cases, two methods are used, one based on accumulation of groundwater flow from upstream areas, and the other on accumulation of soil water from direct infiltration. The methodology delineates areas most prone to shallow land sliding in function of readily available data as topography, land-use and soil types. For the study area only 29% of the soils are unconditionally stable, while 25% of the soils are found to be unstable under fully saturated conditions. The comparison between the methods based on contributing area or on infiltration for quasi-dynamic conditions show that the approach based on infiltration is more reliable for the study area. The proposed methodology for predicting landslide susceptibility on a regional scale, based on basic data in GIS form, may be useful for other remote regions where detailed information is not available.     

The internationalisation of banking,technological change and spatial patterns: a case study in South Wales

This paper analyses the growth of international banking in the post-war era and theorises on this phenonemon. It also traces the growth of banking in the U.K. before reviewing recent technological change within the industry. Spatial patterns of banking activities in the U.K. are reviewed with reference to the aforementioned trends, focussing on a case study of a major relocation of a bank to South Wales and comparing this with other international studies.     

The Transition to Potassic Alkaline Volcanism in Island Arcs: The Ringgit--Beser Complex, East Java, Indonesia

The origin of potassic lavas with within-plate characteristicsin island are settings is unclear. The volcanic complex of Ringgit—Beser,situated in eastern Java, has erupted lavas of both normal islandare calc-alkaline type and atypical potassic lavas, includingsome highly magnesian lavas. The occurrence of these primitivelavas gives an unusual insight into the source characteristicsof the potassic lavas. The lavas from Ringgit—Beser have a wide range of K₂O(1.1–6.4 wt. %) and MgO contents (18.0–1.6 wt.%).The most magnesian lavas have high Ni and Cr contents. The calc-alkalinelavas have incompatible trace element patterns typical of islandare lavas with enrichments in large ion lithophile elements(LILE) and light rare earth elements (LREE) relative to highfield strength elements (HFSE) and heavy REE (HREE). The potassiclavas may be divided into two series on the basis of Ba andNb contents, with the enriched potassic (EK) series having higherBa and Nb contents for a given MgO content than the potassic(K) series. The EK and K series lavas have some incompatibletrace element ratios similar to within-plate lavas (e.g., highCe/Pb, low LILE/HFSE ratios, and low B/Be). However, both theEK series and K series lavas have negative Ti and Zr anomalies,and the EK series lavas have high Ba/La similar to are lavas.There is little distinction in Sr and Nd isotopes between theK and EK series, but the calc-alkaline lavas have lower ₈₇Sr/₈₆Srand higher ₁₄₃Nd/₁₄₄Nd ratios than the potassic lavas. The EKseries lavas have lower ₂₀₆Pb/₂₀₄Pb and higher ₂₀₈Pb/₂₀₄Pb thanthe K series lavas, but similar ₂₀₇Pb/₂₀₄Pb ratios. The K serieslavas define an almost horizontal trend in ₂₀₇Pb–₂₀₆Pbspace. The Pb isotopic ratios indicate that the EK series lavasare derived from a single mantle source, whereas the K seriesoriginate from a mixture of two mantle components. Calc-alkalinelavas have Pb isotope ratios similar to other calc-alkalineand tholeiitic lavas from Java, and plot on a mixing line betweenIndian Ocean mid-ocean ridge basalt (MORB) and Indian Oceansediment. Incompatible trace element and Pb isotope data for the calc-alkalinelavas indicate that these lavas have a similar source to othercalc-alkaline lavas erupted in Java, namely melts of the IndianOcean MORB mantle fluxed by fluids from the subducted slab.The potassic lavas originate from enriched mantle sources withinthe wedge which have not been affected by recent subductionprocesses. The EK series lavas are derived from a metasomatizedzone which has EMI-type characteristics. The K series lavasare derived from mixing of melts from Christmas Island-type(EMII) mantle and the metasomatized zone. The metasomatizedzone is probably situated at the base of the lithosphere andthe Indian Ocean MORB and Christmas Island-type mantle componentsare situated in the asthenosphere of the wedge. Isotopic datafor Ringgit—Beser lavas confirm that the mantle wedgeof the Sunda arc is extremely heterogeneous (Foden & Varne,1980; Varne, 1985; Wheller et al., 1987). The similarity in geochemistry between Indonesian potassic lavasand those erupted in continental settings indicates that themagma source is essentially the same, namely a metasomatizedphlogopite-rich layer generated by melts of recycled subductedlithosphere. The lack of negative Ti anomalies in the continentalpotassic lavas is ascribed to lower oxidation states in themantle in continental settings.     

Disaster risk evaluation using factor analysis: a case study of Chinese regions

Natural Hazards - Regional risk to natural disasters is a critical multi-criteria decision-making (MCDM) problem in the literature due to the complicated and usually conflicting evaluation index...     

Forecasting areas vulnerable to forest conversion using artificial neural network and GIS (case study: northern Ilam forests,Ilam province,Iran)

Forest conversion due to illegal logging and agricultural expansion is a major problem that is hampering biodiversity conservation efforts in the Zagros region. Yet, areas vulnerable to forest conversion are unknown. This study aims to predict the spatial distribution of deforestation in western Iran. Landsat images dated 1988, 2001, and 2007 are classified in order to generate digital deforestation maps which locate deforestation and forest persistence areas. Meanwhile, in order to examine deforestation factors’ investigation, deforestation maps with physiographic and human spatial variables are entered into the model. Areas vulnerable to forest changes in the Zagros forest region are predicted by a multilayer perceptron neural network (MLPNN) with a Markov chain model. The results show that about 19,294 ha forest areas are deforested in the last 19 years. The predictive performance of the model appears successful, which is validated using the actual land cover map of the same year from Landsat data. The validated map is found to be 94 % accurate. The validation is also tested using the relative operating characteristic approach which yielded a value of 0.96. The model is then further extended to predict forest cover losses for 2020. The MLPNN approach was found to have a great potential to predict land use/land cover changes because it permits developing complex, nonlinear models.     

Characterization of acid river dilution and associated trace element behavior through hydrogeochemical modeling: A case study of the Banyu Pahit River in East Java, Indonesia

Kawah Ijen volcano in East Java, Indonesia emits hyperacid (pH ≈ 0) brines rich in toxic elements including F, Al, Cd and Tl, which are transported downstream by the Banyu Pahit River, which is eventually used to irrigate farmland on the Asambagus Plain. The fate and behavior of major and trace elements are investigated, in the region of greatest change to the Banyu Pahit River, where thermal springs and the neutral Kali Sat and Kali Senggon Rivers increase its discharge 6-fold and pH increases from 1.9 to 4.5 with the development of abundant precipitates. The conservative behavior of Cl, F and SO₄ allows determination of the proportions of the mixing constituents at each confluence. Comparing a mass balance model based on the resulting proportions with measured concentrations demonstrates conservative behavior for most cations, with the exception of Si, Zr, Sn and Ba, which precipitate as amorphous silica, barite, and Zr and Sn phases, respectively. Iron is added as particulate Fe-(oxy)hydroxide in mixing with thermal spring outflow, and dissolves in the lower pH water. This also contributes Co, Cd, Mn, Y, and the rare earth elements, which are desorbed from the Fe-(oxy)hydroxide upon entering the acid water. Subsequent saturation in Fe-(oxy)hydroxide after mixing with the neutral rivers leads to a reverse response. Still, element behavior is close to conservative, which means that the volcanogenic toxic element load is almost entirely transferred to the Asambagus Plain with ensuing environmental and health impacts. This study shows that compositions of these acid waters can be understood and reproduced in a thermodynamic model, but only when fine-tuned using measured compositions and field observations. Therefore, the model’s utility in assessing the fate of toxic elements and in planning the environmental mitigation is limited.     

Estimation of spatial patterns of soil erosion using remote sensing and GIS: a case study of Indravati catchment

Soil erosion is a serious environmental problem in Indravati catchment. It carries the highest amount of sediments compared with other catchments in India. This catchment spreading an area of 41,285 km² is drained by river Indravati, which is one of the northern tributaries of the river Godavari in its lower reach. In the present study, USLE is used to estimate potential soil erosion from river Indravati catchment. Both magnitude and spatial distribution of potential soil erosion in the catchment is determined. The derived soil loss map from USLE model is classified into six categories ranging from slight to very severe risk depending on the calculated soil erosion amount. The soil erosion map is linked to elevation and slope maps to identify the area for conservation practice in order to reduce the soil loss. From the model output predictions, it is found that average erosion rate predicted is 18.00 tons/ha/year and sediment yield at the out let of the catchment is 22.30 Million tons per annum. The predicted sediment yield verified with the observed data.     

GIS and ANN-based spatial prediction of DOC in river networks: a case study in Dongjiang, Southern China

This paper investigates the use of an artificial neural network (ANN) model to predict dissolved organic carbon (DOC) in a river network and evaluates the impacts of watershed characteristics on stream DOC. Samples and relevant environmental variables were obtained from field sampling at 28 hydrological response units (HRUs) and a MODIS/SRTM DEM satellite image. HRUs can provide reliable spatial interpolation for filling data gaps and incorporate potential spatial correlation among observations in each ANN neuron. The process and results of neural network modeling were assessed by deterministic and statistical methods and spatial regression kriging. The spatial prediction results show that ANN, using improved back propagation algorithms of 7-15-1 architecture, was the optimal network, by which predictions maintained most of the original spatial variation and eliminated smoothing effects of RK. The sum of the relative contributions of four sensitive variables, including soil organic carbon density, geographic longitude, surface runoff and Chl a in river water, was >75 %. A minor prediction error of ~6 % was found in HRUs of open shrublands, but HRUs of urban and croplands had an error of 24–30 %. This pattern exemplifies anthropogenic impacts in urban areas on stream DOC and agricultural activities in croplands. The usefulness of ANN modeling-based GIS in this study is demonstrated by depiction of spatial variation of stream DOC and indicates the benefits of understanding sensitive factors for watershed impact assessments.     

Occupational transitions in three coastal villages in Central Java, Indonesia, in the context of sea level rise: a case study

The transition from one system to another as a mechanism of adaptation to an external disturbance is widely discussed in terms of ‘regime shifts’ in resilience research. But occupational transitions by communities due to coastal hazards such as coastal erosion and strong waves have not been studied in depth from a systems perspective. Such a perspective can contribute towards a better understanding of the process and pattern behind transformation among coastal societies. The present case study of coastal occupational communities in Central Java province, Indonesia, includes fishers, brackish pond farmers and labourers. It investigates the historical occupational transitions and the factors that drive them. The study draws on Participatory Rural Appraisal exercises such as historical timeline analysis and participatory discussions along with a socio-economic survey to study the factors and processes that led these communities to transitional pathways. Historical narratives of the community reveal the significance and influence of livelihood capitals such as social, human, financial, physical and natural capital in the transitions. Through the ‘Marble and Cup’ conceptual framework of the systems transitions, the irreversibility of occupational transitions due to the destruction of natural assets is outlined. This depicts a multi-locale and one-dimensional transition to a singular occupational mode (essentially labourers) in the face of a disturbance like sea level rise, necessitating transformation and building of the livelihood capitals across geographical scales.