Indonesian Journal of Geography
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Exploring Aceh Fault Zone for Slip Rates and Paleoseismic Trenching Potential along Sumatran Fault
Full text linkWe conducted a study on the Aceh Fault, an active right-lateral strike-slip fault in northern Sumatra, Indonesia. Despite its seismic hazard potential, the slip characteristics of this fault are not well-understood. Using a combination of remote sensing and field methods, we mapped the distribution of displacement recorded by offset channels along the fault. Our goal is to identify evidence of past surface rupture, characterize their tectonic geomorphology setting, and assess their potentials as slip-rate and paleoseismic sites. The documented right-lateral displacements of channels and ridges from 35 observation points are mostly in the order of magnitude of hundreds of meters, with only a few sites exhibiting meter-scale measurable offsets. Our results provide important first-order data that can be used to locate sites suitable for paleoseismic trenching or offset investigations. This information will support the development of a maximum magnitude and earthquake recurrence model of the fault, which are crucial for seismic hazard analysis in the region
The Preliminary Sedimentation Pattern Study in West Borneo NPP Potential Site
Full text linkCoastal environmet dynamics study is one of the NPP site feseability studies that need to be conducted to understand the potential external risk in an NPP development. The Pantai Gosong area was the preferred potential site for the NPP development and was located in the coastal area. Therefore, external factors such as abrasion or sedimentation would influence the NPP site. This research studied the sedimentation pattern of the Pantai Gosong coastal area based on the landform analysis. The results showed that the landform in the Pantai Gosong area was classified as a highly eroded hill, lowly eroded footplain, natural levee-back swamp, beach ridge, alluvial plain, and coastal alluvial plain. The sedimentation process in the northern coastal area of Pantai Gosong that has lowly eroded footplain landform was more intense than in the southern part. The analysis was well correlated with the estimated sediment thickness from the microtremor method analysis that showed that the northern coastal area has higher sediment deposits with 12.7 to 21.7 m of thickness than the southern coastal area with 3.2 to 12.6 m thickness. The northern footplain in the Pantai Gosong coastal area was expected to have higher sedimentation than the southern part continuousl
Dynamics of the Morphological Changes in the Progo River Due to Lahar Transport from Merapi Volcano
No full textThe Merapi eruption in 2010 and 1975 caused lahar floods on the Progo River segment in Kulon Progo. This study aims to analyze the dynamics of river morphology changes that are affected by two lahar floods. Temporal images representing the two lahar flood events up to several years later were used to see river morphology changes. Temporal data from remote sensing and UAV is able to indicate the morphological change of river valleys in the study area. The analysis was carried out based on the parameters of river slope, riverbank morphology, and river curvature. The river slope is 0.74% which means the slope is flat. This condition gives a consequence of the river's meandering morphology. The morphology of the riverbank has the "U" shape, providing more surface area for river water to drain. The sinuosity ratio (SR) is dynamic during two lahar flood periods. In the 2010 lahar flood period, the SR pre-lahar flood was 1.92, increased significantly to 2.65 eight months post-lahar flood, and decreased significantly to 1.60 one year later. Lahar floods are the main factor causing these dynamics in this period. The annual SR for the next ten years is always changing but the fluctuations are more stable and tend to decrease. The SR's fluctuations in this period provide evidence that the river morphology is always changing even without major triggers. In the 1975 lahar flood period, the SR value was known from the PBB maps three years pre-events, five years post-events, and Google Earth images ten years post-events. The SR in this period fluctuated, and the meander became simpler at ten years post-events. The results of this paper provide evidence that spatial analysis with temporal images is more efficient and economical for studying river morphological dynamics
Coastal Vulnerability Assessment to Tidal (ROB) Flooding In Indramayu Coast, West Java, Indonesia
Full text linkAquaculture practices in developing countries, particularly Indonesia, are currently operating without effective control measures, leading to high tidal and other climate-related issues. Therefore, this study aimed to modify Coastal Vulnerability Index (CVI) assessment to evaluate the physical vulnerability of coastal areas in Indramayu Regency, West Java (62 sections) to tidal flooding (Rob). A total of 6 primary characteristics, including geomorphology, beach slope, water level rise sea, coastline alterations, tidal range, and high tide, as well as 2 additional parameters, namely land cover and mangrove breadth, were used for analysis. Based on the evaluation, CVI was divided into four groups, including (1) low, (2) moderate, (3) high, and (4) very high. The results showed that Indramayu District struggled to recover from tidal flooding, with 24.56%, 22.13%, 41.03%, and 12.28% being placed in the very high, high, moderate, and low categories. This underscored the role of local governments in improving coastal communities' capacity to respond to tidal flooding disasters. Furthermore, the results were expected to be used by local governments to enhance disaster mitigation systems, particularly for coastal areas in developing nations with comparable ecological conditions
GIS-Based Assessment of Best Route in Complex Traffic Environment: A Case of Kolkata Municipal Corporation
Full text linkIn an emergency like an urban fire, road accident, or critical condition of patients, the shortest possible route to reach the destination is one of the most sought-after issues in transportation studies. However, the physical distance of the shortest route becomes longer distance than the travel time distance due to traffic congestion in metropolitan cities like that of Kolkata. So, the selection of an alternative route is essential to organize the journey logically. A well-structured road network provides multiple options to road users for selection of the best route from the shortest and alternative route according to their demand. So, the present study aims to identify the structural characteristics of road networks by graph theory and the selection of the best route using the GIS technique. It has been found that the road network of Kolkata is characterized by complex structure and grid configuration of the network. Selection of the best route also ranges from the shortest route to alternative route due to spatial variation of traffic speed on different roads in peak hours. The current study identifies the optimal route in terms of travel time to reach the required destinations during peak hour duration in the city of Kolkata
The Impact of Land Use Change on Groundwater Depth in The Groundwater Transition Zone of Merapi Volcano, Yogyakarta, Indonesia
Full text linkStudies of the impact of land use change on groundwater on the southern slopes of Merapi Volcano tend to be carried out on a macro basis. Micro studies, especially in groundwater transition zones, have not been previously conducted. In-depth studies need to be undertaken in the groundwater transition zone on the southern slope of Merapi Volcano to identify the impact of land use change on the dynamics of groundwater depth in 2012-2021. Data was collected through field surveys and remote sensing. Groundwater depth data were collected through field surveys in 2012 and 2021. Groundwater depth data were measured in dug wells. The location of the excavated well was determined by using the systematic random sampling method. Groundwater depth data were analyzed using the kriging spatial interpolation method. The results of groundwater depth interpolation in 2012 and 2021 were then compared to determine the changes. Rainfall data were also used in the study. Rainfall data were collected using remote sensing data through cloud computing. Literature studies related to the condition of monitoring wells were also used to determine groundwater dynamics based on rainfall conditions. Data on land use change for 2012-2021 were collected using remote sensing data. Land use change was analyzed using pansharpening, supervised classification, and overlay methods. Cross-tabulation analysis was performed to determine the impact of land use change on groundwater depth. The groundwater depths in the study area were classified into 11 m. Changes in land use from irrigated rice fields to settlements and open land to scrub occurred predominantly in the study area. Changes in land use did not have a significant impact on changes in groundwater depth in the study area. Based on cross-tabulation analysis, it is known that 11.46% of the study area experienced groundwater deepening, 7.73% experienced groundwater siltation, and 80.81% experienced no change in groundwater depth in the period of 2012-2021. Groundwater deepening generally occurs in areas dominated by scrub and settlements far from river channels. Groundwater that grows shallower and does not change in depth occurs around irrigated rice fields close to river channels. Land use change that does not significantly impact groundwater depth is likely to occur because rainfall in the study area is high. The aquifer material in the study area also had an excellent ability to drain groundwater coming from the upper slopes of Merapi Volcano
Utilization of Satellite Imagery for Mapping the Distribution of Seagrass on Buhung Pitue Island
Full text linkBuhung Pitue Island has seagrass beds those which are spread almost evenly along its coast. Research using remote sensing technology in an effort to support seagrass conservation in Indonesia needs to be carried out. Spatial data is relatively easy to obtain because there are many types of images with various spatial resolutions. The image can be obtained on google earth. Analysis of the distribution of seagrass areas was obtained by digitizing on screen in ArcGIS software, namely in seagrass areas where the boundaries are known. Digitizing is conducted by enlarging the seagrass area in the downloaded image, performing radiometric and geometric corrections, and digitizing to create a shapefile (shp) storing the location, shape, and attributes of geographic features. The seagrass distribution area of Buhung Pitue Island was of 36.5 Ha in 2014 and was of 39.6 in 2021. The rate of change in area from 2014 to 2021 was of 0.085% (an increase of 3.1 ha). The distribution area of seagrass has increased due to natural factors and restrictions on human activities during the COVID-19 pandemic. In addition, another factor supporting the increase in seagrass distribution is the abundance of Enhalus acoroides seagrass species growing and spreading over long distances. The sea surface temperature was high, which was 30.37 °C, while the current speed was categorized as slow because it was around 0.01 m/s. Although the results are obtained from high-resolution imagery, an accuracy test still needs to be conducted
Contribution of Commuters and Transit Activities on The Road Transport Carbondioxides Emission in Surakarta
Full text linkRoad transportation became a main contributor to the emissions of Surakarta City. The driving factor for these conditions is predicted to originate from massive commuting and transit activities. This research covered the administrative area of Surakarta City in July–August 2022. The aim of the research was to determine the impact of commuting and transit on carbon dioxide (CO2) emissions from Surakarta transportation and develop a spatial interpretation of the distribution of emissions. The emission estimation method uses a Tier 3 calculation approach using the Mobilev software. Estimation based on average daily traffic data for 24 hours as well as the character of the monitored path. The results of the study obtained an estimate of road transportation emissions for the City of Surakarta to reach 722795.3 tons of CO2 peryear. Commuter and transit activities contribute to 50.33% of total major road emissions or 133.77% of local vehicle emissions. Commuter and transit emissions in Surakarta City are dominated by private passenger cars (38.26%) and motorcycles (37.71%). Emission distribution shows a pattern of emission load that is greater on the city gate and transit lines than the central business district (CBD) area
Estimating the contents of Chlorophyll, Nitrogen, and Yields on Rice through Sentinel-2 Vegetation Indices in Heterogeneous Land Management
Full text linkAddressing the global food demand is an urgent priority for governments worldwide. Efficient and effective methods for gauging crop production are crucial. Relying solely on ground-based measurements proves inefficient and expensive, prompting exploration of remote sensing using vegetation indices as a viable alternative. This study sought to achieve three objectives: estimating chlorophyll content in paddy fields, evaluating leaf nitrogen content, and predicting yields. The investigation utilized Sentinel-2A satellite imagery, Soil Plant Analysis Development (SPAD) for chlorophyll measurement, and employed statistical and accuracy analyses. Findings revealed an increase in chlorophyll and leaf nitrogen content from the vegetative to maturity phases, followed by a decline at maturity. NDVI and GNDVI emerged as superior to SAVI and VARI for chlorophyll estimation, attributed to their spectral sensitivity. Likewise, nitrogen prediction showed similar trends, with NDVI and GNDVI exhibiting better RMSE values compared to SAVI and VARI, albeit marginally. However, yield prediction accuracy varied, with NDVI proving most accurate, followed by SAVI, VARI, and GNDVI, indicating the latter's reduced predictive precision due to nitrogen sensitivity. In scenarios where nitrogen is not the predominant yield-limiting factor, NDVI could outperform GNDVI in forecasting yield. Received: 2023-07-22 Revised: 2024-04-18 Accepted: 2024-08-24 Published: 2024-10-10
Problems of Studying the Urbanization Process for Students of the Educational Program "Geography" in Kazakhstan
Full text linkThe study of the urbanization process by students of the educational program "Geography" in Kazakhstan is topical in the context of rapid urban development and evolutions in the geographical space of the country. Various key problems were revealed in the process of the studies such as the need for in-depth research of the theoretical foundations of urbanization, limited access to current data and no work experience on modern methods of data processing and analysis. An online survey was conducted on the basis of the Google Forms and the survey questions were worked out to have the further study of urbanization processes and update knowledge in this field. The study applied a data analysis method using the SPSS Base software package. This method provided the opportunities to structure and process the survey results among 331 teachers and master’s students. The approach ensured an accurate analysis and interpretation of the data which enabled to identify key trends and consistent patterns in respondents’ answers. The results point to both positive and negative conclusions based on the data. The conclusions were made on having evaluated the results with the help of SWOT analysis