Suitable Proportion Sample of Holdout Validation for Spatial Rainfall Interpolation in Surrounding the Makassar Strait

Spatial rainfall interpolation requires a number of suitable validation samples to maintain accuracy. Generally, the larger the areas which can be predicted, the better the interpolation. In addition, the data used for validation should be separated from the modelling data. Moreover, the number of samples determine optimally proportion the independent sites. The objective of this study is to determine the optimal sample ratio for holdout validation in interpolation methods; the Makassar Strait was chosen as the study location because of its daily rainfall variation. The accuracy of the sample selection is tested using correlation, root mean square error (RMSE), mean absolute error (MAE) and the indicators of contingency tables. The results show that accuracy depends on the ratio of the modelling data. Therefore, the more extensive the data used for interpolation, the better the accuracy. Otherwise, if the rain gauge data is separated according to province, there will be a variation in accuracy in the portion of independent samples. For rainfall interpolation, it is recommended to use a minimum 75% of data sites to maintain accuracy. Comparison between kriging and inverse distance weighting or IDW methods indicates that IDW is better. Moreover, rainfall characteristics affect the accuracy and portion of the independent sample

Comparison of Land Surface Temperature During and Before the Emergence of Covid-19 using Modis Imagery in Wuhan City, China

Coronavirus disease (COVID-19) was firstly identified in Wuhan, China. By 23rd January 2020, China’s Government made a decision to execute lockdown policy in Wuhan due to the rapid transmission of COVID-19. It is essential to investigate the land surface temperature (LST) dynamics due to changes in level of anthropogenic activities. Therefore, this study aims (1) to investigate mean LST differences between during, i.e., December 2019 to early March 2020, and before the emergence of COVID-19 in Wuhan; (2) to conduct spatio-temporal analysis of mean LST with regards to lockdown policy; and (3) to examine mean LST differences for each land cover type. MODIS data consist of MOD11A2 and MCD12Q1 were employed. The results showed that during the emergence of COVID-19 with lockdown policy applied, the mean LST was lower than the mean LST of the past three years on the same dates. Whereas, during the emergence of COVID-19 without lockdown policy applied, the mean LST was relatively higher than the mean LST of the past three years. In addition, the mean LST of built-up areas experienced the most significant differences between during the emergence of COVID-19 with lockdown policy applied in comparison to the average of the past three years

Comparison of Total Suspended Particulate (TSP) Measurement in Urban and Suburban Areas of Bali during Nyepi Day 2015

Nyepi or the Balinese Day of Silence (DOS) is a day when people celebrate every New Year according to the Balinese calendar (Saka). On that day, all resident activities were very restricted, with no outdoor activities. This event, which only lasted for 24 hours, is a unique period to conduct air quality measurements such as Total Suspended Particulate (TSP) for assessing the influence of human activities. This study only focuses on TSP monitoring before, during and after the DOS and its comparison with the meteorological data. TSP concentration measurements were conducted in 2 urban areas (Badung and Ubung) and a sub-urban area (Singaraja) from March 17 to March 25, 2015. The results show that TSP concentrations are negatively correlated with temperature and wind speed at each location. Hourly TSP concentrations during DOS are lower than the averaged TSP concentrations before and after DOS. During DOS, TSP concentrations decreased significantly in urban areas by 73-78% relative to regular days, which is likely due to drastically decreasing of human activities. In suburban areas, the decrease of TSP concentration was about 59%. These results show that human activities highly influence the air quality

Spatial Distribution of Drifted-wood Hazard following the July 2017 Sediment-hazards in the Akatani river, Fukuoka Prefecture, Japan

In recent years, heavy rainfall leading to floods, landslides and debris-flow hazards have had increasing impacts on communities in Japan, because of climate change and structural immobilism in a changing and ageing society. Decreasing rural population lowers the human vulnerability in mountains, but hazards can still leave the mountain to the plains and sea, potentially carrying drifted-wood. The aim of the paper is to measure the distribution of wood-debris deposits created by the 2017 Asakura disaster and to rethink the distribution and spatial extension of associated disaster-risk zoning. For this purpose, the authors: (1) digitized and measured the distribution of drifted-wood, (2) statistically analyzed its distribution and (3) calculated the potential impact force of individual drifted timber as a minimal value. The results have shown that there is a shortening of the wood debris as they travel downstream and that the geomorphology has an important control over deposition zones. The result of momentum calculation for different stems’ length show spatially differentiated hazard-zones, which limit different disaster-risk potentials. From the present finding, we can state that we (1) need to develop separate strategies for sediments and wood debris (2) and for wood hazards, zonations can be generated depending on the location and the size of the deposited trees that differs spatially in a watershed

The Compatibility of a GIS Map of Landslide-Prone Areas in Kendari City Southeast Sulawesi with Actual Site Conditions

Kendari is the capital of the Indonesian province of Southeast Sulawesi. It is located on mainly the karst hills region with high rainfall and there were numerous human activities on the karst hills. Many landslides have occurred in these areas. Natural and human factors may contribute to the landslide. The purpose of this study was to determine whether the present GIS map of landslide-prone areas was in agreement or compatible when compared to the actual site conditions in Kendari City. This research is mainly a regional survey. Data was collected through direct interview and observation at the sites. Data were analyzed quantitatively with percentages. The results showed that 87.4% of the area in Kendari City as shown in the map of landslide-prone distribution using GIS was included in the low risk or slightly vulnerable category. The category of landslide-prone areas was divided into; Very low risk, Low, Medium, High risk and Very high risk which represents the less vulnerable areas to the very vulnerable areas. The level of compatibility of landslide-prone maps in Kendari City, when compared with actual site conditions, reaches 75%. This shows that the map of the GIS spatial analysis can be used as a guide in mapping the level of landslide vulnerability in Kendari City. Landslide-prone map may be used as a guideline for engineers, designers, planners, and city officials in planning to reduce the risk of potential disaster

Analysis of Local Spatial Data Infrastructure to Support Volcanic Mudflow Mitigation along Putih River, Magelang Regency, Central Java Province, Indonesia

One of the most devastating disasters in Indonesia was the Mount Merapi eruption in 2010. After the eruption there still exists the secondary hazard of volcanic mudflow, which has caused damage and casualties. Volcanic mudflow is a mixture of pyroclastic material and rainwater, meaning that in the rainy season the area along rivers becomes a high volcanic mudflow hazard, including the area along Putih River in Magelang Regency, Central Java Province. The development of Spatial Data Infrastructure (SDI) plays an important role in disaster management, especially in disaster mitigation efforts. Building an SDI which shares information on spatial conditions in the area along the Putih River could save many lives and reduce the risk from volcanic mudflow. This research was conducted employing interview surveys, field surveys and secondary data collection at government institutions. The results of the analysis have provided a geoportal prototype as an information gateway for the mitigation of volcanic mudflow along the Putih River and the reduction of disaster risk both for the government and community

Comparison of Land Surface Temperature During and Before the Emergence of Covid-19 using Modis Imagery in Wuhan City, China

Coronavirus disease (COVID-19) was firstly identified in Wuhan, China. By 23rd January 2020, China’s Government made a decision to execute lockdown policy in Wuhan due to the rapid transmission of COVID-19. It is essential to investigate the land surface temperature (LST) dynamics due to changes in level of anthropogenic activities. Therefore, this study aims (1) to investigate mean LST differences between during, i.e., December 2019 to early March 2020, and before the emergence of COVID-19 in Wuhan; (2) to conduct spatio-temporal analysis of mean LST with regards to lockdown policy; and (3) to examine mean LST differences for each land cover type. MODIS data consist of MOD11A2 and MCD12Q1 were employed. The results showed that during the emergence of COVID-19 with lockdown policy applied, the mean LST was lower than the mean LST of the past three years on the same dates. Whereas, during the emergence of COVID-19 without lockdown policy applied, the mean LST was relatively higher than the mean LST of the past three years. In addition, the mean LST of built-up areas experienced the most significant differences between during the emergence of COVID-19 with lockdown policy applied in comparison to the average of the past three years

Local Wisdom to Overcome Covid-19 Pandemic of Urug and Cipatat Kolot Societies in Bogor, West Java, Indonesia

Local wisdom can be interpreted as principles of life, behaviour, rules, and punishments, as well as a view of life that regulate life, so that it can regulate and managing natural resources in the natural, social, and economic environments. Even local knowledge have adapted to environment obstacle. This research aims to investigate traditionally local knowledge for confronting Covid-19 pandemic. The method used is qualitative with an ethnography approach and literature review. Data are collected through in-depth interviews with leaders of Urug and Cipatat Kolot societies. In order to investigate Baduy and Ciptagelar communities used a literature review. Data are supported by documentation and observation sources. The sample is selected using a purposive sampling technique. The result is analysed through triangulation, which is by mixing some gathered data methods. The result is that Urug society allocates rice each year from their paddy yields to the vulnerable groups such as orphans, elderlies, widows, and persons need most. Secondly, collective action is used to jump the capacity of people like women through nujuh bulanan. Thirdly, societies exert taboo to combat disaster and Covid-19, including by prohibiting community from trading paddies and rice. Another finding is that indigenous knowledge uses some life strategies and utilizes natural capital optimally for overcoming life perturbances. The last finding is that local knowledge has preserved agriculture jobs as a venue to survive

Remote Sensing Imagery and GIS for Monitoring the Pyroclastic Material of Mount Sinabung

The purpose of this study was to determine the extent of changes in land cover around the Mount Sinabung area after the 2009-2019 eruption by monitoring through remote sensing imagery and GIS. The method used in this research is descriptive quantitative. The technique of data collection used document study techniques by collecting Landsat images are among the widely used satellite remote sensing data and their spectral, spatial and temporal resolution made them useful input for mapping and planning projects (Sadidy et al. 1981). Changes in land cover that occurred around the Mount Sinabung area were dominated by pyroclastic material due to eruption. In addition, changes in land cover also occur due to the abandonment of potential lands, such as local residents who work in the plantation sector are forced to leave that, so they eventually turn into shrubs. The direction of the dominant pyroclastic material slides was directed towards the east-south and southeast of Mount Sinabung, where the area was dominated by the plantation sector. The impact of the eruption of Mount Sinabung was directly and indirectly. The total land cover changes due to pyroclastic material in 2010 was an area of 26.27 Ha, in 2014 it was 475.82 Ha, 2017 was 1339.75 Ha, and 2019 was 1196.11 Ha

The Role of Decision Making for Family Activities by Industrial Labour of Women Migrant Based on Their Migration Characteristics

The presence of women migrants in urban industrial workers proved that women's movement exists. This migration process not only indicates that women are actively involved in economic activity, but also influences the decision-making on important activities within the family and society. This study aims to determine the relationship between mobility patterns and its contribution to economic and decision-making in the family through the survey as research methods. The data were analysed by descriptive analysis, statistics approach, and correlation maps. For the independence test in the bivariate table, we used the chi square method, and to display the distribution of two variables simultaneously, a cross-tabulation was used. After that, to assess whether there is a relationship between the two variables, the table of independence was used. Our study shows that decision-making became an indicator of strengthening the role of women with a pattern of circular migration, which has a relationship on economic contribution. However, the behavior of women who perform the spatial migration in strengthening roles in families is not always relevant with the strengthening role of the economy. A strong role is only demonstrated by industrial migrant workers working on a circular migration pattern