Groundwater Vulnerability to Pollution in Kasihan District, Bantul Regency, Indonesia

The groundwater vulnerability to pollution refers to the ease of pollutants reaching groundwater, so the groundwater will be polluted. The concept shows a probability that pollution will occured which basically bases on the assumption that the physical environment can prevent the flow of pollutants into the aquifer. The purpose of this study was to predict the vulnerability of groundwater in the study area against pollution. To achieve these objectives beside base on secondary data, also measured the depth of phreatic surface, slope and groundwater sampling. Location of measurement and sampling is determinated by considering location of infiltration measurement ever done by Purnama in 2017. To conduct groundwater vulnerability analysis on pollution in the study area, carried out by SINTACS Method which bases on a numerical system of weight and rating. Weight are determined based on the significance of the effect of the parameters on groundwater pollution, while the rating is determined based on the significance of the influence of variables in each parameters against groundwater pollution. As a result, it is known that groundwater vulnerability indeks in research area range from 117,0 to 189,9. According to criteria of SINTACS, the value are classified as moderate vulnerability and rather high vulnerability. Areas that include moderate levels of vulnerability generally located in Sentolo Formations that consist of limestone and has grumusol soil type. Areas that classified as rather high vulnerability is located in Yogyakarta Formation that consist of volcanic rock and has regosol soil type. Based on this phenomena, it can be said that geological aspect and type of soil greatly affect the vulnerability of groundwater to pollution in the research area

Evidence Based Landslide Hazard Mapping in Purworejo using Information Value Model Approach

Purworejo District, which is located in Central Java, Indonesia, is prone to landslides. These are a natural hazard that often occur in mountainous areas, so landslide hazard analysis is needed to develop mitigation strategies. This paper elaborates on the use of an evidence-based statistical approach using the Information Value Model (IVM) to conduct landslide hazard mapping. The parameters of slope, aspect, elevation, rainfall, NDVI, distance from rivers, distance from the road network, and distance from faults were employed for the analysis, which was conducted based on a raster data environment, since the pixel is the most appropriate means to represent continuous data. Landslide evidence data were collected by combining secondary data and interpreting satellite imagery to identify old landslides. The IVM was successfully calculated by combining factors related to disposition to landslides and data on 19 landslide occurrences. The results helped produce a landslide susceptibility map for the northern and eastern parts of Purworejo District

Spatial Analysis of Land Degradation Susceptibility and Alternative Plants for Its Rehabilitation

One of the drawbacks of developing plants for the rehabilitation of degraded land in Indonesia is the relative lack of information about species that are suited to the local conditions. Therefore, spatial information on land degradation and the plants suitable for rehabilitation is crucial. The objectives of this study were to map the susceptibility of land to degradation and to identify some alternative species for its rehabilitation. The research was conducted in Jang Watershed, Bintan Island, Kepulauan Riau Province, Indonesia. A quick assessment of land degradation was carried out to classify the degree of land susceptibility. The land suitability evaluation was conducted manually by matching the existing biophysical condition and plant growth requirements using a geographic information system. This analysis was applied for annual plants, such as Acacia mangium, Durio zibethinus, Artocarpus champeden, Theobroma cacao and Hevea brassiliensis. Furthermore, the maps of land susceptibility to degradation and species suitability were overlaid and the result was used to provide recommendations for rehabilitating the degraded land. This study showed that 22% of the Jang Watershed area can be categorised as highly susceptible to degradation. The suitability analysis illustrated that 59% of the degraded areas were suitable for Acacia mangium. The planting of fast-growing species such as Acacia mangium is expected to improve the physical, chemical and biological properties of the soil

Evidence Based Landslide Hazard Mapping in Purworejo using Information Value Model Approach

Purworejo District, which is located in Central Java, Indonesia, is prone to landslides. These are a natural hazard that often occur in mountainous areas, so landslide hazard analysis is needed to develop mitigation strategies. This paper elaborates on the use of an evidence-based statistical approach using the Information Value Model (IVM) to conduct landslide hazard mapping. The parameters of slope, aspect, elevation, rainfall, NDVI, distance from rivers, distance from the road network, and distance from faults were employed for the analysis, which was conducted based on a raster data environment, since the pixel is the most appropriate means to represent continuous data. Landslide evidence data were collected by combining secondary data and interpreting satellite imagery to identify old landslides. The IVM was successfully calculated by combining factors related to disposition to landslides and data on 19 landslide occurrences. The results helped produce a landslide susceptibility map for the northern and eastern parts of Purworejo District

A Comparative Study of various Indices for extraction urban impervious surface of Landsat 8 OLI

Impervious surface is one of the major land cover types of urban and suburban environment. Conversion of rural landscapes and vegetation area to urban and suburban land use is directly related to the increase of the impervious surface area. The impervious surface expansion is straight-lined with decreasing green spaces in urban areas. Impervious surface is one of indicator for detecting urban heat islands. This study compares various indices for mapping impervious surfaces using Landsat 8 OLI imagery by optimizing the different spectral characteristics of Landsat 8 OLI imagery. The research objectives are (1) to apply various indices for impervious surface mapping and (2) identifies impervious surfaces in urban areas based on multiple indices and provide recommendations and find the best index for mapping impervious surface in urban areas. In addition to utilizing the index, land use supervised classification method, maximum likelihood classification used for extracting built-up, and non-built-up areas. Accuracy assessment of this research used field data collection as primary data for calculating kappa coefficient, producer accuracy, and user accuracy. The study can also be extended to find the land surface temperature and correlate the impervious surface extraction data with urban heat islands

Tourist Attraction Popularity Mapping based on Geotagged Tweets

The development of tourist attractions is now highly influenced by social media. The speed at which information can be disseminated via the Internet has become an essential factor in enabling distinct tourist attractions to potentially gain high popularity in a relatively short time. This condition was not as prevalent several years ago when tourism promotion remained limited to a certain kind of media. As a consequence, rapid change in the relative popularity of tourist attractions is inevitable. Against this, knowledge of tourist attraction hotspots is essential in tourism management. This means there is a need to study how to both quickly determine the popularity level of tourist attractions and encompass a relatively large area. This article utilised tweet data from microblogging website Twitter as the basis from which to determine the popularity level of a tourist attraction. Data mining was conducted using Python and the Tweepy module. The tweet data were collected at the end of April and early May 2017, at times when there are several long holiday weekends. A Tweet Proximity Index (TPI) was used to calculate both the density and frequency of tweets based on a defined search radius. A Density Index (DI) was also used as a technique for determining the popularity. The results from both approaches were then compared to a random survey about people’s perceptions of tourist attractions in the study area. The result shows that geotagged tweet data can be used to determine the popularity of a tourist attraction, although it still only achieved a medium level of accuracy. The TPI approach used in this study produced an accuracy of 76.47%, while the DI achieved only 58.82%. This medium accuracy does indicate that the two approaches are not yet strong enough to be used for decision-making but should be more than adequate as an initial description. Further, it is necessary to improve the method of indexing and the exploration of other aspects of Twitter data

Groundwater Vulnerability to Pollution in Kasihan District, Bantul Regency, Indonesia

The groundwater vulnerability to pollution refers to the ease of pollutants reaching groundwater, so the groundwater will be polluted. The concept shows a probability that pollution will occured which basically bases on the assumption that the physical environment can prevent the flow of pollutants into the aquifer. The purpose of this study was to predict the vulnerability of groundwater in the study area against pollution. To achieve these objectives beside base on secondary data, also measured the depth of phreatic surface, slope and groundwater sampling. Location of measurement and sampling is determinated by considering location of infiltration measurement ever done by Purnama in 2017. To conduct groundwater vulnerability analysis on pollution in the study area, carried out by SINTACS Method which bases on a numerical system of weight and rating. Weight are determined based on the significance of the effect of the parameters on groundwater pollution, while the rating is determined based on the significance of the influence of variables in each parameters against groundwater pollution. As a result, it is known that groundwater vulnerability indeks in research area range from 117,0 to 189,9. According to criteria of SINTACS, the value are classified as moderate vulnerability and rather high vulnerability. Areas that include moderate levels of vulnerability generally located in Sentolo Formations that consist of limestone and has grumusol soil type. Areas that classified as rather high vulnerability is located in Yogyakarta Formation that consist of volcanic rock and has regosol soil type. Based on this phenomena, it can be said that geological aspect and type of soil greatly affect the vulnerability of groundwater to pollution in the research area

Preliminary Assessment of Morphometric and Hydrological Properties of Six Watersheds in the Eastern Part of East Java

A hydrological process on the watersheds is driven by rainfall as the input. Physical properties  also affect the magnitude response of the watershed to produce run-off. This paper presents the identification, assessment and visualisation of morphometric and hydrological properties of the watersheds.  Six watersheds in the eastern part of East Java were used for the analysis.  Physical characteristics obtained by cropping the GIS layer with a watershed. Topographic and morphometric properties of the watersheds derived from the ASTER G-DEM2. Furthermore, hydrological properties are derived statistically by analysing available rainfall and discharge data. Hydrological data (rainfall and discharge) are available from 1996 – 2014.  Finally, simple statistical analysis by plotting obtained values are used to interpret the relation between morphometric and hydrological properties of the watersheds. The results show the quantitative number (unit) to describe the morphometric and hydrological properties of the six watersheds that can be used for watershed classification

Rapid Mapping for Simple Flood Mitigation Using Commercial Drone at Way Galih Village, Lampung, Indonesia

The process to alleviate flood risk, especially flood from a river that occurs excessively in Indonesia, requires a new approach. The attempt to reduce the risk along with the development of technology is by utilising commercial drones and rapid mapping methods for mapping flood plain area. With the rapid mapping method, the flood mitigation process in the village area can be done quickly. The activity carried out was to map the location of possible flooding in the Way Galih Village and case analysis to determine the location of the biogas digester together with the village government authority. The results of the study show that the data acquisition process and aerial photo processing can be carried out within one day and the village policymaker can quickly make policies and decisions about where to place the biogas digester