DOI: 10.17014/ijog.4.1.1-10 A groundwater study has been conducted in the Semarang City in August 2014, aiming to determine the source of shallow groundwater salinization using stable isotopes (18O, 2H) and water chemistry approach, and supported by local hydrogeological data. A number of shallow groundwater samples were taken at several locations with a depth of 0 - 35 m. Based on geological data, shallow groundwater of Semarang alluvium is dominated by insertion of sand-gravel and sandy-clay with average porosity of around 56.0 %. This layer is thinning towards the south and then increasingly thickening to the north and north-east of the studied area. The results of the analyses show that the characteristics of shallow groundwater, i.e. approximately 51% of groundwater, still have the original composition as meteoric water and the remaining approximately 49% obtained a shift in the isotopic composition as caused by interaction with seawater and the little influence of evaporation. The results of chemical analysis of water indicates that in dry seasons, shallow groundwater aquifers in the Semarang City is dominated by chloride (Cl-) with NaCl of water type. While the parameters of bicarbonate, chloride, and Na/Cl ratio, shallow groundwater can be classified into two groups, namely unintruded groundwater around 51% spread from the foot hills to the south towards the hills with elevations of 9 - 142 m above sea level and intruded groundwater around 49% spread from the coastline to the urban direction.

Bandung is a densely populated and rapidly growing city, especially in the Northern Area, with many rivers flowing through it. Infrastructure development if not taken into account the geo hazard potential of the river can cause disaster to occur resulting in damages and casualties. The inundation named “Cileuncang Flood” periodically occurred in the rainy season. Landslide disaster also occurred in 2015 at Mekarsaluyu, Cimenyan and Bukit Dago Selatan. This study explores the phenomena that occurred in the region. The research objectives are to: identify geological conditions contributing to geo hazard, conduct geo hazard assessment in the area and recommend mitigation activities. Research area ranges from Sekeloa to Bojongkoneng, where there are three rivers: Cirapohan, Cidurian, and Cilimus. The research method used mixed method, field observation and desk study (secondary data). Geospatial data and geological field observation was conducted. Lithology layers coring well data was used to determine the detailed geological condition and characteristic. Research results show geological condition that can trigger disaster. There are some locations, which have disasters in the past, this occurrence is connected with geological conditions to determine the potential disaster that may occur in the future. The first site is located on the western part of the Cidurian river consisted of Cikidang Formation. Geo hazard that occurred in this zone is flood. Second site is located on the eastern part of the Cidurian river, has the presence of volcanic eruption product. Geo hazard that can potentially occur in this zone is a landslide. The city stakeholder needs to conduct structural and nonstructural mitigation activities to reduce the risks.

The dry season in Indonesia has been studied in the context of its impact on rainfall extremes, with research indicating that the dry season rainfall extremes are strongly affected by IOD and ENSO (El Niño-Southern Oscillation). The impact of dry season in 2023 based on the data from the Meteorological, Climatological, and Geophysical Agency (BMKG ) mentioned that this dry season started from march to September 2023. Java Island, whose land area is only 138,379 km² or 7 (seven) percent of Indonesia's area, has a very important position because it is crowded by 65 percent of Indonesia's population or an average of 864 people / km² and contributes to GNP of 60 percent. This article aims to review the water resources in Java Island in Indonesia during the dry season in 2017 to 2023. That causes the lack of water resources has become the main problem in some area in Java Island in Indonesia. This research result assesses the water resources during the dry season, the technique, the method, and the findings. There are 287 articles found only from Scopus sources, 40 article reviewed, and only 5 articles have been matched to the topic by using Prisma P. process. Finally, the result shows that one aspect that remains unclear about Indonesia's dry season is how exactly climate change influences its duration and intensity. While it's known that Indonesia undergoes a dry season, the specific impacts of climate change on factors like rainfall patterns, temperature, and the occurrence of extreme weather events are not fully grasped. This lack of understanding presents challenges for planning agriculture, managing water resources, and conserving ecosystems in the region.

Rancaekek and Sayang area, West Java, are the area where many industrial factories are located.Thus, the region becomes the targeted destination for industrial development.The population in the area is rising due to the growth of industries causing the regional development becomes uncontrollable. In addition, the constant increment of waste and also poor-coordinated disposal systems may result in groundwater contamination in the areas. The rapid growth of the area increase the need for groundwater as well as the need for more research about contamination at Rancaekek and Sayang. The research aims to explore the spread of groundwater contamination in the area. The research method is carried out based on the analysis of Geological Mapping, Hydrogeological Mapping and chemical characteristics of the groundwater in the area. Chemical analyses of the groundwater were conducted through laboratory test of groundwater samples at specific spots of dug wells. The lab test results were further analyzed to determine the contamination zone. The findings reveal that the distribution of contamination in the area follow the shallow ground water flow patterns, the water contamination contains heavy metal and there is degradation of soil fertility. The findings suggest the stakeholders to delineate the contaminated area, and increase the dissemination of environmental awareness.

Tourism offer high economic benefits for Indonesia, but at the same time it can cause a decline in environmental conditions. Extensive travel using transportation vehicles and human interaction with nature can damage local ecosystems and contribute to global climate change. Nowadays, more and more stakeholder in tourism are concerned about environmental issues and they often search for a green tourist destination. The tourism stakeholder has proactive efforts to address important issues such as carbon emissions, biodiversity, conservation, waste management, and water supply. They have notice that tourists preferences about what activities they will do during their vacation, preference on transportation and lodgings. Green tourism has not been well promoted to international tourist compared to other countries. The purpose of this research is to describe the preferences to visit green destinations in Indonesia. The study is descriptive type of research and has conducted an FGD on green tourism stakeholders. The results showed stakeholders viewed tourists to have preference for green tourism destination in Indonesia.