Simulasi Hujan Lebat Pemicu Banjir Bandang Di Sub Das Sumbergunung Kota Batu Menggunakan Model WRF-ARW Skema Kessler Kain Fritsch

Peristiwa banjir bandang dipicu oleh curah hujan lebat. Dampak banjir bandang di Kota Batu tanggal 4 November 2021 mengakibatkan kerusakan harta benda, lahan pertanian, hancurnya permukiman masyarakat, matinya hewan ternak dan hilangnya nyawa manusia. Penelitian ini dilakukan di Sub DAS Sumbergunung Kota Batu, Jawa Timur dengan menggunakan model WRF-ARW skema mikrofisika Kessler dan skema cumulus Kain Fritsch. Data yang digunakan dalam penelitian ini adalah data GFS pada tanggal 30 Oktober 2021 dengan resolusi 0,25ox0,250 yang digunakan untuk memprediksi kejadian hujan hingga pada tanggal 4 November 2021.Verfikasi model dilakukan dengan menggunakan tabel kontingensi dan verifikasi menggunakan batas toleransi. Hasil penelitian ini menunjukkan bahwa model ini mampu memprediksi kejadaian hujan dan tidak hujan dengan sangat baik. Akan tetapi model ini belum cukup baik dalam memprediksi ketebalan hujan hingga pada tanggal 4 November 2021. Meskipun demikian, model ini mampu memprediksi hujan hingga 2 hari kedepan yakni hingga tanggal 1 November 2021. Kata kunci: banjir bandang; kota batu; parameterisasi; sub das sumbergunung; WRF-ARW DOI: http://dx.doi.org/10.23960/jpg.v11.i2.2770

Community Resilience to Climate Change in Agricultural Sector (Case Study of Sentolo Subdistrict)

Climate change has become a global issue over last decades. Its impact affects to various aspects of human life. Uncertainty of dry and wet seasons present a consequence to and create losses on agriculture sector. Therefore, resilience to climate change is necessary for farmers. This research aims to identify exposure, sensitivity, and adaptive capacity within the framework of community resilience to climate change in agricultural sector. Parameters used in this research include rainfall variability representing system exposure, landuse and topography representing sensitivity, and farmer’s knowledge and behavior representing adaptive capacity. Secondary data used in this research are daily rainfall data, land use and topographic maps, while primary data obtained by interview using purposive sampling method to measure adaptive capacity of farmers community. We employ trend, spatial, and descriptive analysis. The results show that Sentolo Subdistrict has a relatively high exposure to extreme events both in wet and dry seasons that occurred 5 times in 12 years. However, this high exposure did not affect agriculture sector on Sentolo significantly, both in terms of damages and losses to farmers. It indicates that the sensitivity to climate change in this area is low, while farmers’ community in Sentolo has a high level of adaptive capacity. They have sufficient level of knowledge to climate change, better adjustment to technology and well-managed assets. This interplay shows that the agricultural community in the study area has a relatively high resilience to climate change

Urban Green Space Analysis and its Effect on the Surface Urban Heat Island Phenomenon in Denpasar City, Bali

The Urbanization process in Indonesia’s big cities causes adverse environmental impacts such as climate change and land cover change. Urban climate change causes the warming of urban areas compared to rural areas; it is called Urban Heat Island phenomenon. Loss of vegetation due to urban development is one of several causes that contribute to urban heat islands. This study examines the availability of green spaces and their effects on the surface urban heat island in Denpasar city. This study used the spatial approach for Urban Green space mapping with digitizing methods. Landsat 8's thermal band is used for land surface temperature mapping and to conduct a spatial pattern analysis of the SUHI phenomena. The Global Moran’s Index and Local Indicator of Spatial Association (LISA) were used to determine the correlation between urban green space and SUHI. The study result shows that Denpasar City's urban green space area covers 28.22 km2. That's equal to 22.1% of the Denpasar City Administrative area. Denpasar Selatan district has the largest urban green space cover, with 14.19 km2 covered, or 50.27% of all the green space in Denpasar City. The majority of Denpasar is affected by UHI occurrences, except the northern region of North Denpasar and the southern region of South Denpasar. The maximum UHI level reaches 4-5°C, located on the east side of South Denpasar, especially in the Sanur coastal area. According to the spatial pattern study, the association between urban green space and SUHI only exists on the north side of Denpasar. The correlation between low-SUHI intensity clusters and high cover of green space is shown in the same area. However, the association between High-UHI intensity and low green space cover has not significantly happened. It indicated that other factors besides green space could affect the land surface temperature

SEJARAH LETUSAN GUNUNG MERAPI BERDASARKAN FASIES GUNUNGAPI DI DAERAH ALIRAN SUNGAI BEDOG, DAERAH ISTIMEWA YOGYAKARTA

ABSTRAK Tujuan dari penelitian ini adalah untuk memetakan fasies Gunungapi Merapi yang terletak di DAS Bedog Propinsi Daerah Istimewa Yogyakarta dan bahaya gunungapi yang diakibatkan oleh erupsi Gunungapi Merapi berdasarkan pada fasies gunungapinya. Pengambilan sampel dilakukan dengan sistematic random sampling. Fasies gunungapi ditentukan berdasarkan ciri-ciri litologi dan klasifikasi fasies gunungapi, sedangkan bahaya gunungapi ditentukan berdasarkan identifikasi bahaya-bahaya gunungapi yang dapat menghasilkan batuan-batuan yang menjadi ciri-ciri dari masing-masing fasies. Hasil penelitian menunjukkan bahwa fasies gunungapi di DAS Bedog dari fasies medial dan fasies distal dari Gunungapi Merapi. Hal ini mengindikasikan bahwa pada masa lampau telah terjadi jatuhan awan panas, hujan abu, dan aliran lahar pada fasies medial serta hujan abu pada fasies distal. Kondisi saat ini di mana letak DAS Bedog berada di bawah DAS Krasak dan DAS Boyong (tidak berhulu di puncak Gunungapi Merapi) serta morfologi dan letak DAS Bedog yang berada di belakang Bukit Turgo menyebabkan aliran lahar sulit terjadi

Aquifer characteristics and groundwater potential for domestic requirements in Kediri Regency, Indonesia

Like other natural resources, groundwater is also being exploited at an increasing rate, especially for domestic requirements. Groundwater is preferred as a domestic water source because of its continuous availability and relatively good quality. Unfortunately, not all places have sufficient groundwater availability of good quality. The purpose of this study was to analyze the characteristics of the aquifer in the study area and evaluate its groundwater potential for domestic needs. Aquifer characteristics were determined based on geological and geomorphological conditions, while groundwater potential was calculated using a static approach. The results showed that the characteristics of the aquifers in Kediri Regency are various. In the eastern and central parts of the study area, the characteristics of the aquifer can be in the form of unconfined aquifers with high productivity. In the western part, most of them have non-aquifer material, so it is difficult to find groundwater. Groundwater generally fills joints and diaclase formed in andesitic lava with low discharge. Although the conditions of the aquifer are various, in general, the potential for groundwater in Kediri Regency can still support its requirements because the potential for groundwater in Kediri Regency is 71,121,313,394 m3, while domestic requirements is 52,348,490 m3/year

Extreme precipitation over Indonesian maritime continent: Uncertainties in satellite estimation and its relationship with low storm top height extreme

This paper aims to explain the uncertainties in satellite rainfall estimation due to existence of very high near surface rain, but with relatively low cloud top height over Indonesian maritime continent (MC). More than 15 years of satellite precipitation data recorded by tropical rainfall measuring mission (TRMM) were used in this analysis. The result reveals a large discrepancy between the active precipitation radar (PR 2A25) and passive microwave imager (TMI 2A12) over land surface. PR identifies low storm top height associated with large downward increase of radar reflectivity. In contrast, TMI identifies large ice scattering associated with higher storm top height, but with lower rain rates near surface. Further investigation identifies larger relative humidity and upward vertical velocity at middle part of the troposphere for the low storm height extremes. This condition represents a larger condensation around 300-500 hPa level, but less for the upper part. As a result, it produces lower amount of ice at the upper troposphere, contrasting to the type of extreme precipitation identified by TMI

Characterizing Warm Temperature during April 2019 Monsoon Transition in the Central part of Java

Warmer temperature than normal has been observed in the central part of Java Island-Indonesia during the monsoon transition in 2019. To explain the environmental process related to temperature variability, this research aims to characterize the process related to temperature anomaly and explain the contributing factors in terms of radiation balance and latent heat flux. This research uses the data from two meteorological stations from the Indonesian Bureau of Meteorology, Climatology, and Geophysics (BMKG) and the National Centers for Environmental Prediction (NCEP/NCAR) Reanalysis Project to explain the temperature anomaly. Several parameters, such as near-surface air temperature and humidity, cloudiness, solar and longwave radiation, as well as latent heat flux are obtained from the reanalysis data. This study focuses on descriptive time-series data analysis to explain the factors that contribute to the April 2019 temperatures. The results of this study show the effect of the Madden–Jullian Oscillation (MJO) on weather anomalies. The increase in humidity when the study area is traversed by the MJO causes an increase in humidity followed by intensive cloud formation and the release of latent heat in the cloud. The release of latent heat contributes significantly to the increase in temperature compared to the effect of the shortwave and longwave radiation balance. Thus, atmospheric phenomena in the tropics need to be studied further concerning warmer temperatures because they can be significantly affected by climate change

Identification of precipitation diurnal process using PERSIANN over Central Java Area

The diurnal cycle is a process that repeats daily due to earth rotation. This cycle could significantly affect the hydrological conditions and lithosphere conditions, including humans. This diurnal cycle is also likely to influence seasonal patterns in the region. The diurnal cycle has a close relationship with the time-series pattern and distribution of rainfall. It often affects hydrometeorological disasters in the form of floods and droughts. This paper provides an overview of early identification related to the diurnal cycle of rain in the Central Java region - Indonesia. Rainfall estimation data from The Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) is used as the primary input in the analysis. The research results show that there are differences in rainfall patterns between the northern, central, and southern parts of the study are

The impacts of Seroja Tropical Cyclone towards extreme weather in East Nusa Tenggara

This paper aims to discuss the Seroja Tropical Cyclone and its impact on extreme weather. Seroja tropical cyclones occur from April 4 to 5th 2021, in the East Nusa Tenggara (NTT) region. Based on data from the Meteorology, Climatology and Geophysics Agency (BMKG), the initial position of the Seroja tropical cyclone was in the Savu Sea, southwest of Timor Island. Since April 1, 2021, the NTT region has become the center of low pressure that triggers the formation of this cyclone. When a tropical storm occurs, the intensity of rainfall which initially reaches less than 60 mm/day, increases rapidly to more than 100 mm/day on April 4 to 5, 2021. This is the impact of the low-pressure center that triggers the formation of tropical cyclones in the region

The Analysis of Fire Hotspot Distribution in Kalimantan and Its Relationship with ENSO Phases

Kalimantan experiences fire hazards almost every year, which threaten the largest tropical forest in Southeast Asia. Climatic conditions, such as increasing surface temperature and decreasing rainfall, become important especially when El Nino Southern Oscillation (ENSO) occurs. Studies on fire are commonly conducted based on the climatic condition such as the dry or wet season, but those which focused on analysis of fire occurrences with the specific ENSO phases are still limited. This study aims to identify the spatial and temporal distribution of rainfall, land surface temperature, and soil moisture and analyses the distribution of hotspots in Kalimantan from 2014 to 2020 during different ENSO phases. The data used are Moderate Resolution Imaging Spectroradiometer (MODIS) for hotspot analysis, Global Precipitation Measurement (GPM) for rainfall analysis, MODIS Land Surface Temperature (LST) for surface temperature analysis and Soil Moisture Active Passive (SMAP) for soil moisture analysis. The methods used were descriptive and spatial analyses based on each ENSO phase, which were then combined to analyse the temporal and spatial distribution of fire, rainfall, LST and soil moisture. The temporal distribution shows a positive relationship between ENSO, rainfall, LST, soil moisture and hotspots with a confidence level of 90% in the dry months of August–October. Fire occurred in most parts of West and Central Kalimantan, associated with low elevation, organic soil types and agricultural peatland. The average trend of increasing hotspots is 17.4% in the El Nino phase and decreasing hotspots by 84.7% in the La Nina phase during August–October in Kalimantan