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The urban development increase in the built-up areas leads to more impervious areas with the consequence of larger runoff. Undeniably, this excess water has many benefits. Low-impact development (LID) is one of the innovations to conserve wasted runoff water. The two LID scenarios (water storage – WS; infiltration – I) under different rainfall depths (20, 25, 30, 35 mm) are assessed using Storm Water Management Model (SWMM) and analyzed based on their benefit–cost. This study aims to evaluate the hydrological performance and the benefit–cost ratio to identify the optimal LID design. The benefit calculation is not only projected by runoff reduction aspects, but also the other opportunities aspects. Based on the hydrological performance, scenario I shows a higher runoff reduction performance than scenario WS. Based on the benefits aspects studied, scenario I provides greater benefits with more cost than the WS scenario. Rainfall depth influenced the life cycle cost with 20-mm WS scenario experiencing faster payback period than other scenarios. HIGHLIGHTS Scenario infiltration excels in reducing runoff, particularly in low rainfall conditions.; Scenario water storage with 20-mm rainfall depth offers the best cost-effectiveness, but sensitivity to costs and discount rate emphasized.;

In December 2021, Mount Semeru experienced an eruption accompanied by extreme rainfall, which resulted in lava floods, known as lahars or debris flows. The lava flood destroyed infrastructure, resulting in loss of life. Various rivers surrounding Mount Semeru, including the Rejali River, experienced the effects of this phenomenon. To address this, a study is needed to analyze the occurrence and frequency of lava floods over specific time intervals through the creation of a hazard map. This study aims to map the hazard of lava floods for various return periods using a coupled HEC-HMS and HEC-RAS software alongside a lava flood discharge approach. The HEC-HMS software is used to simulate hydrological processes, to obtain the lava flood discharge, while the HEC-RAS is used to model a two-dimensional (2D) lava flood hazard map. The input parameters of the modeling in this study are rainfall intensity, soil type, land cover, river distance, slope, and elevation. The results show that the flood area covers 9.55% of the total study area by 2 year return period (Q2), 11.80% by Q10, 14.10% by Q50, and 15.72% by Q200 with an overall validation Root Mean Square Error (RMSE) of 0.16. These changes are determined by the discharge volume from each return phase and the river's shallow depth, which causes overflow beyond the river's ability to accommodate the flow. Thus, this study suggests that the models successfully generated a reliable model for mapping the risk of lava floods on the Rejali River. These findings can help the government reduce disaster losses through adequate adaptation and mitigation initiatives.

Low impact development (LID) is a sustainable land use and planning strategy that aims to minimize the environmental impacts of development. A community can enhance their water resources and create sustainable and resilient neighbourhoods. This approach has demonstrated success in managing stormwater and promoting water reuse globally, however, its suitability in developing countries like Indonesia remains uncertain and requires further investigation. The implementation of LID in developing countries may face several challenges including high density and complex drainage networks, combined sewer usage, clay soil type, irregular housing layouts, community socio-economic characteristics, affordability, cost, and the availability of regulations and policies. With proper planning and site-specific strategies, LID can be implemented effectively in Indonesia. Clear regulations, secured funding source and community-based LID are all essential for successful LID deployment. This paper can be used as a starting point for considering LID implementation in Indonesia and other countries with similar characteristics. HIGHLIGHTS The applicability of LID in developing countries like Indonesia remains uncertain and requires further investigation.; The implementation of LID in Indonesia faces several challenges including high-density and complex drainage networks, combined sewer usage, clayey soil type, irregular housing layouts, community socio-economic, affordability, and cost, coupled with the availability of regulations and policies.; With proper planning and site-specific strategies that address these challenges, LID can be implemented effectively in Indonesia.;

Landslides are one of the natural disasters that often occur in the Upper Tanggul Watershed. This study aims to produce a landslide susceptibility map based on the Geographic Information System (GIS). Seven landslides conditioning factors used, namely land cover, river density, slope, aspect, elevation, curvature and Normalized Difference Vegetation Index (NDVI). Landslide susceptibility areas were mapped using the frequency ratio and weights-of-evidence methods. The accuracy of the landslide susceptibility maps generated from both methods is validated using the Area Under Curve (AUC). The estimation results of the AUC plot show that the susceptibility map using the frequency ratio model has an accuracy of 92,6% and the weights-of-evidence method has an accuracy of 90,1%.

The Sub-watershed of Sampean Hulu, located on the slopes of Mount Raung is susceptible to erosion hazards. Erosion indicators have been observed in the irrigation channels, mainly due to frequent sedimentation, which compromises the irrigation infrastructure's optimization and water distribution. To address this, erosion monitoring using the Universal Soil Loss Erosion (USLE) model, along with GIS and remote sensing techniques, is essential. It was found that the irrigation networks associated with Clangap and Tamanan rain gauges are at higher risk due to intense rainfall. Maesan and Wonosari II rain gauges cover a larger irrigation network area, highlighting the need for erosion prevention measures. The dominant soil type, Tv, with a high clay content, is highly susceptible to erosion. Flat and gently sloping slopes have a lower risk compared to steeper slopes, while very steep and steep slopes pose higher erosion risks. Paddy fields and well-managed forest plantations have lower erosion hazards, while bare land and certain agricultural practices contribute to increased erosion risks. The analysis classified the erosion hazard into five classes, with the sub-watershed being predominantly low and very low susceptible to soil erosion. Implementing conservation practices, sustainable land management, and land use regulations are crucial for erosion prevention.

DAS Bedadung merupakan salah satu DAS terbesar di Kabupaten Jember yang didominasi oleh sawah irigasi dan sering mengalami bencana banjir. Salah satu cara untuk mengurangi banjir dengan melakukan peningkatan resapan air menggunakan teknologi rainwater harvesting. Tujuan penelitian ini adalah mengidentifikasi lokasi yang berpotensi untuk diterapkannya 4 tipe rainwater harvesting di DAS Bedadung. Tahapan penelitian ini dibagi menjadi 4 tahap utama, yaitu: analisis dan reklasifikasi kriteria lokasi rainwater harvesting, uji multikolinearitas untuk menemukan korelasi antar kriteria, analisis pembobotan menggunakan metode AHP, dan pemetaan potensi lokasi rainwater harvesting. Berdasarkan hasil uji multikolinearitas, delapan kriteria dapat digunakan untuk analisis lokasi. Bobot terbesar ada pada kriteria elevasi dan bobot terkecil ada pada tutupan lahan. Lokasi yang berpotensi untuk penerapan guludan kontur, pemanenan air hujan dari atap dan kolam pertanian adalah Kecamatan Kaliwates, sedangkan tipe embung berpotensi di Kecamatan Ambulu.

Floods are the most recurring natural disasters and impact human life, causing a severe economic downturn. The level of flood risk is a function of hazard and vulnerability. Flood risk-prone areas need to be identified to reduce the flood risk level. This study aims to assess flood risk based on spatial analysis results with Geographic Information Systems (GIS). The flood hazard map is built from remote sensing-based data in the form of a digital elevation model (DEM) applied using the frequency ratio weighting (FR) technique. Vulnerability maps are generated from social, economic, physical, and environmental data applied through techniques overlays weighted using the analytical hierarchy process (AHP). The resulting risk map shows that 21.93% and 6.40% of the total area are at a very high and high level of flood risk. This map is very useful for planning the flood management.

In January 2006, the flash flood in Panti Sub-district was a national disaster, causing damage to building infrastructure and fatalities. From this incident, it is necessary to have flood mitigation by providing a map of the distribution of flood inundation using a 2D hydraulic model to provide information regarding the extent of flood inundation in the study area. Due to the limited DEM data for 2D modeling, it is necessary to use UAV images to provide a DSM with good and higher resolution. This study aims to assess the performance of 2D flood modeling results using HEC-RAS equipped with RAS Mapper through UAV processing as input. There are 21 GCP in the study area as an increase in accuracy, the RMSE value in the horizontal direction is 0.3853m, and the vertical direction is 0.1836m. From the CE90 accuracy test results for a horizontal accuracy of 0.58m and LE90 for a vertical accuracy of 0.30m, it can be concluded that the map accuracy test meets the 1:2500 scale. Terrain maps are input to HEC-RAS; selected meshes are 5x5m and 2x2m. The modeling results can show the inundation depth in each GCP from the min-max depth. The model calibration shows an RMSE value of 0.183, while the flood depth validation shows an RMSE value of 0.13. In other words, modeling can represent the distribution of flood inundation in the study area and provide benefits for the community to be more alert in the event of a flood in the coming year.

Volcanic mudflow floods occur when rainfall runoff combines with volcanic material and flows downstream. These devastating events cause significant damage to infrastructure, disrupt economies, and result in injuries and casualties. One area where the flow of volcanic material greatly affects the situation is the Rejali River, which receives a substantial amount of volcanic debris from Mount Semeru. To address this issue and begin mitigating the associated risks, it is crucial to start by mapping the potential distribution of volcanic mudflow floods. Therefore, this study aimed to assess factors impacting volcanic mudflow flood susceptibility and to create a corresponding susceptibility map. The study employed the Analytical Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) to determine the influence of various factors and classify the areas, respectively. These methods were integrated with the Geographic Information System (GIS) to enhance the analysis. The weighted analysis results showed that the most impactful factors conditioning volcanic mudflow floods, in descending order, were rainfall (42.40%), land cover (13.89%), elevation (13.39%), slope (12.51%), distance from the river (7.09%), soil type (6.58%), and rock distribution (4.13%). The TOPSIS calculation further highlighted that rainfall intensity between 104.03 and 109.65 mm day-1 had the greatest influence on susceptibility. The successful integration of AHP and TOPSIS methods with GIS helped develop a volcanic mudflow flood susceptibility model with an outstanding accuracy of 0.969. The model showed that approximately 46.40% of the areas along the Rejali River exhibited very high susceptibility to volcanic mudflow floods, while an additional 16.21% indicated high susceptibility and substantial risk in most regions. Therefore, the generated susceptibility map offered important insights for shaping future mitigation strategies and influencing policy decisions.

The southern region of East Java is located on the Indo-Australian plate. The shifting of these plates allows for earthquakes that trigger tsunamis to occur. The earthquake leads to the impact of a tsunami in several areas, one of which is Puger Sub-District, Jember Regency. The main economic activity of the Puger Sub-District is the fishery; hence significant local coastal communities are vulnerable to tsunami threats. This study aims to map the tsunami risk using a Geographic Information System. The tsunami hazard map used the analysis of the tsunami inundation map from the BMKG. Vulnerability and capacity maps were prepared based on BNPB Chief Regulations. Vulnerability is evaluated based on social, physical, environmental, and economic data. Capacity considers components of the institution, early warning and risk analysis or evaluation, disaster awareness education, reduction of basic risk, and preparedness. The hazard, vulnerability, and capacity maps are classified into five classes. The tsunami risk map is then derived by overlaying the three input maps. Results showed that the villages with very high risk are Puger Kulon and Mojosari at the coastal front areas, covering an area of 13.01% of the total regional area of the Puger Sub-District.

The existence of a flood inundation rapid map is needed in flood mitigation. This research is intended to map flood inundation quickly by utilizing satellite image technology. Sentinel 2 Level 1C technology uses before and after the flood. The extraction process uses the methods of NDWI (Normalized Difference Water Index) and MNDWI (Modified Normalized Difference Water Index). The result is treated with a threshold value by dividing the pixel value into flooded and unflooded areas. The performance model shows that the MNDWI method is more accurate than the NDWI method in producing flood inundation maps. Thus, the results of the MNDWI method are practical and able to map flood inundation quickly.

In Indonesia, ground-based rainfall monitoring is uneven and sometimes lacks continuity especially in small watersheds, which makes hydrological modeling difficult. This paper aims to the performance evaluation of the HBV Light model from the manual measurement of rainfall (MMR), Global Precipitation Measurement (GPM-3IMERGDF), and Tropical Rainfall Measuring Mission (TRMM-3B42) as input for the hydrological model. The Hydrologiska Byrans Vattenbalansavdelning (HBV) Light hydrological model is applied to three small watersheds, namely Sampean Baru, Bedadung, and Mayang. The model's performance evaluation is assessed based on the correlation between the average rainfall data for the satellite product area and the MMR product, the stationarity of the rainfall and discharge data, and the model accuracy. The model simulation results show that the MMR rainfall in all watersheds provides a better discharge response than the other two products. Meanwhile, the simulation model of the GPM-3IMERGDF satellite product is slightly better than TRMM-3B42. The stationarity test of rainfall and discharge data needs to be enforced before modeling.

Flood mapping is an essential component of planning flood mitigation. The availability of remote sensing data makes rapid flood mapping possible. This article develops an accurate method for rapid flood mapping using satellite imagery. Sentinel-2 imagery was tested by acquiring data before and after a flood event in a lowland area. Flooding extraction was performed using the newly developed Flood Inundation Extraction Index (FIEI) and compared to the Modified Normalized Difference Water Index (MNDWI), the most commonly used index. Based on the choice of threshold, the results are divided into flooded and non-flooded areas. Evaluation of the performance accuracy based on the total and kappa coefficients showed that the FIEI approach is more accurate than the MNDWI approach.

Banjir merupakan faktor yang mengakibatkan kerusakan infrastruktur jaringan irigasi pada daerah irigasi di aliran Sungai Jompo. Kerusakan tersebut berdampak pada kurang optimalnya kinerja jaringan irigasi. Oleh karena itu, dengan terbatasnya anggaran biaya rehabilitasi maka perlu dilakukan analisis prioritas rehabilitasi jaringan irigasi. Studi ini mengambil lokasi pada Daerah Irigasi (DI) yang berada di aliran Sungai Jompo, Kabupaten Jember, Jawa Timur. Penentuan prioritas rehabilitasi jaringan irigasi dalam penelitian ini menggunakan metode Simple Additive Weighting (SAW) dengan cara menentukan bobot masing-masing kriteria rehabilitasi yang meliputi kondisi prasarana, ketersediaan air, luas areal fungsional, dan produktivitas tanam. Selanjutnya melakukan normalisasi dan perangkingan setiap alternatif dari nilai prioritas. Hasil analisis prioritas rehabilitasi jaringan irigasi menggunakan metode SAW menyatakan bahwa daerah irigasi yang menjadi prioritas utama adalah DI. Bedus. Untuk prioritas kedua hingga kesembilan secara berurutan adalah DI. Arah III, DI. Sekar, DI. Pengarengan, DI. Polo, DI. Langon Patrang, DI. Sembah Kurung, DI. Jaki, dan DI. Sembah.

Banjir bandang di Kabupaten Jember pada pergantian tahun 2006 merupakan salah satu bencana nasional yang membawa banyak korban. Kejadian banjir bandang di Kaliputih terus berulang, untuk itu keberadaan peta zonasi banjir sangat diperlukan untuk antisipasi sebelum kejadian. Tujuan dari penelitian ini adalah untuk melakukan zonasi tingkat kerawanan banjir bandang di sub-DAS Kaliputih dengan bantuan Sistem Informasi Geografis. Metode yang digunakan dalam penelitian ini adalah metode Weights of Evidence. Lima faktor diantaranya kemiringan lereng, tata guna lahan, kerapatan jaringan sungai, jenis tanah dan Normalized Difference Vegetation Index (NDVI) digunakan untuk membuat peta zonasi. Dari yang terkuat, parameter pengkondisi kerawanan banjir adalah jenis tanah latosol coklat dan regosol abu-abu, penggunaan lahan sawah, kemiringan lereng, penggunaan lahan rumah, NDVI pada nilai rendah, dan kerapatan jaringan sungai pada nilai rendah. Hasil yang didapatkan dari analisis menunjukkan sebesar 12,25% dari total wilayah di sub-DAS Kaliputih memiliki tingkat kerawanan banjir bandang yang sangat tinggi, 14,58% tinggi, 12,81% sedang sampai tinggi, 14,89% sedang, 16,98% rendah, dan 28,49% sangat rendah dengan nilai Area Under Curve (AUC) sebesar 80,0%.

Flash floods are among the most frequent natural disasters caused by heavy rain associated with a severe thunderstorm, which leads to social and economic losses in infrastructure and agriculture. Therefore, this research aims to map flash flood potential susceptibility (FFPS) in the Pekalen watershed, using Geographic Information System (GIS) technology and statistical analysis to reduce the risk of flooding. The opinion and experience of an expert on the weight assessment method were carried out using the Analytical Hierarchy Process (AHP). Furthermore, the probability statistical methods and GIS were used in flash flood areas in the Pekalen watershed in Andungbiru, Probolinggo village. This study was carried out using geomorphological factors, namely elevation, slope, stream power index, and topographic wetness index, with a resolution of 30 m. Thematic map scale of the land use, river density, distance to the river, rainfall, and geology is in the ratio of is in a ratio of 1:25.000. Imagery processing was carried out using Landsat 8 30 m x 30 m resolution imagery, such as the Normalized Difference Vegetation Index. The result showed that the model map of FFPS obtained low 8%, low 23%, moderate 27%, moderate to high 26%, high 13%, and very high 2% index values. The next stage of modeling analysis led to validation using statistic receiver operating Characteristic Curve (ROC) of area Under Curve (AUC) with a value of 90.15. In conclusion, the factors that significantly trigger flash floods are distance to the river, land use, and slope.

Pipa pesat merupakan saluran penghubung antara bak penenang dengan turbin pada rumah pembangkit. Meminimalisir kehilangan energi pada pipa pesat sangat penting untuk mengoptimalkan bangkitan energi listrik. Tujuan penelitian ini adalah melakukan optimasi diameter dan tebal pipa pesat untuk mencari hasil yang paling efisien, yang dikaji dari aspek hidrolika dan biayanya. Metode pemilihan pipa pesat yang optimal dapat ditentukan berdasarkan hubungan secara empiris, antara berbagai formula dari diameter dan tebal pipa pesat yang dinilai terhadap energi yang dihasilkan serta harga pipa pesat itu sendiri. Hasil penelitian menunjukkan bahwa besar diameter berbanding lurus dengan besar energi yang dihasilkan dan harga pipa pesat. Berdasarkan perbandingan, didapatkan diameter optimum pipa pesat sebesar 0,45 meter dengan tebal 0,0018 meter yang dihitung menggunakan formula dari Moffat, serta daya bangkitan sebesar 52,16 kW dan energi sebesar 456.914,33 kWh per tahunnya dengan harga pipa IDR 3.610.900 per meter pipa pesat. Penstock is the connecting channel between the forebay and the turbine in the power house. Minimizing the energy loss in the penstock is very important to optimize the generation of electrical energy. The purpose of this research is to optimize the diameter and thickness of penstock to find the most efficient results, which are examined from the aspects of hydraulics and costs. The optimal method of penstock selection can be determined based on the empirical relationship between the various formulas of the diameter and thickness of the penstock as assessed by the energy produced and the price of the penstock itself. The results showed that the diameter was directly proportional to the amount of energy produced and penstock price. Based on the comparison, the optimum diameter of the penstock is 0,45 meters with a thickness of 0,0018 meters which is calculated using the formula from Moffat, as well as a generation power of 52,16 kW and energy of 456.914,33 kWh yearly with the price of IDR 3.610.900 per meter penstock pipe.

Currently, water demand is increasing, both domestic, industrial and agricultural water needs. However, the increase in water demand is not due to an increase in the water availability due to changes in land use and other factors that pose a threat to increased exploitation of water resources. So it is necessary to analyze and evaluate the water needs to anticipate the impact of drought in the Asem-Tekung-Jatirowo sub watersheds. The calculation of water supply and water demand can be carried out using the water balance method, assisted by the WEAP (Evaporation and Water Planning) program, through data integration of streamflow analysis and water user in the river reach. The results showed that the sub-watershed area showed a deficit of water in 2013, with the Jatiroto region having the highest air deficit of 1.58 million m3 or 44.2%. Based on this analysis, urgently needed a recommendation of drought anticipation strategies these are planting patterns to adjust condition of water supply, storage of water reserves, conservation of critical land, and repair of channels that are at risk of water seepage.

Abstrak Air adalah sumber daya yang terus dibutuhkan manusia. Dengan menggunakan sistem Rainwater Harvesting RWH), air hujan dapat dimanfaatkan untuk memenuhi kebutuhan domestik. Penelitian ini tidak hanya membahas potensi air yang dapat dimanfaatkan dari sistem RWH yang ada pada satu lokasi saja, akan tetapi mempertimbangkan dua lokasi yang merupakan lokasi yang lebih padat penduduk dan dikategorikan sebagai wilayah kota (Desa Krajan Timur, Sumbersari) dan lokasi yang lebih jarang penduduknya dan dikategorikan sebagai wilayah desa (Desa Panduman, Jelbuk). Dalam penelitian ini digunakan beberapa data yaitu peta lokasi, data curah hujan, dan data kebutuhan air penduduk. Untuk mengetahui kebutuhan air dan sumber air yang digunakan penduduk sehari-hari, dilakukan survey kepada masyarakat yaitu 20 rumah di wilayah kota dan 20 rumah di wilayah desa. Perhitungan potensi air dari sistem RWH dilakukan dengan metode F. J. Mock menggunakan debit andalan 50%. Dari studi ini diperoleh hasil bahwa pada 20 rumah di wilayah kota, sistem RWH berpotensi menghasilkan air sejumlah 3,168 liter/bulan sampai 31,825 liter/bulan. Adapun pada 20 rumah di wilayah desa, potensi air dari sistem RWH pada setiap rumah berkisar antara 15,090 liter/bulan sampai 33,952 liter/bulan. Potensi air tersebut dapat memenuhi seluruh kebutuhan air pada 20 rumah di desa dan 17 rumah di kota, serta dapat memenuhi 44% sampai 72% kebutuhan air pada 3 rumah di wilayah kota. Kata kunci: Rainwater harvesting, kebutuhan air, kesetimbangan air, kota, desa Abstract Water has always become a vital resource that is needed by a human being. Rainwater may play an essential role as a domestic water supply by rainwater harvesting system. This study compares potential rainwater harvested at two locations considered an urban area with higher population density and a rural area with lower population density. The studied urban area and rural area are Desa Krajan Timur, Sumbersari and Desa Panduman, Jelbuk, respectively. Several data utilized in this study are location maps, precipitation data, and water needs data. Surveys are conducted by interviewing twenty residences in each urban and rural area to obtain water needs and water sources data. Water harvested potential was calculated using F J Mock method. The study results showed that rainwater harvesting system in 20 houses in the urban area could produce 3,168 liters/month until 31,825 liters/month of water. While the rainwater harvesting system in 20 houses in the rural area could produce 15,090 liters/month until 33,952 liters/month of water. The harvested water could fulfill all water needs in 20 houses in the rural area, 17 houses in the urban area, and 44% until 72% of water needs in 3 houses in the urban area. Keywords: Rainwater harvesting, water needs, water balance, urban area, rural area

The limitations of spatial and temporal distribution of rain gauge networks causes inaccuracies in prediction of hydrological modeling. The availability of satellite rain data products is a potential to overcome this limitation. This studies objective is to compare the quality of rain data from the recording of the Manual Rainfall Recorder (MRR) with satellite data TRMM 3B42 which is entered in the HBV hydrological modeling. Calibration results shows that HBV modeling performance with MRR rain data input is better than TRMM. R2 and NSE values from MRR rain data input were 0.7153 and 0.7133 respectively with a mean error of 89 (mm / year). While the R2 and NSE values of the TRMM 3B42 satellite rain data input were 0.57 and 0.55 with a mean error of 305 (mm / year), respectively.

Floods in coastal areas occur yearly in Indonesia, resulting in socio-economic losses. The availability of flood susceptibility maps is essential for flood mitigation. This study aimed to explore four different types of models, namely, frequency ratio (FR), weight of evidence (WofE), random forest (RF), and multi-layer perceptron (MLP), for coastal flood susceptibility assessment in Pasuruan and Probolinggo in the East Java region. Factors were selected based on multi-collinearity and the information gain ratio to build flood susceptibility maps in small watersheds. The comprehensive exploration result showed that seven of the eleven factors, namely, elevation, geology, soil type, land use, rainfall, RD, and TWI, influenced the coastal flood susceptibility. The MLP outperformed the other three models, with an accuracy of 0.977. Assessing flood susceptibility with those four methods can guide flood mitigation management.

Commonly joints problems (especially high strength bolt) were stiffness, ductility, and construction costs. This research was conducted with purpose to analyzed inner force and behavior that could be occurred on high strength bolted joints in steel frame using IWF profiles, such as stress, and reaction force-displacement. This study was divided into 2 step, first step was modeling on finite element software, and second step was analyzing the results and comparing it with the results from experimental study as validation base. In bolted joints model showed the best value on third trial with displacement value of 98,97 mm and reaction force of 41,57 KN. With validation to experimental results each one were 93,45% and 94,05%. Accuracy of hysteretic loop curve area was 98,46%.

This study presents a simulation analysis of the non-linear behavior of retrofit concrete material due to uniaxial loads modeled in the form of cylinders measuring 150 mm in diameter and 200 mm in depth using the ABAQUS. Analysis of this auxiliary program includes cases of normal concrete retrofit, concrete with retrofit concrete with a composition of 1% steel fiber, and concrete with retrofit concrete composed of 2% steel fiber. From the results of the study conducted, it was shown that in modeling the properties of concrete damaged plasticity in ABAQUS, the use of accurate compressive behavior equations for concrete cases with normal concrete retrofit was core concrete and retrofit concrete using the Alfarah, et al equation. For the case of concrete with steel fiber composition retrofit, core concrete uses the Alfarah equation, and retrofit concrete uses Zhou Jiajia, et al. Whereas to model the tensile behavior accurately in the case of concrete with normal concrete retrofit using the Alfarah, et al equation. And the case of concrete with retrofit steel fiber compositions using the CEB-FIB equation and the Ali & Nehdi equation. The results of ABAQUS analysis of force vs. displacement show a graphical pattern close to the similarity of retrofit concrete column experimental results ECC1 error force ratio and displacement 14.86% and -10.60%, and ECC2 14.82% and 8.01). Based on the stress analysis shows that there is a gradual increase in core concrete where the peak of stress is found in the core area of the concrete core and in the retrofit area is divided into two regions, namely stressing on the center and pulling on a small part of upper and lower column retrofit.

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.

Baseflow is an important component affecting the availability of water in the river during the dry season. Availability of water in the dry season is useful for water resources management. This research aims to test and to compare six recursive digital filters (RDF) methods for calculating baseflow and baseflow index. This research was conducted in Brantas Watershed. Two outlets (sub-watersheds) located at Kertosono and Ploso were used. Daily discharge from 1996 to 2015 of the two outlets above was used as main input for this study. While rainfall data were used to determine the calibration period. The sequence procedures of this research, consist of: (1) inventory of daily discharge and rainfall data, (2) data processing, (3) calibration, (4) validation, and (5) evaluation of models’ performances. Six (6) methods of baseflow separation based on recursive digital filters were evaluated. The calibration process was carried out for periods 1996 to 2005. The periods from July to September was assumed to be the peak of the dry season and then selected for calibration process. The parameter values were calibrated using the data from dry season for each year. Furthermore, the average value of parameters obtained from calibration period then used to separate baseflow in validation process (periods 2006 to 2015). The result of separation both in calibration and validation are then evaluated using root mean square error (RMSE), coefficient of determination (R²) and FDC. This research shows that the Lyne-Hollick and EWMA filters perform better than other methods. In Brantas Kertosono sub-watershed, the optimal parameter value for Lyne Hollick algoritmh (αly) = 0.995 dan for EWMA filter (αew) = 0.003 and in Brantas Ploso sub-watershed (αly ) = 0.99 dan (αew) = 0.003.

Disaster is a threat to human life. Many losses are caused by disasters, namely loss of life, injured people, loss of homes, and others. In addition, the frequency and intensity of disasters are also increasing every year. Therefore, research on Disaster Risk Reduction (DRR) is needed both to reduce disaster risk and to manage the disaster. The purpose of this research is to develop an appropriate DRR model in an area to assist decision-making in making policy. This research was compiled based on literature studies from various reputable journals to be used as a reference in the preparation of the right model. Then proceed with the development of a framework to model an efficient and effective DRR. The steps for making a holistic DRR model have been identified and the test design for the model has been determined, namely simulation, validation, and scenario. The recommendation given from this study is the preparation of a DSS (Decision Support System) as a tool for decision-makers to make policies regarding DRR-based regional development. This discussion will be continued in the next research by including case studies in certain urban areas.

Abstract: This study explores accuracy of short term rainfall disaggregation model by modeling rainfall runoff. Storm hydrographs show rapid responses to rainfall with a short time to peak. The spatial rainfall disaggregation process used multivariate daily rainfall (MuDRain) model on 4 manual rainfall rain gauges (MRR) and 3 automatic rainfall rain gauges (ARR) used as reference the hydrographs were satisfactorily modeled using the Hydrologic Engineering Centre–Hydrologic Modeling System (HEC-HMS). Parameter calibrations were done on case 1 that rainfall runoff modeling used the rainfall data from 7 rain gauges (MRR and ARR). Model validation (case 2) used the rainfall data from 3 rain gauges (ARR). The efficiency indexes of (case 1) and (case 2) are 0.97 and 0.74, respectively. Based on these preliminary findings, it could be suggested that rainfall disaggregation would be able to serve reasonably well in regulating basic hydrological functions. Key words: rainfall, runoff, disaggregation, MuDRain