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All Journal JURNAL SUMBER DAYA AIR
Harnita Rosalina, Harnita
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EVALUASI DAMPAK BANJIR AKIBAT PERUBAHAN ALUR SUNGAI CITANDUY HULU DI DESA TANJUNGKERTA, TASIKMALAYA-JAWA BARAT Maulana, Ari Azhar; Rosalina, Harnita
JURNAL SUMBER DAYA AIR Vol 18, No 1 (2022)
Publisher : Direktorat Bina Teknik Sumber Daya Air, Kementerian Pekerjaan Umum dan Perumahan Rakyat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32679/jsda.v18i1.745

Abstract

Since 1996 there have been frequent floods in the upstream area of the Citanduy River, especially during the rainy season. The flood also inundated part area of the Suryalaya Islamic Boarding School located in Tanjungkerta Village, Pagerageung District, Kabupaten Tasikmalaya. In this case, the community took the initiative with self-subsident activities to reduce the impact of flood by diverting the Citanduy River channel without any communication with river authority. This analysis purposed to evaluate the cross-section capacity due to narrowing the upper Citanduy River. Hydrological analysis was initiated to determine the characteristics of catchment area in study area. 1D and 2D hydraulic analysis using HEC-RAS application with unsteady flow analysis to determine water level, flood distribution, and river flow velocity. Using the annual Q25 plan discharge taking into existing capacity and geometric characteristics. Validation of modeling results by observing directly the water level at locations that affected by flooding condition due to high rainfall intensity. Conclusions are based on the results of hydraulic hydrological analysis applied to the research object. Shortening of river channel due to siltation causes a decrease in the area of the river channel in bank conditions. Actually condition of the Citanduy River after draining discharge over a 2-year return period, there was a flood in the river cross-section of Sta. 400 – 1035 rivers overflow with variations in depth of ±40 – 80 cm when model with a discharge period of 25-years.  The recommendation for further research is to assess the river capacity to analyze erosion and sedimentation that occurs in the watershed. Conducting a more comprehensive study, involving the three core components, that is Hydraulics, Ecology, and Morphology, so that proposed alternative solutions have a good impact on all aspects, not only solving one problem but causing other problems.Keywords : Flood modeling, river shortcut, Upper Citanduy River  
IMPLEMENTASI METODE SARIMAX UNTUK PREDIKSI CURAH HUJAN JANGKA PENDEK DI PAGERAGEUNG, TASIKMALAYA Maulana, Ari Azhar; Rosalina, Harnita
JURNAL SUMBER DAYA AIR Vol 20, No 1 (2024)
Publisher : Direktorat Bina Teknik Sumber Daya Air, Kementerian Pekerjaan Umum dan Perumahan Rakyat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32679/jsda.v20i1.874

Abstract

 Rainfall plays a crucial role in shaping the weather in Indonesia, influenced by factors such as latitude, elevation, wind patterns, land and water distribution, as well as topography. Rising temperatures contribute to the increased intensity of extreme rainfall, amplifying the potential risk of disasters. Therefore, it is necessary to conduct analyses to predict weather based on historical time series data. This study aims to identify short-term rainfall patterns and trends using the SARIMAX method. The initial stage involves data processing and splitting the data into training data (2005-2014) and test data (2015-2019). Time series decomposition is then performed to identify patterns, followed by period identification and stationarity testing using the ADF test. The SARIMAX model is selected based on the lowest AIC value, followed by parameter estimation and diagnostic tests. Rainfall predictions are evaluated using model performance evaluation methods, while inferential statistics are used to describe population attributes through confidence intervals. The forecasting results show that using the SARIMAX (0, 0, 1)(0, 1, 1, 12)12 model for short-term rainfall prediction achieved the best performance with the smallest MSE, MAE, and MAPE values on the test sample with a 95% confidence level. Repeating rainfall patterns with a mid-year decline and significant variation in magnitude were identified from the sample data for August 2020-2027, with the lowest rainfall at 39.05 mm and the highest at 397.03 mm in December. The implications of this study support efforts to mitigate natural disasters due to unexpected weather changes by integrating this model into early warning systems and water resource planning.Keywords : hydrology, precipitation, time series, short-term, SARIMAX