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Soil and Water Assessment Tool (SWAT) model for hydrological response analysis in the Gajahwong subwatershed, Yogyakarta, Indonesia Hermawan, Sekar Gading; Suprayogi, Slamet; Fadlillah, Lintang Nur
Journal of Degraded and Mining Lands Management Vol. 12 No. 2 (2025)
Publisher : Brawijaya University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15243/jdmlm.2025.122.7287

Abstract

Hydrological response is a specific reaction of a watershed to rainfall, and one form is surface runoff, which can be influenced by climatic and physiographic factors. These factors are represented by various parameters that have their own impact on surface runoff, otherwise known as parameter sensitivity. The purpose of this study was to identify the hydrological response in the form of flow discharge based on the application of the Soil and Water Assessment Tool (SWAT) model and to identify the sensitivity of parameters that affect the hydrological response in the Gajahwong subwatershed. The data used in this study came from secondary data obtained from relevant agencies and primary data collected through sampling and laboratory testing. Flow discharge modeling was carried out using SWAT+ software, and the modeling results were automatically calibrated and validated using statistical tests. Meanwhile, sensitivity analysis was conducted by calculating the relative sensitivity values. The results showed that the flow discharge modeling of the Gajahwong subwatershed exhibited a pattern that is similar to the observed discharge. Based on this finding and the validation results with statistical tests, it can be said that the SWAT model can model and predict the flow discharge in the watershed quite well. The input parameter that is very sensitive and has a significant influence on the hydrological response in the subwatershed is the curve number (cn2), with a relative sensitivity value of 1.12.
Modeling Seasonal Variations of Sediment Transport and Morphological Changes in Delta Ecosystem: A Case Study of the Wulan Delta, Indonesia Fadlillah, Lintang Nur; Widyastuti, Margaretha; Kim, Dong Hyeon; Marfai, Muh Aris
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 30, No 1 (2025): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.30.1.21-30

Abstract

The suspended sediment from the Serang River plays a crucial role in the development of the Wulan Delta. This study employs the open-source DELFT3D model to investigate seasonal hydrodynamics, sediment distribution, and morphodynamic changes in the delta. Sediment dynamics during both the rainy and dry seasons were analyzed using the DELFT3D-Flow model. Tidal data were sourced from TPXO 9v1 and field measurements, while bathymetric data from GEBCO were validated against in-situ observations. Model results indicate seasonal sediment concentration patterns, which were further validated against satellite imagery, demonstrating consistency between simulated and observed sediment distribution. Statistical analysis revealed an RMSE range of 0.001 to 0.061. The estimated sediment deposition rate is approximately 1.2 t·yr⁻¹, with a deposition rate of 2.74 t·m⁻²·yr⁻¹ at both river mouths. About 12% of the sediment accumulates near the river mouth, while the remainder is redistributed by currents influenced by the Java Sea's bed morphology. Erosion was primarily observed in the eastern part of the delta and at the OWR mouth, whereas the western delta exhibited significant deposition due to strong river currents and substantial sediment supply. This sediment distribution suggests potential delta expansion from the west to the north. Findings contribute to the understanding of sediment transport processes in deltas, with implications for mitigating coastal erosion, enhancing delta resilience, and preserving ecosystems in similar regions across northern Java.