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Analysis of erosion hazard level and land rehabilitation pattern with the RUSLE method based on GIS at Wai Tala Watershed in West Seram Regency Maluku Province Talakua, Silwanus Matheus; Osok, Rafael M; Talakua, Cristina M
Journal of Degraded and Mining Lands Management Vol. 11 No. 2 (2024)
Publisher : Brawijaya University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15243/jdmlm.2024.112.5385

Abstract

This study used the Revised Universal Soil Loss Equation (RUSLE) and Geographical Information System (GIS) to estimate the annual rate of soil loss, map erosion factors, and recommend a suitable pattern of land rehabilitation in Wai Tala watershed, Regency of Western Seram. The research material used in this study were rainfall data for 38 years, Digital Elevation Model Nasional (DEMNAS) Image Map, Rupa Bumi Indonesia (RBI), geology, soil, land use, and watershed boundaries of Maluku Province. Field research was conducted on 187 land units, and each land unit contained RUSLE erosion factors: topography, soil type, and land use. The spatial distribution of erosion factors was processed using the Arc.GIS10.8, and the soil erosion rates were estimated using the RUSLE method, then corrected using the land degradation model developed in small islands in Maluku. The results showed that the level of erosion hazard in the Wai Tala watershed was none to slight (mean = 3.54 t/ha/yr), moderate erosion (21.52 t/ha/yr), high erosion (110.01 t/ha/yr), and very high erosion (252.84 t/ha/yr). The recommended land rehabilitation patterns that can reduce annual soil loss lower than the tolerable limit are maintaining the none to slight erosion areas with the present land uses in particular primary and secondary forests, and with reforestation or agroforestry patterns combined with low to high-density garden plants or with low to high densities cover crop at the moderate to very high erosion areas.
ANALISIS DEBIT RENCANA UNTUK PERENCANAAN BANGUNAN PENGENDALI BANJIR DI DAS WAI RUATA KABUPATEN MALUKU TENGAH Marasabessy, Syamsudin; Talakua, Silwanus Matheus; Siregar, Adelina; Osok, Rafael Marthinus
MAKILA Vol 18 No 2 (2024): Makila: Jurnal Penelitian Kehutanan
Publisher : Universitas Pattimura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/makila.v18i2.14006

Abstract

The high rainfall, rapid urbanization, and the presence of impermeable surfaces have drastically increased surface runoff, overwhelming river systems with high water volumes. Changes in land use and rapid population growth further escalate flood risks. Analyzing planned discharge rates and flood control building planning becomes urgent to mitigate losses and risks caused by floods in the Wai Ruata watershed. Calculations indicate that for the Q100 Log Normal (2475.17 m3/s, the channel height is 2.50302 m, closely approximating public information (2.5 m), with a difference of 0.00302 m or 0.302 cm. This suggests that the calculated maximum flood water level based on planned discharge analysis using the rational method for Log Normal probability of 2.503 m is reasonably accurate. It can serve as a reference for flood control building design heights, potentially lasting around 100 years in the Wai Ruata watershed. Planned flood discharges in the Wai Ruata watershed are as follows: for a 2-year return period, 505.80 m3/s (Gumbel), 449.27 m3/s (Log Normal), 462.56 m3/s (Log-Pearson Type III); for a 50-year return period, 1868.80 m3/s (Gumbel), 2016.26 m3/s (Log-Normal), and 1837.18 m3/s (Log-Pearson); and for a 100-year return period, 2137.98 m3/s (Gumbel), 2475.17 m3/s (Log-Normal), 2166.93 m3/s (Log-Pearson). Gumbel planned flood discharge data can be used for a 25-year lifespan of water structures, whereas for a 100-year lifespan, Log-Normal planned flood discharge is more suitable.
Land Degradation Assessment Model Using Field Assessment And RUSLE Methods In Wai Ruhu Watershed, Ambon Island, Mollucas Province Talakua, Silwanus Matheus; Osok, Rafael Marthinus
Indonesian Journal of Geography Vol 57, No 3 (2025): Indonesian Journal of Geography
Publisher : Faculty of Geography, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijg.98955

Abstract

Land degradation due to erosion is a serious threat to land sustainability of small tropical islands in Maluku, Indonesia. The current research was carried out in the Wai Ruhu Watershed, Ambon Island, Maluku; it was a part of studies conducted in Maluku in order to develop a suitable land degradation assessment model based on local conditions. Soil loss as the indicator of land degradation were determined using Stocking’s field assessment and RUSLE methods. The study found that land degradation rates in the study area using field indicators ranged from the lowest soil loss 4.40–19.15t/ha/yr to the highest 202.84-675.62t/ha/yr, while the RUSLE method ranged from 0.11-16.92t/ha/yr to the highest 287.63-4207.41t/ha/yr. The developed land degradation model (LD) due to erosion LD = 0.1499xR1.000 xK0.0026xLS0.0933xC0.133xP1.000xBd0.700xAv-0.652 is statistically significant because their p-values equal 0.000 with high R2 of 82,5% at a confidence level of 95%. The second model was also produced with a correction factor of 0.2158, so LD = 0,2158xRxKxLSxCxP, where LD= land degradation (tons/ha/yr), R = rain erosivity value (ton.m/ha/cm-rain), K= soil erodibility index, LS= slope length and steepness factor index, C= plant or vegetation or land use factor index, P= soil conservation practices factor index, Bd= soil bulk weight factor (g/cm3), and Av= vegetation/plant or land use stage factor (years). These results promote the importance fact that the Stocking’s land degradation field assessment indicators could be considered as a suitable land degradation assessment model for the specific local condition of small islands in Maluku.Received: 2024-08-06 Revised: 2025-12-11 Accepted: 2025-12-31 Published: 2025-12-31