Erosion Rate Analysis and Land Conservation Direction Based on Geographic Information System in Way Rarem Subwatershed, Lampung Province

Way Sekampung subwatershed is the watershed area of Way Sekampung dam. The changes in land use that occurred in the Way Sekampung subwatershed caused flooding and landslides. To reduce existing problems, vegetative and mechanical land conservation efforts are needed. In this study, the USLE method was used to estimate the rate of erosion and then map the distribution of the Erosion Hazard Index in the Way Sekampung Subwatershed with the help of Geographic Information System (GIS). Based on existing conditions, the erosion rate in 2017 was 29626.262 tons/ha/year; in 2022, the erosion rate was 76617.579 tons/ha/year. The results of the analysis of the Erosion Hazard Index in 2017 and 2022 showed four criteria, namely low with a difference of -1.115%, moderate with an increase of 1.140%, high with a difference of -0.097%, and very high with a difference of 0.071%. Conservation with new land use, construction of terraces, and check dams has resulted in a reduction in erosion in the Way Sekampung Subwatershed with an Erosion Hazard Index, which is a low index increase of 26.992% from the existing condition and a very high 22.819% reduction from the existing condition. These results show that land conservation can reduce erosion in the Way Sekampung Subwatershed.

This study aims to determine the level of erosion hazard through erosion prediction by USLE method and Geographic Information System (GIS) at Water Catchment Area (WCA) Danau Wisata Bandar Kayangan. This research was conducted at WCA Danau Wisata Bandar Kayangan, Limbungan Village, District Rumbai, Pekanbaru. The research data was collected by survey method. Secondary data collection includes a slope digital map, land cover map, rainfall data, and soil type map of WCA Danau Wisata Bandar Kayangan. While the primary data is done by field checking to know land use pattern and soil type around WCA Danau Wisata Bandar Kayangan. The result shows that the erosivity index (R) is 108. The soil erodibility index (K) in Podsolik Merah Kuning (PMK) is 0.166. Slope length index (LS) on slope <8% flatland (20), 8 -15% ramps (15), 16 - 25% slightly steep (10). Crop management and soil conservation (CP) index covers settlement (1), Bush / 0.01), plantation (0,02), and lake (0,01). The result of overlay of rainfall maps, soil type, slope class, and crop management and soil conservation obtained 46 land units at WCA Danau Wisata Bandar Kayangan. The highest Erosion Hazard Index (EHI) is found on land unit 45 of 358 on residential land cover. The largest potential erosion on land unit 44 with soil loss is 41,189.45 ton / ha / yr. Level of EHI in WCA Area of Danau Wisata Bandar Kayangan includes Class EHI1: Very Light area of 32,627 ha; EHI Class 2: Lightweight of 59.86 ha; Class EHI 3: Medium area of 247.52 ha; Class EHI 4: Weight of 977,127 ha, Class EHI 5: Very Weight of 4,549.43 ha.

Ministry of Forestry has designated Kreo Sub-watershed, part of Garang Watershed, a critical area due to high erosion rates contributing to flooding in Semarang. Rapid land use changes accelerate environmental degradation, increasing erosion and sedimentation risks. This study measures erosion and sedimentation rates in Kreo Sub-watershed using SWAT (Soil and Water Assessment Tool), determines Erosion Hazard Index, and proposes erosion control solutions based on Land Rehabilitation and Soil Conservation Analysis (ARLKT) with vegetative conservation. ARLKT approach includes simulating new land use scenarios to assess their impact on erosion reduction. To ensure SWAT modelling accurately represents field conditions and not overestimate, allowing conservation recommendations based on ARLKT applied appropriately, a field-based sedimentation analysis also conducted. The study utilizes rainfall, soil type, slope, and land use data in 2019 and 2024 from satellite imagery and validated using a confusion matrix. Results indicate a shift in Erosion Hazard Index from predominantly ‘Moderate’ in 2019 to ‘High’ in 2024, underscoring urgent need for sustainable watershed management. By integrating remote sensing, field validation, and hydrological modeling, this study offers a precise, data-driven approach to erosion control. The findings serve critical reference for policymakers in developing effective conservation strategies to enhance watershed resilience.

This study aims to determine the erosion rate of land use, determine the allowable erosion, determine the erosion hazard index and conservation action efforts in Pasui Sub Watershed Upper Saddang Watershed Enrekang Regency, the research was conducted from March to May 2023. Analysis of the results of this study using Wischmeier (1978) or USLE method to test Erosion Prediction, Allowable Erosion, and determine the value of Erosion Hazard Index in Pasui Sub Watershed Upper Saddang Watershed Enrekang Regency. Prediction of the level of erosion rate (A) generated in the study in land use with two types of soil, the highest erosion rate (A) value is dominated by residential land use on Inceptisol soil with a value of 1457.12 tons/ha/year while the lowest erosion rate (A) value is obtained in primary dryland forest land use on Ultisol soil with a value of 3.58 tons/ha/year. Allowable Erosion in the Upper Pasui Sub Watershed of the Saddang Watershed, from the results of the study, is found in the land use of Ultisol soil settlements and Inceptisol soil dry land farming, where the Ultisol soil settlement land has an effective soil depth value of 288.00 mm while the Inceptisol soil primary dry farming is 266.00 mm, this indicates that the soil layer is shallow. The results of the IBE research have shown that residential land use, dryland agricultural land use mixed with shrubs and shrubs that experience erosion with a very high rate.

This study aims to predict the occurrence of erosion in the downstream Krueng Meureubo watershed, West Aceh Regency. Erosion is the loss of topsoil due to rain splash which is analyzed as a factor of rain erosivity, but the occurrence of erosion is not necessarily calculated by the occurrence of rain alone, but many other factors, such as soil erodibility, slope and length of land, land cover and the presence or absence of land conservation efforts. the. The Krueng Meurebo watershed shows a large sediment transport, with an indication that the river is getting shallower caused by sediment deposition at the riverbed, this sediment comes from sediment carried through the process of soil erosion. The method used in analyzing the occurrence of soil erosion in this study is the USLE method and uses a Geographic Information System (GIS). The results obtained are the distribution of erosion rate values in 228 polygons, with the largest erosion rate value occurring in polygon 1 with an erosion rate of 8495.308 tons/ha/year. The smallest erosion rate occurs in polygons 30, 34, 35, 179, and 180, with an erosion rate of 0 meaning that there is no land erosion event, which occurs in organosol and glehumus and regosol soil types, land cover is settlements and water bodies. It is concluded that the occurrence of erosion in a land is very dependent on the type of soil and the type of land cover. It is recommended for land with large erosion events to take serious land conservation actions so that erosion events can be minimized and do not occur continuously which of course can cause the watershed to become critical. Conservation efforts can be carried out in various ways, one of which is by vegetative means using plants that can reduce the rate of soil erosion.

One of the causes of the silting of the Sagara Anakan, estuary of Citanduy River is due to sedimentation caused by changes in land use, which causes the erosion rate to become uncontrollable. To predict the rate of surface erosion of the Ciseel watershed, one of Citanduy tributary, the USLE (Universal Soil Loss Equation) method was used, while the Geographic Information System was used to assist in the analysis of spatial data. The results of the analysis of the rate of erosion in the Ciseel watershed show that in 2006 it was 28 tons/ha/yr, in 2012 it was 44.2 tons/ha/yr and in 2016 it was 49.9 tons/ha/yr, so it belongs to the erosion hazard class II/mild. based on the USDA classification. From the results of this study, it can be shown that the rate of surface erosion in the Ciseel watershed has a small contribution to sedimentation in Sagara Anakan. The simulation of land use change as an effort to reduce the rate of erosion from dry agricultural land to rice fields is expected to reduce the rate of erosion up to 24.7% in 2016.

The storage capacity of the reservoir is affected by poor management of the Watershed (DTA), which in turn influences erosion and sedimentation levels. In 1972, the erosion rate at Sutami Reservoir was 0,18 mm/year, rising to 1.44 mm/year by 2022. This data reflects a significant increase in the erosion rate within the Sutami Reservoir watershed, highlighting the need for effective watershed management modeling. The Soil and Water Assessment Tool (SWAT) is commonly used for watershed management assessment. This study aims to predict erosion and sedimentation rates using SWAT and evaluate the accuracy of its simulations through calibration and validation. The simulation results from SWAT show that the total erosion rate is 5,280.45 tons/ha/year, with a total sedimentation of 11,662,851.94 tons/year. Additionally, These results were compared with an analysis using the USLE method, which indicated an erosion rate of 5,178.98 tons/ha/year and sedimentation of 11,060,798.14 tons/year. The comparison of both methods showed similar outcomes, suggesting that the SWAT model provides reasonably accurate predictions. The calibration process, using observed discharge data from 2022 and SWAT-simulated discharge, yielded an NSE value of 0.778, classified as 'very good.' On the other hand, validation using discharge data from 2023 and SWAT-simulated discharge yielded an NSE value of 0.660, classified as "good." Based on these results, the SWAT simulation offers a reliable representation of calibration and validation, making it an appropriate model for this study.

Inappropriate land use and lack of cover crops may increase erosion rates. The purpose of this study was to compare the erosion rates of land use in Rembangan sub-watershed in 2001 and 2014. The erosion rates were calculated using a USLE (Universal Soil Loss Equation) method. The input data used were rainfall from 2004 to 2014, soil erodibility values based on field measurements, DEM (Digital Elevation Model), and land use maps in 2001 and 2014. USLE modeling showed that erosion rates in the study area in 2001 and 2014 were 873.1 tons/ha/year and 881.9 tons/ha/year, respectively. The erosion rates were classified as a very high level, which covered 42.5% of the total area. So, land conservation action is vital in the Rembangan Sub-watershed.

Introduction: Erosion can be caused by natural activities or human activities. Erosion events that occur naturally do not cause too many problems, but erosion events caused by humans can cause various problems of land damage or degradation and experience an accelerated rate of erosion. The Dolago watershed has an area of ±17,283.09 ha and is a priority watershed that needs attention because several natural disasters such as erosion, landslides, and floods have harmed the community when rainfall increases. Method: Based on the case above, researchers studied the erosion risk class of the Dolago watershed by combining erosion prediction methods, namely USLE and Geographic Information Systems. Erosion hazard class research was carried out in the Dolago watershed for 3 months, from September to November 2022 using the Universal Soil Loss Equation method and Geographic Information System, namely Overlay of several data (erosion determining parameters) to determine the erosion hazard class in the Dolago watershed. Results and Discussion: The results of research using the Geographic Information System and the Universal Soil Loss Equation method show that the amount of eroded soil in the Dolago watershed is 23,888.80 tons/ha/year and the erosion hazard class is divided into 5 classes, namely Class I (very light) erosion rate <15 tons/ha/year with an area of 15,111.55 ha, class II (light) erosion rate 15 - 60 tons/ha/year with an area of 175.52 ha, class III (medium) erosion rate 61 - 180 tons/ha/year with an area of 1,244.87 ha, class IV (heavy) erosion rate 180 - 480 tonnes/ha/year with an area of 491.66 ha and class V (very heavy) erosion rate >480 tonnes/ha/year with an area of 259.49 ha. Conclusion: Combining the geographic information system and the USLE method, five types of erosion hazard classes can be produced, namely class I classified as very light with an area of 15,111.55 ha percentage of 82.81%, class II classified as light with an area of 193.52 ha percentage of 1.12%, class III classified as moderate with an area of 1,815.52 ha percentage of 10.50%, class IV classified as heavy with an area of 682.32 ha percentage of 3.95% and class V classified as very heavy with an area of 279.56 ha percentage of 1.62%.

Introduction to the special issue ‘Tracer Applications in Sediment Research’

Water-borne erosion problem is one of the environmental problems faced globally particularly in developing countries. The objective of this study was to estimate the erosion rate at the Pansoon sub-basin using combination of conventional approach and remote sensing technology. Pansoon sub-basin is the upper stream of Langat watershed, Malaysia located in the mountainous area dominated by steep slopes and various type of soils which are the important factors contributed to soil erosion. The Revised Universal Soil Loss Equation (RUSLE) integrated in a Geographical Information System used to predict the soil erosion rate and spatially maps its distribution using rainfall, soil series and topography data to generate rainfall erosivity factor, soil erodibility factor and topography factor. Land use map was used to produce coverage and management practice factor. The result shows that 66% (7433 ha) of the Pansoon sub-basin is classified at very low risk, 22% of low risk (2433 ha), 5% of moderate (582 ha), 2% of the area with high risk (251 ha) and 5% of very high risk of erosion (549 ha). Pansoon sub-basin is prone to soil erosion problem on the southwest region may due to soil erodibility factor, slope length and slope steepness. Accuracy assessment was obtained between prediction model and field observation data (p=0.97) which means the RUSLE approach integrated in GIS is suitable to be used to predict and assessing the soil erosion rate. In conclusion, the prediction of soil erosion using RUSLE in GIS can be accurately assessed with the combination of field observation data.

Using 137Cs measurements to quantify soil erosion and redistribution rates for areas under different land use in the Upper Kaleya River basin, southern Zambia

Soil erosion is a significant environmental challenge, especially in tropical regions where heavy rainfall and land use changes accelerate soil degradation. Effective land management and conservation strategies require understanding and predicting soil erosion potential. This study presents a Soil Erosion Potential Model (SEPM) tailored for tropical catchments, integrating remote sensing and Geographic Information Systems (GIS) with the Revised Universal Soil Loss Equation (RUSLE). The Ulu Kinta Catchment in Malaysia, spanning 30,752 hectares and linked to the Ulu Kinta Dam in Ipoh, serves as a case study. To estimate the Rainfall (R) factor, rainfall data was correlated with topographical variables using rain gauge data and the downscaled tropical rainfall measuring mission (TRMM) 3B43 dataset over 11 years. Fieldwork involved soil sampling to determine the Soil Erodibility (K) factor. Shuttle radar topography mission (SRTM) data assessed topographical effects through Digital Elevation Models (DEMs), and Normalized Different Vegetation Index (NDVI) alongside Land Use/Land Cover (LULC) data from SPOT5 imagery was used to estimate the Cover (C) and Support Practice (P) factors. The annual soil erosion map indicated a mean erosion rate of 34.72 tons per hectare per year, peaking at 150 tons per hectare per year, associated with steep slopes, high rainfall, and insufficient support practices. Alarmingly, 19.98% of the catchment experienced severe to extremely severe erosion rates. The SEPM model was validated against previous studies, achieving a validation rate of 71.9%, demonstrating a reasonable correlation with similar research.

Paguyaman watershed is the second largest watershed in Gorontalo province with an area of 3,485.65 which is a critical watershed. There is a problem of sedimentation in the watershed causing the river flow rate to slow down. It is hoped that it can be used as an alternative to overcome siltation. The research aims to estimate the amount of sedimentation and determine the spatial distribution of sedimentation in the Paguyaman sub-watershed, the method used is the Soil and Water Assessment Tool (SWAT) model. carried out with the help of geographic information systems (GIS) with ArcGIS 10.4 software, SWAT can describe hydrological processes (sedimentation). DEM data resolution (10x10) as the main input for the DAS delineation process. Soil data, land use, soil type, determines the land unit/hydrologic response unit (HRU) of the watershed. Rainfall and climate data (temperature, average humidity, solar intensity, wind speed) obtained from stations spread over the area are integrated into SWAT to calculate sedimentation. The results of the Paguyaman watershed have a very steep slope (> 40), land use is dominated by primary and secondary dryland forest with a total area of 49511.90 with a percentage of 45.39%, Tropudults soil type; Dystropepts area of 22125.96 with a percentage of 20.28%, DAS Paguyaman has 8202 HRU's and sub-basin 475 there are 5 classifications of sedimentation quantities, namely very high sedimentation 285.25 ha, with a percentage of 0.26%, high sedimentation 87.78 ha with a percentage of 0.08%, moderate sedimentation 505.94 ha with a percentage of 0.45%, low sedimentation 3040.37 ha a percentage of 2.79% and very low sedimentation 105171.27 ha with a percentage of 96.41%.

Watatu Village is one of the villages located in Donggala Regency and as the capital city of South Banawa Sub-District which has significant potential in the agricultural sector, including cocoa plantations, oil palm trees, and paddy fields. This research aims as a source of information correlated to land-use policies and the erosion hazard index in Watatu Village, South Banawa Sub-District, Donggala Regency. The research was carried out by using the descriptive explorative method, and the observed variables were carried out through a survey. Soil sampling was determined purposively (purposive sampling) based on the category of land use and slope at the research location. Intact and incomplete soil samples were taken as many as 21 samples at seven land-use units. Sample analysis was performed at the Soil Science Laboratory on the Erosion Hazard Index, namely (1) soil texture, (2) soil structure, (3) organic matter content, and (4) permeability, and (5) bulk density. The results of the Erosion Hazard Index analysis showed that the high erosion hazard index was found in Land use unit 2 (mixed gardens), Land use unit 4 (cocoa gardens), Land use unit 5 (mixed gardens), and Land use unit 7 (Shrub). Thereby, conservation actions needed to preserve the environment to prevent or inhibit the rate of erosion and maintain the stability of land use.