Sub-watershed Area Research Articles

Effect of slope on water run-off and soil vulnerability in an unglaciated sub-watershed: a case study of conservation practice siting

For maximization of soil and water quality benefits, the right agricultural conservation practices (CPs) should be practiced for the right place. The Agricultural Conservation Planning Framework (ACPF) is a tool that helps decision makers achieve precise conservation within a target watershed using rapid, low-cost Geographic Information System-based tools. ACPF takes the information on landscape characteristics and combines it with user input to identify locations susceptible to soil loss and water run-off and suggest potential CP locations. Suggested CPs may further be analyzed for urgency, installation cost, and effectiveness. In this study, ACPF was applied to analyze soil and water vulnerability within a small unglaciated sub-watershed in southwest Wisconsin and identify potential CP practices and recommended placement sites. To promote environmental sustainability in the agriculture sector, land managers are tasked with implementing CPs, but often lack adequate information on the most effective practice and placement strategy. Field-scale siting of CPs was achieved using high-resolution terrain derivatives and accurate simulation of the stream network. Slope disaggregation among soil loss vulnerability categories was also conducted. Greatest sources of vulnerability were associated with slope and erodibility factors, with average slope within cropped fields being 6% and erodibility being as high as 43%. Fields classified as critical for conservation had a mean slope of 7.4%. Suggested contour buffer strip (CBS) placement per field varied with slope, with steeper fields having denser placement. The results suggested that 3% of cropland could be removed from production if the recommended placement of CBS was implemented. A further 0.2% of the sub-watershed area would go to grassed waterways. The results support implementation of effective CPs based on local conditions and act as a tool to help reveal if existing practices in the sub-watershed are of a size and extent comparable to the predicted potential.

Assessment of area at risk of flood and drought in the SeThamok Sub-basin

The problem of floods and drought is a serious problem and has affected many areas in many areas of the world including Lao PDR. SeThaMok sub-basin is a sub-basin that suffers from disasters as mentioned almost every year, especially in Phin district, which has caused enormous damage. Because of such a problem, it is necessary to assess the risk areas for floods and droughts in order to manage floods and droughts that are suitable for the area in order to move forward in planning to deal with floods and droughts in the future. Therefore, this study aims to study flood and drought risk areas as well as create flood maps in (2014, 2018, 2019) and drought maps in (2006, 2012, 2015) using ArcGIS 10.5. This study uses rainfall data from 4 stations using the Thiessen Polygon Method to calculate the average rainfall and using data from the survey, collecting actual data from the field together with the data collected by the Department of Natural Resources and Environment. The results of the study found that: in 2014, there was a flood area covering 11.93% of the total catchment area and the maximum flood level was about 26 meters compared to the lowest level of the catchment area. Among them, the flood event covered 20 villages; In 2018, there is a flood area covering 16.06% of the total catchment area and the maximum flood level is about 32 meters. Among them, the flood event covered 27 villages; In 2019, there is a flood area covering 20.91% and the maximum flood level is about 34 meters. Among them, the flood event covered 39 villages and the results of the evaluation of areas at risk of drought showed that: in 2007, there were areas at risk of drought covering 39.18% of the area of the SeThaMok sub-watershed which covered the number of villages around 32 villages; In 2012, there is a drought-prone area covering 43.29% of the SeThaMok sub-watershed area, which covers about 38 villages; In 2015, there is a drought-prone area covering 36.73% of the SeThaMok sub-basin area, which covers about 30 villages.

Assessment of Groundwater Vulnerability to Pollution in the Metro Subwatershed Area Using the GOD Method

The assessment of groundwater vulnerability to contamination in the Sub-Watershed (Sub DAS) Metro plays a crucial role in maintaining the sustainability of water resources. As an integral part of a complex river system, Sub DAS Metro faces the risk of groundwater pollution caused by human activities such as agriculture, industry, and domestic. Thus, research was conducted to determine the level of groundwater vulnerability using the GOD method (Groundwater Occurrence, Depth to Water Table, and Aquifer Media). The study identified three vulnerability classes out of the five existing classes, namely very low, low, and moderate. The GOD index indicates very low vulnerability with values ranging from 0.08 to 0.10, low vulnerability ranging from 0.11 to 0.12, and moderate vulnerability with a value of 0.48. Following the vulnerability assessment using the GOD method, mapping was conducted, assigning green for very low vulnerability areas, yellow for low vulnerability, and red for moderate vulnerability. The research findings provide strategic insights for designing effective mitigation and sustainable management of groundwater quality in Sub DAS Metro, playing a crucial role in preserving the sustainability of the groundwater ecosystem in the region

IDENTIFIKASI LAHAN KRITIS SKALA 1:25.000 BERBASIS CITRA SENTINEL 2 DAN DEMNAS RESOLUSI 8 METER (STUDI KASUS SUB DAS CIKAPUNDUNG JAWA BARAT)

Critical land is a condition of land that is no longer able to carry out its functions properly because it has experienced physical, chemical, and biological damage. One area that has the potential to experience critical land problems is the Cikapundung Sub-watershed, West Java. This research aims to identify the existence of critical land in the Cikapundung Sub-watershed area by integrating the Geographic Information System, Sentinel-2 Imagery, and DEMNAS as well as mapping the distribution of land criticality levels in the Cikapundung Sub-watershed at a detailed scale (1:25,000). The research was carried out from May to August 2023. The research was carried out using spatial analysis methods by overlaying thematic maps of each critical land parameter consisting of maps of land cover, erosion, and slope. The results of overlaying all critical land parameter maps were then analyzed using a scoring method to classify the level of land criticality and create a critical land distribution map in the Cikapundung Sub-watershed area. The results of identifying critical land in the Cikapundung Sub-watershed area produced five classes of land criticality, namely uncritical, potentially critical, rather critical, critical, and very critical. The identification results show that there are 4210.94 ha (13.83%) of land identified as critical land in the Cikapundung Sub-watershed area. The results of mapping the level of land criticality in the Cikapundung Sub-watershed show that the Cikapundung Sub-watershed area which is included in the forest area is dominated by the moderately critical land criticality class, while the Cikapundung Sub-watershed area which is outside the forest area is dominated by the uncritical land criticality class.

Evaluation of Aggregate Stability Using the Slaking Index Method with Soil Physical Approach in Keduang Sub-Watershed, Indonesia

The Keduang Sub-Watershed area has faced multiple natural disasters like landslides, erosion, and flooding because of the poorly managed terrain in the area. This study examines the distribution of the slaking index on agricultural land in the Keduang Sub-Watershed, analyzes the impact of soil type on it, and identifies the soil physical elements that have the most significant influence on it. The study took place in the Keduang Sub-Watershed, Indonesia, utilizing agricultural land from woods, plantations, drylands, and paddy fields with Andisols, Alfisols, Inceptisols, and Entisols soil types. This survey research was supported by laboratory analysis of the soil's physical and chemical properties and used GIS for data interpretation. Soil samples were collected from 22 Land Map Units (LMUs) with 3 replications each, resulting in 66 samples. The SLAKES software assesses the primary parameter, the slaking index. The supporting parameters analyzed were aggregate stability, bulk density, texture, structure, pH, organic C, and Cation Exchange Capacity (CEC). The research showed that soil types in the Keduang Sub-Watershed significantly affect the slaking index value. The slaking index ranged from 0.13-11.63, with the highest values for Andisols in a forest, while the lowest values were Inceptisols in a plantation. The allophane mineral in Andisols was causing the high slaking index. The soil factors determining the slaking index were bulk density and exchangeable K. The lower the bulk density, the higher the slaking index. Meanwhile, the lower the exchangeable K, the lower the slaking index. The land management recommendations based on determinant factors are adding organic material and reducing soil cultivation practices.

Soil Fertility Mapping Using GIS in Sirur Sub-Watershed of Kundagol Taluk of Dharwad District, Karnataka, India

Aims: To identify available nutrient constraints in soils and to generate soil fertility maps using remote sensing and GIS of Sirur sub-watershed in northern dry zone of Karnataka. Place and Duration of Study: The study was carried out in the Sirur sub-watershed (4D5B5j) located in Kundagol taluk of Dharwad district, Karnataka during 2022-24. Methodology: Soil samples (601) from Sirur sub-watershed in northern dry zone of Karnataka were drawn at 320 m x 320 m grid interval and assessed for fertility parameters. Analytical data was interpreted and statistical parameters like range, mean, standard deviation and coefficient of variation were calculated for each parameter. Soil fertility maps were prepared for each parameter using interpolation technique. Results: Soils were neutral to alkaline in reaction and non-saline. Soil organic carbon content was low to medium. Available nitrogen and phosphorus were low to medium, available potassium was high and sulphur was medium to high. Regarding available micronutrients, iron, copper and manganese were sufficient in the soils whereas Zn was deficient in about half of the sub-watershed area and B content was medium to high. Conclusion: The major constraints in sub-watershed are low content of OC, poor status of available N, P2O5 and Zn indicating their immediate attention for sustained crop production.

Characteristics of Soil Chemical Properties in Several Types of Oil Palm (Elaeis guineensis Jacq.) Land and Shrubs in Negeri Lama Seberang Village (Case Study of Lower Bilah Watershed)

The Bilah Sub-Watershed area includes areas that have somewhat critical or semi-critical land so that land use is the result of human efforts in managing the available resources to meet their various needs. This often results in land use not being in accordance with its capabilities. This research aims to examine the chemical properties of several vegetation in Negeri Lama Seberang Village, Bilah Hilir District, Labuhanbatu Regency. The research was carried out from December to March 2024 using a survey method. Soil samples were taken at 3 points for each vegetation and different slopes at depths of 1-10 cm and 10-20 cm using a simple random method. The soil parameters measured were soil acidity (electrometry), soil organic carbon content (Walkley and Black), and soil texture (bouyoucos hydrometer). Soil analysis was carried out at the Laboratory of the Faculty of Agriculture, University of North Sumatra. The results of this research show that on a slope of 0-8% the average soil pH value is 4.61% and organic C is 1.04%, while on a slope of 8-15% the average soil pH value is 4.46% and C -organic 0.91%. On a slope of 0-8% the average value of the clay fraction is 20.27%, the dust fraction is 15.02% and the sand fraction is 64.41%, while on a slope of 8-15% the average value of the clay fraction is 27.48%, the dust fraction 19.87%, and sand fraction 52.63%.

Identification, Prioritization and Mapping of Major Constraints and Potentials in the Medo Watershed the Case of West Arsi District in Central Rift Valley Area of Ethiopia

The concentration to characterize the biophysical and socio-economic features in the integrated watersheds is to identify and prioritize production constraints for designing appropriate research and development interventions. The objective of this study was to assess the current biophysical of characteristics of Medo watershed, West Arsi Zone of Oromia, Ethiopia. To do so relevant data and tools were used; ArcGIS, Microsoft Excel sheet and fundamental formulae were applied for the analysis are some. The results of the study indicated that the major land use types in the watershed are agricultural land covering 50%, vegetation (shrubs, forests and, plantations) covering 24% and settlement covering 16% out of the total land use. Slope gradient of Medo watershed ranges from zero to more than 20 and the slope gradient of 2-5 and 5-10 cover the greatest in area coverage representing 201 ha and 170 ha respectively. We can also observe that about 8% out of the total area is subjected to severe erosion. Sandy clay loam was the dominant soil textural classes in the surface soils and Phaeozems, Retinols and Andosols are the dominant soil types, which cover 57%, 36% and 7% of the sub-watershed area for lower, middle, and upper slope positions, respectively. Mean annual rainfall of the area ranges from 960.09 mm at lower part of the watershed to the 1304.93 mm at upper part of the watershed. Accordingly, Medo sub-watershed is laid in majority of at sub humid agro ecological zone. An assessment of the trees within the landscape of watershed showed some remnant natural forests and a wide variety of shrubby vegetation is encountered at all landscapes. About 40 percent of the watershed, is under high to extremely severe soil loss values (>45 ton per hectare per year). The baseline study also identified that those natural resources degradation such as land, and or/ soil fertility, reduction, and recent changes in the areas’ weather condition in line of climate change prevailing in current years are few of the many factors that are contributing to the land and crop productivity reductions in the area. Therefore, prioritizing the identified problem and preparing intervention of different technologies and development plans to solve the problems by taking into consideration the existing opportunities of the watershed.

Low Flow of Cascade Reservoir in Sekampung Watershed

Purpose: This research intends to analyze the low flow in the cascade reservoir in Sekampung watershed Theoretical reference: The low flow analysis uses the HEC-HMS model with the input parameters are GPM satellite rainfall that is calibrated by the ground station data in the Sekampung watershed, variation of land use, and soil type. Method: The methodology consist of by using the HEC-HMS model. Then, this model is calibrated with the flow discharge in Batutegi reservoir. Result and Conclusion: The model result produces the linear average discharge with the comparation ratio of sub-watershed area in each outlet is as follow: 11.0% (W1), 10.4% (W2), 39.9% (B1), 9.2% (W3), and 30.5% (B2). Half monthly average discharge is in the range of 2.6-40.8 m3/s (W1), 2.6-35.8 m3/s (W2), 11.9-151.4 m3/s (B1), 2.6-34.8 m3/s (W3), and 8.8-116.2 m3/s (B2). Percentile of dependable discharge that is used is >66.6% for dry year, 66.6%-33.3% for normal year, and <33.3% for wet year with the value between 6.6-25.4 m3/s (W1), 5.7-23.2 m3/s (W2), 24.2-97.3 m3/s (B1), 5.4-22.4 m3/s (W3), and 18.0-74.8 m3/s (B2). Implication of research: The calibration of discharge as the modelling result to the observed discharge produces the RMSE value is 0.462, the NSE value is 0.787, the PBIAS is 0.04% with the result interpretation is very good. The validation produces the RMSE value is 0.632, the NSE value is 0.601, and the PBIAS value is 0.01% with the result interpretation is very good. Originality/ value: The model that is used for analyzing flood in the study location is the HEC-HMS software by carrying out the watershed division into smaller sub-watershed.

Analysis of Factors Influencing Spatial Distribution of Soil Erosion under Diverse Subwatershed Based on Geospatial Perspective: A Case Study at Citarum Watershed, West Java, Indonesia.

The application of remote sensing data has been significant in modeling soil erosion. However, previous studies have fallen short in elucidating and lacked an understanding of the multifactor influencing erosion. This study addresses these limitations by employing the InVEST and the Geodetector models. Specifically, it aims (1) to delineate both spatial and temporal variations in soil erosion within the Citarum watershed from 2010 to 2020, (2) to identify the key drivers of soil erosion and unravel the underlying mechanisms, and (3) to identify the high-risk zones for soil erosion. Both models consider a range of natural predictors, including topography (slope factor), climate (precipitation factor), and vegetation cover (vegetation factor). In addition, they incorporate social parameters such as income per capita and population density, which interact with the watershed's position in the downstream, middle, and upper streams. The results reveal that, over a decade, the average soil erosion increased by 15.50 × 106 tons, marking a 16.65% surge. The impact of factors varies significantly across different subwatershed areas. For example, fraction vegetation cover interactions influence upper- and middle-stream regions, while the downstream area is notably affected by precipitation interactions. The high-risk erosion areas in the watershed are primarily influenced by slope, precipitation, and fractional vegetation cover. In these areas, factors causing high erosion risks include slope, precipitation, and other environmental variables categorized into strata. The study highlights the varying influential factors in different watershed areas.

PEMODELAN DEBIT SUNGAI MENGGUNAKAN SOIL AND WATER ASSESSMENT TOOL DI SUBDAS MAMASA

ABSTRACT
 Issues related to watershed have received primary attention in the past few decades. The hydrological conditions of the watershed area are considered crucial as a source of life. In efforts to achieve sustainable watershed management, understanding the complex hydrological dynamics is very important. The objective of this research is to simulate river discharge using the Soil and Water Assessment Tools (SWAT) model. This study was conducted in the Mamasa Sub-watershed area. The results show that the river discharge in the Mamasa Sub-watershed has increased as it approaches the outlet (downstream) through the accumulation of discharge in larger order rivers. The Mamasa Sub-watershed also experiences a trend of increasing average annual discharge at a rate of 0.74 m3/s per year. Improvement in the discharge simulation results was achieved through a calibration process using 11 parameters. The calibration results indicate that the calibrated discharge has a higher R2 value compared to the initial simulation discharge, showing that the model calibration successfully improved the quality of the expected discharge results to reach 79.50 percent. However, the calibration results still have a low R2 value, influenced by the selection of appropriate parameters and accurate observational data.
 Keywords: Modeling, River discharge, SWAT, Watershed

Analysis of Surface Runoff and Remote Sensing Data to Identify Flood Potential in Simbang Sub-Watershed

Increased water runoff due to land use change phenomena has triggered flooding events. The objective is to identify flood potential in Simbang Sub-Watershed in Maros Regency using rational methods and remote sensing data. Potential flood hazards were analyzed using the weighting method with the parameters NDVI, MNDWI, NDSI, rainfall, and annual flow coefficient. The highest debit of runoff occurred in 2017, with a value of 113.36 m3/s, while the lowest occurred in 2019, with a value of 63.91 m3/s. The NDVI value is 0.37–1 with high vegetation covering an area of 3,089 ha, while the low-very low vegetation has value -0.03–0.25 with an area of 1,668 ha. The MNDWI value ranges from 0-0.33 with a moderate wetness level covering an area of 741 ha and an NDSI value ranging from -0.06–0.43 for bare land surrounding an area of 738 ha, which has an impact on reducing water catchment areas which can trigger an increase in surface water runoff discharge. The average rainfall is 2,965 mm/year, the area with low potential for flooding is 3,705 ha, and the area prone (moderate) to flooding is 1,450 ha. The rainfall factor is the main priority trigger for flood events with weight of 0.266, and the soil index is the lowest priority factor with weight of 0.145. Surface water runoff in the Simbang Sub-Watershed area makes a small contribution to the flood events that occurred in Maros Regency with an annual flow coefficient value of 0.23.

Effect of Land Use and Land Cover Change on Soil Erosion in Alaba Sub-Watersheds of Central Rift Valley Basin, Ethiopia

The magnitude of soil erosion rates has been accelerating in the Central Rift Valley Area of Ethiopia due to land use and land cover change (LULCC). This study aimed to analyze the trends and changes in land use and land cover dynamics and to analyze the impact of LULC change on soil erosion over the Alaba Sub-Watershed, Central Rift Valley Area of Ethiopia. This study would help to plan and use appropriate land use planning, soil, and water conservation practices, thereby reducing soil erosion in the study area. The soil loss rates were estimated using an empirical prediction model of the Revised Universal Soil Loss Equation (RUSLE) outlined in the ArcGIS environment. During the study period between 1987 and 2018, the rate of change in cultivated land and bare land was raised by 9.09% and 1.08%, respectively. On the contrary, vegetation cover and grasslands had dropped by –2.03%, and -1.42% respectively. From trends of LULC changes, cultivated land revealed an increasing trend increasing from 181.28 hectares to 351.23 hectares for the period 1987 to 2018, respectively. On the other hand, vegetation and grasslands showed a declining trend from -271.92,-22.66 hectares to -305.91, -124.63 hectares, respectively. The findings of the study generally elucidate that the LULCC has a detrimental impact on soil erosion. The estimated total annual actual soil loss in the study landscape was 25707.77 tons in 1987, 29310.71 tons in 2000, and 31769.32 tons in 2018. It was also found that the mean annual soil loss rate of the study catchment was 22.69t/ha/yr., 25.87t/ha/yr. and 28.04t/ha/yr. in 1987, 2000, and 2018 respectively. About 35% and 42% of the Sub-watershed experienced high to very severe soil erosion in 1987 and 2018, respectively. The results indicate that the estimated erosion rate for about 39 % of the sub-basin area exceeds the maximum tolerable soil erosion threshold and this shows that the erosion risk condition is deteriorating in the study landscape. The top three priority levels delineated for urgent SWC measures represent those areas within the large increase in erosion risk levels, with an area of 188 hectares and accounting for 17 % of the sub-watershed area. Therefore, further detailed investigations based on data from primary and secondary sources would be important in identifying driving socioeconomic forces and consequences of LULCCs and suggesting possible alternative options to establish sustainable resource management practices in the study area.

Sosialisasi Area Rawan Longsor Dan Upaya Mitigasinya Di Kecamatan Lingsar Kabupaten Lombok Barat

The Meninting Sub-watershed area, West Lombok Regency is one of the areas prone to landslides. This is due to the topographic conditions of the area which are dominated by very steep slopes. Landslides are one of the disasters that often occur, especially in West Lombok Regency. High rainfall intensity with a long duration is one of the factors causing erosion and landslides on critical slopes. This service activity was carried out with the aim of increasing the knowledge and insight of the community around the Meninting watershed, especially in the Lingsar District, regarding the risk of landslides and mitigation actions that can be taken. The target of this service is the Lingsar District Government and surrounding communities affected by the landslide disaster. The result of this service activity is an agreement on a follow-up plan for this activity with the Lingsar District and also the affected communities. This agreement is demonstrated by the willingness of the service target community to utilize data and information disseminated in various disaster mitigation and adaptation actions. Mitigation actions that can be taken include mapping areas prone to landslides, controlling land use, improving the quality of infrastructure, education and training and emergency planning. Handling adaptation to landslide disasters can be done by arranging housing, strengthening infrastructure, utilizing technology, increasing community capacity, and sustainable environmental management.

Analysis of changes in vegetation density with sentinel-2a image on Malino sub-watershed

Changes in vegetation density, especially in sub-watershed areas, will continue to occur over time. This is due to increasing human activities impacting land use change. The Malino sub-watershed one part of the Jeneberang watershed, almost all located in Tinggimoncong District. Monitoring changes in vegetation density in the Malino Sub-watershed is carried out by utilizing remote sensing technology in the form of sentinel-2A imagery and using the NDVI type of vegetation index method. This study aims to determine the distribution and changes in vegetation density in the Malino Sub-watershed in 2017, 2019, and 2021. From the analysis results conducted using the NDVI vegetation index, the distribution of vegetation density in the Malino Sub-watershed is divided into four classes, namely the non- vegetation, sparse vegetation, medium vegetation, and dense vegetation. Changes in vegetation density in the Malino sub-watershed from 2017 to 2019 occurred in the dense vegetation density class of 2.21% or 192.69 ha, while the smallest occurred in the non-vegetation density class of 0.24% or 20. 97 ha. Meanwhile, the most significant change in vegetation density in the Malino sub-watershed from 2019 to 2021 occurred in the dense vegetation density class of 11.64% or 1,016.60 ha, while the smallest occurred in the non-vegetation density class of 0.12% or 10.46 ha.

ANALYSIS OF FLOOD HYDROGRAPH IN THE LANDAK SUB WATERSHED

This research is motivated by the natural flooding disaster in the Landak sub-watershed area, which can be caused by river overflow due to high rain intensity. Flood discharge can be calculated using the Synthetic Unit Hydrograph method if the available data is limited, such as only obtaining rainfall data and watershed characteristics.Several Synthetic Unit Hydrograph (SUH) methodologies, including SUH Snyder, Nakayasu, Soil Conservation Services (SCS), Gama I, ITB, and Limantara, were utilized in this study. The analyzed data included precipitation data and measured discharge data. Rainfall data are analyzed using the homogeneity test, statistical descriptors, and chi-squared to determine the planned flood discharge. Then, continue with the study of rainfall frequency and analysis of rainfall intensity so that the maximal discharge can be analyzed using three SUH methods: HSS Snyder, Nakayasu, and SCS. The analysis of measured release is conducted by statistically analyzing estimated discharge data.The analysis results are then compared to obtain the percentage error between the discharge plan and the minimum measured discharge. The results showed that the HSS Snyder method was selected for analyzing flood discharge in the Landak sub-watershed basin because it has the minimum percentage error from comparing planned release and measured discharge values. Therefore, for the calculation of flood discharge analysis of the Landak sub-watershed basin, the HSS Snyder method is used with the acquisition of flood discharge plans for the return period of 2, 5, 10, 20, 50, and 100 years of 648,880 m3/sec, 896,335 m3/sec, 1025,954 m3/sec, 1132,006 m3/sec, 1252,788 m3/sec, 1335,273 m3/sec.

Identifikasi Perubahan Luasan Lahan di Wilayah Sub-DAS Cikeruh Menggunakan Citra Landsat 8 dengan Google Earth Engine (GEE)

Land cover information is the data neede in the management of watersheds. Identification to obtain land cover using a cloud-based spatial data processing platform Google Earth Engine (GEE). This study aims to identify changes in land area in the Cikeruh sub-watershed area by classifying them using a machine learning basis on GEE. Utilization of landsat imagery is applied in the operation of the Google Earth Engine (GEE) platform using landsat 8 imagery. The analysis method used is the interpretation of Support Vector Machine (SVM) imagery with the identified years since 2015 until 2020. This research still has deficiencies, especially in the validation of land cover classes and area mapped and analyzed.

Assessment of Factors Affecting Agricultural Soil Damage in the Upper Stream Sub-Watershed

Soil damage can be caused naturally or by human activities. Potential areas that have high soil damage are sub-watershed areas and one of them is the Upper Serang Sub-watershed in Central Java. Assessment of potential and actual land damage will help to make wise land use planning. This research aims to assess actual and potential soil damage and the factors affecting the Upper Serang Sub-watershed. This research used descriptive quantitative and qualitative methods, where quantitative descriptive methods were used to assess soil damage and descriptive qualitative methods were used to determine farmer activity factors about soil conservation. The research result, that potential soil damage was included in the highly class soil damaged category with limiting factors are high rainfall of around > 2500 mm/year, slopes that exceed 25% (25-40% and >40%), soil type was dominated by Inceptisol soil and land use dominated by the moor. Meanwhile, actual soil damage has a slightly soil-damaged class with the limiting factors being permeability, redox potential, and the combined permeability and the soil fraction composition. Actual soil damage has a slightly soil-damaged class (RI) because farmers have taken soil conservation measures by mechanical methods dominant. Future efforts that farmers must do are to increase soil conservation measures with a combination of mechanical and biological conservation methods. Keywords: Actual soil damage, Potential soil damage, Upper Serang Sub-watershed.

Taxonomical Classification of soils of Asvaru Sub-watershed, Hunsur Taluk, Mysuru District

Soil characterization and classification is crucial to all soil studies, as it is an important tool for understanding the nature of soil along with successful transfer of research results from one study area to another. The proper understanding of the nature and properties of soil and their management based on their potential and problems is important for increasing crop production to the optimum level. For understanding the problems and potentials, detailed soil survey plays an important role which provides adequate information in terms of land form, slope, land use as well as characteristics of soils (viz., texture, depth, structure, stoniness, drainage, acidity, salinity etc.) which can be utilized for the planning and development. The purpose of the study is to classify the soils of Asavru sub-watershed in Mysuru district to categorize the soils into different soil order upto family level of Soil taxonomy Classification and enhance the productivity and profitability of the area. The detailed soil survey was carried out in Asvaru sub-watershed. Seventy two profiles were studied for its different morphology, physical and chemical properties. The subwatershed area was grouped into 75 mapping units consisting of 16 soil series. The soils were shallow to very deep with texture varying from sandy loam to sandy clay. The structure was sub-angular blocky in all profiles with friable consistency. Soil reaction varied from moderately acidic to moderately alkaline and non saline in +2 + + + nature. Exchangeable cations followed the pattern of Ca >Mg >Na >K . The soil series identified in the sub-watershed area were classified under different soil orders (Alfisols and Inceptisols) upto family level according to revision of Soil Taxonomy. Major proportion of the soils of the sub-watershed belonged to Alfisols (Pedons1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12 and 15) and Inceptisols (Pedon5, 13 and 16).

Erosion and sedimentation analysis as basic reference for land conservation planning on lesti Sub-watershed

The Lesti sub-watershed area is mostly steep mountain slopes, when the rain fall it carries erosion and sediment material. This study aims to discover the trend of land-use changes; measure the amount of erosion rate and Erosion Hazard Levels; obtain the sediment-transport actual quantity based on SWAT application; discover the scatter of land critical-level; and determine the strategy for implementing conservation and controlling the erosion rates. Erosion Hazard Level were obtained as follows: Class I 11.92%; Class II 27.45%; Class III 43.85%; Class IV 13.06%; Class V 3.99%. Four (4) parameters overlaid to determine the land criticality level are: land coverage, land slope, erosion risk level, and management aspect. Generally, Lesti Sub-Watershed is categorized as: very critical 0.14%; critical 4.61%; a rather critical 28.06%; critical potential 53.66%; and normal 13.51%. From SWAT analysis the average value respectively soil erosion is 119.60 tons/ha/year; sediment yields 310.77 tons/ha/year; rainfall 2143.27 mm/year; and surface runoff 1120.65 mm/year. The suggestions of the watershed area conservancy requires a vegetative (planting) and mechanical (building) method. The vegetative method such as: alleys cropping; reforestation; agroforestry; relay cropping; soil cover cropping as natural green manure; living fence; mixed cropping farm; mulch; environment greening; strip cropping with 20.65% effectivity; and filter strip with 26.03% effectivity. The mechanical method such as: contour tillage with 29.71% effectivity; terracing with 23.41% effectivity; check dam with 17.50% effectivity; and mound.