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  • Title/Summary/Keyword: soil classification

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Assessment of Slope Failures Potential in Forest Roads using a Logistic Regression Model (로지스틱 회귀분석을 이용한 임도붕괴 위험도 평가)

  • Baek, Seung-An;Cho, Koo-Hyun;Hwang, Jin-Sung;Jung, Do-Hyun;Park, Jin-Woo;Choi, Byoungkoo;Cha, Du-Song
    • Journal of Korean Society of Forest Science
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    • v.105 no.4
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    • pp.429-434
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    • 2016
  • Slope failures in forest roads often result in social and economic loss as well as environmental damage. This study was carried out to assess susceptibility of slope failures of forest roads in Hongcheon-gun, Gangwon-do where many slope failures occurred after heavy rainfall in 2013 using GIS and logistic regression analysis. The results showed that sandy soil (6.616) in soil texture type had the highest susceptibility to slope failures while medium class (-3.282) in tree diameter showed the lowest susceptibility. A error matrix for both slope failure and non-slope failure area was made and a model was developed showing a classification accuracy of 74.6%. Non-slope failures area in the forest roads were classified mostly in the range of >0.7 which was higher values than the classification criteria (0.5) used by the logistic regression model. It is suggested that considering forest environment and site factors related to forest road failures would improve the accuracy in predicting susceptibility of slope failures.

Hydrogeochemistry of shallow groundwaters in western coastal area of Korea : A study on seawater mixing in coastal aquifers (서해 연안지역 천부지하수의 수리지구화학 : 연안 대수층의 해수 혼입에 관한 연구)

  • 박세창;윤성택;채기탁;이상규
    • Journal of Soil and Groundwater Environment
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    • v.7 no.1
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    • pp.63-77
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    • 2002
  • Salinization is an important environmental problem encountered in coastal aquifers. In order to evaluate the salinization problem in the western coastal area of Korea, we have performed a regional hydrochemical study on shallow well groundwaters (N=229) collected within 10 km away from the coastline. The concentrations of analyzed solutes are very wide in range, suggesting that the hydrochemistry is controlled by several processes such as water-rock interaction, seawater mixing, and anthropogenic contamination. Based on the graphical interpretation of cumulative frequency curves for some hydrochemical parameters (esp., Cl and NO3), the collected water samples were grouped into two major populations (1) a background population whose chemistry is predominantly affected by water-rock interaction, and (2) an anomalous population which records the potential influences by either seawater mixing or anthropogenic pollution. The threshold values obtained are 34.7 mg/l for Cl and 37.2 mg/l for NO3, Using these two constituents, groundwaters were further grouped into four water types as follows (the numbers in parenthesis indicate the percentage of each type water) : (1) type 1 waters (38%) that are relatively poor in Cl and NO3, which may represent their relatively little contamination due to seawater mixing and anthropogenic pollution; (2) type 2 waters (21%) which are enriched in Cl, Indicating the considerable influence by seawater mixing; (3) NO3-rich, type 3 waters (11%) which record significant anthropogenic pollution; and (4) type 4 waters (30%) enriched in both Cl and NO3, reflecting the effects of both seawater mixing and anthropogenic contamination. The results of the water type classification correspond well with the grouping on a Piper's diagram. On a Br x 104versus Cl molar ratio diagram, most of type 2 waters are also plotted along or near the seawater mixing line. The discriminant analysis of hydrochemical data also shows that the classification of waters into four types are so realistic to adequately reflect the major process(es) proposed for the hydrochemical evolution of each water type. As a tool for evaluating the degree of seawater mixing, we propose a parameter called 'Seawater Mixing Index (S.M.I.)’ which is based on the concentrations of Na, Mg, Cl, and SO4. All the type 1 and 3 waters have the S.M.I. values smaller than one, while type 2 and type 4 waters mostly have the values greater than 1. In the western coastal area of Korea, more than 21% of shallow groundwaters appear to be more or less affected by salinization process.

Variation of Seasonal Groundwater Recharge Analyzed Using Landsat-8 OLI Data and a CART Algorithm (CART알고리즘과 Landsat-8 위성영상 분석을 통한 계절별 지하수함양량 변화)

  • Park, Seunghyuk;Jeong, Gyo-Cheol
    • The Journal of Engineering Geology
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    • v.31 no.3
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    • pp.395-432
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    • 2021
  • Groundwater recharge rates vary widely by location and with time. They are difficult to measure directly and are thus often estimated using simulations. This study employed frequency and regression analysis and a classification and regression tree (CART) algorithm in a machine learning method to estimate groundwater recharge. CART algorithms are considered for the distribution of precipitation by subbasin (PCP), geomorphological data, indices of the relationship between vegetation and landuse, and soil type. The considered geomorphological data were digital elevaion model (DEM), surface slope (SLOP), surface aspect (ASPT), and indices were the perpendicular vegetation index (PVI), normalized difference vegetation index (NDVI), normalized difference tillage index (NDTI), normalized difference residue index (NDRI). The spatio-temperal distribution of groundwater recharge in the SWAT-MOD-FLOW program, was classified as group 4, run in R, sampled for random and a model trained its groundwater recharge was predicted by CART condidering modified PVI, NDVI, NDTI, NDRI, PCP, and geomorphological data. To assess inter-rater reliability for group 4 groundwater recharge, the Kappa coefficient and overall accuracy and confusion matrix using K-fold cross-validation were calculated. The model obtained a Kappa coefficient of 0.3-0.6 and an overall accuracy of 0.5-0.7, indicating that the proposed model for estimating groundwater recharge with respect to soil type and vegetation cover is quite reliable.

Effects of Forest Fire on the Forest Vegetation and Soil (II) (황폐산지(荒廢山地)에서의 산불이 삼림식생(森林植生) 및 토양(土壤)에 미치는 영향(影響)에 관한 연구(研究)(II))

  • Woo, Bo Myeong;Kwon, Tae Ho;Ma, Ho Seop;Lee, Heon Ho;Lee, Jong Hak
    • Journal of Korean Society of Forest Science
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    • v.68 no.1
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    • pp.37-45
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    • 1985
  • The second year's results of surface fire effects on forest vegetation and soil properties and fire tolerance of various tree species were investigated in Mt. Gwanak, Kyunggi-do, successively after the study of the first year's effect in the same place. Soil moisture contents, organic matters, and most of soil nutrients including exchangeable bases had increased just after fire and went down to become somewhat constant. Available phosphorous at fired area decreased until it became similar to that at unfired area, while pH of subsoil was continuously increasing from just after fire till after 1 year. For Lespedeza and Weigela species, fire tolerance of tree crown was the lowest but reproductive capacity was the highest. And both of them were high for Rhododendron species. More exact classification into Increasers, Decreasers, Invaders and Neutral species was possible in the second year's study. According to comparison of similarities, it was found that the vegetational structure at fired area is slowly restoring to original state as time goes.

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Environmental Survey and Properties of Establishable Grassland (초지조성 대상지 환경조사)

  • Choi, S.S.;Hwang, S.J.;Seo, S.;Lee, J.Y.;Jung, Y.K.
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.5 no.2
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    • pp.93-99
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    • 1985
  • All soil characteristics for 10,077ha of establishable grassland in 1984 were statistically summarized. Soils could be classified into 5 of Order, 7 Suborder, 11 Great group, 28 Subgroup, and 105 Series by the new comprehensive classification system. Distribution rate of farm houses managed the extent magnitude of 3.0ha was 70.8% and its total extent was 35.9%. Extent rate of uncultivated method was 71.3%. These soils were distributed with regard to hilly land and mountain foot slope at, 82.0, and to 0-30% slope at 66.9%. Soil texture was light such as sandy loam to loam at 85.0%, available soil depth more than 20cm at 97.8%, and gravel content less than 35% at 98.4%. Soil would be distributed in 67.3 of first class, 29.7 second class, and 3.0% third class for suitability. Mean values of pH, available P2O5, OM, Ca, Mg and K for topsoil were 5.6, 31ppm, 3.2%, 2.23me/100gr, 1.05me/100gr, and 0.37me/100gr, respectively.

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Classification of Volcanic Ash Soils and contribution of Organic Matter and Clay to Cation Exchange Capacity (화산회토(火山灰土) 분류(分類) 및 CEC에 대(對)한 유기물(有機物)과 점토(粘土)의 기여도(寄與度))

  • Park, Chang-Seo;Kim, Lee-Yul;Cho, Seong-Jin
    • Korean Journal of Soil Science and Fertilizer
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    • v.18 no.2
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    • pp.161-168
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    • 1985
  • The 38 typical profiles representing volcanic ash soils (VAS) in Korea were subjected to multiple regression analysis to determine the relative contribution of organic matter (OM) and clay content to total cation-exchange capacity (CEC). This study, also, was examined the soil characteristics of VAS. VAS in Korea could be classified into 3 Orders, 5 Suborders, 8 Great groups, 15 Subgroups, 23 Families, and 38 Series. Total area of VAS was 139, 162ha and the most of them occured in Jeju Island. Simple correlation coefficients showed significance relations at OM-CEC and clay-CEC in top-soil of VAS. The partial regression coefficients indicated that CEC for each gram of OM as calculated to be 0.46 and 0.40 me per of topsoils for the black volcanic ash soils (BVAS) and the very dark brown volcanic ash soils (VDBVAS), respectively. The clay contributions of topsoils for BVAD and VDBVAS were 0.11 and 0.19 me. The standard partial regression coefficients appeared that OM content of topsoil for BVAS and VDBVAS was 2.97 and 1.23 times as important as clay content in predicting CEC.

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Investigation on the Contamination of the Vicinity of Abandoned Coal Mines Located Near the Obong Darn and Preventive Measures (오봉댐 유역의 폐탄광에 의한 오염특성과 감소방안 연구)

  • Park, Sun Hwan;Chang, Yoon Young;Jeong, Jeong Ho;Son, Jeong Ho;Park, Seok Hyo
    • Journal of Environmental Impact Assessment
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    • v.16 no.2
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    • pp.143-156
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    • 2007
  • This study has researched the management status and the pollution level of water, soil, stream sediments of 11 abandoned coal mines out of a total of 12 within Obong-Dam area except Bukyung mine, which was submerged when constructing Obong-Dam, and selected areas which are in needs to have pollution control facilities in the first place. From the results of examination on the runoff at the waste rock pile and mineheads, the runoff from Sueun mine (pH, Fe, Al), Samwon mine (pH, Al), Wangdo mine (pH, Al), Mose mine (pH, Fe, Al) and Daeryeong mine (pH) exceeded the permissible discharge standards of the water quality, but the water at merging point with Obong-Dam after joined with Doma branch satisfied both Water Quality Standards and Drinking Water Quality Standards. In regard to groundwater contamination, it is found that areas where exceeded the Drinking Water Quality Standards are Wangdo mine (pH), Jangjae mine (pH, Zn), Daeryeong mine (pH) whereas all areas satisfied Soil Contamination Warning Standards of Soil Environmental Conservation Law. When comparing a research result on underwater sediments of branches of abandoned mines to the EPA Guidelines for classification of great lakes harbor sediments, Dongguk Gaerim (Fe), Jungwon mine (Fe), Daebo mine (Mn), Samwon mine (Mn) and Daeryeong mine (Mn) showed mid-level of contamination, whereas Sueun (Fe, Mn), Daebo mine (Fe), Woosung mine (Fe, Mn), Wangdo mine (Fe, Mn), Mose mine (Fe) and Daeryeong mine (Fe) showed high-level of contamination. In addition, contamination levels of underwater sediments in Wangsan and Doma branch where abandoned mine's branches merge together, Wangsan branch showed no contamination at all whereas Doma branch shows mid-level of contamination which reflect the Doma branch is affected by waste rock pile and minehead runoff of the abandoned mines in the Doma branch area. It is concluded that Mose mine and Sueun mine required treatment of acid mine drainage. and Wangdo, Jungwon, and Samwon mines were in need of mine tailing and erosion control work. The Samwon mine additionally required a control system for closed minehead runoff. Although the Samwon mine reached a high concentration of Al, Mn Ca2+, SO42 in the runoff, the levels decreased after it was combined with a tributary. It has been concluded that after further monitoring of the cause of pollution, a preventive measure system may be needed to be built.

Effects of Grain Size Distribution on the Shear Strength and Rheological Properties of Debris Flow Using Direct Shear Apparatus (직접전단장비를 이용한 토석류의 전단강도 및 유변학적 특성에 대한 입도분포의 영향 연구)

  • Park, Geun-Woo;Hong, Won-Taek;Hong, Young-Ho;Jeong, Sueng-Won;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.33 no.12
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    • pp.7-20
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    • 2017
  • In this study, effects of grain size distribution on the shear strength and rheological properties are investigated for coarse- and fine-grained soils by using direct shear apparatus. Shear strengths are estimated for fine-grained soils with the maximum particle size of 0.075 mm and coarse-grained soils with the maximum particle size of 0.425 mm and fine contents of 17% prepared at dry and liquid limit states. The direct shear tests are conducted under the relatively slow shear velocity, which corresponds to the reactivated landslide or debris flow after collapse according to the landslide classification. In addition, for the evaluation of rheological properties, residual shear strengths for both fine- and coarsegrained soils prepared under liquid limit states are obtained by multiple reversal shear tests under three shear velocities. From the relationship between residual shear strengths and shear rates, Bingham plastic viscosity and yield stress are estimated. The direct shear tests show that cohesions of fine-grained soil are greater than those of coarse-grained soil at both dry and liquid limit states. However, internal friction angles of fine-grained soil are smaller than those of coarse-grained soil. In case of rheological parameters, the plastic viscosity and yield stress of fine-grained soils are greater than those of coarse-grained soils. This study may be effectively used for the prediction of the reactivated landslide or debris flow after collapse.

Analysis of Forest Resources in Anmyondo for Forest Management Harmonizing with Nature (자연친화적(自然親和的)인 산림경영(山林經營)을 위한 안면도(安眠島) 산림자원(山林資源) 분석(分析))

  • Song, Ho Kyung;Lee, Sun;Heo, Won Mu;Lee, Mi Jeong
    • Journal of Korean Society of Forest Science
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    • v.89 no.2
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    • pp.185-197
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    • 2000
  • This study was carried out to research structure of forest vegetation and site condition, and supply basic data for conservation of pine forest and ecologically sustainable forest management and control in Anmyondo area. The forest of Anmyondo were largely classified as four forest community : Pinus densiflora community, Pinus thunbergii community, Pinus rigida community, and Quercus variabilis community. Organic matter, total nitrogen, and other nutrients in soil of the study area were relatively low, and average soil pH was 4.9. Soil texture was sandy clay or heavy clay and so the aeration and permeability could be poor. In this study site, the methods such as the promotion of germination of pine seeds through removal of forest floor and inducement of natural regeneration through such method as regeneration under shelter wood would be better than the method such as afforestation after clear-cutting for conservation the pine forests. Also, it will be a good method to practice tending for hardwood species in the dominant areas by hardwood species.

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Germination of Buried Seeds in Secondary Forest of Basla Zone - Coniferous and Broadleaved Forest of Low Slope, Yesan-gun, Korea - (저지대 이차림지역의 매토종자 발아특성 -예산군의 침엽수림과 활엽수림-)

  • Kang, Hee-Kyoung;Park, Jun-Young;Ahn, Sang-Kyo;Cho, Yong-Hyeon;Park, Bong-Ju;Kim, Won-Tae;Shin, Kyung-Jun;Eo, Yang-Joon;Song, Hong-Seon
    • Korean Journal of Environment and Ecology
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    • v.28 no.6
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    • pp.705-714
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    • 2014
  • This text was analyzed and investigated the aerial part plants and buried seed plants at coniferous forest and broadleaved forest in Yesan-gun, in order to offer the basic data of potential natural vegetation change on secondary forest. Plants of buried seed germination were consisted of 29 taxa in coniferous forest (28 species, 1 varieties, of 27 genus, 20 families) and 36 taxa in broadleaved forest (34 species, 2 varieties, of 32 genus, 18 families). Family classification of buried seed plant was the most in Compositae, and emergent plot frequency was the highest of Cyperus amuricus in coniferous forest and Crepidiastrum sonchifolium in broadleaved forest. The soil depth of the most plants appearance was 0~10 cm in coniferous forest and 0~5 cm in broadleaved forest, and the soil depth of the most population appearance was 0~2 cm in coniferous forest and broadleaved forest. Population of buried seed germination was decreased according as soil is deep. Crepidiastrum sonchifolium was a plant that population of buried seed germination is the most. Similarity index of the aerial part plants and buried seed plants was low as 0.22, and coniferous forest and broadleaved forest was 0.40.