• Journal of Korean Society for Geospatial Information Science
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• v.18 no.4
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• pp.131-139
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• 2010

Recent spread of GIS and the increasing demand of spatial data have brought about the development of web GIS. In addition to sharing and mapping spatial data, web GIS is also required to provide spatial analytic functions on the web. The FOSS(free and open source software) can play an important role in developing such a system for web GIS. In this paper, we proposed a web-based system for raster data analysis using map algebra. We employed GRASS as an open source software and implemented the GRASS functionalities on the web using java methods for invocation of server-side commands. Map algebra and AHP were combined for the raster data analysis in our system. For a feasibility test, the landslide susceptibility in South Korea was calculated using rainfall, elevation, slope angle, slope aspect, and soil layers. It is anticipated that our system will be extensible to other web GIS for raster data analysis with GRASS.

• Spatial Information Research
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• v.14 no.3 s.38
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• pp.285-297
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• 2006

We aim to investigate the morphological and environmental characteristics of royal tombs of Chosun Dynasty by using GIS technique and remotely-sensed data. Most of the royal tombs are located on the banded gneiss and granite and over the south- and east. facing slopes and have altitudinal ranges of 150 to 200 meters. Due to the time gaps, exact locational preferences of the royal families can not be understood at this moment and also proximity to the running water is hard to be quantified. Close examination of Gwangneung indicates that the artificial modification and weathering have severe impacts on the slope and stone artefacts. The results from this research can be useful to preserve the valueless cultural heritages.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.1 no.1
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• pp.141-150
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• 1998

This study was conducted to find out the possibility of seeding of Zoysia japonica and woody plants for the revegetation of rock-exposed-cutslopes by Natural Topsoil Restoration Methods (NTRM). The 5cm thick layer of artificial soil was attached at rock-exposed cutslopes for the growth of Zoysia japonica and native woody plants by NTRM. The main results were summarized as follows. 1. Artificial soil attached at rock-exposed-slopes by NTRM was not eroded until recovered by Zoysia japonica and native woody plants. It shows extremely low soil erodibility. 2. One year later after seeding, woody plants show 100% ground coverage. But, in early stage, they grew more quickly at northwest slopes than at southeast slopes. 3. In seeding of Zoysia japonica, it grew more quickly at southeast slopes than at northwest slopes. Also, it grew better at lower part of the slopes than at middle part of the slopes. 4. After one year from seeding, the height of Lespedeza cyrtobotrya and Indigo/era pseudo-tinctoria were longer than any other plants. The next were Albizzia julibrissin, Lespedeza cuneata and wild flowers. The tree height of Rhus chinensis shows 28cm length, so it has enough possibility to be used for roadside revegetation works. 5. Lespedeza cyrtobotrya and Indigo/era pseudo-tinctoria show different importance values according to slope aspect. But, they show tendency to outweigh the other plants at all slope-aspects. 6. Most of the plants seeded by NTRM were germinated well and they covered rock-exposed-slopes so quickly and effectively. Thus it leads to conclusion that the revegetation methods used in this experiment was a very effective methods to recover rock-exposed-slopes by seeding of zoysia japonica and native woody plants.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.97-106
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• 2006

Site index is an essential tool to estimate forest productivity. Generally, a site index equation is developed and used from the relationship between stand age and dominant tree heights. However, there is a limit to the use of the site index equation in the application of variable ages, environmental influence, and estimation of site index for the unstocked forest. Therefore, it has been attempted to develop a new site index equation based on various environmental factors including site, climate, and topographical variables. This study was conducted to develop a site index equation based on the relationship between site index and environmental factors for the species of Pinus koraiensis in Yangpyung-Gun, Gyunggi Province. The influence of climatic factors (temperature and solar irradiation ratio), topographical factors (elevation, slope, ratio of slope to valley and aspect) and soil profiles (soil depth by layer and soil consistency) on site index were evaluated by multiple regression analysis. Five environmental factors were selected in the final site index equation for Pinus koraiensis. The site index equation developed in this study was also verified by three evaluation statistics: model's estimation bias, model's precision, and mean square error of measurement. Based on the site index equation, the number of productive areas for Pinus koraiensis were estimated by applying GIS technique to digitized forest maps. In addition, the distribution of productive areas was compared with the areas of current distribution of Pinus koraiensis. It is expected that the results obtained in this study could provide valuable information about the amount and distribution of productive areas for Pinus koraiensis reforestation.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.4
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• pp.59-73
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• 2009

In this study, we performed a GIS-based landslide hazard analysis by employing historical landslide data in Korea, coupling with geomorphological, geological, climatic and rainfall data. Based on 596 landslide data from 2001 to 2003, the correlations between landslide occurrence and various factors (elevation, slope angle, slope aspect, soil type and rainfall) that affect the occurrence were estimated by the statistical analysis, zonal statistics. The weights and hazard indices of 6 raster layers were derived from the estimated correlations in order to generate a landslide hazard map by applying raster calculation technique. As a result of this study, GIS technique can be used effectively to incorporate the landslide hazard contributions from various data sets simultaneously.

• Korean Journal of Remote Sensing
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• v.13 no.1
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• pp.57-73
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• 1997

This paper is related to the correction of radiometric distortions induced by topographic relief. RADARSAT SAR image data were obtained over the mountainous area near southern part of Seoul. Initially, the SAR data was geometrically corrected and registered to plane rectangular coordinates so that each pixel of the SAR image has known topographic parameters. The topographic parameters (slope and aspect) at each pixel position were calculated from the digital elevation model (DEM) data having a comparable spatial resolution with the SAR data. Local incidence angle between the incoming microwave and the surface normal to terrain slope was selected as a primary geometric factor to analyze and to correct the radiometric distortions. Using digital maps of forest stands, several fields of rather homogeneous forest stands were delineated over the SAR image. Once the effects of local incidence angle on the radar backscatter were defined, the radiometric correction was performed by an empirical fuction that was derived from the relationship between the geometric parameters and mean radar backscatter. The correction effects were examined by ground truth data.

• Geomechanics and Engineering
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• v.24 no.5
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• pp.407-418
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• 2021

Due to the complexity of the causes of the sliding mass instabilities, landslide susceptibility and hazard evaluation are difficult, but they can be more carefully considered and regionally evaluated by using new programming technologies to minimize the hazard. This study aims to evaluate the landslide hazard zonation in the Tabriz region, Iran. A fuzzy logic-based multi-criteria decision-making method was proposed for susceptibility analysis and preparing the hazard zonation maps implemented in MATLAB programming language and Geographic Information System (GIS) environment. In this study, five main factors have been identified as triggering including climate (i.e., precipitation, temperature), geomorphology (i.e., slope gradient, slope aspect, land cover), tectonic and seismic parameters (i.e., tectonic lineament congestion, distribution of earthquakes, the unsafe radius of main faults, seismicity), geological and hydrological conditions (i.e., drainage patterns, hydraulic gradient, groundwater table depth, weathered geo-materials), and human activities (i.e., distance to roads, distance to the municipal areas) in the study area. The results of analyses are presented as a landslide hazard map which is classified into 5 different sensitive categories (i.e., insignificant to very high potential). Then, landslide susceptibility maps were prepared for the Tabriz region, which is categorized in a high-sensitive area located in the northern parts of the area. Based on these maps, the Bozgoosh-Sahand mountainous belt, Misho-Miro Mountains and western highlands of Jolfa have been delineated as risk-able zones.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.164-164
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• 2023

This study investigates the importance of flood-influencing factors on the accuracy of flood risk mapping using the integration of remote sensing-based and machine learning techniques. Here, the Extreme Gradient Boosting (XGBoost) and Random Forest (RF) algorithms integrated with GIS-based techniques were considered to develop and generate flood risk maps. For the study area of NAPA County in the United States, rainfall data from the 12 stations, Sentinel-1 SAR, and Sentinel-2 optical images were applied to extract 13 flood-influencing factors including altitude, aspect, slope, topographic wetness index, normalized difference vegetation index, stream power index, sediment transport index, land use/land cover, terrain roughness index, distance from the river, soil, rainfall, and geology. These 13 raster maps were used as input data for the XGBoost and RF algorithms for modeling flood-prone areas using ArcGIS, Python, and R. As results, it indicates that XGBoost showed better performance than RF in modeling flood-prone areas with an ROC of 97.45%, Kappa of 93.65%, and accuracy score of 96.83% compared to RF's 82.21%, 70.54%, and 88%, respectively. In conclusion, XGBoost is more efficient than RF for flood risk mapping and can be potentially utilized for flood mitigation strategies. It should be noted that all flood influencing factors had a positive effect, but altitude, slope, and rainfall were the most influential features in modeling flood risk maps using XGBoost.

• Journal of Forest and Environmental Science
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• v.26 no.3
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• pp.149-159
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• 2010

This paper analyzes data on the composition, status, diversity, and distribution pattern of invasive forest undergrowth in a protected area (Khadimnagar National Park) of Northeastern Bangladesh. Assessment was done by means of stratified random sampling to diversify the invasive forest undergrowth species. For vegetation survey, 45 plots were taken randomly in ($2m{\times}2m$) circular plot from three topographical regions namely top of the hill, middle slope and plain land (15 plots from each region) and a total of 715 individuals, 22 invasive species belonging to 17 families were recorded from the study site. Among invasive species, shrubs constitute 10 species, herbs 9 species, and vines 3 species respectively. Mass number of invasive undergrowth species was grows in plain land (45.45%) followed by middle slope (31.82%). Based on the survey, invasive undergrowth plants of study areas were also categorized into three degrees of invasiveness e.g., highly invasive, moderately invasive and potentially invasive. Herbs, shrubs, and vines constitute the highest density at Chromolaema odorata (Linn.) King. (1.09), relative density at Chromolaema odorata (Linn.) King. 6.85%; highest and lowest frequency was calculated at Cassia alata L. (64.44%) and Diplazium esculentum (24.44%); for relative frequency the highest was Cassia alata L., which occupies 6.64%. Determination of the abundance of the different species revealed that Cassia alata L., constitutes (3.36) followed by Pteris cretica Wilsonii (3.14) of the area. The presence of invasive undergrowth species always reduced the number of associated species. Therefore, an extensive in-depth long-term investigation, proper policy formulation and management interventions and further study and continuous monitoring on their impacts need to be triggered targeting the control of the invasive undergrowth species of this protected area. In this aspect, national and international organization could help to conserve its biodiversity.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.2 s.17
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• pp.37-44
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• 2005

It reflects well feature of slope that is characteristic of urban river basin of Busan local. In this study, process various hydrological data and basin details data which is collected through basin basis data, hydrological monitoring system(EMS-DEU) and automatic water level equipment(AWS-DEU) for urban flood disaster prevention and use as basin input data of ILLUDAS, SWMM and HEC-HMS in order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed detention pond(volume $54,000m^3$) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.