• Journal of Korean Society of Forest Science
• /
• v.102 no.2
• /
• pp.161-169
• /
• 2013

This study was carried out to examine characteristics of physical and chemical current status and problems of Salix spp. communities based on growth characteristics by tree age and height of the tree species in around Namgang Dam reservoir area. Tree density in 4 survey areas was 5,284 trees/ha, but all areas need to control high tree density. Tree crown area in 4 survey areas was 9,786.4 $m^2/ha$ and crown area of Salix spp. was the most dominant among tree species in watershed of the Jinyang lake. Mean soil depth in 4 survey areas was 65.5 cm higher in the sedimental deposit soil (78 cm) than in forest soil (12.5 cm) near the watershed. Soil bulk density was also higher in the sedimental deposit soil than in forest soil because of poor porosity in the sandy sediment. Soil pH was higher in sedimental deposit soil (A, B horizon:pH 6.7) than in forest soil (A horizon:pH 5.3; B horizon:pH 5.2) because of originated from non-point source polution and detergent of domestic sewage. The results suggest that growth of Salix spp. could be poor because of low fertility with low cation exchange capacity in sedimental deposit soil.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.1360-1364
• /
• 2010

도시유역 물순환 해석 모형(Catchment hydrologic cycle Analysis Tool, CAT)은 기존의 개념적 매개변수 기반의 집중형 수문모형과 물리적 매개변수 기반의 분포형 수문모형의 장점을 최대한 집약하여, 도시유역 개발 전/후의 장/단기적 물순환 변화특성을 정량적으로 평가하고 물순환 개선시설의 효과적인 설계를 지원하기 위한 물순환 해석 모형이다. 이 모형은 수문학적으로 균일하게 판단되는 범위를 소유역으로 분할하여 지형학적 요인에 의한 유출 특성을 객관적으로 반영할 수 있으며, 개발 공간 단위별로 침투, 증발, 지하수 흐름 등의 모의가 가능하도록 하는 링크-노드 방식으로 개발되었다. 모형의 UI(User Interface)는 사용자가 손쉽게 모형을 적용/관리하고, 여러 시나리오를 동시에 효과적으로 모의하여 분석할 수 있도록 설계되었다. 또한, 모든 입/출력 자료를 엑셀이나 텍스트 형식과 연동되도록 하여 프로젝트별 매개변수 관리가 용이하도록 개발하였다. 특히 본 모형에서는 사용자의 목적에 맞는 다양한 물순환 개선시설(침투시설, 저류지, 습지, 빗물저장시설, 리사이클 및 외부급수 등)의 구현 및 모의가 가능하도록 개발하였다. 여기서, 물순환 개선시설이란 빗물을 흡수하고 저류할 수 있는 도시녹지시설 혹은 구조물로서 도심 내의 불투수면을 저감시키고 유출수를 줄이면서 동시에 녹지를 확보하여 효과적인 물순환 기능에 영향을 미치는 시설들이다. 이러한 물순환 개선시설은 신도시 및 지역 혁신도시 개발 등의 대규모 토지이용변화가 예상되는 개발지역에 대한 평가 및 개선 기술을 제공하여 물순환 건전화를 위한 설계에 직접적으로 활용될 수 있는 큰 장점을 지니고 있다. 먼저 침투 시설은 계획침투량을 반영하며 토양으로의 침투량과 지하수로의 이동을 모의한다. 저류시설은 하도 내에 위치한 online 저류지와 하도 외에 위치한 offline 저류지로 구분하고 저류지 수면의 증발량과 취수량을 고려하며, 방류구를 통한 방류량을 반영하였다. offline 저류지의 경우는 하도 내의 흐름의 규모에 따라서 일정량을 넘는 경우만 offline 저류지로 유입될 수 있는 양을 산정하도록 하였으며 하류 하천으로의 방류를 반영하여 홍수 후에 저류지가 비워지도록 하였다. 유역 내의 습지는 식생과 수면에서의 증발산을 반영하였다. 습지의 저류능력을 넘는 양은 월류되어 하류로 유출되며, 방류구를 통한 방류량을 반영하였다. 빗물저장시설의 경우는 초기우수와 같은 일정량 이하의 유입량과 시설용량을 초과하는 양은 방류하도록 하였고, 물 사용량을 반영하였다. 또한, 본 모형에서는 하천 내에서 취수하여 유역으로 공급할 수 있도록 리사이클 처리노드를 계획하였다. 리사이클은 용수 이용 목적에 따라 필요지역으로 공급되는 것으로 하였으며, 하천유지용수의 목적으로 취수되어 상류 혹은 하류의 임의 지역으로 공급되는 것을 포함하였다. 또한, 유역외부에 광역으로 급수되는 공급량도 반영하도록 하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.461-461
• /
• 2017

기후변화 적응 유역 물순환 개선 기술은 기후변화가 진행 중에 있거나 예상되는 지역에 대하여 강우-유출수를 지연, 저류, 침투시켜 지속가능한 물순환체계를 유지 회복하도록 하는 기술이라 할 수 있다. 본 연구에서는 기후변화에 따른 국내 유역의 특성 및 기후를 반영하기 수월한 물순환 개선 및 평가시스템을 국내 기술로 개발하였다. 개발된 유역 물순환 개선 및 평가시스템은 기존 국가연구개발사업을 통해 개발되고 사업화에 성공한 바 있는 유역 물순환 평가 모형인 CAT(Catchment hydrologic cycle Assessment Tool)을 수정 및 개선하여 기후변화에 따른 영향을 평가하고 적응 대책을 수립하기 위한 실무적인 소프트웨어이다. 침투트렌치, 식생침투트렌치, 습지, 저류지, 빗물탱크 등의 물순환개선시설에 대한 효과를 평가할 수 있도록 개별시설의 제원에 따른 물순환개선 효과를 정량적으로 평가할 수 있다. 본 연구의 대상유역으로는 팔당댐 상류의 경안천 유역을 선정하였다. 경안천 유역의 기후변화에 따른 물순환 개선 기술 적용을 위해서 기후변화 시나리오 자료는 기상청 수원 측후소의 1976~2099년 FGOALS-s2, HadGEM-ES, INM-CM4 RCP8.5 시나리오를 적용하였으며 분석기간은 2020s(2010~2039), 2050s(2040~2069), 2080s(2070~2099)로 구분하였다. Baseline은 수원 측후소 과거 30년 1971~2000년 자료를 이용하였고 각 시나리오별 수문성분 및 구조적 물순환 개선기술 적용에 따른 수문성분을 비교 분석하였다. 물순환 개선기술 시나리오 중 침투시설 시나리오는 도시 면적의 20%, 설계침투량은 일본 우수저류침투기술협회 기준인 단위면적($1m^2$)당 10mm 적용하였고, 빗물저장시설 시나리오의 저장시설의 용량은 수도법시행규칙(2011)의 빗물 이용시설기준(도시면적 ${\times}0.05$)을 적용하였다. 시나리오별 강우량은 HadGEM-ES가 증가폭이 크게 나타났고 INM-CM4는 2080s에서 감소 경향을 보였다. 증발산량은 거의 모든 시나리오에서 대부분 감소하였고, 개선기술 적용에 따라 크게 증가하거나 감소폭이 줄어들었다. 직접유출량 및 중간유출량은 기후변화 시나리오별 강우증가분에 따른 미세한 증가 양상을 보였고, 개선기술 적용에 따라 약간 증가하는 양상을 보였다. 지하수유출량의 경우 침투시설 적용으로 함양량이 크게 증가함에 따라 증가폭이 매우 크게 나타났다.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.6
• /
• pp.487-497
• /
• 2018

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical chemical biological functions ((1) flotation and oxidization using microbubbles, (2) vegetation purification and (3) bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than $3.5kgf/cm^2$. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.47 no.1
• /
• pp.49-56
• /
• 2019

Urban green spaces have been contributing to the improvement of environmental, mental, and physical health for humans. In addition, recent studies showed the potential role of vegetation in reducing the amount of crime in inner-city neighborhoods at the micro-scale level. However, little is known about the positive role of urban green areas in improving urban safety at the regional level. The purpose of this study is to examine the relationship between urban green areas and actual outdoor crime rates, while also considering socio-demographic factors. The study area is the city of Austin, Texas, USA, which consists of 506 block groups. This study utilized socio-demographic factors based on U.S. Census data and vegetation-related factors utilizing GIS and ENVI software. For analyses, the analysis of variance (ANOVA) and an ordinary least square (OLS) regression were utilized. The results from ANOVA showed that yearly crime rates per acre for areas having 0%~25% trees in their neighborhoods were 0.46% and 1.05% higher than those of having 25%~50% and >50% trees in the neighborhoods, respectively. The results from the OLS regression represented that income, NDVI and park rates in neighborhoods were negatively associated with the crime rate per acre, whereas the percentage of minorities and the percentage of teenage school dropouts were positively associated with the crime rate per acre. This study implies that urban green areas may help to improve the safety of urban areas.

• The Journal of Engineering Geology
• /
• v.32 no.4
• /
• pp.585-596
• /
• 2022

This study determined major factors influencing landslide occurrence along a forest road near Sangsan village, Sancheok-myeon, Chungju-si, Chungcheongbuk-do, South Korea. Within a 2 km radius of the study area, landslides occur intensively during periods of heavy rainfall (August 2020). This makes study of the area advantageous, as it allows examination of the influence of only geological and tomographic factors while excluding the effects of rainfall and vegetation. Data for 82 locations (37 experiencing landslides and 45 not) were obtained from geological surveys, laboratory tests, and geo-spatial analysis. After some data preprocessing (e.g., error filtering, minimum-maximum normalization, and multicollinearity), structural equation model (SEM) and logistic regression (LR) analyses were conducted. These showed the regolith thickness, porosity, and saturated unit weight to be the factors most influential of landslide risk in the study area. The sums of the influence magnitudes of these factors are 71% in SEM and 83% in LR.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.5B
• /
• pp.459-469
• /
• 2010

This study is to develop a grid-based daily runoff model considering seasonal vegetation canopy condition. The model simulates the temporal and spatial variation of runoff components (surface, interflow, and baseflow), evapotranspiration (ET) and soil moisture contents of each grid element. The model is composed of three main modules of runoff, ET, and soil moisture. The total runoff was simulated by using soil water storage capacity of the day, and was allocated by introducing recession curves of each runoff component. The ET was calculated by Penman-Monteith method considering MODIS leaf area index (LAI). The daily soil moisture was routed by soil water balance equation. The model was evaluated for 930 $km^2$ Yongdam watershed. The model uses 1 km spatial data on landuse, soil, boundary, MODIS LAI. The daily weather data was built using IDW method (2000-2008). Model calibration was carried out to compare with the observed streamflow at the watershed outlet. The Nash-Sutcliffe model efficiency was 0.78~0.93. The watershed soil moisture was sensitive to precipitation and soil texture, consequently affected the streamflow, and the evapotranspiration responded to landuse type.

• Journal of Korean Society of Forest Science
• /
• v.82 no.2
• /
• pp.139-151
• /
• 1993

The virgin forests on and around Sungin-bong in Ulreung-do, an island situated between the Korean peninsula and Japanese archipelago, were investigated phytosociologically. They were classified into two communities, i.e. Fagus crenata var. multinervis - Majanthemum dilatatum community and F. crenata var. multinervis - Sasa kuriensis community. The former was subdivided into several units ; Acer takesimense - Allium victorialis var. platyphyllum group, including Tsuga sieboldii - Taxus cuspidata var. tatifolia subgroup and a typical subgroup, and Acer mono var. savatieri - Rumohra standishii group, including Dystaenia takeshimana subgroup and a typical subgroup. The other was subdivided into two subunits ; Acer okamotoanum group and a typical group. It was estimated that this area was orginally covered with beech and maple dominated forest vegetation and with Machilus dominated forest or bamboo forest. However, in these days, The natural vegetation of it has been destroyed and in future, may also be disturbed gradually by human activities. Judging from the coincidence method, the structure and distribution of the forest communities was more related to altitude than to topography. The phytomass, based upon the basal area of each community to $100m^2$ showed that Acer mono var. savatieri - Rumohra standishii group ($BA=7574.1cm^2$, $P=9,882,058cm^3$) haved the largest value and Tsuga sieboldii - Taxus cuspidata var. latifolia subgroup($BA=2126.3cm^2$, $P=1,746,755cm^3$) showed the smallest value. The flora of the vascular plants collected from this area consists of 71 families, 187 genera, 243 species, 1 subspecies, 44 varieties, 6 forms and 294 taxa in total.

• Korean Journal of Remote Sensing
• /
• v.27 no.4
• /
• pp.481-494
• /
• 2011

Investigation of the $CO_2$ exchange between biosphere and atmosphere at regional, continental, and global scales can be directed to combining remote sensing with carbon cycle process to estimate vegetation productivity. NASA Earth Observing System (EOS) currently produces a regular global estimate of gross primary productivity (GPP) and annual net primary productivity (NPP) of the entire terrestrial earth surface at 1 km spatial resolution. While the MODIS GPP algorithm uses meteorological data provided by the NASA Data Assimilation Office (DAO), the sub-pixel heterogeneity or complex terrain are generally reflected due to coarse spatial resolutions of the DAO data (a resolution of $1{\circ}\;{\times}\;1.25{\circ}$). In this study, we estimated inputs retrieved from MODIS products of the AQUA and TERRA satellites with 5 km spatial resolution for the purpose of finer GPP and/or NPP determinations. The derivatives included temperature, VPD, and solar radiation. Seven AmeriFlux data located in the Corn Belt region were obtained to use for evaluation of the input data from MODIS. MODIS-derived air temperature values showed a good agreement with ground-based observations. The mean error (ME) and coefficient of correlation (R) ranged from $-0.9^{\circ}C$ to $+5.2^{\circ}C$ and from 0.83 to 0.98, respectively. VPD somewhat coarsely agreed with tower observations (ME = -183.8 Pa ~ +382.1 Pa; R = 0.51 ~ 0.92). While MODIS-derived shortwave radiation showed a good correlation with observations, it was slightly overestimated (ME = -0.4 MJ $day^{-1}$ ~ +7.9 MJ $day^{-1}$; R = 0.67 ~ 0.97). Our results indicate that the use of inputs derived MODIS atmosphere and land products can provide a useful tool for estimating crop GPP.

• Economic and Environmental Geology
• /
• v.54 no.2
• /
• pp.161-176
• /
• 2021

In this study, one of the distributed hydrologic models, VELAS, was used to analyze the variation of hydrologic elements based on water balance analysis to evaluate the groundwater recharge in more detail than the annual time scale for the past and future. The study area is located in Yanggok-ri, Seobu-myeon, Hongseong-gun, Chungnam-do, which is very vulnerable to drought. To implement the VELAS model, spatial characteristic data such as digital elevation model (DEM), vegetation, and slope were established, and GIS data were constructed through spatial interpolation on the daily air temperature, precipitation, average wind speed, and relative humidity of the Korea Meteorological Stations. The results of the analysis showed that annual precipitation was 799.1-1750.8 mm, average 1210.7 mm, groundwater recharge of 28.8-492.9 mm, and average 196.9 mm over the past 18 years from 2001 to 2018 in the study area. Annual groundwater recharge rate compared to annual precipitation was from 3.6 to 28.2% with a very large variation and average 14.9%. By the climate change RCP 8.5 scenario, the annual precipitation from 2019 to 2100 was 572.8-1996.5 mm (average 1078.4 mm) and groundwater recharge of 26.7-432.5 mm (average precipitation 16.2%). The annual groundwater recharge rates in the future were projected from 2.8% to 45.1%, 18.2% on average. The components that make up the water balance were well correlated with precipitation, especially in the annual data rather than the daily data. However, the amount of evapotranspiration seems to be more affected by other climatic factors such as temperature. Groundwater recharge in more detailed time scale rather than annual scale is expected to provide basic data that can be used for groundwater development and management if precipitation are severely varied by time, such as droughts or floods.