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Multi-scale evaluation of global gross primary productivity and evapotranspiration products derived from Breathing Earth System Simulator (BESS)

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REMOTE SENSING OF ENVIRONMENT 2016年 186卷 528-547页

作者： Jiang, Chongya Ryu, Youngryel Seoul Natl Univ Res Inst Agr & Life Sci Seoul South Korea Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Agr & Forest Meteorol Seoul South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul South Korea

Several global gross primary production (GPP) and evapotranspiration (ET) remote sensing products exist, mainly provided by machine-learning (e.g. MPI-BGC) and semi-empirical (e.g. MODIS) approaches. Process-based approaches have the advantage of representing the atmosphere-vegetation-soil system and associated fluxes as an organic integration, but their sophistication results in a lack of high spatiotemporal resolution continuous products. Targeting this gap, we reported a new set of global 8-day composite 1-km resolution GPP and ET products from 2000 to 2015, using a simplified process-based model, the Breathing Earth System Simulator (BESS). BESS couples atmosphere and canopy radiative transfer, photosynthesis and evapotranspiration, and uses MODIS atmosphere and land data and other satellite data sources as inputs. We evaluated BESS products against FLUXNET observations at site scale (total of 113 sites, 742 site years), and against MPI-BGC products at global scale. At site scale, BESS 8-day Products agreed with FLUXNET observations with R-2 = 0.67 and RMSE = 2.58 gCm(-2) d(-1) for GPP, and R-2 = 0.62 and RMSE = 0.78 mm d(-1) for ET, respectively, and they captured a majority of seasonal variability, about half of spatial variability, and a minority of interannual variability in FLUXNET observations. At global scale, BESS mean annual sum GPP and ET maps agreed with MPI-BGC products with R-2 = 0.93 and RMSE = 229 gC m(-2) y(-1) for GPP, and R-2 = 0.90 and RMSE = 118 mm y(-1) for ET, respectively. Over the period of 2001-2011, BESS quantified the mean global GPP and ET as 122 +/- 25 PgC y(-1) and 65 x 10(3) +/- 11 x 10(3) km(3) y(-1), respectively, with a significant ascending GPP trend by 0.27 PgC y(-2) (p < 0.05), similar to MPI-BGC products as well. Overall, BESS GPP and ET estimates were comparable with FLUXNET observations and MPI-BGC products. The process-based BESS can serve as a set of independent GPP and ET products from official MODIS GPP and ET products

关键词： Gross primary productivity Evapotranspiration BESS Global MPI-BGC MODIS

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Finite element analysis for deeply buried concrete pipes in proposed imperfect trench installations with expanded polystyrene (EPS) foams

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ENGINEERING STRUCTURES 2019年 189卷 286-295页

作者： Kang, Junsuk Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul 08826 South Korea Seoul Natl Univ Res Inst Agr & Life Sci Seoul 08826 South Korea Seoul Natl Univ Interdisciplinary Program Urban Design Seoul 08826 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 08826 South Korea

The objective of this study was to evaluate the performance of imperfect trench installations incorporating a soft material zone for buried concrete pipes. Traditionally, imperfect trench installations locate highly compressible lightweight materials such as expanded polystyrene foams, baled hay or straw above buried pipes in order to induce positive soil arching without trenches and hence reduce vertical top pressure and horizontal pressure. However, bottom pressure is not significantly reduced due to the additional downward shearing forces induced by transferring top pressure to the adjacent sides. Previous FE models that take account of plane strain elements suggest that soft zones surrounding pipes can markedly reduce bottom pressure, as well as the top and lateral pressures, but these models have not yet been validated by field tests and there have also been difficulties in evaluating the longitudinal behaviors of pipes. This study revisited the proposed use of soft zones using three-dimensional finite element analyses and validated the modeling methodologies using Valsangkar's field tests. The results confirm that soft zones are a highly effective way to reduce the surrounding pressures on deeply buried concrete pipes, and the new finite element models presented here successfully overcome the limitations of the previous plane strain approach.

关键词： Imperfect trench installation Soil arching Expanded polystyrene foam Pipes Finite element analysis Earth pressure

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Impact of green infrastructure on PM10 in port-adjacent residential complexes: A finite volume method-based computational fluid dynamics study

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SUSTAINABLE CITIES AND SOCIETY 2024年 115卷

作者： Baek, Seunghun Kim, Jaekyoung Kang, Junsuk Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul 08826 South Korea Seoul Natl Univ Interdisciplinary Program Smart City Global Conver Seoul 08826 South Korea Gangneung Wonju Natl Univ Deparment Environm Landscape Architecture Kangnung 25457 South Korea Seoul Natl Univ Res Inst Agr & Life Sci Seoul 08826 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 08826 South Korea

This study examines the effects of PM10 reduction by introducing green infrastructure (GI) in residential areas adjacent to ports, where significant pollutant emissions from ships are prevalent. Using finite volume method (FVM)-based computational fluid dynamics (CFD) simulations, we evaluated 30 scenarios based on various GI types and spacings and validated these simulations using observational data. The assessed GI types included trees and shrubs (hedges). Planting configurations were categorized into single (T for trees, H for hedges) and mixed (TH for both trees and hedges) plantings, with one or two rows and spacings of trees from 6 m to 14 m at 2 m intervals. We also considered both aerodynamic and depositional effects as mechanisms for PM10 reduction by GI. Our results revealed the following: 1) Plant spacing significantly influenced PM10 reduction, with both excessively narrow and wide spacings being suboptimal. (2) Trees proved to be more effective, whereas combining them with shrubs offers limited advantages. 3) Among the shrubs, the adsorption effect was more influential on PM10 reduction than the aerodynamic effects. These insights are not limited to port regions but also offer foundational knowledge for enhancing urban air quality, setting the groundwork for subsequent studies.

关键词： Green Infrastructure Port-adjacent air quality Computational fluid dynamics(CFD) PM10

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Interannual variability of regional evapotranspiration under precipitation extremes: A case study of the Youngsan River basin in Korea

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JOURNAL OF HYDROLOGY 2014年第PartD期519卷 3531-3540页

作者： Song, Youngkeun Ryu, Youngryel Jeon, Soohyun Seoul Natl Univ Brain Korea Plus Team 21 Seoul 151921 South Korea Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Agr & Forest Meteorol Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 151921 South Korea

Understanding basin-scale evapotranspiration (ET) is an important issue for the management of regional water resources, especially with the recent trend of intensified precipitation (P). This study assessed the spatial and temporal variations of regional ET in response to P extremes, for various types of land-cover across the Youngsan River basin in Korea. The spatial distribution of monthly P and ET from 2001 to 2009 were estimated using rainfall records from 40 weather stations located across the basin and a satellite-derived, process-based ET model Breathing Earth System Simulator (BESS) (Ryu et al., 2011), respectively. The study periods were focused on the recent years with abnormally large, small and normal P, which were identified from anomalies in the z-sores of long-term (1973-2011) rainfall records. The variation of regional Er was assessed in terms of: (1) the controlling factors, using the statistics of related meteorological and geographical data, (2) a waterenergy balance, using Budyko's framework, and (3) the water balance of four selected watersheds in the region, using the partitioning of annual P into ET and riverflow discharge (Q). The total annual ET of this region decreased in abnorthally large-P year and increased in small-P year, because the ET in July to August (which accounts for more than 36% of annual ET) was limited by the available energy rather than available water due to the summer monsoon. In terms of land cover types, forests showed larger interannual variability in ET than paddy fields or cropland, with the differences in ET between large and small-P years being 108 and 82 mm yr(-1), respectively. The sensitivity of annual ET to P extremes was significantly related to the leaf area index (LAI), rather than soil properties, topography, or specific land-cover type (p < 0.05, generalized linear model). However, the interannual variations of ET were not large (15-18%) compared to those of annual P (51-62%) and Q(108-232%) during 2002-20

关键词： Evapotranspiration Budyko curve Water balance MODIS Climate extremes

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Rockfall Hazard Analysis Based on the Concept of Functional Safety with Application to the Highway Network in South Korea

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ROCK MECHANICS AND ROCK ENGINEERING 2021年第12期54卷 6633-6647页

作者： Lee, Jongook Barbato, Michele Lee, Dong Kun Seoul Natl Univ Grad Sch Environm Studies Interdisciplinary Program Landscape Architecture Seoul South Korea Univ Calif Davis Dept Civil & Environm Engn Davis CA 95616 USA Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul South Korea

Numerous rockfall incidents involving infrastructure damage and loss of life have been reported along roads in mountainous terrain. Previous studies have used quantitative risk assessment approaches to identify the level of rockfall risk. However, appropriate quantitative indicators that are able to describe time-varying risk have not yet been developed. This study aims to develop a rockfall risk mitigation method based on reliability concepts, to classify rockfall data, to model the probability of rockfall occurrence, and to estimate the magnitude of risk reduction through mitigation measures. A synthetic measure of rockfall risk is proposed, which allows to compare directly and quantitatively the rockfall risk for different cut slopes under unmitigated and mitigated conditions. The proposed methodology can estimate the risk reduction obtained using mitigation measures, such as introducing protections barriers, their periodic maintenance, and horizontal coverage ratio. This methodology was applied to 20 years of rockfall data collected by the Korea Expressway Corporation from 1215 artificial cut slopes along the highway network in South Korea. The rockfall frequency was analyzed based on the inventory data, and a rockfall hazard mitigation strategy was demonstrated using the suggested methodology for the case study. It was shown that appropriate mitigation strategies, based on number of protection barriers, interval of periodic maintenance, and horizontal coverage ratio, can be devised to reduce the risk of different artificial slopes below a target failure probability. The approach shown in this study can provide insights into ways of improving overall risk management to prevent losses by rockfall.

关键词： Rockfall hazard Rockfall mitigation Risk management Time-varying risk Reliability

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Describing the spatial patterns of heat vulnerability from urban design perspectives

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INTERNATIONAL JOURNAL OF SUSTAINABLE DEVELOPMENT AND WORLD ECOLOGY 2015年第3期22卷 189-200页

作者： Kim, Saehoon Ryu, Youngryel Seoul Natl Univ Grad Sch Environm Studies Dept Landscape Architecture Urban Design Concentr Seoul 151742 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 151742 South Korea Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Coll Agr & Life Sci Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Agr & Forest Meteorol Seoul 151921 South Korea

A large number of East Asian cities, like cities in other parts of the world, are being affected by extreme heatwaves. Yet, little is known about the general urban design characteristics of sites with significant heat vulnerability within the localized context. In this study, empirical data sets were constructed describing the biomedical, social, environmental, and place-based parameters associated with the location of heat-related emergency calls in Suwon, South Korea, between 2010 and 2014. The results showed that the distribution of heat vulnerability appeared to be highly clustered within a few places, although the area did not have a high proportion of socioeconomically vulnerable populations. Here, three urban design characteristics were described in association with the location of emergency calls: (1) high-rise building complexes built on a superblock gridiron layout with large open spaces in between, (2) low-rise, high-density residential districts with a fine-scaled street layout, and (3) hilly terrain parkland sites adjacent to a densely urbanized district. These general characteristics of the sites and their potential links to heat vulnerability were explained in terms easily understandable by urban design and planning professionals so that climatic knowledge can be more effectively integrated with urban form-making practices.

关键词： heatwave vulnerability sustainable development Korea urban design

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Stakeholder Subjectives Toward Ecotourism Development using Q methodology: The Case of Maha Ecotourism Site in Pyeongchang, Korea

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ASIA PACIFIC JOURNAL OF TOURISM RESEARCH 2016年第8期21卷 931-951页

作者： Lee, Jae-hyuck Son, Yong-hoon Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul South Korea Seoul Natl Univ Grad Sch Environm Studies Dept Landscape Architecture Seoul South Korea

Ecotourism needs ecological sensitivity and respect for the ecological culture of local residents. From this perspective, listening to the opinion of local residents, collaborating with the local residents in conjunction with an appropriate governance structure, is of prime importance in ecotourism. However, many ecotourism sites have numerous problems because of conflicts among stakeholders such as local government and local residents. This study investigates the conflicts and the stakeholders' subjectives in the case of Maha ecotourism site in Pyeongchang-gun, the site of the 2018 Winter Olympic games. Before the analysis, the conflicts seem to be caused by the different attitudes of government officials and local residents' representatives. From the analysis of subjectives, the difference in attitudes is caused by generation gaps. Young people show relatively uniform attitudes, where different occupation sectors exert little influence. It means that conflicts can be decreased if more opportunities for council participation are allowed. Young people have few consideration about ecology and tradition. The ecological and traditional lessons of the older generation are needed for young people. This study shows that conflicts between development and conservation are caused by the different attitudes represented in different generation, and hence plans for harmonizing different generation should be considered.

关键词： ecotourism conflict management Q methodology Pyeongchang

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Land use and land cover changes explain spatial and temporal variations of the soil organic carbon stocks in a constructed urban park

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landscape AND URBAN PLANNING 2015年 136卷 57-67页

作者： Bae, Jeehwan Ryu, Youngryel Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Agr & Forest Meteorol Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 151921 South Korea Seoul Natl Univ Res Inst Agr & Life Sci Seoul 151921 South Korea

Urban parks offer valuable ecosystem services to citizens and they have long been recognized for their recreational service;however, less attention has been paid to their carbon sequestration value. Here, we report on soil organic carbon (SOC) stocks in an urban park, Seoul Forest Park, which was built in 2004. We had two objectives: (1) to estimate SOC stocks (to a dept. of 1 m) in different land-cover types (wetland, forest, lawn, and bare soil) and (2) quantify the change in the SOC concentration in topsoil in different land-use types over a 10 year period (2003-2013). We found a tenfold difference in SOC stocks across the different land-cover types within the park. Wetland soils had the highest stocks of SOC (13.99 +/- 1.05 kg m(-2)), followed by forest, lawn, and bare soils. We found that a "cultural layer" that preserved previous land use history located deep in the soil profile substantially increased SOC stocks in the wetland. SOC concentrations in the topsoil were approximately three times higher in 2013 than in 2003 (256 +/- 130%). The normalized difference vegetation index (NDVI) derived from MODIS and Landsat satellite images revealed that land-use history, expansion of plant areas and growth of plants could explain the increase in SOC concentrations in topsoil over the 10 year period. These findings imply that urban park soils could act as a carbon sink, and understanding the land-use history and the choice of land-cover types in park planning can substantially influence the carbon budget of urban parks. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Land cover change Land use change NDVI Soil carbon Urban park

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Monitoring multi-layer canopy spring phenology of temperate deciduous and evergreen forests using low-cost spectral sensors

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REMOTE SENSING OF ENVIRONMENT 2014年 149卷 227-238页

作者： Ryu, Youngryel Lee, Galam Jeon, Soohyun Song, Youngkeun Kimm, Hyungsuk Seoul Natl Univ Dept Landscape Architecture & Rural Syst Engn Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Agr & Forest Meteorol Seoul 151921 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 151921 South Korea Seoul Natl Univ Res Inst Agr & Life Sci Seoul 151921 South Korea

Emerging near-surface remote sensing techniques have advanced our ability to monitor forest canopy phenology. Thus far, however, little effort has been made to monitor the phenologies of the various canopies of multilayer forests separately, despite their importance in regulating forest biogeochemical cycles. Here we report phenological changes in multi-layer canopies of deciduous broadleaf and evergreen needleleaf forests in the Republic of Korea during the spring of 2013. We installed light-emitting diode (LED) sensors at four different canopy heights at two sites to measure the normalized difference vegetation index (NDVI) using red and near-infrared (NIR) spectral reflectance and to estimate leaf area index (LAI) using the blue band gap fraction. LED-sensors identified leaf-out dates of over- and understory canopies at both sites;leaves unfolded 8-11 days earlier in the understory canopy than the overstory canopy. At the deciduous forest site, LED-NDVI failed to capture the leaf-out date in the overstory canopy, because all four LED-sensors started to see green-up from the understory canopy while the overstory canopy was leafless. LED-LAI identified different leaf-out dates for the over- and understory canopy, because the gap fraction was measured explicitly for each canopy layer. In the evergreen forest site, LED-NDVI signals between the top of the tower and beneath the overstory canopy were decoupled because of the dense evergreen overstory canopy. Both LED-NDVI and LED-LAI identified new needle expansion in the overstory canopy and understory canopy development. MODIS NDVI agreed well with LED-NDVI data (R-2 = 0.96, RMSE = 0.04) at the deciduous forest site, and we discovered that understory canopy development determined the onset of greenness based on MODIS NDVI data. LED-LAI data agreed well with independent estimates from the other instruments, indicating that LED-sensors could be used to monitor multi-layer canopy LAI. Continuous, in-situ observation of m

关键词： Leaf area index Spectral reflectance LED NDVI Phenology MODIS Multi-layer canopy

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Meso- or micro-scale? Environmental factors influencing pedestrian satisfaction

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TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT 2014年第Jul.期30卷 10-20页

作者： Kim, Saehoon Park, Sungjin Lee, Jae Seung Seoul Natl Univ Grad Sch Environm Studies Dept Landscape Architecture Urban Design concentr Seoul 151742 South Korea Seoul Natl Univ Interdisciplinary Program Landscape Architecture Seoul 151742 South Korea Hongik Univ Dept Urban Design & Planning Seoul 121791 South Korea

Despite interest in walking and its environmental, health, and social benefits, little research has investigated pedestrian satisfaction, and its potential influence on walking decisions. The present study examines the relationships between pedestrian satisfaction, and a variety of built environment factors, in order to gain insight into urban design strategies that can improve pedestrian satisfaction. We analyzed a pedestrian survey, carried out in Seoul, Korea, which includes questions about personal characteristics, micro-scale environmental attributes, and the level of pedestrian satisfaction, together with Seoul GIS data, which provided meso-scale environmental variables. The multilevel models estimated the effects of environmental factors on the level of satisfaction of utilitarian and recreational walkers. The analysis identified significant effects of both meso-scale (e.g. density, intersection density, hilliness, and the presence of bus stops), and micro-scale (e.g. sidewalk width, and the presence of bus dedicated lanes, crossings, lamps, and trees) variables on pedestrian satisfaction. The results calls on researchers to investigate a comprehensive set of psychological and environmental factors, in order to understand the various aspects of pedestrian satisfaction, and the diverse motivations behind it, as well as on planners, to adopt diverse design approaches that will produce more satisfactory pedestrian environments. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Pedestrian satisfaction Meso-scale environmental attributes Micro-scale environmental attributes Multilevel modeling

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