• Journal of Environmental Policy
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• v.7 no.3
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• pp.121-140
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• 2008

The impervious cover ratio has been used as an important measure for tracing water environment characteristics in watershed. Impervious cover is divided into total impervious cover and effective impervious cover, and its size varies depending on the land use characteristics of a watershed. Total impervious cover can be easily measured using existing land use maps or land cover map, while it takes a considerable amount of time and labor to measure the effective impervious cover, as water flow should be identified at each site. This study is intended to calculate the total impervious cover and effective cover of a sample site, compare their characteristics, and find a method to apply effective and total impervious cover ratios toward watershed management. The analysis of the sample site showed that the effective impervious cover rate(39.7%) was less than the total impervious cover rate(43%). This suggests that it would be acceptable, in terms of time and cost, if total impervious cover is applied as the representative impervious cover ratio of a watershed considering that it was used as basic data to analyze the effect that impervious cover has on the water environment.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.767-772
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• 2008

Studies regarding the application of the impervious cover rate as a watershed management index have increased in number due to concerns over watershed management. The impervious cover rate is suggested as an index that can manage not only water quality but also water volume and the water ecosystem. This study intends to prove its applicability through the interconnection of the impervious cover rate and the water environment in Korea. Analysis of a selected watershed with reference to impervious cover rates showed that a watershed with an impervious cover rate of over 30% had a direct runoff in excess of 60% of precipitation, while a watershed with an impervious cover rate of 7% had a direct runoff of 39%. Watersheds with higher impervious cover rates were also found to have higher BOD, though different watersheds showed slightly different aspects in connection with BOD. Monitoring of benthic macroinvertebrates showed that species inhabiting clean water appear more frequently in areas with lower impervious cover rates than areas with higher impervious cover rates, and in mainstream areas, relatively larger numbers of species appeared in areas with lower impervious cover rates. This suggests that impervious cover rates can be appropriately used as an index for watershed management, as it effectively represents changes to the water environment.

• Journal of Environmental Impact Assessment
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• v.17 no.5
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• pp.289-297
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• 2008

An impervious cover is one of most important factors which effect on a water body environment in a watershed. There are many researches on the impact of an impervious cover on water quality, quantity and ecosystem and most of these researches have been focused on an impervious rate or area in a watershed without considering structure features as like shape, edge, connection of impervious cover. In this study, we focused on a landscape structure which includes shape, density, contiguity, distance, aggregation of land cover type as well as area and rate. The calculation of a landscape indices made to analyse a landscape structure is conducted by applying Fragastats 3.3 program. Osan-cheon watershed where has rapidly urbanized is selected as a study field. Land information for 2002 and 2007 is from land classification maps provided by Ministry of Environment. The result shows that the increasing rate of an impervious cover is more conspicious in Kiheung dam watershed but the fragment of impervious cover areas is shown remarkably in the Osan sub-watershed. The trend of aggregation and connection of impervious covers is increasing. But it was very difficult to say that which type of landscape structure is more beneficial for a watershed management. The implication of this study is to find the need to come over the conventional ways to evaluate landscape structure of a watershed such as rates and areas of impervious cover, and define the importance of landscape feature as like connection, distance, edge density, fragment of impervious covers.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.53-61
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• 2010

An impervious cover in the watershed management has been used as effective indicators. It is a very useful barometer to measure the impacts of watershed development on aquatic systems. Hence, it is necessary to survey the impervious cover of a watershed and to develop an impervious cover model (ICM) for supporting best management practices. The main objectives of this study were to investigate the spatial patterns of the impervious cover, to calculate landscape indices using FRAGSTATS, and to develop an ICM in the Gap-stream watershed and its six sub-watersheds. The results showed that the impervious cover of the Gap-stream watershed increased from 4.9 % in 1975 to more than 11.2 % in 2000, the number of impervious cover fragments increased from 662 to 3,578, and the landscape shape index increased from 27.0796 to 91.1982. Fragmentation was severe within the Yudeungcheon downstream and the Gapcheon downstream of six sub-watersheds. This paper presented the results derived landscape indices to define landscape patterns and structure for the Gap-stream watershed. Our results indicate that altered land use might be influenced changes in landscape structure.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.561-569
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• 2012

This study estimates landscape indices of the Gyeongan-stream watershed from 1975 to 2000 by classifying the land cover into impervious cover and pervious cover depending on its state using a landscape analysis program. For the indicator of biodiversity this study uses Total Core Area(TCA) among landscape indices. The estimated TCA is then used along with an Impervious Cover Model(ICM) to compare the number of fish species that appear in the Gyeongan-stream watershed. In the relations between TCA and the impervious cover ratio, it has been found that as the impervious cover ratio increases, TCA decreases accordingly. It shows that as the ratio of impervious cover in the landscape increases due to urbanization and development, the critical area that individual species need for isolation from outside has decreased. Also, the monitoring of the number of fish species that appear in the Gyeongan-stream watershed shows that in the areas with low impervious cover ratio there are more fish species appearing that inhabit in clean, uncontaminated water. It has been identified that the Gyeongan-stream watershed falls into the category of Impacted Stream and that its state is worsening, and since the watershed in this area responds to the impervious cover ratio very sensitively, its fish diversity it is required to improve the state of the basin through its proper and careful management.

• Journal of Korean Society of Rural Planning
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• v.28 no.4
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• pp.19-29
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• 2022

This study aimed to estimate the impervious area rate by rural water districts in 2009 and 2021 and analyze the changes. From the EGIS(Environmental Geographic Information Service) land cover maps, the impervious areas were defined as residential, commercial, industrial, culture·sports·recreational, traffic, public facilities, and greenhouses of land cover classes. For 496 rural water districts excluding the border area with North Korea, the nationwide impervious area rate increased from 5.96% in 2009 to 7.50% in 2021. The average of the top 50 rural water districts increased from 23.4% in 2009 to 27.1% in 2021. E ven for the bottom 50 rural water districts, the average impervious area rate rose from 1.12% in 2009 to 1.40% in 2021. Rural water districts with a high impervious area rate are mainly distributed in metro cities and industrial areas. The contraries are primarily found in Gangwon, Gyeongsang, and Jeolla regions covered with forests and farmlands. Notably, the impervious area rate changed more in the neighboring rural water districts than in large cities, and the rate kept increasing slightly even in rural areas with a low impervious area rate. The findings of this study will help prepare a reasonable alternative for managing the impermeable surface of rural areas for safe and sound rural water cycle.

• Korean Journal of Remote Sensing
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• v.30 no.3
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• pp.399-415
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• 2014

The intensity of stormwater runoff is particularly acute across cities located in arid climates. During flash floods loose sediment and pollutants are typically transported across sun-hardened surfaces contributing to widespread degradation of water quality. Rapid, dense urbanization exacerbates the problem by creating continuous areas of impervious surfaces, perforated only by a few green patches. Our work demonstrates how the latest techniques in remote sensing can be used to routinely measure urban land cover types, impervious cover, and vegetated areas. In addition, multiple regression models can then infer relationships between urban land use and land cover types with stormwater quality data, initially sampled at discrete monitoring sites, and then extrapolated annually across an arid city; in our case, the city of Phoenix in Arizona, USA. Results reveal that from 30 storm event samples, solids and heavy metal pollutants were found to be highly related with general impervious surfaces; in particular, with industrial and commercial land use types. Repercussions stemming from this work include support for public policies that advocate environmental sustainability and the more recent focus on urban livability. Also, advocacy for new urban construction and re-development that both steer away from vast unbroken impervious surfaces, in place of more fragmented landscapes that harmonize built and green spaces.

• Journal of Korean Society on Water Environment
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• v.39 no.2
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• pp.142-152
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• 2023

Infiltration is a process by which precipitation infuses into subsurface soils. The process determines the surface flow and baseflow volume, and it is one of most important hydrological processes regarding nonpoint source pollution management. Therefore, the Ministry of Environment has developed a guideline to determine the impervious area ratio to understand the hydrological process in administrative districts and watersheds. The impervious area ratio can be determined using land use or land cover maps. Three approaches were explored to determine the impervious area ratio in 25 districts in Seoul. The impervious area ratio was determined by employing the Land registration map and Land property data in the first approach, Land property map in the second approach, and Land cover map in the third approach. The ratio ranged from 38.96% to 83.01% in the first approach, 38.98% to 83.02% in the second approach, and 37.62% to 76.63% in the third approach. Although the ranges did not provide any significant differences in the approaches, some districts displayed differences up to 9.48% by the approach. These differences resulted from the fact that the data were land use or land cover, especially in the area of airport, residential complex area, and school sites. In other words, division of the pervious and impervious areas in an individual plot was not allowed in the Land registration map, while it was allowed in the Land cover map. Therefore, it was concluded that there is a need to revise the guideline so that a reasonable impervious area ratio can be determined in the districts.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.378-381
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• 2008

The regulating and relaxing targets in the Land Use Regulation and Total Maximum Daily Loads are influenced by Land cover information. For the providing more accurate land information, this study attempted to generate an impervious surface map using KOMPSAT-2 image which a Korea manufactured high resolution satellite image. The classification progress of this study carried out by tasseled-cap spectral enhancement through each class extraction technique neither existing classification method. KOMPSAT-2 image of this study is enhanced by Soil Brightness Index(SBI), Green vegetation Index(GVI), None-Such wetness Index(NWI). Then ranges of extracted each index in enhanced image are determined. And then, Confidence Interval of classes was determined through the calculating Non-exceedance Probability. Spectral distributions of each class are changed according to changing of Control coefficient(${\alpha}$) at the calculated Non-exceedance Probability. Previously, Land cover classification map was generated based on established ranges of classes, and then, pervious and impervious surface was reclassified. Finally, impervious ratio of reclassified impervious surface map was calculated with blocks in the study area.

• Journal of Korea Water Resources Association
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• v.38 no.12 s.161
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• pp.1009-1020
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• 2005

In this paper, impervious area ratios for 11 land cover types of Seoul city were estimated and corresponding CNs were calculated. And linear regression equations were derived to predict impervious area ratios based on five major urban land cover types including the residential, industrial, transportation, commercial, and commercial-residential mixed areas. From the comparative analysis of impervious area ratios for the US SCS CNs and the CNs derived in this study for Seoul city, it is revealed that residential areas show the biggest difference followed by industrial and commercial ones. And in turn, these increased impervious area ratios resulted in Increased CNs for Seoul city including increases by 13 for residential, 12 for industrial and 5 for commercial areas. Therefore, it is suggested that applying the US SCS CNs to Korean urbanized areas may underestimate the flood runoff potential.