Abstract:The purpose of this study was to develop a low impact development-based district unit planning (LID-DP) model and to verify the model by applying it to a test site. To develop the model, we identified various barriers to the urban planning process and examined the advantages of various LID-related techniques to determine where in the urban development process LID would provide the greatest benefit. The resulting model provides (1) a set of district unit planning processes that consider LID standards and (2) a set of evaluation methods that measure the benefits of the LID-DP model over standard urban development practices. The developed LID-DP process is composed of status analysis, comprehensive analysis, basic plan, and sectoral plans. To determine whether the LID-DP model met the proposed LID targets, we applied the model to a test site in Cheongju City, Chungcheongbuk-do Province, Republic of Korea. The test simulation showed that the LID-DP plan reduced nonpoint source pollutants (total nitrogen, 113%; total phosphorous, 193%; and biological oxygen demand, 199%); reduced rainfall runoff (infiltration volume, 102%; surface runoff, 101%); and improved the conservation rate of the natural environment area (132%). The successful application of this model also lent support for the greater importance of non-structural techniques over structural techniques in urban planning when taking ecological factors into account.Keywords: low impact development; urban planning; district unit planning; LID-based district unit planning model; land-use planning

ab s t r ac tA riparian buffer strip (RBS) that locates in boundaries between streams and lands efficiently and sustainably performs ecological functions and reduces non-point pollution as a multipurpose practice. The present paper investigates the feasibility of introducing a riparian buffering strip for protection of the Paldang Lake and the Han River in Korea from worsening ecological environment and water quality. For experiments, a pilot RBS (five types of plants) appropriate for the conditions of targeted watersheds was set up and tested according to the pollution loads and area precipitation. The measurements show that suspended solids (SS), total nitrogen (T-N), and total phosphorus (T-P) decrease by more than 50% within the 20 m width of the pilot RBS and, at the maximum, decline by up to 84%, 87%, and 98% respectively depending on a plant type in the pilot RBS. The catchment area per 1 ha in the pilot RBS was 12 ha. In case a 20-m wide RBS is set up in the watershed with the biggest agricultural area (72,049 ha) among the three unit-watersheds in the upper reaches of the Paldang Lake, the catchment area per the RBS of 1 ha can be estimated as 4 ha leading to reduction of agricultural non-point pollution loads by more than 79%. From the findings, the introduction of RBS is expected to be appropriate and versatile for reduction of agricultural non-point pollution and improvement of ecological conditions.

This study is to find appropriate plant for infiltration swale (which is natural LID infrastructure) and suggest basic research database for building infrastructure of LID facilities. Through the research inside, it first selects the plant strong to flooding and salt tolerance. Also, the research built infiltration swale along the road, planted those strong plants and monitored how well those plants adapted into the environment. Particularly, it showered 72mm/hr-speed artificial shower, also with natural shower, given that plants were vulnerable to flood because of influx of the rain. As a result of field applicability monitoring, Pennisetum alopecuroides and Equisetum hyemale (which degrade the pollutant well and adapt into rainy environment) are planting individually, or Juncus effusus var. decipiens, Liriope platyphylla, Miscanthus sinensis Andersson, Euonymus japonica (which are strong to rainy environment) and Pennisetum alopecuroides and Equisetum hyemale are mixed planting. The research should have monitored the plant for more than one year to study them, but the research only lasted five months. Therefore, it is hard to generalize. After all, through the long term research, it should pursue study more on appropriate plant materials and database that can be the reference for infrastructure establishment and maintenance.