Water and Soil Management for Water Conservation in a Watershed - Water and Agriculture: Sustainability, Markets and Policies - page 299

Figure 7. Classification of each farmland using high resolution aerial image
4. Assessment of soil erosion potential and BMP application
BMP is one of a number of methodological and structural practices designed to
prevent or reduce water pollution and soil loss caused by runoff. The BMP in farmland
deals specifically with non-point source pollutants, such as minerals, and chemicals such
as pesticides. Implicit within the BMP concept is a voluntary, site-specific approach to
addressing water quality problems. The site-specific approach based on this concept will
provide a better management system for farm resources, especially loss of nutrients and
soil particles in each field for protecting from water pollution. BMP includes information,
technologies and practices based on a management system now possible owing to several
technologies currently available for farming. BMP tools could be differently expressed
depending on policies, GIS, GPS, pollution monitoring, soil-plant-weather characteristics,
and various technologies for application of inputs. Many of these tools are already
standard practices, known to be both environmentally and economically sustainable. The
goal of BMP is to protect water resources from non-point pollution while maintaining the
economic viability of Korean agriculture and related industries. The following figures
(Figures 8 and 9) show examples of BMP for soil conservation in each field and potential
grade of soil erosion in paddy fields and non-paddy fields in a watershed. The size of this
site was about 4,700 ha and the mother rock of the soil was composed of 68% granite
gneiss, 26% granite and 6% other. The land use in this area was 68% for forest, 11% for
paddy rice farming, 12% for upland farming and 9% for other uses including villages,
rivers, reservoirs, etc. Maps for soil erosion and BMP were made by using data on
steepness and slope length determined by geographical maps, soil erodability (K factor)
by a super-detailed soil map (1:5,000), and land cover and practice factors by image data,
respectively. This result could be connected to policies such as direct payment, and it
could be also used as a standard of financial support to achieve environmental goals.