ESTABLISHMENT OF OPTIMAL MANAGEMENT PLANS ON AGRICULTURAL GROUNDWATER

This study was conducted to establish a conservative management plan on groundwater resources for one representative rural area in South Korea. In order to designate the groundwater-quantity management zone, firstly, the exploitable groundwater amounts of the area were estimated using a local recharge rate (16.95 %) with a precipitation (1,454 mm year^-1). The exploitable groundwater amounts were estimated to be 1.64 x 10⁷ m³ year^-1. From the local groundwater statistics, secondary, the usage amounts of groundwater in this area was identified to be 2.63 x 10⁶ m³ year^-1, which is accounted for 16.10 % of the groundwater exploitable ones. The rate between the groundwater exploitable- and usage amounts appears to be relatively small. Nonetheless, usage amounts in six administrative towns (33%) among 18 ones in the study area revealed relatively high, where required an optimal groundwater-quantity management plan. In addition, nitrate-nitrogen concentrations causing a blue-blood syndrome for infant were analyzed from groundwater samples in 181 wells over the study area. Average nitrate-nitrogen concentration was identified to be 6.67 mg-N L^-1, which was twice higher than the national average one (3.3 mg-N L^-1). Approximate 6% of the samples exceeded the agricultural groundwater-quality guideline for nitrate-nitrogen (20 mg-N L^-1). In order to designate the groundwater-quality management zone, four indicators including average nitrate-nitrogen concentration, pollutants, DRASTIC index, and pollutant loads: twelve administrative towns (67%) among 18 ones including the zones exceeding nitrate-nitrogen concentrations of 20 mg-N L^-1 revealed required an optimal groundwater-quality management plan. As a result, a permissive pumping rate of each groundwater well should be mandatorily kept. In addition, monitoring for groundwater-quality should be consistently conducted on the groundwater-quality management zone.

This study was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry (IPET) through Agricultural Facilities and Disaster Management Technology Development Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) (grant number 320052-3)