Correlation Analysis on the Runoff Pollutants from a Small Plot Unit in an Agricultural Area

This study was carried out to investigate the important factors relating to runoff and pollutant loads in a plot unit located in an agricultural area. Of the precipitation parameters, such as total precipitation, days since last rainfall (antecedent dry day [ADD], the rainfall was more than 10 mm) and average rainfall intensity on runoff, the strongest effect was obtained due to total precipitation, but the rainfall intensity showed a slightly positive correlation. It was expected that both variables, i.e. total precipitation and rainfall intensity, would lead to the generation of greater runoff. In contrast, runoff was negatively correlated with ADD, which is understandable because more infiltration and less runoff would be expected after a long dry period. The total suspended solids (TSS) load varied greatly, between 75.6 and 5.18×104 g, per event. With the exception of total nitrogen (TN), the TSS, biological oxygen demand (BOD), chemical oxygen demand (COD) and TP loads were affected by runoff. The correlations of these items were proportional to the runoff volume, with correlation coefficients (R2) greater than 0.70, which are suitable for use as non-point source model data. The TSS load showed very good relationships with organics (BOD & COD) and nutrients (TN & total phosphate), with correlation coefficients greater than 0.79. Therefore, the removal of TSS is a promising factor for protecting water basins. KCI Citation Count: 3