Phosphorus loadings and eutrohication status uncertainty using fuzzy logic

Abstract

This study vitalized the uncertainty and fuzzy rules consideration in the estimation of phosphorus loadings and eutrophication status of this particularly hydrologic system namely detention pond using Fuzzy Logic (MATLAB) and Monte Carlo analysis. These methods were chosen to cater for the uncertainty of loading factors such as sediment and phosphorus inflow, inflowing discharge and pond storage volume. The average of phosphorus concentrations obtained from site investigation was 0.178 mg/L, hydraulic residence time was 1.77 year and the average annual hydraulic loadings was 694.70 m/yr, obtained based on the 11 years period (2000-2010). The results showed that the maximum and minimum of phosphorus loadings was 2.00 x 10-3 ton/year and 5.00 x 10-3 ton/year. Phosphorus loadings obtained from MATLAB was 3.9 x 10-3 ton/year while 2.31 x 10-3 ton/year was obtained from the Monte Carlo simulation. The eutrophication status of the detention pond was investigated using Fuzzy Logic Approach, incorporating various fuzzy rules (MATLAB). This evaluation required the twinning usage of Vollenweider PLoadings diagram. Generally, eutrophication stage in the detention pond at Kolam Tadahan UTM was still considered Oligotrophic stage. However precautions need to be established as the pond are alarmingly approaching the Eutrophic Status. Several recommendations in treatment process also presented in this study based on the previous.