Assessing the Impact of Agriculture on Water Quality in the Brantas Catchment

Abstract

In this study, the relationship between water quality and agriculture in the upstream region of the Brantas catchment has been investigated, with a focus on Electric Conductivity (EC), Dissolved Oxygen (DO), pH, nitrate, Biological Oxygen Demand (BOD), phosphate and ammonia concentrations. The EC concentrations ranged from 120 to 570 μS/cm, the DO concentrations from 3.15 to 8.57 mg/L, the nitrate concentrations from 0 to 20 ppm, the nitrite concentrations from 0 to 3 ppm, the BOD concentrations from 6.22 to 6.87 mg/L, the phosphate concentrations from 0.25 to 1 mg/L and the ammonia concentrations from 0 to 0.25 mg/L. Using detailed land use data, the correlation between land use classes and water quality parameters was analyzed. Nitrate concentrations of streams of which the catchment area consists of over 70% Ladang area ranged from 2.5 to 11 ppm, while catchment areas consisting of over 70% of Kebun area featured nitrate concentrations of up until 4 ppm. Regarding EC, this difference is 200 to 475 μS/cm versus 200 up until 375 μS/cm. Certain parameter concentrations, in particular BOD, raise potential concern. While this research provides some insights into water quality in the Brantas catchment, it also underlines the need for further investigations employing improved methodologies, increased sampling over a larger timescale and area, and comprehensive, multidisciplinary approaches. It is recommended that further studies in the area focus more on different parameters, in particular BOD.