ESTIMATION OF BOD/DO FROM UNMONITORED/NON-POINT SOURCES OF POLLUTION

This paper presents estimation procedures for computing the equivalent rate of BOD flowing from Non-Point Sources (NPS) into a stream, where monitoring stations and some point sources' data are available. QUAL2E model has been adopted to simulate the flow kinematics and Oxygen budget along the stream. Mass balance equation has been used to compute the equivalent discharge from unknown point and/or non-point sources. Iterations have been made for the equivalent BOD concentrations from non-point and/or un-known point sources of pollution along the stream such that the computed BOD concentration matches the measured value at the downstream monitoring station. Another set of runs has been conducted by assuming the equivalent DO concentrations as well as the equivalent BOD concentration from non-point and/or un-known point sources in a trial to match the computed DO and BOD concentration with the measured ones. Application has been made to the catchment of El-Nizam drain of Egypt (August 1997 to July 2000). It has been found that the technique performed well to compare the equivalent BOD pollution along various reaches and to identify hot spots. It can also detect the existence of serious point sources of pollution, but it is hard to iterate until matching both DO and BOD concentration at a monitoring station.