Management of water quality in middle and lower THA CHIN river using mathematical model (MIKE 1) in corporation with geographic information

Abstract

This study aimed to predict water quality in the middle and lower Tha Chin River by using Mathematical Modeling (MIKE11) incorporated with the Geographic Information System (GIS). Calibration of MIKE 11 model: Hydrodynamic Module, Advection-Dispersion Module and Water quality Module were made during low flow period, i.e. February – May, in the year 2005. Verification of the model was further conducted during the low flow period in the year 2006. The study areas covered the middle and lower parts of Tha Chin River, which was about 202 km long, starting from Phopraya Regulators in Suphanburi through the estuary at Samut Sakorn. Selected water quality parameters i.e. dissolved oxygen (DO), biochemical oxygen demand (BOD), ammonia, salinity and temperature were made. BOD loading in the year 2005 was calculated based on information about communities, industries, fishery farms, and piggery sources in the areas of Suphanburi, Nakhon Pathom, and Samut Sakorn provinces. Simulation water quality in Tha Chin river year 2005 was calculated by taking into account the population, pig farm, fishery farm numbers and recorded data of factories in the study area. The study results and prediction indicated that water quality of middle and lower Tha Chin River in the year 2005 was higher than those of the required surface water quality standard level 4. However, the average values of water quality actually met the required standards if proper controlled pollution discharge under 3 scenarios (50% reduction of all pollution discharge by an equal loading, 75% reduction of only the fishery farm discharge and 20-75% reduction of pollution discharge at the critical point) were established. Therefore, development of a proper pollution management strategy to ensure good water quality in the river should be seriously considered