A comparative study of water quality of the Bangpakong river predicted by the mathematical models MIKE11 and WASP 7.2

Abstract

The study area covers the Bangpakong River from Tambon Bangtaen, Amphoe Bansang, Prachinburi Province through to the Gulf of Thailand in Bangpakong District, Chachoengsao Province. The total length of the stretch is 122 kilometers. The research aimed to predict water quality in the Bangpakong River by using the mathematical models MIKE11 and WASP7.2. Calibrations of MIKE 11 and WASP7.2 were made during the low flow period (March) in 2001. Verification processes of MIKE 11 and WASP7.2 could not be done because the monitoring data of water quality in the year 2002 to 2004 were fluctuating and inconsistent. Selected water quality parameters were dissolved oxygen (DO), biochemical oxygen demand (BOD), ammonia, nitrate and salinity. As for the wastewater loading, BOD, ammonia and nitrate loadings were calculated from communities, industrial, rice farm, agriculture, pig farm and shrimp farm sources. Wastewater loading in the years 2011 and 2021 were estimated from population growth and economic growth figures. The results indicated that water quality of Bangpakong River in 2011 and 2021 will be lower than in the year 2001 but not lower than the surface water quality standard class 3. Furthermore the predicted results of MIKE11 and WASP7.2 models were similar, but the MIKE11 model was more refined and sensitive