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To gain a better
understanding of seawater penetration into the U-Tapho River, a 2-D
vertically - averaged mathematical model has been employed to simulate
the hydrodynamics of salinity intrusion into the river. The outcome was
compared with field observations collected during the dry April August
1997 season. The parametric study yielded a diffusion coefficient of
about 0.006m2/s. The results indicate that salinity in the river is
significantly sensitive to variation in the freshwater input. When the
freshwater discharge is approximately 1 m3/s for a period of 24 days,
the seawater intrudes into the river as far as 23km upstream into the
Hat Yai District. On the contrary, the entire river is practically fresh
when the discharge is about 5 m3/s. The study also shows that if the
river was deeper (+50%) , the salinity intrusion would increase
slightly. While shoaling the river (-50%) would reduce the salinity
significantly. The study, however, cannot explain density stratification
as revealed by the field observations.
Key words: 2-D
mathematical model, hydrodynamics, salinity intrusion, U-Tapho
river |
