The study area covers the Southwest area of Tha Chin river basin.
The overall flow is assumed to be the flow from Supanburi Province. Both in river and floodplain.
The physical ability of this area to refers by field survey.
The drainage system at downstream have effect from sea level, the study use the information at during from October to December 2011 and prediction data of sea level rise.
This study concerns with the drainage system under the gravity force.