Analysis of Recurring Flooding Areas in Thung Song District, Nakhon Si

Abstract

Digital Elevation Models (DEMs) are the altitude data of the terrain that are used to study and simulate hydrological models. The objectives of this research are to create terrain with Mathematica and hydrographic simulation with Arc GIS to analyze numerical altitude Thung Song District, Nakhon Si Thammarat Province. It was carry out by using the DEM data of the Royal Thai Survey Departmen with scale of 1:50,000.  Subcells that have a resolution of 30X30 m² according to the Universal Transverse Mercator (UTM) coordinate system. The simulation results showed that Thung Song Municipality area was experiencing repeated flooding, due to the fact that most of the land is composed of pan basin area with low mountains surrounding the steep slopes of the Nakhon Si Thammarat Mountain Range. There are 3 main streams flowing through Tha Lao Canal, Perk Canal, and Tha Lone Canal making it unable to drain the water out in time. There is also a tributary of Canals connected to one another and the confluence of these canals go with Wang Heep Canal. Therefore, during the flooding period, part of the Wang Heep Canal flows into the area of ​​Thung Song Municipality and Chamai Subdistrict Municipality flooding along the banks of Tha Lao and Tha Lon canals. The flooding has become even worse because of the growth of land development with the encroaches the waterways and canals. The construction of Wang Heep Dam has blocked Wang Heep Canal, which is the main waterway of Trang River Basin. Because of the dam, the flood level in Thung Song Municipality can be reduce, but the flood problem cannot be directly prevent.