The effects of urbanization on river discharge and river flood potential in a central northern watershed, Thailand

The purpose of this study was to determine how Land Use/Land Cover (LULC) has changed in the Yom watershed over a period of 16 years (1990-2006), and to examine potential causes for river flooding by assessing the impact of LULC changes, especially urbanization. Satellite images from Landsat 5 and 7 were used to produce a time series of LULC change. The LULC changes over the study period show an accelerating growth rate of more than 130% of urban areas (from 210 km2 in 1990 to 488 km2 in 2006). The most change was the transformation of some agricultural lands to urban land. River discharge changes exhibited positive temporal trends as the urban areas expanded. The change in discharge of pre-urbanization to post-urbanization showed a systematic increase from 0.057 to 0.175 m 3/s with the increase of urbanized area from 80.86 to 148.81% in Phrea and Sukhothai provinces. These results confirmed that urbanization affect the surface hydrology of a watershed by increasing river discharge that leading to increase urban flood potential in the Yom Watershed.