Phitsanulok is primarily flat lands with some hills. The eastern portion of the city has some wooded area. The city is situated in the nan basin, which is part of the Chao Phraya Watershed. Phitsanulok is sometimes called Song Khwae , the city of two rivers, an ancient name dating to a time centuries ago when the Nan and Khwae Noi Rivers met near the city. Today, only The Nan River flows through Phitsanulok.

http://en.wikipedia.org/wiki/Phitsanulok