The western part of the study area is riverine floodplain next to the Tanaosri mountain range along the Thai-Myanmar border. The Phetchaburi and Pranburi rivers are the two main rivers of PB and PK EPAs. They and their tributaries flow from the range to the Gulf of Thailand. The eastern part of the study area is uplifted, flat, sandy floodplain to the Gulf of Thailand. There are important economic fisheries and tourism along this floodplain.