Nakhon Sawan Province is 240 kilometers north of Bangkok covering an area of 9,597.677 square kilometers and with population of 1,077,808 (December 2006). It is located in the lower north of Thailand and is regarded as the center of business and hub of goods transportation for the north. Its general topography mostly consists of low-lying plain. In central part of the province, Ping River merges with Nan River at Pak Nam Pho District forming Chao Phraya River, which is one of the most significant river sustaining people in lower north and many provinces in the central part of Thailand. Moreover, according to the Seventh National Economic and Social Development Plan, the government has determined Nakhon Sawan Province as the center of growth in this region so as to spread the development from the central to the region.

In 1995, there was a big flood disaster causing flood problem to Nakon Sawan because water from Ping River, Nan River and Chao Phraya River overflew the riverbank entering to almost every part of municipality areas. The water was confined for months and caused a lot of damages to people’s economic including government and private properties.  

The Public Works and Town & Country Planning  Department  then initiated the feasibility study of the detailed design for flood protection systems for community areas in Nakonsawan  with the main objectives of protecting and mitigating future flood damage. Progress Technology Consultants Co., Ltd. has been contracted to undertake the study which consists of the preparation of a master plan for flood protection systems, a feasibility study for selected areas and the detailed design of the flood protection system.

The Master Plan for flood protection systems for all 18 municipalities in Nakonsawan had identified 8 prioritized areas which are eligible for the feasibility study. From the review of Master Plan Study by analyzing more detail on causes and factors of flood problem occurred in total 8 studied areas including utilizing math model to analyze water level based on measures on flood mitigation and prevention, the studied area can be divided into 4 groups as hereunder;

Group  1 : Flood occurred due to water overflowing the riverbank of the main rivers – occurred from the main rivers in Nakhon Sawan Province are Ping River (Tambon Banphot Phisai Municipality and Nakhon Sawan Municipality), Nan River (Chum Saeng Town Municipality and Tambon Thap Krit Municipality) and Chao Phraya River (Nakhon Sawan Municipality, Tambon Krok Phra Municipality and Tambon Phayuha Municipality).

Group  2 : Flood occurred due to water overflowing the riverbank of tributary stream – occurred from tributary stream flowing into the main rivers which is Lat Yao Irrigation Channel in Tambon Lat Yao Municipality.

Group  3 : Flood occurred due to unable to drain quantity of rainfall in the area –mostly happened when water level in the stream is high and in Nakhon Sawan Municipality, Chum Saeng Town Municipality, Tambon Krok Phra Municipality, Tambon Banphot Phisai Municipality, Tambon Phayuha Municipality, Tambon Lat Yao Municipality and Tambon Thab Krit Municipality.

Group  4 : No problem on flood but only on riverbank erosion –occurred in the area of Tambon Kao Liao Municipality.

From the condition of flood and drainage problem as above-mentioned, possible approaches in solving problem of flood and drainage occurred in the communities can be considered as hereunder;

1) Flood Protection System
Flood prevention line along the road/klong should be determined. The uplift of road and improvement of riverbank to be in enough high level.

2) Drainage System
Elements of drainage system should be specified to be sufficient with the drainage capacity required for the area, especially when water level of the stream is rather high. The elements of drainage system comprise of; Drainage line, Pumping station/Watergate and Irrigation canal

From the results of economical analysis, it can be concluded that the Feasibility Study for the Detailed Design of Flood Protection Systems for the Community Areas in Nakonsawan  has identified 7 areas suitable for the project implementation as follows:

 1. Nakhon Sawan Municipality and its neighboring
 2. Tambon Chum Saeng Municipality and its neighboring
 3. Tambon Krok Phra Municipality and its neighboring
 4. Tambon Kao Liao Municipality and its neighboring
 5. Tambon Banphot Phisai Municipality and its neighboring
 6. Tambon Phayuha and its neighboring
 7. Tambon Lat Yao Municipality and its neighboring