Western Chao Phraya River Flood Diversion Channel Project

Flood way on the western side of the Chao Phraya River (Kanu Woraluk – Tha Muang) (RID, 2013a).

This research reviews the plans of the Royal Irrigation Department (RID), which are slightly different from the national water management plans. The previous government team of water management suggests the different starting point in the Nakhon Sawan province. However, the Thai Royal Irrigation Department sets the starting point of the flood way route in the area of the Kanu Waraluk district in the Kamphaeng Phet Province while ending at the Samut Songkram Province. The distance is approximately 288 km. The design of the flood diversion channel will pass through the following 6 provinces: Kamphaeng Phet, Nakhon Sawan, Uthai Thani, Chainat, Suphan Buri and Kanchana Buri.

The main objective of the project is to relieve flooding in the Chao Phraya River basin from the Nakhon Sawan province to the Gulf of Thailand. Before starting the construction, the Royal Irrigation Department had been considering the construction processes which were presented by three consultancy companies (RID, 2013a p.7-1 and p.7-4).

Furthermore, there are four different alternative estuaries of the western flood diversion, which have to be chosen before considering of the construction as well.

The purpose of the report project is to cover the whole water management of the western part of the Chao Phraya River with the following actions:

1. To suggest collaboration and cooperation by working together on the water management of private sectors and public sectors of the western part of the Chao Phraya River.

2. To have an efficient and sustainable water management in the duration of the rainy season and the dry season which will make it possible to reduce flood problems and lack of fresh water supply. In particularly, by satisfying the basic needs of the local residents to gain their acceptance.

3. To make priorities for the important projects for solving flooding and a lack of fresh water supply during the dry season by systematically well managing the projects.

4. To up-grade the standard of living and the quality of life for the local residents who live near by the water management projects by having a good attitude of solving problems together.

5. To select the high essential projects which are connected to the water management strategy of the royal irrigation to make a good preparation for continuing the working progress.

Benefits of the flood way project on the western Chao Phraya River:

1) Reduction and prevention of flooding along the Chao Phraya River Basin from Nakhon Sawan until the Thai Gulf.

2) Extension of the potential of irrigation water drainage, in order to cultivate during the raining season 557,308 rai (1 Rai = 1600 sq.m) = 891,692.8 sq.m

3) People who live near the flood way (radial 2 km) including area of 42 sub-districts, 4 municipalities and 115 villages will have water to consume for the whole year.

4) A new support of water resources from the Mae klong Yai and Kraseaw royal irrigation project in the raining season.

5) The water diversion will support the Mae klong Yai royal irrigation project and Kraseaw royal irrigation project. A bigger dam will keep a higher amount of water, which will help to push back the salt water from the sea in the drought season.

6) Transportation links between the northern- and western-southern parts of Thailand.

Figure 5.8 Flood diversion channel on the western part of the Chao Phraya River (RID, 2013b)

The western flood way project designed the area ( ) to keep water for agricultural benefits.

Figure 5.9 The cross section of the Western Chao Phraya River Diversion Channel (RID, 2013b)

The Irrigation Department (RID, 2013b) reported seven issues in the Environmental Impact Assessment (EIA):

1) Impact to the owners of land along the site of the flood diversion channel, which includes 6 Provinces, 19 Districts, 55 Sub-Districts and 39,456 Villages.

2) Impact of the land use on the site of the flood diversion channel which will affect 90%

of the agricultural land, 3.9% of communities and 6.1% of forest, water areas and vacant lands.

3) Impacts on forest areas, whereas the EIA emphasized that the impacts are quite small.

The project undertakes not to have impacts directly on preservation forests and it will only affect some kind of economic forests or community forests.

4) Impacts on soil digging (for dredging a new flood way cannel), due to the huge amount of soil (approximately 190 million cubic meters). The digging is necessary for the new canal construction. Due to the digging, a huge volume of soil has to be moved to the big vacant land. Some of those soils will be used for building the dyke walls, however, there will still be some soil left over which has to be deposited somewhere. Searching the vacant land for keeping the soil will impact the lands surface in the future.

5) Impact of the sea salt contamination, which will occur when the fresh water from the river will meet with the seawater on the estuary area. This area will affect the ecology systems and the water animals, for instance fish and seashell farms. Especially, in case of long periods of drainage floodwater, the local residents like the fishermen or seashell farmers need the government to pay a compensation payment for them during that period.

Maximum water level

Minimum water level

10 m 4 m 50 – 65 m

Right of way on the west side of 95 – 105 m Right of way on the east side of 110 – 120 m 205 – 225 m

Western Embankment Road Eastern Embankment Road

Diversion Channel

Right of way to extend a 4-lane road in the future

Side Drain Channel

West side East side

6) Impact on the transportation, will be partly beneficial and partly negative. The connection of the logistic systems will support linking the transportation from the part of the north, the west and the south of Thailand. In contrast, there will be a loss of social interaction between neighborhoods that used to travel via small canals between houses.

7) Impact on lands and properties. The local residents who have the right of tenure is approximately 28,358 rai (45.37 km²) (1 rai = 1,600 m²). Some of them do not have a title of the land ownership – approximately 8,032 rai (12.85 km²). Furthermore, around 1,019 multi-functional buildings will lose their own land and properties while the government will pay approximately 3,050 million Baht (76.25 million Euro) in total as compensation. With this project, these local residents will lose their area for working and for earning their income in 6 provinces, 19 districts and 55 sub-districts.

On balance, my conclusion is that those impacts require effective planning and design. The flood way on the western part of the Chao Phraya River seems to have a lot of impacts to local residents according to the Environmental Impact Assessment (EIA), the public interviewing and their participation. Many issues of this project, especially the issues on the communities, cannot be denied, such as the local dwellers complaining that even for a big scale project there is less and not clear information provided for the communities.

Even more important is, that the destruction of the forests or the ecology system will have high impacts and the affected areas will take a long time until they recover. Building back the nature in a short-term period while constructing the project will be not possible. The natural forest is taking a long time to be created in a perfectly natural way.

In contrast, there are more criteria which have to be brought to consideration, for example the topographical aspects of the western part of the Chao Phraya River, which are not so far from the mountain range as compared to the eastern part. As a matter of fact, the western concept of construction can find the water reservoir in the western parts and flow water in the western new diversion channel. However, the highly-elevated area will lead to a more cost intensive construction, while soil textures and also morphology conditions from survey data have to be considered. For the soil data, it is reported that on the western part the soil is mostly mixed with rocks. These circumstances are also proving, that the eastern part of the Chao Phraya River will be more suitable for a flood diversion channel project.

Undoubtedly, the challenge that the planning of the flood diversion channel provides is the search of the proper area with least social and environmental impacts. Therefore, this research is trying to clarify the issues and tries to find the best solution.