The role of Xa No Canal in the irrigation system in Ca Mau peninsula

THE ROLE OF XA NO CANAL IN THE IRRIGATION SYSTEM IN CA MAU PENINSULA
MA. Nguyen Xuan Hien-Senior Engineer Thai Dinh Khang-South Vietnam Irrigation Planning Institute

Hau Giang region overlooking gulf of Thailand that is a landlocked embayment and has the diurnal tide system with a small oscillation amplitute (approximately ¼ the tide amplitute of East sea), a low ebb and fall frequency, and quiet water surface; and the warm sea current creates the developed and diversified ecosystem, associated with the rapid growth of seafood species, and the great exploiting potential of sea economy.

U Minh forest is well-known as the very potential forest, with the rich of forestal special produce. In the two former centuries, Hau Giang region covered by the wild indigo forest. This was the sparsely populated area with the life mainly depending on the natural special produce resources. The economy was characterized by self-supply property. Rivers and arroyos were still in natural state, without the great actions from the people. The roadway wasn’t still developed, and the waterway is few – It was limited in external communication. The French people early found the role of waterway traffic network. In 1876, in the statement submitted the Governor of South Vietnam, Engineer Bernabeng wrote: “No traffic channel no colony because security going together with waterway traffic”.

Like Lai Hieu, Thot Not, Rach Gia - Ha Tien canals, Xa No canal initiated towards Nga Nam, Nga Bay… and helped the crowded social-cultural exchange locations formed in Hau Giang region. Xa No canal is about 40 km in length, rises from Can Tho and connects with Cai Tu river (Rach Gia province). The works was commenced in 1901 and completed in the midyear of 1903 with 60 m in width of the canal.

Together with the canal dredging process, the unprompted process of residential areas along the canal also formed. The inhabitants reclaimed and built their houses wherever the canal dredged. The rice farming area expanded rapidly. Rice production brought the farmers the great benefits. The landowners raced against each other to set up reclaiming hamlet. The French people who weren’t familiar with the wet rice farming also raced each other to invest in building irrigation infrastructure such as sewers, dams,…. and the large-scale plantations with great along Xa No canal.

Xa No canal not only helped the inhabitants solve the drainage in the area of 40,000 ha of Hau Giang region but also served them in reclaiming, producing and living; it was also the very important canal axis in trading the rice in this region. Formerly, the rice export mainly carried out by waterway through Rach Gia – Ha Tien commercial port. Since Xa No canal formed and connected West Sea with Hau river, most the rice from Hau Giang has been collected and concentrated in Cai Rang market through the canal, and many very big “rice storehouses” have also been built along the canal line. In the statistic data 1899, 500,000 rice tons from South Vietnam exported, and this number increased up 1,300,000 tons after Xa No canal formed.

Mr. San Nam, a writer, considered that dredging Xa No canal which connects Can Tho with Rach Gia, could be named a “strategic punch” on economy and politics for the French people because it not only shew the Occidental mechanic strength but also opened the new prospect in the formation process of the granary of Hau Giang region.

However, the said initial results discontinued because of the war lasted more than 40 years. The fields fallowed, the irrigation works damaged, and the bushes with weeds spreaded on the surface of the canal. Until 1975, upon national reunification by peaceful means, Hau Giang region wasn’t developed corresponding to the regional great potential. Intensive farming and increasing the number of crops weren’t, too. The whole large area from Hoa Luu, Cau Duc to the head of Cai Lon and Cai Be rivers was still wild and not reclaimed.

To exploit the great potential in the Mekong Delta (ĐBSCL), since 1975, South Vietnam Irrigation Planning and Surveying Sub-Institute, currently being South Vietnam Irrigation Planning Institute in Ho Chi Minh city and Mekong Delta Irrigation Planning Union in Can Tho city, has been established by Ministry of Irrigation for following-up the area and carrying out the survey as well as making the construction plan of irrigation system in Hau Giang region.

In geographic feature, Hau Giang located in the region where is under the complicated current regime – the interference of three current regimes: • The semidiurnal tide regime from East Sea with the oscilation amplitude of more than 3m.

• The diurnal tide regime from the Gulf of Thailand with the oscilation amplitude of less 1m.
• The current regime changed seasonal from the upper stream of Mekong river.

The region is bounded by the water in the head of Cai Lon - Cai Be rivers, which creates the difficulty in draining, and results in the salty water intrusion from East Sea and West Sea, and the latent alum soil areas, …, and the water supply capacity of Xa No canal as well as the intake canals from Hau river limited.

The irrigation model set up by professor Nguyen Nhu Khue shew that the water level in Ca Mau – U Minh could be declined by the intercepting sewer system of East Sea tide – for creating the gradient of the water surface on Xa No canal, and Quan Lo canal – Phung Hiep… and intaking more the freshwater from Hau river. This was also the great progressive step which differed completely from the Dutch experts’ outlook that “to intake the freshwater for Ca Mau – U Minh area, it is required to build the very big pumping station on Quan Lo canal – Phung Hiep”.

Together with digging KH canal system (KH1, Kh3, Kh5, KH6, KH7, Kh8, KH9…), which connects Kien Giang, Hau Giang provinces with Can Tho city; dredging, expanding the vertical canals connecting with Hau river including Quang Lo – Phung Hiep, Xa No, Thot Not, O Mon, ect, also carried out with the objectives as follows:

• Exploiting the maximum water capacity from Hau river, expanding the areas under the effects of freshwater for increasing the area of rice farming and developing aquaculture in Hau Giang, Ca Mau peninsula and U Minh forest.
• Developing into the waterway traffic line which connects Ca Mau with Ho Chi Minh city, expanding the Integration Way for Hau Giang region.

A series of salty water control sewers along Bac Lieu – Ca Mau canal have been built, and this is not only the salty water preventing works for Quang Lo – Phung Hiep but also makes the water level in Cai Tu area where is located in the end of Xa No canal, and Chac Bang, Canh Den canals – which creates the convenient conditions for the system of KH canal, Quang Lo – Phung Hiep canal, especially Xa No canal and the vertical one for promoting the effect of intaking the freshwater from Hau river.

With the advantage of water resources, Hau Giang people can farm the rice with three crops per year and obtain the high yield by popular models such as three crops of rice, 2 crops of rice and one crop of vegetables or 2 crops of rice + aquaculture. The life of Hau Giang people improved more and more, and Hau Giang becomes the region where plays an important role in ensuring the national food security as well as the rice export of the Mekong Delta in specifically and the whole country in generally.

At present, the climatic changes (BĐKH) and the rise of sea water are great challenges for the human in the 21th century. The acts of God and other extreme climatic phenomenons are increasing all over the world, the global mean temperature and the global mean sea level are going on the unheard-of and rapid increase and also the problems of all countries in the world. In the assessment of World Bank (2007), Viet Nam was one of five countries that had to suffer the serious effects caused by the climatic changes and the rise of sea water, in which the Red river Delta and especially the Mekong Delta would suffer the most heavy effects.

The consequence from the climatic changes for Viet Nam is very serious and the existing danger which results in the objective of eliminating hunger and reducing poverty, the millennium objective and the stable development in our country. The fields, the industries and the localities that are damaged easily and suffer the strongest effects by the climatic changes include water resources, agriculture and food security, human health in the plain areas and the coastal areas.

To deal with the climatic changes – the rise of sea water, in the irrigation planning project for Ca Mau peninsula (approved by Ministry of Agriculture & Rural Development in May 2009), the content of building Cai Lon, Cai Ba sewers inserted in the performance process of 2009-2015 period by South Vietnam Irrigation Planning Institute. The sewers and the ship locks on Cai Lon, Cai Be rivers play the important role in preventing the salty water intrusion and the loss of freshwater from Hau river to West Sea, and enhancing the water head so that the water from Hau river supplied stably for U Minh Thuong, U Minh Ha and Southwest Quang Lo – Phung Hiep areas through the system of KH canal, vertical canals and especially Xa No canal.

The great river separating works will be automated high-levelledly and operated by the coding program for carrying out exactly the human’s control purposes in order to minimize the negative aspect and promote maximum the positive aspect caused by the climatic changes – the rise of sea water.

We believe that with experiencing the hundreds of years development, Hau Giang people were determined creatively to build Hau Giang, the existing populous and rich region, and they are also going on creating the further right steps in order to make Xa No canal become the “Integration” way with Nga Nam, Nga Bay,…, the one-time cultural centre in Hau Giang region, and help Hau Giang be in the fast strong and steady progress by the “Integration” way together with Ho Chi Minh city and the world.