Erosion of Mekong Bank in Cambodia
1. Introduction
The Mekong river plays a major role on physical geography and on the economy of countries that it crosses. The erosion of Mekong banks have caused the change of the original ground surfaces and the depth of river bed.
2. Hydrology of Mekong River
The Mekong river has got a distance of 4880 kilometers from Tibet's plateau up to China sea. It ranks the 12th for its length and the 21st for its surface in the world. During the rain season, the water level goes up from June or July to November or December with the discharge of 85% to 90% of annual flow. At the end of November, the discharge decreases from 20 to 30% of annual flow. The Mekong river flows from Yunnan's province of China across Myanmar, Lao PDR, Thailand, Cambodia and Vietnam. After the sites researches, the natural resources in the Mekong catchment's areas are still in good condition except in some regions only. The Mekong river allows the population, vegetables, plates and ecosystem to grow up with its flood and low water cycle. The annual flow of Mekong is about 475 10 cubic meters.
The Mekong river crosses Cambodia from the North to the South in distance of 480 kilometers and provides 86% of Cambodia surface with its water regimes. Every year, its flood about 450 10 cubic meters steaming into the plain and the Tonle Sap reservoir before going into the sea of China.
The annual discharge of Mekong river in Cambodia is about 300 10 cubic meters distributing to its hand reservoirs, and about 500 10 cubic meters flowing out China's sea.
3. Choice of Site Erosions
After the sites studies along the Mekong river from Kratie to Phnom Penh, one enormous collapse zone is situated in village CHROUY TAEK of Kandal province. Every year, this site has caved-in about 20 to 30 meters along the actual banks into water river. Since 30 years, the total collapse sites is about 500 meters in distance forcing many people in place to move from the dangerous zones. Consequently, the sedimentation has formed its size about 1 kilometer at downstream of collapse zones. The depots due to the ground erosion have formed a big sand island at the bottom of Mekong river disturbing water circulation during the dry season.
4. Taking Soil Sample
At Chrouy Taek, the caved-in banks are vertical and depth. The installation of big rotary is difficult and impossible. So, the soil sampling at erosion banks were done by hands digging a hole to take a soil sample with PVC tubes of 10cm diameter and 20cm height. The soil samples were taken at 4 different stratum (2cm, 6cm, 8cm, 10cm) in 3 ranks of 20 meters from each others.
Reference
The Mekong river plays a major role on physical geography and on the economy of countries that it crosses. The erosion of Mekong banks have caused the change of the original ground surfaces and the depth of river bed.
2. Hydrology of Mekong River
The Mekong river has got a distance of 4880 kilometers from Tibet's plateau up to China sea. It ranks the 12th for its length and the 21st for its surface in the world. During the rain season, the water level goes up from June or July to November or December with the discharge of 85% to 90% of annual flow. At the end of November, the discharge decreases from 20 to 30% of annual flow. The Mekong river flows from Yunnan's province of China across Myanmar, Lao PDR, Thailand, Cambodia and Vietnam. After the sites researches, the natural resources in the Mekong catchment's areas are still in good condition except in some regions only. The Mekong river allows the population, vegetables, plates and ecosystem to grow up with its flood and low water cycle. The annual flow of Mekong is about 475 10 cubic meters.
The Mekong river crosses Cambodia from the North to the South in distance of 480 kilometers and provides 86% of Cambodia surface with its water regimes. Every year, its flood about 450 10 cubic meters steaming into the plain and the Tonle Sap reservoir before going into the sea of China.
The annual discharge of Mekong river in Cambodia is about 300 10 cubic meters distributing to its hand reservoirs, and about 500 10 cubic meters flowing out China's sea.
3. Choice of Site Erosions
After the sites studies along the Mekong river from Kratie to Phnom Penh, one enormous collapse zone is situated in village CHROUY TAEK of Kandal province. Every year, this site has caved-in about 20 to 30 meters along the actual banks into water river. Since 30 years, the total collapse sites is about 500 meters in distance forcing many people in place to move from the dangerous zones. Consequently, the sedimentation has formed its size about 1 kilometer at downstream of collapse zones. The depots due to the ground erosion have formed a big sand island at the bottom of Mekong river disturbing water circulation during the dry season.
4. Taking Soil Sample
At Chrouy Taek, the caved-in banks are vertical and depth. The installation of big rotary is difficult and impossible. So, the soil sampling at erosion banks were done by hands digging a hole to take a soil sample with PVC tubes of 10cm diameter and 20cm height. The soil samples were taken at 4 different stratum (2cm, 6cm, 8cm, 10cm) in 3 ranks of 20 meters from each others.
Reference
- NU Newsletter, Updated Edition, September 2011, p.160
