VietNamNet Bridge – Last year, 14 storms and five tropical depressions affected Vietnam, reaching the highest number of storms and tropical depressions on the East Sea in history.

Disasters have been exposed

According to the Center for Hydrometeorology Forecast of the Central Region, every year, there are an average of 11-12 storms and tropical depressions in the East Sea, with an average of 5-6 storms and tropical depressions directly affecting Vietnam. The number of storms and tropical depressions always fluctuates and tends to increase the number of super storms.

Extreme phenomena

In 2013, the Central Region of Vietnam was directly affected by four storms and one tropical depression from mid- September to mid- November.

In 35 years (1964-1999), on the Vu Gia - Thu Bon river valley in Quang Nam province, there were only two major floods but since 1999, the frequency of large floods has increased remarkably.

Historic floods have appeared in the rivers in Quang Ngai province over the past 30 years. The flood in 1999 surpassed history within 35 years, but in 2009 the Tra Bong River flood broke the record of 1999. In 2013, flood peaks on the Tra Khuc and Ve rivers set a new record.

Mr. Tran Quang Chu, director of the Center for Hydrometeorological Forecast of the Central Region, said climate change has made the unusual weather, the extremes of climate and weather occurs more often. Storms and floods therefore also change in accordance with the negative direction--more storms, more floods which are more powerful than before.

Dr. Le Van Thang - Director of the Institute of Natural Resources and Environmental Biotechnology at the University of Hue, who chaired the research project "Adaptation to climate change at community level model in low-lying areas in Thua Thien - Hue province," said temperatures in the summer months of Thua Thien - Hue markedly decreased at a rate of 0.1 degrees per decade, in contrast to the country’s situation. The average temperature of the 90s was higher in the previous decades by 0.1-0.4 degrees Celsius. Freezing winters appeared relatively more in the past few years.

Due to climate change and human impacts, the interaction and movement between the ocean and the continent is more complicated, greatly influencing the topography, geomorphology and shape of the lagoons along the central coast.

Mr. Thang also said that the annual average rainfall in 2013 exceeded the average rainfall of the previous years from 114% to 119%. The rainfall from October to March of the following year and in July and August seems to rise.

In the past, floods usually occured in Thua Thien - Hue from September to November, but now it occurs earlier (from August through December). Floods occur with increasing intensity, with higher flood peaks and stronger flow.

The Tam Giang - Cau Hai lagoon system in Thua Thien - Hue province also changes very complicatedly, greatly affecting the natural ecosystems. Initially, water from the Tam Giang - Cau Hai lagoons run to the sea through only the Tu Hien estuary. Flood then opened one more estuary – the Hoa Duan. This estuary shifted north to form the current Thuan An estuary in Phu Vang district.

A lot of floods, rain and unusually large storm caused by climate change have spurred the formation and deposition of the gates of Tam Giang - Cau Hai lagoon system. There were times when many estuaries were formed (after historic floods in 1999). This is called a state of catastrophe for lagoons.

The sudden change and formation of estuaries of lagoons due to the weather abnormalities usually cause serious consequences on the environment and ecology. Consequences of the sudden sedimentation of the Tu Hien estuary increased level of flooding, causing damage to aquaculture and agricultural operation of 38 communes and towns, congested waterways, and destroying the lagoons.

Severe salinity

Da Nang City is primarily provided water from only one river – Cau Do. However, unlike in the past, the salinity of water is now very high in the dry season, up to more than 1,000 mg/l in some years.

The Cau Do Water Supply Company said that this phenomenon has occurred from mid-2012 and it is a very unusual phenomenon. Sometimes, salinity is more than 10 times of the permitted level.

This phenomenon has great impacts on the lives and activities of city residents, especially thousands of hectares of rice fields in the dry season.

NLD