Hue University Journal of Science (HU JOS)

ASSESSING THE MOTIVE OF EROSION PROCESS OF RIVERS IN THE MID-CENTRAL PART OF VIETNAM

2017-06-02T10:24:10+00:00

Abstract: In this report, we wish to show some initial achievements of our researches about the motive of erosion process of rivers in the mid-central part of Vietnam from Quang Binh to Phu Yen (They include Gianh river, Nhat Le river, Thach Han river, Huong river, Thu Bon river, Tra Khuc river, Ba river). In order to assess danger's degree generated from the rivers themself, we apply two criteria including the intensity and the rate of erosion. Among which, erosion intensity is defined by erosion coefficient (K_e - %) and erosion width (B_e - m) at measuring time. With the coefficient is the ration between total erosion lenght at measuring time and the length of the studied segment. The annual pace of erosion V_e (m/year) is measured by the width of erosion each year or each flood. From this motive scale and results of surveys and monitorings in the field, it is possible to assess and propose the basic comments associated with the eroion motive of rivers in the mid-central part of Vietnam. This is expected will be very useful for following studyings of geological hazards.

ASSESSING THE STUDY OF CLIMATE CHANGE TREND IN VIETNAM: A CASE STUDY IN DANANG CITY

2017-06-02T10:24:10+00:00

ABSTRACT

This paper aims to present the results of trend analysis of climate change in Vietnam, a typical case study in Danang City. With the use of statistical analysis by non-parametric Mann-Kendall test, the research conducted the test of climate change trend based on the review process of precipitation and temperature trends. The results were evaluated based on the statistical analysis at the 0.05 level by ProUCL 4.1 software. The research has shown clear signs of climate change related to precipitation and temperature factors. The general situation of precipitation change in Danang had the upward trend in observed time series (p <0.05). For each specific season, there exists increasing trend of the precipitation in January, March, August and decreasing trend in June of observed period. According to the scenario in 2100, the average precipitation in Danang will increase about 1.04% in comparison with the period 1980 – 1999. Regarding the temperature factor and based on the results of the Mann-Kendall test, the June’s average temperature in Danang will increase about 0.315⁰C in every ten years. Therefore, the urgent solutions are required to reduce and adapt to climate change.

Keywords: Climate change, trend, precipitation, temperature, Mann-Kendall.

THERMAL REMOTE SENSING METHOD IN DETECT AND MONITORING SUBSURFACE COAL FIRE IN KHANH HOA COAL MINE, THAI NGUYEN PROVINCE

2017-06-02T10:24:11+00:00

The Khanh Hoa coal mine is a surface coal mine in the Thai Nguyen province, which is one of the largest deposits of coal in the Vietnam. In recent years due to many reasons such as backward mining techniques and unauthorized mining caused subsurface coal fire in this area. Coal fire is a dangerous phenomenon which affects the environment seriously by releasing toxic fumes which causes forest fires, and subsidence of infrastructure surface. This article presents study on the application of LANDSAT multi – temporal thermal infrared images, which help to detect coal fire. The results obtained in this study can be used to monitor fire zones so as to give warnings and solutions to prevent coal fire.

RESEARCHING AND ZONING SOIL SALINIZATION RISK IN THE COASTAL PLAIN OF THUA THIEN HUE PROVINCE

2017-06-02T10:24:11+00:00

The coastal plain of Thua Thien Hue province covers an area of 1,080 km², which is susceptible to soil salinization due to significant impacts by climate change. In this study area with highly sensitive risk of soil salinization, about 6.290 hectares of saline soil scattered distribution tends to increase terrestrial areas in the next time. To assess and map risk of soil salinization, the authors chose 09 criteria including: annually average rainfall, annually average temperature, annually average evaporation, number of sunny hours, number of months of dry season, soil type, vegetation cover, density of river network, submerged areas following the strategies of sea level rise. The spatial data for determing criteria were processed by using GIS (Geographic Information System) and the Analytic Hierarchy Process (AHP) method. The study results show that the area with the high risk of soil salinization is about 16.4% of total area located in the coastal region of Phu Vang, Quang Dien and Phong Dien district.

STUDY OF VEGETATION COVER CHANGES DURING 1989 – 2010 FOR NATURAL RESOURCES, ENVIRONMENTAL MANAGEMENT AND DISASTER PREVENTION AT PHU LOC DISTRICT, THUA THIEN HUE PROVINCE

2017-06-02T10:24:11+00:00

Vegetation cover play an important role in water regulation, flood protection, drought and soil erosion reduction, landslide, flash flood... Vegetation cover change causes to lose ecosystems as well as rare plants and animals, increases the consequences of natural disasters and climate change. By using GIS and remote sensing methods for processing and analyzing Landsat-7, the study shows Phu Loc’s vegetation cover had changed from 1989 to 2010 with the fluctuation area of more than 27,000 hectares, nearly 38% of the district. In which, the natural vegetation cover, mainly tropical vegetation cover below 800m was significant decline, with the area of more than 8,000 hectares. This has increased the impact of natural disasters e.g.. typhoons, floods, landslides, erosion,... affecting the local regionsocio - economic development.

THE CONTENTS OF SOME HEAVY METALS IN FOOD-CROPS PLANTED AT TUY LOAN AND DIEN MINH VEGETABLE-FIELDS

2017-06-02T10:24:12+00:00

This study was carried out to assess the heavy metal contents (Zn, Pb and Cr) in Indian mustard (Brassica juncea L.) grown at Tuy Loan and lettuce (Lactuca sativa L.) grown at Dien Minh’s vegetable-field. The results showed that the contents of all heavy metals in soil samples didn’t exceed the permissible levels according to GB 15618:1995 and QCVN 03:2008/MONRE. These were accordance with soil assessment by pollution load index (PLI). Similarly, the contents of Zn, Pb, and Cr in Indian mustard and lettuce’s leaves at Tuy Loan and Dien Minh were lower than permissible limits compared with GB13106-1991, GB 2762: 2005 and QCVN 8-2:2011/MOH. Most of the heavy metals contents in roots were higher than in leaves. For Indian mustard, the TF_soil-root values of Zn and Cr from soil to root were higher than TF_root-leaf values from the root to the leaf, which was in contrast with Pb. While, for lettuce, the TF_soil-root values of Zn, and Pb were higher than TF_root-leaf, which was in contrast with Cr. The results also indicated that there weren’t any risk to human health when using vegetables planted at these areas in daily meal (HI < 1).

EFFECT OF TEMPERATURE, LIGHT ON THE GROWTH AND LIPID ACCUMULATION OF NANNOCHLOROPSIS OCULATA

2017-06-02T10:24:12+00:00

Abstract

N. oculata, the micro-algae, has rapid growth rates, the ability to accumulate high levels of lipid and lipid composition suitable for producing biodiesel. Therefore, this microalgae is selected as a research object. In this article, we conducted the effects of temperature as well as light on the growth and the lipid accumulation of microalgae. By means of quantitative analysis showed that at 30⁰C and 9000 lux, the growth and microalgae lipid accumulation reached the highest value. For example, dry biomass obtained 460.7 mg /l, the amount of crude lipid obtained 59.6 mg /l and the total lipid accounted for 12.9% of dry biomass.

Keywords: N. oculata, biodiesel, producing micro-algae

Characteristics of phosphate phase (fluorapatite and monazite) in the South Nam Xe carbonatites, Northwest Vietnam

2017-11-20T03:12:44+00:00

This paper presents characteristics of appearance and mineral chemistry of phosphate phase, including fluorapatite and monazite in the South Nam Xe carbonatite dykes in Northwest Vietnam. These minerals occur in both calcio- and ferrocarbonatites in various modes. Most of the fluorapatites in the calciocarbonatites are oblong to elongated, and have sharp contacts with calcite, aegirine and phlogopite suggesting their primary origin; whereas those in the ferrocarbonatites are commonly present in forms of stubby to perfect hexagonal prismatic crystals, which partly replaced by the monazite. The monazites in the ferrocarbonatites also occur as hundreds micro isolated crystals, which associated with ankerite, feldspar, magnetite and phlogopite.

Contents of fluor and rare earth elements (REE) are relatively high (F up to 4.26 wt.%; REE up to 5.19 wt.%) indicating a F- and REE-enriched precipitation for the carbonatites. The enrichment in light REEs in the fluorapatite is paired with an enrichment in Na, varying from 0.25 wt.% to 0.89 wt.%. The replacement of REE and Na for Ca in the fluorapatites, which leads to change in CaO/P₂O₅ ratios might show an open system where Ca and P are added to areas of the fluorapatite depleted in light REE (LREE). REE contents in the monazite show a very limited variation, and are mainly composed of La, Ce and Nd (La₂O₃ = 21.09-22.72 wt.%, Ce₂O₃ = 32.82-33.35 wt.%, Nd₂O₃ = 6.96-8.20 wt.% in calciocarbonatite; La₂O₃ = 16.61-17.39 wt.%, Ce₂O₃ = 32.07-33.52 wt.%, Nd₂O₃ = 8.92-10.94 wt.% in ferrocarbonatite).

VULNERABILITY TO FLOODING AND COPING BEHAVIOR FOUND IN HOUSING CONDITION: A CASE STUDY IN VAN QUAT DONG VILLAGE, TAM GIANG LAGOON AREA, CENTRAL VIETNAM

2017-06-02T10:24:13+00:00

Vietnam is a country that is suffered from frequent natural disasters. The most common types of natural disasters experienced are typhoon and flood. From 1951 to 2010, there were 166 typhoons come to Vietnam, of which 67 % hit the central region, 25 % to the north and 8 % to the south of the country. Typhoons bring heavy rains and high tides which accelerate floods, particularly in the coastal and lagoon areas of Central Vietnam. Identification of vulnerability to flooding and coping behavior of local people is required in the efforts to strengthen local capacity related to livelihood security in the study area. This study aims at characterizing the vulnerability of housing condition to flooding and the coping behaviors of local people after experienced big floods in Tam Giang lagoon area, Central Vietnam. Measurement of house’s foundation, observation of types of housing, interview to collect information about the water level during the events of big floods, year of construction and change of people’s behavior after the 1999’s flood were conducted with 427 households in Van Quat Dong village where four big flooding occurred in 1983, 1999, 2007 and 2009 during the last 30 years. The study shows that the 1999’s flood was the biggest flood with water height reached to 148.7 ± 23.9 cmfrom house floor and 222.6 ± 15.4 cmfrom ground level. The households located in the eastern part of the village are recognized more vulnerable to flood due to the lower altitude. The temporary and semi-permanent houses, which share 77.0 % to the entire houses, are considered to be relatively vulnerable to flooding due to weak housing materials and low height of foundation. The houses which categorized to permanent and semi-permanent types constructed after the 1999’s flood have higher foundation than the other houses constructed before the 1999’s flood. The raising of foundation height of permanent and semi-permanent houses, as well as an increase in numbers of two-storey houses, are recognized to be a behavior of local people to cope with flooding. The study also shows the relationship between the poverty level and the coping behaviors of households. Some of poor households in the village are still not in good preparedness to flooding. It suggests that poverty level of household concerns to the vulnerability to flooding and, therefore, rural development assistance to improve household economy for poverty alleviation is required in the efforts to strengthen local capacity related to livelihood security.