Tạp chí Khoa học Trái Đất và Môi trường Đại học Quốc gia Thành phố Hồ Chí Minh

Geological environment zonation is to divide the areas into relatively homogeneous units based on their natural factors such as hydrology, topography, geology, disasters... to create geoenvironmental units which suit a specific type of exploitation for the purpose of research or regional management. This study presents a process of integrating GIS and remotely sensed data to develop a map of environmental geological zonning for the planning of development of the efective and safety construction sites. Data used in this work include Landsat 8 satellite image classified by application of Fuzzy Logic method to build the map of land use status which includes construction sites, and the GIS data including geology, topography, engineering geology and hydrogeology. The result from this process of integration is the suitability maps of appropriate units for the development of construction sites on the Thi Vai river basin. This map shows 3 different levels of geological environmental condition for development of the construction sites. This result demonstrates the efficiency of the integration of GIS and remote sensing to build tools to assist for the environmental capacity management, for data analysis, and beyond, to identify and incorporate the influencing factors to the subjects of management or research.  

The problem of studying, calculating, simulating the process of transporting sediment and calculating erosion and accretion in rivers is very complicated. There are many methods that are applied and have shown their own effectiveness. However, at present, the development of a computer system as well as a good data base (especially topographic data) will ensure the ability to apply hydrodynamic models to simulate high results. In the Mekong Delta, there are currently 406 landslide sections, with a total length of 891km, of which An Giang is assessed as one of the localities most severely affected by riverbank erosion. Currently, there are many methods used to assess and predict riverbank erosion through the calculation of sediment content and regime in the river in specific areas, such as: document analysis method. real measurement; physical model; experience formula and mathematical model. Research using 2D Mike 21FM model is being widely used to simulate sediment regime on Tien and Hau river systems and analyze in detail for Long Xuyen city, An Giang province, which is a serious landslide area in recent years. The criteria to evaluate the reliability of the model both in terms of hydrodynamics and sediment at Vam Nao hydrological station show that the set of parameters ensures enough reliability to conduct the simulation of sediment on the system. Simulation results of flow regime and velocity show that the direction of sediment movement is from the right bank to the left bank, and this area has many scour holes and the level of sediment moving away from the shore is up to 50kg/m3. Many locations also clearly show a high risk of landslides in this area. This result will strengthen the scientific basis of the mathematical modeling method along with other methods for simulating finding mechanisms and causes of riverbank erosion, serving the prevention and mitigation of riverbank erosion. damage caused by landslides.

This study proposed a multiple criteria decision process to identify the industrial facilities and operations that represent potential environmental accidents associated with uncontrolled release of chemicals. Unlike the existing approaches that simply rely on the storing capacity (quantity) and hazard of chemical substances at site, the proposed process takes into consideration the common root causes and recurring themes of the accidents such as unsafe onsite storing and using, inadequate operation training, inadequate safety management and analysis, equipment failure… The issues have been aggregated in a criteria system demonstrating a potential of environmental accident. The screening process comprises of 2 steps: 1) primary screening based on logic analysis; 2) detailed screening based on analytic hierarchy process. This method may overcome some limitations of the traditional approaches such as failure to take into account the state of the chemical safety or the ability to respond to chemical incidents of the facilities. The proposed process has been applied for screening a number of industrial facilities and operations in Hiep Phuoc industrial zone, Ho Chi Minh City. The results are consistent with the regulatory requirements, and reflect the current state of risk of chemical incidents at the facilities. Thus it is expected to facilitate the proper management of chemical safety and development of a feasible chemical accident prevention and response plan.

Applying the methodology of the Intergovernmental Panel on Climate Change (IPCC) in calculating the greenhouse gas emission from pig farming operations at Lam Dong province in 2015, calculated results show that the application of swine manure management solutions can significantly reduce emissions of greenhouse gases into the environment. Using of energy in pig farming operations around 0.0007 tCO2 emissions/ head/ month, the digestion of pig feed create a greenhouse gas emission at around 152.96 tCO2/month with emission factor of 0.0029 tCO2/head / month. Greenhouse gases emitted from the current manure management system (manure are treated by various forms and the rest will directly disposed into the environment) into the atmosphere is around 400.08tCO2/month, respectively a pig emitted about 0.0076 tCO2/head/month. The total emission factor during pig production under the scenarios: (1) manure are directly discharged into the environment, (2) manure are managed by current management system, (3) manure are managed by current management systems with the gas generated from biogas recovery is converted into electrical energy and (4) manure are managed by Biogas recovery system, respectively 0.0593; 0.0112; 0.0101; 0.0077 tCO2/ head/month.

This research aims to evaluate climate change effects on livelihoods of residents living in the buffer zones surrounding U Minh Ha National Park, specifically in Vo Doi Hamlet, Tran Hoi Village, Tran Van Thoi Town. The research data is collected from 65 households living and working in the study area by semi-structured interview (SSI). This research applied the Livelihood Vulnerability Index (LVI) established by Hahn and his associates in 2009 which illustrated that the inhabitants of the mentioned area are considerably affected by climate change. The results of this study demonstrated that the LVI values decreased following the elements of social networks (M4), food and finance (M5), livelihood strategies (M2), natural disasters and climate change (M7), household characteristics (M1), water sources (M6) and health (M3) at the values of 0.538, 0.422, 0.420, 0.327, 0.309, 0.197 and 0.105 respectively. The total value of the Livelihood Vulnerability Index (LVI) of the residential community in Vo Doi hamlet is high: 0.333. However, thanks to the local government's well-implemented climate change education and communication, policy support, and the flexible adaptation to climate change of the people living here, the negative impacts of climate change have been significantly reduced.

The study was carried out to set up the evaluation criteria that is satisfactory the level of a green industrial park. A set of criteria consists of 2 parts: screening and evaluation criteria, to evaluate the 2 objects: Investment company IZ infrastructure & factories within the industrial zone. Researchers have applied this set of criteria to evaluate the Tan Thuan Export Processing Zone, HCMC. From the results of the evaluation by the criteria, researchers have proposed 6 solutions and roadmap for implementation of solutions to meet the requirements of a green industrial park.

Thach Khoan, Phu Tho area is the area with great potential for weathered kaolinite source from pegmatites of the Tan Phuong complex. This kaolin has quite good quality and is used in many traditional applications such as high quality ceramic glaze, high-grade bricks. However, the use of this material in the treatment of water pollution is still limited. In this study, the natural kaolin material from Thach Khoan area, Phu Tho province with about 87% amount of tubular halloysites was used to remove Cd2+ ion from water. The factors of pH, contact time, the adsorbent weight, and initial concentration of Cd2+ were studied to access their effects on the Cd2+ ion adsorption process using this raw material. The results indicated that under the conditions of pH0 of 6.5 and at room temperature (25 oC), with 0.8 g of halloysite powder and Cd2+ initial concentration of 30 mg/L, the adsorption of Cd2+ could reach equilibrium after 50 minutes with an efficiency of 86.31%. The adsorption process follows the Langmuir adsorption isotherm model with the maximum monolayer adsorption capacity of 2.75 mg/g and follows the second-order pseudo-adsorption kinetic equation. The results show that the natural halloysite material without treatment has the potential in using to remove heavy metal ions in polluted water and needs to be studied further.

The impacts of urbanization and climate change are drastically changing rainfall patterns in urban areas that exacerbate water-related risks such as inundation/flooding, drought, and environmental pollution. Predicting rainfall trends provides useful information to proactively mitigate the impact of water-related risks. This research aims to quantitatively identify the changes of rainfall patterns in durations of 15, 30, 45, 60, 90, 120, 180, and 360 mins covering from 1982 to 2019 at Tan Son Hoa meteorological station located in Ho Chi Minh City. In the period 1982-2019, the observed rainfall data showed 579 rainfall events with a total volume higher than 30mm (average of about 15 events/year), and extreme rainfall events have occurred quite frequently since 2016. Mann- Kendall's nonparametric test and Sen's slope estimator showed that rainfall trend strongly increased (statistical significance) for the short durations of 15, 30, 45, 60, 90 mins and increased moderately (statistical significance) for 120 mins duration but slightly increased for the durations of 180 and 360 mins and it was not statistically significant. The trend of rainfall in the duration of 45 mins increased the most with an average rate of about 0.7 mm/year. An increase in short-duration rainfall can exacerbate urban flooding due to overloaded drainage systems. The findings of this research could support urban flood risk management and other water-related environmental issues in Ho Chi Minh City.

The Nui Beo mine is located in the southern part of the Quang Ninh province. It belongs to the Hon Gai-Cam Pha coal zone, where many coal resources have been estimated in Vietnam. Based on synthesizing and processing data of the coal seam parameters and coal quality by using K-means and regression methods, results allow dividing the Nui Beo mine into three areas, the area 1 bearing coal thickness greater than or equal to 18.5m, the area 2 containing coal thickness less than 18.5m, and coal seam dipping angle less than 32.0 degrees; and the area 3 obtaining coal thickness less than 18.5m, and coal seam dipping angle greater than or equal to 32.0 degrees, combining with five interlayers as the scared boundary. Identifying results using K-means and regression methods for 2 or 3 coal seam parameters is very low; only coal seams of V4, V12, and V14 are higher (over 50%). After dividing the mining area, the identifying rate is higher, especially the coal seams of V5, V7, V11, V12, and V14 reach 30.38% on average compared to 16.83% for the whole mining area. Identifying coal seams based on six analyzed parameters shows 16.64% on average; the nine analyzed parameters show 25.93% on average. Generally, each environment has increased significantly after dividing the identifying rates of coal seams according to seam parameters and coal quality. Using the seam characteristics as thickness, dip angle, the number of interlayers, and coal quality, they help divide the Nui Beo mine into 07 relatively homogenous blocks, namely A1, A2, A3, B, C, D, and E, respectively. In which block A1 is formed in a swamp environment; blocks A2 and A3 are characterized by a mudflat environment; block B is suggested a flow environment; block C is characterized by mudflat; block D features a swampy and block E in the periphery. The results confirm that applied mathematical methods in geological science are effective, especially in identifying coal seams and sedimentary environments.

The study was conducted to evaluate the impact of domestic wastewater discharges on surface water quality (BOD5 and DO) at pumping stations on Sai Gon – Dong Nai river during the dry season and the wet season using the MIKE 21FM model. The results indicated that the water quality in Dong Nai river is rated better than the Sai Gon River. Specifically, the BOD5 concentration was high, and the DO concentration was low at Hoa Phu station in Sai Gon River. However, the surface water quality at pumping stations on Dong Nai river, namely Hoa An and Binh An was up to standard compared to column A2 for domestic water supply purposes according to QCVN 08- MT:2015/BTNMT. Specifically, the wastewater source from Thu Dau Mot city on the Sai Gon river was about 4 km from Hoa Phu pumping station with a discharge volume of 0,66 m3/s, and another source from Bien Hoa city on the Dong Nai river reached a discharge volume of 2,15 m3/s, which was about 4.7 km and 5.5 km from Hoa An and Binh An intakes, respectively. The outcomes proved that Hoa Phu and Hoa An pumping stations were not affected by the wastewater from these cities. Otherwise, there was markedly degraded water quality at Binh An intake in the dry season, which was unsatisfied with QCVN 08- MT:2015/BTNMT (A2 type).