Chau Thanh A district, considered as the gateway of Hau Giang province adjacent to Can Tho city converges many advantages for agricultural development. The research is aimed to determine of land potential for agricultural development at Chau Thanh A district to promote the available benifit and to propose solutions to solve the limiting factors in the agricultural cultivation. Seventy households were interviewed to indentify advantages and disadvantages in agricultural production by participatory rapid appraisal method (10 meets), and land evaluation by FAO (1976, 2007) was used to identify land potential about nature and economy. The twenty-four land units from five land characteristics was established. The study has built five suitability zones for combination of natural, economic conditions for five land use types (triple rice crops, triple rice crops - fish, double rice crops, rice - cash crops and fruits). Based on the land potential, the study proposed five zones for agricultural development towards sustainable development in agricultural cultivation at Chau Thanh A district, Hau Giang province.

This research is aimed to provide an overview in the current status about the community-based tourism (CBT), thereby to point out constraints during the CBT’s formation and development. A survey with 40 local people was conducted in Hong Ha commune, Thua Thien Hue province, Vietnam. The results showed that although it was a potential region, the CBT in Hong Ha has not deservedly developed as its prospects. The CBT was basically designed and implemented in a top-down approach and low human capacity were the main reasons. The study suggested that for the CBT’s effective and sustainable development, it is needed to create a symbiotic relationship between communities, government and private sectors.

The study is aimed at estimating suspended sediment concentration (SSC) in the Vietnamese Mekong River mainstreams by analyzing Landsat images. Measured SSC data at Can Tho and My Thuan stations were collected by the Cuu Long River Hydrological Center. Landsat 8 images of the study area in the period from 2013 to 2014 were downloaded and analyzed. A multiple linear regression model was built to estimate SSC based on reflectance values of selected bands which have high correlation coefficient with SSC. As a result, it was found that the green band (band 3) and the red band (band 4) have a strong relationship with SSC (R2 = 0.71). In addition, the SSCs estimated by the linear regression model have a reasonably good agreement with the measured SSC (r = 0,84, Bias = -4 x 10-5). Besides, the seasonal variation of river plumes is also reproduced. These results enable further application of remotely sensed images on monitoring SSCs.

This study is aimed to identify the factors influencing students’ intention to participate in educational tours designed for students in Can Tho University at Lung Ngoc Hoang Nature Reserve and Mua Xuan Agricultural Center by Cronbach’s Alpha test and Principle Component Analysis and Binary Logit model. The results of 330 student interviews show that 76% of them intended to participate in designed educational tours. Factors affecting their intention to participate in designed tours are characteristics of students (major, course (second- and third-year students prefer to participate educational tours to last year students), cumulative grade and income), attraction and safety of tourism sites, motivation and perception on educational tourism and economic factors. This study will contribute practical contribution in designing tourists’ activities at two sites, especially targeting to students who experience both pure and educational tourism.

Principal component analysis (PCA) and cluster analysis (CA) were used in this study to assess the surface water quality variation by the depth of acid sulfate soil (shallow and deep ASS) in the areas of planted Acacia hybrid, planted Melaleuca cajuputi in buffer zone and natural Melaleuca Cajuputi in the core of U Minh Ha National Park. Water samples were collected from 30 points in September 2018. Nine water quality parameters including pH, EC, DO, BOD5, COD, N-NH4+, N-NO3-, Al3+ and Fe3+ were selected for PCA and CA analysis. The findings revealed that surface water quality in the study area has been polluted by organic matters, acid sulfate condition and salinity. BOD5 and COD in surface water in the planted Melaleuca Cajuputi and Acacia hybrid were high (52.8 - 245.4 mg/l), leading to low DO. Al3+ and Fe3+ in water in shallow ASS sites were higher than those in deep ASS since ASS becomes higher active in the shallow layer. EC was found high (1,806 ± 1,256 µS/cm) due to acidic and saline contaminating water. PCA showed that there were at least two polluting sources affecting surface water quality parameters of pH, ​​EC, BOD, N-NH4+, Al3+, and Fe3+. CA showed that four out of 30 sampling locations could be selected to representively monitor water quality for the study area in U Minh Ha National Park.

The research was aimed to identify sustainable land use types in agricultural production, which could be a proper foundation for proposing zones to improve argicultural land use effectiveness in the future. Data of agricultural land use and associated advantages and disadvantages in cultivation were collected through interviews of 391 farmers practicing four main typical production patterns. The research was determined physical and economic suitability of each land use type based on the FAO approaches (1976 and 2007). It was identified that aquaculture is the main activity in Phu Tan district, and shrimp-forest farming system is the most sustainable type of cultivation while intensive shrimp farming system is the least. Four zones of agricultural production towards sustainable agricultural production were proposed based on the assessment of physical and economic potentials. The findings of this research could be a scientific base to help managers plan strategies for sustainable agricultural production for Phu Tan district.

This research was to evaluate the use of Landsat 8 images for establishing the rice crop maps and estimating total rice productivity at Soc Trang province in 2018. In this research, time series vegetation index based on the Landsat 8 data with 30 m of spatial resolution from 2015 to 2017, through the field survey at 186 locations.  The ENVI software was used to classify Landsat 8 images, and tools in Mapinfo was used to calculate rice crop area in the period from 2015 to 2017 and to establish a rice crop map with an overall accuracy of 94,6% and the Kappa coefficient of 93%. Besides, comparison between rice areas from classifying remote sensing and from reports in the Department of Agriculture and Rural Development in the Soc Trang province was similar (>95% of similarity). Thus, the total products of rice from classification images was 2.094.423,4 tons while from reports it was 2.127.316,6 tons (lower 1,5%). Therefore, the Landsat 8 images can be applied to build the rice crop map and estimate rice total product effectively. However, it is just the first steps of estimating total rice productivity the combination between NDVI time series with the mathematical models is necessary to improve the accuracy.

The study was aimed to create flood inundation extent mapping with Landsat imagery and its impact on agricultural land use in Quang Dien district, Thua Thien Hue province. The flooded area was indicated by some indicators such as land surface water index (LSWI) and enhanced vegetation index (EVI) from Landsat-7/TM images. Comparisons between the floodplain samples (GPS point)-based flood mapping results with the ground-truth data indicated that the overall accuracy and Kappa coefficient achieved in 2015 were 96.5% and 0.72. The results showed the flooded area of Quang Dien district in the year of 2015 is 912.90 hectares and the biggest flooding was happening in March. The most flood affected on the communes including Quang An, Quang Phuoc, and Quang Thanh. In terms of land use, paddy land and annual cropland are the most affected by flood in 2015.

The aims of this study are to (i) have a descriptiton soil profile morphology and (ii) evaluate the change of some soil chemical properties and toxicity of actual acid sulfate soil when being kept in dry condition at different periods of time. Survey of soil profile morphology was conducted in May, 2015 at Hoa An commune, Phung Hiep district, Hau Giang province. The drying and re-flooding experiment was conducted from August, 2015 to February, 2016 at Soil Science Department, College of Agriculture, Can Tho University. The results showed that the active acid sulfate soil was classified Orthi Thionic Fluvisols in which topsoil is accumulated by decomposing organic matter, soil ripening was dertermined from the depth of 25-50 cm. The diangostic sulfuric horizon, which contains jarosite mottles was determined at the depth of 25-110 cm. Pyrite (FeS2) was found at the depth >110 cm from the soil surface. Results from these lysimeters showed following changes of soil chemical properties. SO42- values experienced abnormal fluctuations that are difficult to assess the data of these streatments. The fluctuation in the direction of increasing the toxicity of Al3+, Fe2+ at the layers of Bgj1, Bgj2 and Crp in the conditions of dry soil in one, two, and three months compared to the treatment to wet continuously. Treatments of dry soil conditions, the concentration of SO42-, Al3+ and Fe2+ in in Crp layer increased much higher than soil layers Bgj1 and Bgj2.

The Dong Nai River is one of the main water supply sources for living and production activities in Binh Duong province. However, the Dong Nai River is currently under pressure by emissions from industries, urban, agriculture and service activities. In this paper, the generalized regression neural network model (GRNN) and the interpolation algorithm was used to evaluate water quality of the Dong Nai river and tributaries. Monitoring data used was for 7 years from 2012 to 2018 at 12 monitoring stations. The results of the study indicated that the GRNN model was a good performance to assess the water quality of the Dong Nai river and tributaries. Comparing the results of the GRNN model with the water quality index showed that the GRNN model was reliable and in close agreement with the actual results with R2 = 0.938, RMSE = 0.055, E = 0.935. Water quality interpolation map also illustrated that the water quality in the neighbor area was still good. Besides, the GRNN model has a lower cost and less time consumption compared to the WQI method of the Vietnam Environment Administration.

The aim of the study was to identify and compare the composition of benthic microalgae living on artificial substrates (refined bricks) of intensive rice cultivation in the Winter-Spring crop from 2016 to 2017 and Summer-Autumn crop in 2017. The experiment was carried out in three paddy fields with area of 1,000 m2 each. Comparative morphological method was used to identify algae species. Qualitative results showed that there were 157 taxa belonging to 63 genera, 34 families, 15 orders, and 3 phyla (Chlorophyta, Bacillariophyta, and Cyanobacteria), in which Chlorophyta predominated. The composition of benthic microalgae characterizes intensive rice fields with strong development of Pennales belonging to Bacillariophyta, Volvocales, Desmidiales, and Chlorococcales belonging to Chlorophyta. Heavy rain, the cover of leaf canopy, low fertilizer mass, and spraying pesticides were capable of reducing composition species and density of benthic microalgae.

The study is to analyze the hydrodynamic regime and sediment transport under the effect of the East Sea’s tide and evaluate bed topography, sediment distribution of My Thanh River, Soc Trang province. the study data which were measured at My Thanh River from June to October 2018 included 1) water discharge, water velocity and cross-section profiles by using Acoustic Doppler Current Profiler, 2) suspended sediment concentration (SSC) and sediment texture by samples of the water and bed soil. Based on in-situ data, riverbed topography, sediment distribution and the fluctuation of SSC due to water discharge, velocity and tide will be evaluated under the effect of climate change and sea-level rise. This research will be a good reference for modelling and simulating studies in river bed topography, sediment deposition, and erosion in the coastal area of the Mekong Delta in the future.

This study was conducted to assess the impact of extreme year (drought induced by El Niño) to GPP of deciduous forest (DF) at Ratchaburi province, Thailand. The measured meteorology data was analyzed to assess the changes in temperature and precipitation over the period of study, 2009-2012. The time series of MODIS NDVI were used to evaluate the shifting of DF phenology in period 2009-2011. The analysis of shifting phenology was compared to the measured GPP between extreme event and other normal years. The results showed that in dry season 2010 (drought year), the air temperature increased, rainfall decreased, corresponding to delay of starting of season (49-50 days), length of season shorter than (54-57 days) in comparision to year 2009 and 2011. The GPP was also significantly reduced in drought year 2010 (376.4 kgC/ha) comparing to year 2009 (581.1 kgC/ha) and 2011 (530.0 kgC/ha). The further studies on the long term monitoring of soil moisture and climate factors to enhance the understanding on main drivers effecting the phenology shift and reduce of the GPP of DF are encouraged.

Acute toxicity and effects of insecticide Marshal 200SC on cholinesterase (ChE) and growth performances of fingerling Tilapia (Oreochoromis niloticus) were carried out in laboratory conditions. An experiment was conducted in static non-renewed system for estimating LC50-96h. Other experiments with three levels of Marshal 200SC (1, 5 and 10%LC50-96h) and control were conducted in 50L glass aquaria during 96hrs and in 600L glass fiber tanks during 60 days for examining effects of this insecticide on ChE and growth of this species, respectively. Result showed that Marshal 200SC is very toxic for Tilapia, LC50-96h is 0.52 ppm (0.1 mg/L of Carbosulfan). At concentrations ≤10%LC50-96h, the insecticide causes significantly short-term effects on brain ChE activity but insignificant effects on growth parameters. Activity of ChE is the most sensitive parameter to Marshal 200SC. At sub-lethal concentrations, it is quickly inhibited within 6 hrs of exposure and fully recovers within 48 hrs.Lowest observed effect concentration of Marshal 200SC for ChE is 0.05ppm (10%LC50-96h).

The Can Tho river is  an important source of  water supply to the local people. An  evaluate of the Can Tho river water quality is very necessary. Therefore, the use of water quality indices (WQIs) as a tool to evaluate the status of water quality in rivers has been studied  for the period of  2010-2014. For this purpose, monitoring data obtained during this period was collected. Physical, biological and chemical parameters of surface water including pH, TSS, DO, BOD, COD, NH3, NO3-, and coliform were determined . The results indicated that most of the indicators exceeded the Vietnamese standard. However, they has significantly improved in the last years (2014) of the research period. In addition, the use of WQIs  is fundamental to represent a large number of parameters in a single number. The WQI values showed that river water quality in districts of Ninh Kieu, Cai Rang and Phong Dien has the water quality has significantly improved during the research period.

Integrated agro-forestry farming is considered a way to improve livelihoods of farmers and performance of mountainous agro-ecological systems. The aim of the present study is to evaluate the current situation and identify factors that affect the efficiency of mountainous agro-forestry systems in An Giang province in order to identify solutions to further develop these farming systems. Agro-ecological system analysese and household surveys were conducted. Ninety farmers practicing integrated agro-forestry farming systems in Tri Ton and Tinh Bien districts were interviewed. Fruit and forest tree inter-cropping system is dominant with an average rate in inter-cropping area of 80:20, respectively. In this way, farmers can maintain the forest area covering about 14,2%. Inter-cropping pomelo or mango with forest trees helped improving farming income of farmers, compared to other fruits. Irrigation water and fruit growing density were important factors of economic efficiency of the farming system. Providing irrigation water, exploiting the efficiency of forest trees and improving fruit cropping techniques are of great importance in improving resource use efficiency while reducing economic and environmental trade-offs in the agro-ecological system.

This study was to investigate the diversity of the zooplankton in the buffer zone of the U Minh Ha National Park, Ca Mau province. Thirty samples of the zooplankton were collected in three models including planted Melaleuca cajuputi, natural Melaleuca cajuputi and Acacia hybrid on two types of shallow and deep acid sulfate soil (ASS) in October 2018. The results showed that there were 131 species of Protozoa, Rotifera, Cladocera, and Copepoda which accounted for 55.7%, 18.3%, 15.3% and 10.7%, respectively. The total species density ranged from 41,773 - 589,418 individuals/m3, of which Rotifera was the highest density species. The Shannon index H’ was low, from 0.74 to 1.24, the highest H’ was found i  deep ASS Acacia hydrid model, and the lowest H’ was found in shallow ASS in the planted Melaleuca cajuputi model. The H’ indicates the water environment in the study area was from moderately to severely polluted. According to cluster analysis, the diversity of the zooplankton was divided into two groups in which group 1 was the Acacia hybrid model on two ASS, and group 2 included natural and planted Melaleuca cajuputi models. The overall results showed that the cultivation model has a great influence on diversity of the zooplankton and it’s indicators for water environment.

The research was to determine the morphological and physicochemical properties of acid sulfate soil profile from pineapple monoculture and pineapple intercropped with King orange, coconut-palm. Based on soil morphological characteristics, soil profiles from pineapple monoculture were classified as potential acid sulfate soil with the very deep presence of sulfidic material while soil profiles from pineapple intercropped with King orange and coconut-palm were categorized as potential acid sulfate soil with the deep presence of sulfidic material. For soil chemical properties, surface soil pHKCl was lower than 3.5. Aluminum (meq Al3+.100 g-1) and ferrous toxicity (mg Fe2+. kg-1) were approximately 6.0. Besides, total nitrogen content was evaluated at medium – high level, and total phosphorus concentration was categorized at a low threshold, with 0.39 – 0.60% and 0.03 – 0.06%, respectively, in all models. Concentration of available ammonium and soluble phosphorus were 88.1 – 313.5 mg NH4+.kg-1 and 16.5 – 38.9 mg P.kg-1. However, soil phosphorus fractions of aluminum phosphorus and ferrous phosphorus possess high concentration, with 83.5 – 110.7 and 16.5 – 38.9 mg P.kg-1. Of those, P-Al and P-Fe concentration of pineapple monoculture were lower than in intercropped models. Organic matter was assessed at medium level in all models. The cation exchangable capacity was evaluated at low to medium condition. Soil texture was determined as silty clay. In general, acid sulfate soils from pineapple monoculture and pineapple intercropped with King orange, coconut-palm were evaluated poor fertility.

In order to study the applicability of combined wastewater treatment processes of A2/O-MBR, a lab scale model of A2/O-MBR processes with 55-liter A2/O tank combined with 26-liter MBR tank was used to remove contaminants from an aquatic products processing wastewater at relatively high concentration of nitrogen and phosphorus. The COD, BOD5, N-NO3-, N-NH4+, TKN, TN and TP of the influent wastewater are 749± 41,73 mg/L, 507± 49.08 mg/L, 4.35± 1,43 mg/L, 18.77± 0.92 mg/L, 72.9 ± 11.38 mg/L, 77.25 ± 10.01 mg/L, and 37.67± 9.07 mg/L and at pH 6.9 respectively. The A2/O-MBR model was run at hydraulic retention time of 8 hours, organic matter loading of 1.52 kg BOD/m3.day, COD loading rate for anaerobic chamber of 22.47 kg COD/m3.day and MLSS concentration for A2/O tank of 4.163 mg/L. The COD, BOD5, N-NO3-, N-NH4+, TKN, TN, and TP in the effluent were 21.49 ± 0.86 mg/L, 16.8 ± 1.56 mg/L, 2.4 ± 0.28 mg/L, 0.75 ± 0.13 mg/L, 1.32 ± 0.39 mg/L, 3.72 ± 0.41 mg/L, and 5.87 ± 1.0 mg/L, respectively. The effluent quality met the column A of the national technical regulation on the effluent of aquatic products processing industry, with corresponding removal efficiency of 97% COD; 96% BOD5; 45% N-NO3-, 96% N-NH4+; 98% TKN, 95% TN, and 84% TP. Therefore, the A2/O-MBR combined processes can be applied to treat aquatic products processing wastewaste and all other wastewaters of the same characteristics.

This research is aimed to apply remote sensing and GIS technologies to monitor shoreline changes and assess erosion processes in Tien and Hau riverbanks of the period from 1989 to 2017. The methodology was applied LANDSAT time-series combined with normalized difference water index to extract shoreline and GIS methods to monitor shoreline changes during 30 years. The research results showed that the total area of erosion is 14,685.83 ha mainly in two provinces of An Giang at 3,146.94 ha (21.43% total erosion area) and Dong Thap at 3,787.68 ha (25.79% total erosion area). The erosion rate in major provinces is from high to very high levels and almost focus on An Giang province about 381.97 ha per year in the period of the year from 2000 to 2005. The accuracy assessment of classification imagery was assessed with overall accuracy (T) from 78.8 to 85.7 and Kappa coefficient (K) from 0.58 to 0.71 in Tien and Hau riverbanks.

The study was conducted to assess soil fertility and determine water retention capacity and total available water in the dry season on farmland with upland crops production, to serve sustainable agricultural production and climate change adaptation in U Minh Thuong district. Soil samples were taken at depths of 0-20 cm and 20-40 cm to determine the physical and chemical properties of soil in three crop systems of chives, corn and turmeric. The soil samples were randomly collected in six different fields of each cropping system - a total of 18 fields for three crop systems. The results show that the soil texture is silty clay with clay and silt content> 95%. Turmeric and maize cropping systems have low content of soil organic matter, compacted soil, low permeability, weak soil structure and low soil water holding capacity. Farmer used organic fertilizers combined inorganic fertilizers for chives cultivation, so it has better soil physical fertility and water holding capacity compared to turmeric and corn cultivation. Soil water retention is poor and soil surface sealing is high in turmeric and maize cropping system cultivation, therefore it is necessary to pay attention to adequate water supply in the dry season and good drainage in the rainy season.

The research was conducted to explore important factors affecting the changes of land use systems related to the destruction of forest areas in Giong Rieng district, Kien Giang province. The approaches applied in the study include secondary data collection, household interviews, the multi-criteria evaluation (MCE), land evaluation (LE) and the optimization mathematics model (Solver). The findings had identified the economic factor had a significant role in determining the land use of local farmers. Besides, the agricultural land-use scenarios to ensure people’s livelihood and protect the scale of the forest land were proposed. The results revealed that the integration of the three methods MCE, LE (FAO, 1976), and optimization mathematic model (Solver) in land use planning helped the local council and farmers optimize the use of their land and preserve the sustainable development of the ecosystem.

Chau Thanh A district, Hau Giang province is an agricultural district. Therefore, the land use allocation plays an important role in sustainable agricultural development. Additionally, a feasible land-use planning must achieve high consensus of local communities and stakeholders. In this study, the data were collected  from technical reports, field survey, household interview, participatory rural appraisal (PRA). The analysis conducted via land evaluation method (FAO,1976) and participatory land use planning (PLUP). Agricultural land-use plans were developed in near future (2020) for Chau Thanh A district based on the potential of land and active participation of the concerned stakeholders in land-use planning process. The local land-use planning was discussed to get the agreement and the coordination among stakeholders on adaptation practices. The result could support decision makers for sustainable agricultural development.

The Vietnamese Mekong Delta (VMD) is facing to serious impacts of climate change. Soc Trang is a coastal province located in VMD that is easily influenced by salinity intrusion in livelihood and agricultural production. Geoprocessing is applied with union algorithm of Geographic Information System (GIS) technique to detect land use types, which are vulnerable in the brackish and saline zones. The research findings show that the major land use type in Soc Trang province in 2014 was agricultural land with more than 50% of total area, in which, the rice cultivation land is about 32%, and brackish aquaculture ocuppies 11%. The areas affected by saline intrusion mainly on land use located in the coastal areas of the districts of Cu Lao Dung, My Xuyen, Tran De and Vinh Chau Town, a part of Long Phu, Thanh Tri, My Tu, Ke Sach, Nga Nam town and Soc Trang city. In particular, the affected areas is mainly double – triple rice crops with more than 113,368 ha. Regarding to the orientation of land use in brackish and saline areas, it is necessary to change the structure of crops with salt-tolerant plants, continue to promote brackish aquaculture, or cultivate specialty fruit trees.

The change of land area with construction works in Hue city from 2013 to 2017 was calculated based on Landsat 8 satellite images that are provided from the website: earthexplore.usgs.gov by the USA National Aeronautics and Space Administration. Three main methods of secondary data, GIS and remote sensing and data analysis were used with the intention of answering the question about what is the relationship between construction land area and population density. It is noticed that in the period from 2013 to 2017, the urban space in Hue city has expanded to 382.82 ha, besides, the population density from 242 people per square km is up to 247 people per square km. The relationship between land area with urban space and population density, expressed through the equation Y = 65,294X - 11415 has a correlation coefficient of r = 0.808 and the coefficient of determination R2 = 0.6531. The results show that the increase in population density has a certain correlation with an increase in urban space.

The objective of study was to analyze the conversion of rice, cash crop production in Binh Minh and Binh Tan districts, Vinh Long province. The methods of descriptive statistic, data synthesis and analysis, methods of multi-criteria evaluation (MCE) were used for analysis, the total of collected sample were 120 by managers concerned; processing calculations using Excel and SPSS 20 software. The results rating MCE showed that six factors that affected land use changes in rice land included elements of economic (W= 0,33); state policy (W= 0,22); land use demand (W= 0,15); soil (W= 0,15); irrigation water (W= 0,12); and climate, weather (W= 0,11). Six factors affecting land use changes in upland crop land were elements of economic were W= 0,33; land and soil (W= 0,18); land use demand (W= 0,13); climate, weather (W = 0,13); irrigation water (W= 0,12); and state policy (W= 0,09).

Can Tho is a dynamic riverside city located in the lower Mekong River basin and at the right bank of the Hau River. In the city, rapid urbanization with a fast growing population caused great difficulties and challenges for water supply management in Can Tho city, especially in the urban districts. GIS with capacity of spatial data management and analysis is a suitable tool for urban water supply management. In order to apply GIS to water supply management, one of the indispensable elements is the spatial data component. This paper presents the application of GIS in the development of an urban water supply spatial database for Can Tho city. The database is developed in the form of ESRI Personal Geodatabase that consists of one raster dataset (DigitalGlobe image) and six vector datasets (five basemap datasets and one thematic dataset) including 34 vector layers (19 basemap layers and 15 thematic layers) for the city. This is considered as a fundamental source of data for application of GIS in urban water supply research and management in Can Tho city.

This study is aimed to evaluate ecosystem services in the buffer zone of the National Park of U Minh Ha, Ca Mau province. One hundred and twenty households representing four cultivating models including intensive cultivation of Acacia hybrid and Melaleuca cajuputy, two rice crops, and integrated rice-shrimp were interviewed for the direct and indirect benefits supporting local people’s livelihoods in order to control and harvest the forest’s production as well as to maintain this natural resources concurrently. The overall results showed that provisioning services, regulating services and supporting services were the most important evaluation form those models (scored 5) accounting for 46.8%, 28.13%, and 25%, respectively whereas cultural services get no ideas for evaluation (0%). In this scope, it is necessary to identify Melaleuca ecosystem services under perception of different local stakeholders, in order for the local government to have a closer look on the common benefits among multi-stakeholders depending on Melaleuca forest, and thus to apply more appropriate strategies to conserve this ecosystem services such as ecotourism activities, scientific research enhancement.

The study was to access the tidal wave reduction of coastal mangrove forest at Tran De district, Soc Trang province, along the East Sea of the Vietnam Mekong Delta. The wave properties were measured by the water pressure principle logger version wave height meter (INFINITY-WH AWH-USB). Three treatments corresponding to three forest thicknesses along a profile from the sea toward the inland, included 0 m, 50 m and 100 m and repeated at three sites (Cong 1, Cong 3 and Mo O). The wave properties were measured at two times in a day at high tide and low tide periods. The data of mangrove structures were collected such as tidal flat elevation, tree diameter, stump diameter, tree densiy, tree height, root density, and root height. The results showed that the coastal mangrove forest at Tran De district could reduce the tidal wave during both the high and low tide periods. The denser the forest structure, the greater the  ratio of wave reducing  and the lower coefficient of wave reducing.

Multi-objective optimization is an effective approach to analyzing and determining agricultural land use for each region. In order to build land optimazation models, it is necessary to predict the surface restriction for the land use types to obtain the optimal productions. The paper is aimed to predict the land use demands as constraint conditions for the optimization of each agricultural land use type. The Monte Carlo simulation was used to calculate the area of vegetable and fruit for Long Phu district based on historical area of these land use type from 2013 to 2017, and the calulated results were used as the constraint values in the multi-objective optimization with the LandOptimizer program. The results showed that area of vegetable and fruit was estimated for 2020. Then, the land use optimization for five land use types three rice crops, two rice crops, two rice – vegetable crops, vegetable, and fruit was calculated with three optimal options: maximizing land suitability, maximizing benefits and maximizing multi-objective.

The study was conducted in the net house to evaluate salt tolerance capacity of Para grass, Paspalum grass and Setaria grass which were grown in hydroponics condition with Hoagland solution. NaCl was added to get five levels of 0, 5, 10, 15 and 20‰, with a weekly increment 5‰ was added into the solution until reached the level of 20‰. The experiment was arranged in a completely randomized design with three replications. The results showed that the NaCl level of 15‰ and 20‰ affected the growth of the three studied species, but did not affect survival rate of Para and Setaria grass. Chlorophyll content (SPAD unit) was increased in Para grass and was remained in African grass, whereas it was reduced in Paspalum grass. Para grass accumulated the highest proline content in leaves tissues. The results indicated that salinity tolerance capacity of Paspalum grass is lower than that of Para grass and African grass; therefore, the later two species were the potential species for fodder production in the coastal area or salt-affected soils in the Mekong Delta.

The study was aimed at investigating groundwater exploitation situation and estimating groundwater recharge in the period of 2013-2017 in Di An town, Binh Duong province. The main methods used in this study include primary and secondary data collection, field survey, interview, data analysis and calculation of the groundwater recharge from precipitation by Bindeman (1963). The results showed that the currently groundwater exploitation was equal to 84,855.38 m3/day, which was 1.21 times higher than the groundwater recharge. In which, the results reveal that the lowest amount of groundwater recharge was in 2013 and maximum in 2017. In the period from 2013 to 2017, there was a significant reduction of groundwater sources with the average value of 12,485 m3/day. In addition, the result also showed that the infiltration flow and total precipitation ratio has significantly decreasing trend in Di An town. Therefore, in the long term, it is needed the solutions of relevant management aiming to reduce the extreme groundwater exploitation.

This research was carried out to explore the current status and level of reliability of farmers’ indigenous knowledge and their adaptive capacity to floods in production and life in An Giang province. Results of the research will provide scientific foundation for proposing solutions to conserve and enhance the effectiveness of valuable indigenous knowledge in reducing vulnerability of people living in flooded-prone areas. The study compiled 39 indigenous knowledge and adaptability to floods and weather forecasts in agricultural production and livelihoods of local people in the study area. Of which, 31(indigenous knowledge) remain valuable in predicting and adapting to floods. However, this knowledge has not been specifically recorded and stored appropriately for transmission to the latter and widely shared in the community. The other 8 were no longer relevant (and misleading) to the current context as under human impacts and climate change. The research suggested some solutions to conserve the most valuable indigenous knowledge for pro-active adaptation of local people in changing climate.

The Melaleuca forest plays an important role in preserving ecosystem services in My Phuoc, Soc Trang. Full-dyke and sluice gate system hasbeen built to prevent salinity and manage water. However, the change in water regime inside the dyke system may impact native plants. The aim of this research is to assess the effect of changes in water level and discharge to plant development inside the dyke system. The survey of cross section and average velocity was carried out during the dry season (5/2018) and rainy season (8/2018). The multivariates analysis and direct interview were also used to evaluate the water regime changing and plant development during both wet and dry seasons. The results show that the water level changes slightly and similarly in both seasons. Besides, the tendency of native plants area reduction is being paid attention and looked for solutions.

The study was conducted to evaluate the feasibility of using biogas effluent (BE) from a biogas digester with cow-dung material for rice cropping, reducing the amount of chemical fertilizers application for paddy field. The pot 0.24 m2 (length x width = 0.6 m x 0.4 m) experiment was designed randomly in triplicate, four treatments in greenhouse condition Econtrol (chemical fertilizer apply with 140 kg urea-N.ha-1), ENH4 (application of BE with 140 kg N.ha-1 based on NH4-N), ETKN (application of BE with 140 kg N.ha-1  based on N-TKN) and EM (application of BE with 140 kg N.ha-1  based on the average of ENH4 and ETKN doses). The results showed that the rice yield was lowest in NTcontrol treatment with 0.9 kg.m-2 (equivalent to 9 tons.ha-1) and highest in ENH4 treatment ,nearly double (1.8 times) compare with NTcontrol. The effluent from a biogas digester has a potential to partly replace chemical fertilizers for rice cropping.

The study is aimed to analyze the impacts of surface water resources changes on agriculture in supporting water resources management in the floodplains of Dong Thap province in the context of uncertainty changes. The study applied system analysis approach based on the DPSIR framework to describe the interaction between surface water resources changes and current land use on agriculture in the floodplains of Dong Thap province. The results showed that there was a high fluctuation of the highest flood level (Hmax) in Tan Chau station (from 2010) that caused the difficulties in management and adaptation to surface water resources changes in the floodplains of Dong Thap in the future. In addition, the current land use has impacted directly and indirectly on the reduction of water and soil quality in the floodplains of Dong Thap. The interaction between surface water changes and current land use can affect the instability in agriculture in the floodplains of Dong Thap in the future.

Composition of wild fish in forests such as Acacia Hybrid, Melaleuca Cajuputi and natural Melaleuca Cajuputi influenced by acid sulfate soil (ASS) layer and ages of trees was studied from 09/2018-03/2019 at U Minh Ha National Park, Ca Mau province. Fish samplings were collected through common fishing gears such as trawl, snare, trap, pot, fyke net, pound net, throw net, aerial net in dry and wet seasons. In wet season, 21 fish species belong to 6 taxa, 12 families were found wheareas 25 species belong to 8 taxa, 15 families discovered in dry season. Perciformes taxon was dominant with 11 species in both seasons. The fish weight in wet and dry seasons were 2.28 g and 2.32 g; 2.13 g - 7,652.53 g and 1.52 g - 10,339.85 g, respectively. Fish weight in the deep ASS were higher than those in shallow ASS. The fish including Puntius brevis, Puntius orphoides, Parachela siamensis, Hampala macrolepidota were dominant at the shallow ASS while Anabas testudineus, Trichopsis vittata, Betta taeniata appeared frequently dominant shallow ASS. Fish diversity was clustered in three groups in rainy season and two groups in the dry season. The findings revealed that cultivating types, depth of ASS, and seasons greatly influenced wild fish diversity in the study area.

This research was done to assess surface water quality of the Tien river that flows through the Tan Chau River from June 2017 to September 2018 in Tan Chau town, An Giang province through the water quality indicators (pH, temperature, DO, salinity and TDS) measured at the middle of a cross- section along the river. In addition, surface water samples were also collected technically according to the TCVN 6663-6:2008 (ISO 5667-6: 2005) standards and analyzed in laboratory for different chemical parameters according to TCVN 6494: 1999 and TCVN 6194: 1996 (ISO 9297: 1989), including chloride ion (Cl-), total hardness (Ca2+, Mg2+), nitrite (NO2-), nitrate (NO3-), ammonium (NH4+), phosphate (PO43-), sulfate (SO42-), alkali metal ions (Na+, K+), arsenic (As), silicon dioxide (SiO2-), bromide ion (Br-) and fluoride (F-). The values of PO43-, NH4+ and NO2- were within the acceptable range according to the QCVN 08-MT:2015/BTNMT with the reference to column A2. Br-, As, F- and SiO2- were not detected in the study. This result could provide a proper foundation for developing a proper surface water quality data set for the study area.