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The main goal of this study is to examine future changes in meteorological, hydrological drought under the impact of climate change in Dong Nai River Basin, using Standardized Precipitation Index (SPI) and Stream flow Drought Index (SDI). The Soil and Water Assessment Tool (SWAT) is used as a simulated tool to estimate the streamflow in baseline (1980–2005) and climate change (RCP 4.5, 2016–2035) scenarios for meteorological, hydrological calculation. The results show that both types of drought tend to occur in the dry season. The area affected by meteorological and hydrological drought expand in both baseline and RCP 4.5 scenarios. In addition, meteorological drought duration is also significantly increased, especially severely drought months. Although it was detected slightly decreasing in the duration of hydrological drought, the number of months which is occurred moderately drought in sub-basins still goes up in the climate change scenario. These findings could be useful for water shortage assessment and allocation planning in this area in the climate change context in the Dong Nai River Basin.

This paper employed the Sen’s innovative trend analysis (ITA) method to identify overall and partial trends in annual rainfall records over the Central Highlands of Vietnam. Additionally, the lowest values of Standardized Precipitation Index (SPI) for 3 and 12 months were subjected to the analysis to reveal potential changes in the greatest intensity of meteorological drought. The outcomes from a preliminary assessment by applying the normal (Gaussian) probability distribution functions (PDFs) indicate significant increases in standard deviation values of the second half subseries (current climate), thereby implying greater level of rainfall variability. The results from temporal trend analysis show that there is high domination of neutral and decreasing trends in annual rainfall records, with the estimated ITA slopes varying mainly from − 10 to − 14 mm/year. Furthermore, the low value sub-groups are mainly characterized by significant decreasing trends, which is an evident indication of possible increases in drought intensity. These results were further demonstrated by evaluating the ITA plots for the lowest values of SPI in both 3-month and 12-month timescales. The lowest values of SPI are mainly lower than − 1.5 and − 2.0 corresponding to severe and extreme drought categories, and most of the scatter points in low SPI cluster are accumulated in the lower triangular area of 1:1 line. Generally, it is expected that these findings will contribute various well-founded foundations to manage water–use activities and natural hazards associated with rainfall shortages.

Air pollution in major cities of developing countries is a matter of great concern for managers, scientists, and people. In recent years, many studies have been done to simulate and forecast air quality for big cities in Vietnam as well as in the world with many air quality models have been used. However, studies using air quality models to evaluate the capacity of receiving air emission load in the atmospheric environment in local scale have not been carried out, especially in Vietnam. Therefore, the objective of this study is to assess load-carrying capacity in the atmospheric environment on a local scale for a smaller city at Mekong Delta, with a case study of Can Tho city, Vietnam. The FVM-TAPOM model system was established for the study area with the smallest grid resolution of 2km x 2km. The study results show that the atmospheric environment in Can Tho city still can receive more air emissions according to two seasons of the year (dry and rainy seasons) which are different depending on the seasonal wind direction. The central districts of Can Tho city (Ninh Kieu, Cai Rang, Binh Thuy, O Mon, and Thot Not) can only receive a smaller amount of emissions compared to the others (Vinh Thanh, Co Do, Thoi Lai, and Phong Dien). The amount of air emissions that can be received at the central districts is as follows: CO from 82,000 to 172,000 tons/year/district (696 – 2,142 tons/year/km2); SO2 from 3,800 to 4,900 tons/year/district (31 – 56 tons/year/km2); NOx from 217 to 328 tons/year/district (1.8 – 3.4 tons/year/km2). Similarly, the remaining districts can be received the emission is 164,000 – 653,000 tons of CO/year/district (1,308 – 2,555 tons/year/km2); 5,500 – 7,300 tons of SO2/year/district (17 – 29 tons/year/km2) and 31,000 – 44,000 tons of NOx/year/district (77 – 147 tons/year/km2).

Ho Chi Minh City plays a role as a leading economic and social center in the South of Vietnam, together with the urbanization, transportation system is being rapidly developing, resulting in an increase in emissions from these activities, and worsen the quality of the city. Therefore in this study, emission inventory for transportation has been conducted using the EMISENS model and then using GIS solfware to distribute the emissions in space in order to have the overall picture of air emissions of this city. The results showed that on-road activites especially from using motorcycles are the major contributer to air emissions in the city. On-road source in general accounting for 88% of NOx, 99% of CO, 79% of SO2, 99% of NMVOC, 88% of PM in total emissions from transportation activities. Key finding in this study is that hahour activities contribute up to 20% of total SOx and 10% of total PM. Other sources of transportation (airport, habour, bus station, rail way) only accounting for negligible amount of emissions Emission maps of transportation showed that central areas (District 1, District 10, District 3 and District 5) reached higer level of emissions than others. In additions, harbours areas as District 2, District 4 and District 7 where Saigon Port and Cat Lat Port are located in suffer the highest emissions of SO2, NOx and Dust.