Water resources vulnerability assessment provides the basis for the policymakers and the stakeholders regarding the state of the river basin to be focused for its better management. This research aims to assess the vulnerability index (VI) of the upper part of the Dong Nai (UPDN) river basin, which plays a crucial role for the socio-economic development of Ho Chi Minh City and 10 other provinces in the Southeast Vietnam, as well as its sub-basins. This study accounts from the year 1994 to 2030 (36 years) by using an integrated solution between the GIS, remote sensing (RS) and SWAT model in collaboration with guidelines prepared by United Nations Environment Programme (UNEP) and Peking University. Results from the land cover classification of Landsat images in the period of 1994–2020 revealed that the forest area decreased by 324,586 ha (approximately 29.4% of the basin area) and greatly influenced the VI. The UPDN basin’s water vulnerability was a moderate level of which VI was 0.276, 0.303 and 0.310 in 1994, 2004 and 2014, respectively. By 2030, the projected VI value could expect to be 0.318 under the climate change scenarios of the representative concentration pathway (RCP4.5). At the sub-basins, Dak Nong and Dak R‘Keh were two of the most vulnerable sub-basins of which VIs have could reach approximately 0.4 categorized as highly vulnerable areas. The results evidenced that the integrated techniques could be an efficient approach to provide useful information on the status of water resources to stakeholders in evaluating comprehensive options in terms of sustainable water resources management.

This study aims to investigate the impacts of climate change and reservoir operation on drought in the Upper Part of Dong Nai (UPDN) River Basin. Climate change scenarios for the UPDN River Basin were portrayed according to the Coupled Model Intercomparison Project Phase 6 (CMIP6) based on an ensemble of five general circulation models (GCMs), namely, EC-Earth3-Veg, CanESM5, EC-Earth3, HadGEM3-GC31-LL, and CNRM-CM6-1-HR for two Shared Socioeconomic Pathway scenarios, SSP2-4.5 and SSP5-8.5. The historical climate monitoring data at five weather stations and three hydrological gauges related to upstream reservoirs in the period 1990–2020 were collected. The streamflow for the period 2021–2099 was simulated by applying the Soil and Water Assessment Tool (SWAT) model. Two meteorological and hydrological drought indices of the 6-month time scale, namely, standardized precipitation index (SPI6) and streamflow drought index (SDI6), were calculated through designed modules integrated in the Drought Index Calculator (DrinC) software. The results show that climate change coupled with reservoir operation has seasonally changed the runoff, which has changed the drought situation in the entire basin. The lag time variations of hydrological drought in response to meteorological drought were significant in the main basin of the UPDN River Basin. These findings provide useful information for managers and policymakers in sustainable water resources management and development adapting to climate change.

Mapping hydrological drought under the CMIP6 climate change scenarios in sub-basin scale: A case study in the upper part of Dong Nai river basin

Đánh giá sự phù hợp của một số mô hình khí hậu toàn cầu CMIP6-GCMs trong mô phỏng lượng mưa và nhiệt độ trên lưu vực thượng nguồn sông Đồng Nai