Water balance changes in the upper part of Dong Nai River basin

In recent decades, changes in land use and land cover (LULC) arising from socio-economic development, coupled with climate change, have severely undermined and compromised the environmental sustainability of the upper part of Dong Nai (UPDN) river basin. Assessing the long-term impacts of climate change and changes in LULC on hydrological conditions and water balance in the UPDN river basin is essential for sustainable watershed management. In the present study, Landsat images and SWAT (Soil and Water Assessment Tool) model were used to assess water balance changes due to changes of climate and LULC at three different intervals: 1994, 2004, and 2014. The results of Landsat images classification indicated that forest land was the main LULC type in the basin. In 1994 the forest cover was 706,803 ha (72.68% of the total landmass). In 2004 the forest area dropped to 520,359 ha (53.51%). In 2014 the forest area dropped further to 485,908 ha (49.97%). The change in LULC has caused changes in the annual and peak water flows. The analysis of the results revealed that the effect of historical climate variations on water yield was greater than the LULC change. With the scenario of LULC 2014, the consumption of irrigation water was the highest and mainly in the dry season. The findings can provide useful information for decision-makers in planning and formulating policies for sustainable watershed management and climate change adaptation.