The responses of river discharge and sediment load to historical land-use/land-cover change in the Mekong River Basin

The large river basins throughout the world have undergone land-use/land-cover (LULC)-induced changes in river discharge and sediment load. Evaluating these changes is consequently important for efficient management of soil and water resources. In addition, these changes in the transboundary Mekong River Basin (Mekong RB) are not well-known. The present study aimed to investigate the impacts of LULC changes on river discharge and sediment load in the Mekong RB during the period 1980-2015 using Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated using measured data of daily river discharge and monthly sediment load. Analysis of LULC change showed a 2.35% decrease in forest land and a 2.29% increase in agricultural land during the period of 1997-2010. LULC changes in 1997 and 2010 caused increases in river discharge and sediment load by 0.24 to 0.32% and 1.78 to 2.86%, respectively in the study region. Moreover, the river discharge and sediment load of the Mekong River have significantly positive correlation with agricultural land and negative correlation with forest land. The findings give beneficial insights to implement appropriate strategies of water and soil conservation measures to adapt and mitigate the adverse impacts of LULC in the Mekong RB. Further study will consider the impact of future LULC changes and uncertainties associated with the LULC projections for future management of soil and water conservation in the study region.

Automated summary

This study used the SWAT model to analyze the impacts of land-use/land-cover changes on river discharge and sediment load in the Mekong River Basin. The results showed that forest land decreased by 2.35% and agricultural land increased by 2.29% from 1997 to 2010. These changes led to increases in river discharge and sediment load by 0.24% to 0.32% and 1.78% to 2.86%, respectively. Additionally, the river discharge and sediment load of the Mekong River were positively correlated with agricultural land and negatively correlated with forest land. The findings are important for implementing effective water and soil conservation measures in the Mekong River Basin.