Water yield service in the Lancang-Mekong River Basin: Cross-border changes and driving factors

• China’s total water yield accounts for 12.43% of the Lancang-Mekong River Basin (LMRB) • Water yield decreased at a rate of 8.23 mm/yr in the LMRB from 2000 to 2018. • The years of low water yield in China are inconsistent with those of the MRB. • Precipitation greatly impacted the water yield in the LMRB during 2000–2018. The Water Yield (WY) service is the basis for cross-border cooperation in the Lancang-Mekong River Basin (LMRB) and has become the focus of disputes among LMRB countries in recent years. However, most studies have mainly focused on runoff changes in the LMRB, and there is a lack of research on basin-scale WY service. The cross-border changes in the WY service in the LMRB and the factors behind those changes are largely unknown. Thus, this study explores the cross-border spatiotemporal changes in the WY in the LMRB from 2000 to 2018, using the InVEST model, and identifies the key driving factors influencing the WY. The results reveal that the WY distribution in the LMRB exhibits a spatial pattern of high in the south and low in the north. Notably, Laos has the highest average total WY (1847.85 × 10 8 m 3 ), while China has approximately 12.43 % (593.88 × 10 8 m 3 ) of the total WY in the basin. From 2000 to 2018, the annual average WY in the LMRB shows a significant decrease of 8.23 mm/yr, with Thailand and Cambodia having the largest declines. However, China shows a lower decrease rate in the WY (3.81 mm/yr) than the whole basin and downstream regions. Precipitation (PRE), Potential Evapotranspiration (PET), Temperature (TEM), Actual Evapotranspiration (AET), and Net Primary Productivity (NPP) are the primary factors influencing spatial variations in the WY. Among them, the PRE and NPP were positively correlated with the WY, whereas the PET, TEM, and AET were negatively correlated with it. These results provide valuable insights into cross-border water resource utilization and water security regulation among countries in the LMRB and are of great strategic significance to promote the sustainable development of the LMRB.