Differences Of Water Resources Utilization Among 5 Riparian Countries In The Langcang-Mekong River Basin

Lancang-Mekong River is the most important international river in China and Southeastern Asia.With the increase of population,development of economy and the high intensity of water utilization among riparian countries,demand for cooperation on transboundary water resources grows.Therefore,our study focused on the topic of Lancang-Mekong water resources utilization and analyzed the differences of water resources utilization among 5 riparian countries.Further,we discussed the possibility of competition for water resources in time and space within the basin.This study can provide scientific support for the coordination of water resources utilization among riparian countries,and lay a foundation for exploring the road of water resources cooperation in the Lancang-Mekong Cooperation Mechanism.Firstly,based on stream flow data at main stream's hydrological station,contribution rates of runoff in tributaries and area of riparian countries,we estimated the contribution of water resources in each riparian countries on the three time scales(year,dry and rainy seasons).Secondly,based on the validity of data and material,we explored the differences of water resources utilization among 5 riparian countries from 6 aspects:irrigated water use,domestic water use,ecological water demand,etc.Thirdly,through analyzing demand of consumptive water and non-consumptive water,we identified water resources that may be used for competition in 2007 and 2016 on 3 time scales(year,dry seasons and rainy seasons).The main results are as follows.(1)In the total 4750×108m3 annual runoff of the Lancang-Mekong River,Lao has the largest contribution of water resources 1967×108m3,accounting for 41%of the total annual runoff in the basin.Followed by Cambodia,China and Thailand.Vietnam has the least amount of runoff except Myanmar,and its average contribution of runoff is 481×10gm3,accounting for 10%of the total annual runoff in the basin.(2)The differences of water utilization among 5 riparian countries in 2016 are as follows.The utilization rate of hydropower in non-consumptive water in China is high,while the consumptive water(irrigated and domestic water)is low.Laos has better development of hydropower and low level development of navigation and fishery.And its consumptive water is not high currently,but it will grow rapidly in the future.Thailand has large amount consumptive water and will increase in the future.In non-consumptive water,Thailand fishery has good development and its hydropower development is lower.In Cambodia,fishery has good development,followed by navigation.Cambodia's consumptive water in domestic water is high and its irrigated water is lower currently,but will increase rapidly in the future.Vietnam has large amount consumptive water,especially in irrigated water.And in non-consumptive water,its navigation and fishery is the highest in the basin.Water shortages occurred in dry season of 2016 in the basin,especially in Vietnam the downstream country.Its irrigated water was 3.6 times larger than its contribution of runoff.But in other 4 countries,there are different degrees of water left.