Cause of the reduction in flow-
Recently china is building a dam on Mekong river which is concern for South East countries.mekong river flows through mayanmar, Cambodia,Laos, Vietnam, Thailand so these country are directly affected.china is storing water for power generation so it may disrupt the free flow of river.moreover china may have used the water of this river for another reason like that agriculture, irrigation e.t.c.
Concern for India-
In 2015 china built a dam on Brahmaputra river.since then India objected such kind of project to china.But china always show this argument that they are building dam on run off river which will not affect the flow of river in downside.But the argument of China is not true which we can see from data findings 1992-2019.If this way china builds dam then we have to face many hazard.If the amount of water in river decrease then there may be problem of navigation for shipping.It may have trouble for aquatic flora and fauna.Agriculture can be hampered.
Conclusion- There should be agreement among the countries by which every country can maintain their own interest.