
In the background are rubber plantations and shifting cultivation
Source: www.natureproducts.net/Ecotourism/Mekong.html
Poverty stricken Cambodia is an example of one nation that is completely dependent on the river for food and the vast majority of its fledgling economy.

Dai ladies gleaning the shallow waters of the Mekong for shells
Source: http://natureproducts.net/Ecotourism/Dai_gleaning400.jpg
The annual floods provide much needed water for crops of the otherwise dry dusty land, and to refresh Tonle Sap, a combined lake and river system of huge importance to Cambodia.
A satellite image of Tonle Sap
Source: http://en.wikipedia.org/wiki/Tonle_Sap
Flooding at a village near Tonle Sap
Source: http://www.scienceclarified.com/landforms/images/ueol_02_img0058.jpg
Dams have been built across Mekong River to use its water to generate hydroelectricity.
Pak Mun dam at Thailand
Source: http://www.prachatai.com/english/upload/pictitle/20070619132619_18_065256_47.jpg