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What is river regulation?River regulation refer to strategies and modifications to the natural flow of a river. This can include changes to improve navigations such as dredging or river widening, building of levees to protect populations in times of floods, construction of dams, and diversions for agriculture. How is the Mekong River regulated?In built up areas, some parts of the Mekong have been modified by having natural river beds replaced by cement. In rural areas, dwellings are built out into the river and the Mekong is used for a range of activities including washing, catching fish, rubbish and sewage disposal. While the Mekong has been modified and changed over time, the most significant changes have occurred in the past 20 years with the constructed of dams along the length of the river. Useful links: Mekong River Commission Mekong River nations defer dam decision Save the Mekong Power and responsibility: Mekong River Commission and Lower Mekong mainstream dams
Biophysical Interactions A variety of factors affect the flow of rivers. These factors include climate, vegetation cover, soil, rock structure or ground covering, shape and slope of landforms. Atmopshere - Climate Climate has a direct impact on the way a river flows. At times of heavy rainfall a river will have greater volume of flow (more water flowing). At times of hot weather evaporation of water increases. This reduces the volume of water (less water flowing). Biosphere - Vegetation Vegetation absorbs water from soil to use in plant growth. Vegetation greatly reduces runoff. The less vegetation, the more abundant and rapid the runoff will be. A close plant cover will modify the violent affects of heavy rains. Vegetation growing in and on river channels may be regarded as a surface roughness which can slow the flow of the river (this is particularly important in times of flood). Lithosphere - Soil/Rock structure/Ground covering The ground surface surrounding a river will affect how much water will enter the river as run-off and groundwater. Together with vegetation, the ground cover type influences the amount of water that will infiltrate or run-off. Some soils or rock structures are highly permeable (they absorb water) and have a large water-holding capacity, e.g. coarse-grained sandstones and porous limestones. These rocks and soils can even out the groundwater discharge even during dry seasons. Other ground surfaces such as cement pathways, driveways and tarred roads greatly increase the amount of run-off because no water is able to infiltrate. This increased run-off generally known as stormwater enters drains and is directed to nearby creeks and rivers. Lithosphere - Landform shape and slope Slope greatly affects the amount of run-off which will occur and thus how much water will enter a river. Generally the steeper the slope, the more run-off. Flat areas (especially where marshes and lakes occur) tend to accumulate water and slow down the flow of water. Catchments which are bordered by or contain high, steep landforms are more likely to have greater volumes of water due to the occurrence of orographic rainfall (cool air travels across the land and warms up, it hits mountains and rises causing rainfall). The size of the catchment can also influence the volume of water flow. Small drainage basins (catchments) show a great increase of flow after rainfall, while large catchments are more able to absorb the effects of precipitation. True or false - A flow of water in a river in a larger catchment will be affected more by rainfall than a river in a smaller catchment. - An area with little or no vegetation is likely to have more run-off than an area with dense vegetation - An impermeable ground cover will allow water to soak into the surface. Rivers - Key Terms river source river mouth tributary delta pool cutoff riffle billabong/backswamp meander meander scar upstream downstream stream velocity river discharge stream capacity eyot wetland flood plain
The Mekong - Sensitivity to change Xayaburi Dam and the Fate of the Mekong An overview of the pros and cons of the Xayaburi dam in Laos. Read more... New Mekong Dam a Go, and a Blow to Megafishes? An indepth examination of the impacts of dams along the Mekong. Read more... Photos: Dams threaten Mekong River Megafishes A photo gallery from the National Geographic exploring the impact of dams on the Mekong. Read more... Why we shouldn't dam the worlds most productive river Zeb Hogan from the National Geographic describes how changes to the Mekong River are likely to drive many of the mega fish found in the river to extinction. Read more... Mekong countries at odds over Mega-dams Kirk Herbetson explores relations between Cambodia, Laos, Thailand and Vietnam Environmental issues in the Greater Mekong WWF outlines some of the greatest ecological issues in the Greater Mekong region including hydropower and infrastructure development, climate change, deforestation and degradation, wildlife trade. Read more... Exploring the Mekong's Uncertain Future Jeff Opperman writes a series of blogs about his trip along the Mekong, exploring the interconnected components of the environment and livelihoods of the people who liv Hydropower development in the Greater Mekong WWF examines how hydropower developments impact on sediment and nutrient transfer, impact on water flow and natural regulation, the relocation of loc Mekong giant catfishWWF explores threats to the Mekong giant catfish including dam developments, alterations to migration routes, dredging and over-fishing. Read more... Irrawaddy dolphins in the MekongWWF explores the reasons that the Irrawaddy dolphin is threatened. Threats include pollutants, fishing, hydropower developments and ecosystem degradation. Read more...
Management Regional Cooperation on Mekong in tatters WWF article outlining issues with management agreements between countr WWF - Solutions in the MekongWWF outlines some of the initiatives currently being put in place to address some of the issues in the Greater Mekong. These solutions include conservation efforts in threatened forests and rivers, ensuring that hydropower developments are sustainable, and strengthening law enforcement. Read more... Catalyzing sustainable hydropowerWWF is encouraging a 5 year ban on mainstream dams in the lower Mekong river to counter some of the many environmental costs of dams. Read more... River fieldwork Examples of fieldwork that can be conducting on rivers: - Measuring changes in channel shape - Measuring velocity at different parts of the river - Discharge - Material carried in the stream Examine fieldwork currently being conducted in the Mekong region: Stelar-S2S Whale and Dolphin Conservation Society - Irrawaddy dolphins fieldwork Sustainable Energy - Thoughts on fieldwork in Laos Mekong River Problem Based Learning The aim of this activity will be to identify a range of environmental problems affecting the Mekong River, and to explore possible solutions to some of these problems. Below is a very brief overview of the lesson sequence. The attached file contains much more detail includin scaffolding of the activities. Overview Lesson 1 Begin reading through the booklet of readings that you have been provided with. The readings all relate to issues impacting on the Mekong region. Summarise the articles in the table provided. Lesson 2 Continue reading and summarizing the articles provided. Pair work - Determine one underlying issue affecting the Mekong Region. Lesson 3 Create a flow chart which explores how your problem impacts on the biophysical environment. Individual work - Write a summary of how the Mekong Region is sensitive to change. Lesson 4 In pairs, suggest a range of solutions or management strategies to address your underlying problem. Design a management strategy that can be applied across countries, up and downstream to address the issues in the Mekong Region. Identify a range of professionals that you will need to employ to put your management plans into place. Lesson 5 Mekong overview and presentation of management plans.
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