In our article Introduction to Water Wheels we introduced Undershot and Overshot water wheels together with other alternatives.

Each different type of water wheel has its advantages and disadvantages as well as features which make them suitable or unsuitable for different situations. In this article we will present a detailed mathematical analysis looking at the maximum possible efficiency of the overshot and undershot designs of water wheel. Many thanks to retired radio physics lecturer Bill for sharing this work with us. Read more

A Water wheel (or Waterwheel) is a system for extracting usable power from the water flowing in a river or stream. Along with windmills, water wheels have being powering the milling of flour and other industry for hundreds of years. Waterwheels are still in common use in Nepal (25,000+), and India (over 200,000 waterwheels). Water wheels come in two main flavours: undershot, and overshot.

Undershot Waterwheels

Historically the undershot water wheel was the commonest as it is the cheaper and simpler to build. It was used frequently by the Romans and the undershot water wheel is sometimes known as a Vitruvian water wheel after the Roman engineer Vitruvius. In this system the wheel is simply placed over a fast flowing river. The water hits paddles which protrude all around the wheel and therefore turns the wheel. This system can only be used where the flow of water is very fast as little of the energy of the water (around 20%) is used. Click here to read our article on run of river hydro power. Read more

The region of Mesoamerica is comprised by the southern states of Mexico and the seven countries of Central America. While Mesoamerica is rich in freshwater, the area is extremely vulnerable to changes which, in the medium to long term, could diminish its availability.

Such challenges such as waste, pollution and lack of governance pose serious threats to the precious supply of this resource. Non-governmental organizations from the region plan to denounce this situation at the 6th World Water Forum, taking place Mar. 12-17 in Marseille, France. Read more

Recent widespread news coverage heralded the success of a United Nations’ goal of greatly improving access to safe drinking water around the world.

But while major progress has been made, a new study from the University of North Carolina at Chapel Hill indicates that far greater challenges persist than headline statistics suggested.

Earlier this month (March 6), UNICEF and the World Health Organization issued a report stating that the world had met the U.N.’s Millennium Development Goal target of halving the proportion of people without access to safe drinking water, well in advance of a deadline. Read more

University at Albany climate scientist, Mathias Vuille, will lead the development of a network of local scientists and stakeholders in four South American countries to address the impact on water supplies of shrinking glaciers in the Andes.

A number of studies in recent years have documented the general retreat of glaciers in the Andes. As a result, water managers and decision makers are increasingly asking the scientific community for quantitative projections regarding future water supply.

According to Vuille, an assistant professor in the Department of Atmospheric and Environmental Sciences at UAlbany, the four countries – Colombia, Ecuador, Peru, and Chile – all rely to a great extent on water released by glaciers. Warming temperatures, however, have resulted in significant glacial retreat, shrinkage and thinning, and the situation suggests the potential for a severe future water crisis in the region. Read more