What are the opportunities for development of small hydro and low-head hydropower technologies?

Berkeley, August 27, 2018 4:30 PM

The days of buildings hydropower dams seems to have already gone. Not only for the environmental impacts that they produce, but also because it is an old technology, developed in massively at the beginning of the 20 century.

These massive development has helped the world to develop additional sources of electricity. Only 17% of the world large dams produce hydropower. I detailed other percentages in yesterday’s post. In the United States, hydropower generation represents only the 7% of the total electricity generation.

After several findings of dam impacts in the river, such us sediment trapping, which among the impacts, incise the channel downstream, which subsequently will have a negative impact in the riparian vegetation, habitat, and built infrastructure, such as roads, and bridges.

Dams also has an impact fishes, not only in their migration, but also in their ecological habitat and population. Altering the natural water and sediment flows impact aquatic population, plus dams not only trap sediments but also fish eggs.

There are about 59,000 large dams in the world. Most of them were built between 1900 and 1970’s. With a rapid increase in population, over the 20 century, potential places for dam construction would be already important human settlement. I strongly discourage large human relocation for building dams.

What is next?

In the developed world, bringing up the United States case, implementing pumping storage hydropower facilities in the dams that are currently used only for water purpose will be the cheapest and most effective effective solution for using the the hydropower potential, without further large infrastructure constructions in fragile ecological systems, as river and streams are.

Second, the Public Utility Regulatory Policies Act (PURPA) of 1978 had an excellent impact on energy conservation, improvement of energy efficiency of power generation facilities, research and development of new technologies for power generation, and was important for the deregularization of the energy market.

While solar technologies had a rapid increase, beyond the recent tax increase for importing Chinese manufactured solar panels, and wind energy had also rapidly increased their installations. What are the opportunities for producing small hydro and low-head hydropower from streams?

I will continue elaborating the small hydro and low-head hydropower technologies and their potential in next time. It is time to complete the post.


Water Infrastructure

Dams and reduction of water storage capacity

Excerpt from the description of a colloquium that I am organizing on Water Infrastructure:

There are 59,000 dams in the world; 1,400 in the state of California alone. While these dams provide fundamental services, such as irrigation (36% of the dams), hydropower (17%), water supply (15%), flood control (13%), recreation (8%), and the remaining part is for navigation, fish farming, among other usages, these comes at an environmental, social, and economic cost. The vast majority of these dams were constructed between the 1890’s and the early 1980’s, before the major environmental and social impacts of dams were fully recognized. For example, historic dam construction did not consider sediment management scenarios in their designs or locations. Many dams were designed as if rivers carry only clean water, however, dams trap 100% of the gravel that rivers carry, while in fact part of the suspended sediments would pass the dams through their outlets. This problem has resulted than reservoirs behind the dams are losing their water storage capacity by filling up with sediments in a rate of 0.5 to 1% per year.

Since 1978 the global dam construction has slowed down due to an increasing awareness of their environmental and social impacts, but still there are about 3,000 new dam projects planned in Asia, Africa, and South America.

Recuperating that global storage capacity costs approximately 13 billion USD per year. On a more local scale, the state of California recently passed a bill that allocates over 2.5 billion USD for water storage projects, including dams and reservoirs. Our undeniable reliance and need for water supply coupled with the social and environmental impacts of existing technologies lead to many questions: How can we ensure water supply security for next generations? How should we adapt our life styles to conserve limited resources?

Water in California

Water cycle in California (simplified version)

“The amount of precipitation that falls in California has not varied significantly between the time of European contact and the present. Annual rainfall and snowfall produce approximately 200 million acre-feet”, which is equivalent to 250 billion cubic meters per year. “Most of this precipitation, about 65 percent, evaporates directly into the atmosphere, with nearly all the remaining 71 million acre-feet (88 billion cubic meters) making its way into streams and, ultimately in aboriginal times, the ocean, save for the water entering underground basins or aquifers.” (Hundley, 2001)

How is distributed this rainfall in time and in space across the 164,000 square miles of California’s land (424,000 square kilometers)?

How is the annual distribution and yearly recurrence of droughts and floods?

I will explore those topics in next short posts, where my main goal is to analyze the best solutions to direct the recently approved bill, 2.5 billion USD, for enhancing water storage in California. Its name is Proposition 1.


Hundley, N., 2001. The Great Thirst: Californians and Water: A History. University of California Press. pp. 1-26


Soil and Water Management Research (SOWAMAR)

Sowamar is a project which will post advances in environmental science, practice, economics, and public policy in the soil and water management field. It aims aims to contribute with knowledge and to promote best management practices for managing our natural resources in our continuous developing world. Knowledge would have an impact in our daily life actions and decisions, which in a larger scale can become a key aspect for improving the environment quality, and so it would results in improvements on entire communities quality of life. The ultimate goal is to promoting a sustainable growth in developing as well as in developed countries.

This webpage is a platform, where people can share their insights, comments, arguments, and interests. It provide opportunities for research collaboration and for donations which would expand this work.

I will feed this webpage as I advance with my studies and career.