Sustainable development | One step at a time


Essential steps are being taken towards the sustainable development of hydropower and the conservation of water resources and biodiversity


New research published in June 2021 warns that the ‘live fast, die young’ cycle is threatening California’s ecosystems. The team, which included researchers from Cardiff University in Wales, found that an entire ecosystem of rare and endangered species along the streams and rivers of the US state is being threatened by intensive water management – causing short- term gains but long-term damage to one of the most biodiverse regions in the world. California contains more species than the rest of the US and Canada combined but widespread and long- lasting damage is being caused by “subsidies of water” delivered via human regulation of rivers, agricultural canals and discharges from wastewater treatment plants. Whilst this huge influx of water was shown to


provide a short-term boon to these ecosystems, the artificial supply creates an unintended dependence on its bounty, creating a “live fast, die young” cycle that is threatening the long-term survival of riparian forest ecosystems. This in turn has repercussions related to habitat for endangered species, biodiversity, carbon sequestration and climate change.


Below: Extended drought in California has caused trees along the Santa Clara River to die. New research warns that the ‘live fast, die young’ cycle is threatening California’s ecosystems Photo Credit: JOHN STELLA


Since the Gold Rush in the 1850s, the massive human settlement that followed led to the clearing of 95% of the natural floodplain woodlands across the region. These isolated and restricted riparian – or streamside – forests now provide an important habitat for a wide variety of threatened and endangered species. “As water is rerouted from rivers into canals to accommodate urbanisation and the multibillion-dollar agricultural industry, it creates an artificially stable environment for riparian woodland ecosystems,” said co-author of the study Dr Michael Singer, from Cardiff University’s School of Earth and Environmental Sciences. “This produces a live fast, die young phenomenon favouring fast-growing trees that peak and then decline within a few decades.” In their study, published in Proceedings of the National Academy of Sciences, the team analysed five years of vegetation greenness data from publicly available satellite imagery, including Google Earth. Their innovative and ground-breaking approach, combining several big datasets, allowed them to understand how climate and water management interact to put these sensitive ecosystems at risk in a way that has never been done before. In California’s seasonally dry Mediterranean climate,


plants and animals rely on rainfall and soil moisture recharge during the rainy winter and spring seasons for reproduction and growth during the typically dry summers. Once soil moisture is exhausted, tree species such as willows, cottonwoods and oaks typically use groundwater from deeper depths. To the team’s surprise, the study showed that the


streamside woodlands in the most arid regions of the state, which had been altered by humans, stayed greener longer into the dry season and were less responsive to changes in groundwater levels than natural ecosystems.


40 | August 2021 | www.waterpowermagazine.com Similarly, the team showed that the regeneration of


new forests was being compromised by the extensive alterations to streamflow and to river channels, which are fixed in place and no longer create new floodplain areas where young trees can establish. “We call these forests the ‘living dead’ because the


forest floor is devoid of saplings and younger trees that can replace the mature trees when they die,” said lead-author of the study Melissa Rhode, from State University of New York College of Environmental Science and Forestry (ESF) and scientist with The Nature Conservancy of California. “Our methods and findings open up a whole new world of interdisciplinary research possibilities and ways that water practitioners can consider ecosystem water needs to achieve sustainable water management.” The study is part of a US$2.5 million suite of


projects between collaborators at ESF, the University of California Santa Barbara and Cardiff University, to develop water stress indicators for dryland riparian forest ecosystems threatened by climate change and increasing human water demand.


Biodiversity Avoiding or mitigating the potential impact of


hydropower development on biodiversity in rivers, is “an essential step towards a more sustainable hydropower sector”, the International Hydropower Association (IHA) said.


On Earth Day in April 2021 (an annual United Nations celebration to raise public awareness of the well-being of the planet and the life it supports), the association said it was proud to publish its How-to Guide on Biodiversity and Invasive species. Alain Kilajian, Senior Sustainability Specialist at IHA, said: “The construction of a hydropower project will inevitably bring change to the local ecosystem in which it is built. Those who use this guide will be able to ensure that biodiversity impacts arising from developments are managed responsibly and that there remains healthy, functional and viable aquatic and terrestrial ecosystems in areas affected by development. This will help to ensure that global carbon emissions are reduced while conserving crucial biodiversity.” The guide wants to promote biodiversity management as a priority for all developers and operators. It details methodologies and technologies that can be used for basin-level planning; identifying project boundaries and areas of influence; understanding the distribution and value of biodiversity, mitigation and compensation measures; as well as monitoring and reporting throughout hydropower development and operation. “Direct biodiversity impacts from dams and their


reservoirs are often hard to mitigate or compensate,” Jamie Skinner, Principal Researcher at the International Institute for Environment and Development and co-


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