A Dam Shame: Water Where We Need It When We Need It

Video: Wrong Climate for Damming Rivers – with Nnimmo Bassey.

It is a dam shame that water isn’t where we need it, when we need it.

I was asked for an opinion of this video clip after my previous blog post on water diversions. I am very conflicted about water resource development projects. I have fond memories of whitewater kayaking in Northern California in the late 1970’s and several of my favorite rivers have since been lost for good. On the other hand, I understand that if there were no dams or diversions the global population would be limited to that which could survive during the low extremes and drought episodes of the hydrological cycle. My environmental ethic is not so radical that I would wish for a human population cycle that follows the hydrological cycle.

It is very difficult to get a large dam approved in any country with a robust environmental impact assessment and review process. Such a process for a large project may take decades, which is an investment disincentive and these projects require massive investment. A multi-objective evaluation of any change in timing and/or magnitude of flow with respect to the natural regime is an extremely complex study. There are many risks and the consequences of these risk factors are difficult to predict.

Alternatives need to be carefully considered. The process for approval for a micro hydro plant is much less onerous than for a large hydro project but, ultimately, is a 1 GW hydro megaproject, designed with extensive review and oversight,  worse  than a thousand 1 MW micro-hydro projects? The ‘not-in-my-backyard’ scenario is almost never benign – the consequence of not developing renewable power is increased reliance on non-renewable energy. Nuclear, Solar, and Wind power all have arguments that can be made for or against but there is no panacea. Each project needs to be evaluated on its own merit in a local context.

Whereas a variety of options exist for energy there is no substitute for water for agriculture hence the alternative to a regulated water supply may be mass starvation as a result of crop failures. Dam break flood events can be catastrophic but are infrequent whereas reservoirs are very effective at taking the top off of the natural variability and turning otherwise devastating events into a source of productive water for a variety of functions.

Dams are widely believed to be long-lived but many dams built within the last century already need to be decommissioned and re-establishing natural channel flow can be as disruptive to the environment as the original impoundment. Natural streams are remarkably resilient and, with proper engineering, there are many successful examples of river rehabilitation following dam removal.

Given the benefits that a dam can provide – a very substantial investment in environmental impact assessment and review is warranted to identify the risks and constrain unwanted consequences. The key difference between projects that damage ecosystems from those that deliver beneficial uses is whether the planning process was driven by evidence-based decisions. It takes time, and a great deal of care and effort, to collect the data needed to inform wise choices. Investments made in data collection are investments in our future; in our environmental health; and in our social and economic well-being.

No comments yet.

Join the conversation

This site uses Akismet to reduce spam. Learn how your comment data is processed.