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INCREASED FREQUENCY, MAGNITUDE, DURATION AND LIABILITY OF FLOODS: “Thinking about cumulative effects is what has been lost in the science. And that is what continues to be lost obviously in the professional practice,” stated Dr. Younes Alila, professional engineer and professor in the UBC Faculty of Forestry

Note to Reader:

Published by the Partnership for Water Sustainability in British Columbia, Waterbucket eNews celebrates the leadership of individuals and organizations who are guided by the Living Water Smart vision. Stories are structured in three parts: One-Minute Takeaway, Editor’s Perspective, and the Story Behind the Story. 

The edition published on October 21, 2025 is about profiles in courage and is reproduced in part below. It featured two individuals: former BC cabinet minister Mike Morris; and University of BC professor Dr. Younes Alila. The story behind the story is about how they have aligned efforts to build awareness of Dr. Alila’s Flood Risk Methodology for flood protection. Their compelling message is that removal of forest cover, whether in rural or urban watersheds, increases the frequency, magnitude, duration and liability of floods.

ONE MINUTE TAKEAWAY for the extremely busy reader

In July 2025, the University of BC issued a news release titled Clear-cutting linked to 18-fold rise in extreme floods. This followed release of the gripping 25-minute documentary titled Trouble in the Headwaters the month before. This combination generated extensive media coverage.

Trouble in the Headwaters

The documentary profiles research by Dr. Younes Alila of UBC Forestry that reveals how loss of forest cover has triggered a cycle of flooding, landslides and drought. The two announcement provides context for this edition of Waterbucket eNews.

 

 

Images are mostly from the Partnership’s library. Some are from the public domain and Creative Commons.

 

STORY BEHIND THE STORY: Increased frequency, magnitude, duration and LIABILITY of floods  – conversations with Mike Morris and Younes Alila

PART TWO: What motivates Younes Alila? His belief and inspiration that science without passion is not science!

The context for the conversation with Mike Morris and Younes Alila is Clear-cutting linked to 18-fold rise in extreme floods, UBC study finds, a story published by UBC Reports in July 2025. The story generated major news coverage in BC because of its relevance for forest management practices.

A few months later, in October, a new study published in the open access journal Frontiers in Environmental Sciences received global attention as featured in a Science Magazine by a press release titled UBC Study Highlights Importance of Monitoring Flood Frequency for Safeguarding B.C. Communities.

TOPIC 5: A watershed is a system and everything is connected

“The forest owes its power to the landscape features, not to its ability to evapotranspirate. That is the headline,” says Younes Alila with passion in his voice.

 

 

“Evapotranspiration is necessary but not sufficient to empower the forest and affect hydrology in general and floods and droughts in particular. This can only be revealed through a probabilistic framework.”

“Our research also highlights the potential for natural asset management which supports the context and ecosystem service based approach to land and natural resource management.”

 

Cause-effect and the space-time relationship

“Thinking like a system means you do not make decisions at the site scale. It is not about a particular cut block, stream reach or cross-section, or a bridge or a culvert. You need to step back and look at the big picture.”

“You need to look at the entire stream network and what these flows are doing OVER TIME…AND IN THE LANDSCAPE OF THE WATERSHED.”

 

 

“It is the modern SCIENCE OF CAUSATION which imposes the probabilistic framework for investigating the causal relationship between the climate and/or land use coverage change.”

An understanding of cumulative effects is foundational

“The cause-effect relationship is the only way to put to the forefront the desperate need for an understanding of cumulative effects. And the desperate need for thinking about the headwaters when we are making decisions downstream.”

 

 

“And guess what? That cumulative effect study, investigation or assessment…that UPSTREAM-DOWNSTREAM CONNECTION…can only be investigated through a causal framework.”

 

 

“Cause-effect. The climate is the cause. The effect is the hydrological response. The land use, land cover changes are the cause…and the hydrological response is the effect.”

TOPIC 6: Nature’s laws are inherently probabilistic

“If the cause-effect relationship is not investigated in the probabilistic framework, it is non-causal, which means that it is scientifically indefensible which means that it is not even science.”

 

 

“And why do we need that probabilistic framework? Because the hydrologic response is driven by many factors, all of which are occurring RANDOMLY OVER TIME AND IN SPACE. Period.”

 

 

“The response is inherently stochastic. Inherently probabilistic. NATURE’S LAWS ARE INHERENTLY PROBABILISTIC. And the only way we can understand nature…in this case the hydrologic response of the landscape…is through that stochastic or probabilistic framework.”

 

TOPIC 7: Time means the climate dimension and space means the landscape

“The frequency imposes itself by the nature of the response. The response is stochastic by nature. The response of the landscape, the response of the hydrology, or geomorphology or climatology are all stochastic.”

 

Build an understanding of hydrologic system response based on flow duration analysis

“Our professional practice does not portray an understanding of the environmental controls of the dimension of the frequency, which is critical for proper management of the hydrologic risk. And when I say frequency, it is not just the frequency of the floods and the droughts, IT IS THE FREQUENCY OF THE FLOWS IN GENERAL.”

“Which brings us to the flow duration curve which underpins both Jim Dumont’s Stream Health Methodology and my Flood Risk Methodology. One axis is duration or percent of time. That is basically probability. Frequency is the only thing that makes the investigation of hydrology causal and hence scientifically defensible.”

 

 

“My Flood Risk Methodology is about peak flow frequency analysis in a rural setting while Jim Dumont’s Stream Health Methodology is about low flow duration analysis in the urban setting.”

“Both are founded on the probabilistic framework for understanding and predicting hydrology. And that is what is gratifying for me. Independently and for over 30 years, Jim Dumont and I both have been advocating for the same framework.”

“Now the Partnership for Water Sustainability and I have combined forces to reinforce each other’s efforts to make hydrology in professional practice causal and hence defensible in both settings. Hydrology is hydrology!”

TOPIC 8: Attribution science is Younes Alila’s Flood Risk Methodology by another name!

“Climate change scientists have always been overly consumed with extremes. The probabilistic framework has guided them since the mid-1980s. It has evolved into what they now refer to as attribution science. It has been developed aggressively by climate change scientists.”

“Attribution science is also known as extreme event attribution. It is the study of how much human-caused climate change influences specific weather and climate events. It compares observed conditions to what might have happened without human influence.”

 

“That new framework is PROBABLISTIC in nature. It tells us for instance the extent to which the BC flood of November 2021, which resulted in over $17 billion of damage, is caused by climate and/or land use and forest cover changes. Independently, and without knowing about attribution science, I have been developing that same framework. I rest my case!”

 

To Learn More:

Waterbucket eNews stories are structured in three parts: One-Minute Takeaway, Editor’s Perspective and Context for Busy Reader, and the Story Behind the Story. To read the complete 3-part storyline, download a PDF  copy of Living Water Smart in British Columbia: Increased frequency, magnitude, duration and LIABILITY of floods.

 

DOWNLOAD A COPY:  https://waterbucket.ca/wcp/wp-content/uploads/sites/6/2025/10/PWSBC_Living-Water-Smart_Mike-Morris-on-flood-risk-and-liability_2025.pdf