Dr. David M. Hannah is Professor of Hydrology and UNESCO Chair in Water Science in the School of Geography, Earth & Environmental Sciences, University of Birmingham, UK. @freshwaterflows
What does ecohydrology mean to you?
We have written commentaries and a book about defining “ecohydrology” and “hydroecology”, so rather than revisiting those discussions, I will go for simply… how ecological processes shape hydrological dynamics, how living things are influenced by hydrological processes, and how these two process sets feedback/ interact. We need to frame ecohydrology around coupled systems and, increasingly importantly, add people to the equations. So for me, in a nutshell, it is all about taking a wider perspective to understand complex, variable, interconnected, water-dependent systems and how we can use this knowledge towards sustainable management for the betterment of the environment and society. In terms of application, I try to use this perspective to research snow- and glacier-fed watersheds; river temperature dynamics and impacts; and space-time ecohydrological patterns beyond the individual river basin-scale and under global change.
What are your undergraduate and graduate degrees in?
My undergraduate degree is a BSc Physical Geography (1994) from the University of Aberdeen, Scotland. I was taught by some outstanding faculty and developed a passion for glaciers, mountains and rivers. Field courses are an integral part of geographical learning; and Aberdeen’s location (between the Rivers Dee and Don and near the Cairngorm Mountains) meant we were spoilt for choice of real world examples to test theory. For my undergraduate dissertation, I travelled to the Italian Alps (beside Mont Blanc) to undertake a project on climate drivers of glacier stream runoff. I was amazed by the dynamism of alpine environments; and this enthused me to do more research. So, I went to the University of Birmingham, England, to study for a PhD Geography (1997) under the supervision of Angela Gurnell (now Queen Mary University of London) and Glenn McGregor (now Durham University) that focused on meltwater generation and drainage in a small glacierized basin in the French Pyrenees. I was fortunate to have great field support from my supervisors and some people who became future research collaborators as well as friends. In my second summer field season, we were joined by a group of aquatic ecologists - which kindled my interests in ecohydrology.
How did you arrive at working in/thinking about ecohydrology?
As mentioned above, during my PhD, I did fieldwork with ecologists who were working on a European Commission project on Arctic and Alpine Stream Ecosystem Research. This project used similar field protocols to link stream ecology to physico-chemical river habitat along a latitudinal gradient of glacier-fed watershed for Europe (spanning from the French Pyrenees in the south to Svalbard in the north). These harsh, cold river systems are highly deterministic - with aquatic macroinvertebrate communities conditioned (most notably) by downstream patterns in water temperature and channel stability. By quantifying these ecohydrological links, it is possible to predict alpine stream biodiversity response to climate and hydrological change. After my PhD, I gained a lectureship at Birmingham and extended these glacier-fed river ecohydrological studies to other mountain regions and to the Arctic. In addition, I broadened my ecohydrological interests to river water temperature and flow-ecology links in temperate, forested, ephemeral and urban environments.
What do you see as an important emerging area of ecohydrology?
There are a number of topic areas that I could highlight (some are the same as our commentary in 2007) as ‘new’ and emerging themes: ecosystem sensitivity to hydrological change; aquatic-terrestrial linkages; disturbance - water and ecological stress; modern and palaeo-analogue studies; and applied hydroecology/ ecohydrology at the science-policy interface. In 2020, as an outcome from an international workshop led by Del Levia (University of Delaware), we offered a roadmap to advance ecohydrology. For this blog, it might be most interesting to reflect on the ‘how’ (rather than the ‘what’) we do in ecohydrology. (1) We need to develop and apply new tools - for example, recently we have used drones, high-frequency water sensing technologies and smart-tracers to identify space-time heterogeneity in ecohydrological systems and processes. We need to look to the innovation horizon for new methods to bring from other disciplines into ecohydrology as well as develop our own tools. (2) We need to release the huge potential of intrinsic interdisciplinary collaborations in ecohydrology – extending our teams beyond the natural sciences to include data scientists, social scientists and other researchers. (3) We need to undertake ‘research that matters’ – that is do work of relevance beyond the scientist who is doing it - by working with different stakeholders (leveraging practitioner and indigenous knowledges) to co-create new applications of scientific knowledge and generate important new research questions based on practical need. (4) In terms of new fundamental questions, we need to consider how we are joining the scales to go from our (often) small-scale process understanding to larger-scale proxies, controls and responses (for example, we still do not understand fully why particular times and places have a disproportionate influence on watershed ecohydrological response). In doing so, we may be able to better understand the scales of influence of climate, land management and other drivers of ecohydrological response to inform sustainable water management and develop better mitigation/ adaptation strategies for a changing water world.
Do you have a favorite ecohydrology paper? Describe/explain.
Sticking to just one paper (such a difficult choice!), I would opt for “How much water does a river need?” by Brian Richter and co-authors. This article introduced a new method (the Range of Variability Approach - RVA) for setting river ecosystem management targets - based the link between hydrological variability and aquatic ecosystem response. It got me thinking about how the five facets of what I often refer to as “wiggly river flow-time series” (magnitude, frequency, timing, duration, and rates of change) can influence aquatic species distributions, communities and biodiversity. This paper inspired a number of our collaborations and publications: on methods for hydrograph classification; searching for ecologically-meaningful hydrological variables; and the underpinning scientific basis for river management and conservation practice.
What do you do for fun (apart from ecohydrology)?
We spend time together as a family - usually outdoors (walking, cycling and in the garden) or at football/soccer matches. We all enjoy travelling to see new places and peoples, but that has been put on hold for the moment. I listen to a wide range of music, although classic and alternative rock is my favourite. Birmingham is a great city to see headliners as well as emerging bands, so I look forward to doing that once we recover from the pandemic. I still go running, although <20 min AGU Fun Runs were quite a while ago.
We have written commentaries and a book about defining “ecohydrology” and “hydroecology”, so rather than revisiting those discussions, I will go for simply… how ecological processes shape hydrological dynamics, how living things are influenced by hydrological processes, and how these two process sets feedback/ interact. We need to frame ecohydrology around coupled systems and, increasingly importantly, add people to the equations. So for me, in a nutshell, it is all about taking a wider perspective to understand complex, variable, interconnected, water-dependent systems and how we can use this knowledge towards sustainable management for the betterment of the environment and society. In terms of application, I try to use this perspective to research snow- and glacier-fed watersheds; river temperature dynamics and impacts; and space-time ecohydrological patterns beyond the individual river basin-scale and under global change.
What are your undergraduate and graduate degrees in?
My undergraduate degree is a BSc Physical Geography (1994) from the University of Aberdeen, Scotland. I was taught by some outstanding faculty and developed a passion for glaciers, mountains and rivers. Field courses are an integral part of geographical learning; and Aberdeen’s location (between the Rivers Dee and Don and near the Cairngorm Mountains) meant we were spoilt for choice of real world examples to test theory. For my undergraduate dissertation, I travelled to the Italian Alps (beside Mont Blanc) to undertake a project on climate drivers of glacier stream runoff. I was amazed by the dynamism of alpine environments; and this enthused me to do more research. So, I went to the University of Birmingham, England, to study for a PhD Geography (1997) under the supervision of Angela Gurnell (now Queen Mary University of London) and Glenn McGregor (now Durham University) that focused on meltwater generation and drainage in a small glacierized basin in the French Pyrenees. I was fortunate to have great field support from my supervisors and some people who became future research collaborators as well as friends. In my second summer field season, we were joined by a group of aquatic ecologists - which kindled my interests in ecohydrology.
How did you arrive at working in/thinking about ecohydrology?
As mentioned above, during my PhD, I did fieldwork with ecologists who were working on a European Commission project on Arctic and Alpine Stream Ecosystem Research. This project used similar field protocols to link stream ecology to physico-chemical river habitat along a latitudinal gradient of glacier-fed watershed for Europe (spanning from the French Pyrenees in the south to Svalbard in the north). These harsh, cold river systems are highly deterministic - with aquatic macroinvertebrate communities conditioned (most notably) by downstream patterns in water temperature and channel stability. By quantifying these ecohydrological links, it is possible to predict alpine stream biodiversity response to climate and hydrological change. After my PhD, I gained a lectureship at Birmingham and extended these glacier-fed river ecohydrological studies to other mountain regions and to the Arctic. In addition, I broadened my ecohydrological interests to river water temperature and flow-ecology links in temperate, forested, ephemeral and urban environments.
What do you see as an important emerging area of ecohydrology?
There are a number of topic areas that I could highlight (some are the same as our commentary in 2007) as ‘new’ and emerging themes: ecosystem sensitivity to hydrological change; aquatic-terrestrial linkages; disturbance - water and ecological stress; modern and palaeo-analogue studies; and applied hydroecology/ ecohydrology at the science-policy interface. In 2020, as an outcome from an international workshop led by Del Levia (University of Delaware), we offered a roadmap to advance ecohydrology. For this blog, it might be most interesting to reflect on the ‘how’ (rather than the ‘what’) we do in ecohydrology. (1) We need to develop and apply new tools - for example, recently we have used drones, high-frequency water sensing technologies and smart-tracers to identify space-time heterogeneity in ecohydrological systems and processes. We need to look to the innovation horizon for new methods to bring from other disciplines into ecohydrology as well as develop our own tools. (2) We need to release the huge potential of intrinsic interdisciplinary collaborations in ecohydrology – extending our teams beyond the natural sciences to include data scientists, social scientists and other researchers. (3) We need to undertake ‘research that matters’ – that is do work of relevance beyond the scientist who is doing it - by working with different stakeholders (leveraging practitioner and indigenous knowledges) to co-create new applications of scientific knowledge and generate important new research questions based on practical need. (4) In terms of new fundamental questions, we need to consider how we are joining the scales to go from our (often) small-scale process understanding to larger-scale proxies, controls and responses (for example, we still do not understand fully why particular times and places have a disproportionate influence on watershed ecohydrological response). In doing so, we may be able to better understand the scales of influence of climate, land management and other drivers of ecohydrological response to inform sustainable water management and develop better mitigation/ adaptation strategies for a changing water world.
Do you have a favorite ecohydrology paper? Describe/explain.
Sticking to just one paper (such a difficult choice!), I would opt for “How much water does a river need?” by Brian Richter and co-authors. This article introduced a new method (the Range of Variability Approach - RVA) for setting river ecosystem management targets - based the link between hydrological variability and aquatic ecosystem response. It got me thinking about how the five facets of what I often refer to as “wiggly river flow-time series” (magnitude, frequency, timing, duration, and rates of change) can influence aquatic species distributions, communities and biodiversity. This paper inspired a number of our collaborations and publications: on methods for hydrograph classification; searching for ecologically-meaningful hydrological variables; and the underpinning scientific basis for river management and conservation practice.
What do you do for fun (apart from ecohydrology)?
We spend time together as a family - usually outdoors (walking, cycling and in the garden) or at football/soccer matches. We all enjoy travelling to see new places and peoples, but that has been put on hold for the moment. I listen to a wide range of music, although classic and alternative rock is my favourite. Birmingham is a great city to see headliners as well as emerging bands, so I look forward to doing that once we recover from the pandemic. I still go running, although <20 min AGU Fun Runs were quite a while ago.
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