Scoping Urban Hazards in Kenya and Malawi

Technically I had been to Nairobi before our last trip last month, so I replied yes when people there asked. But then I told them it was when I was two years old and they laughed about how that didn’t count – partly because I can’t remember a thing from that time and partly because the city has changed so much. Back in 1982, the population of the city was around 900,000 but today it is over 3 million, and possibly up nearer 4 million during the day as people come into the city to work.

I was in Nairobi with colleagues Bruce Malamud and Faith Taylor on an initial research trip for our work on the physical dimensions of hazards in urban areas of Africa. During a meeting on the trip at Mzuzu University near another of our study sites – Karonga in Malawi – someone asked why we were focusing on hazards in urban areas particularly. The answer is partly because of the growth exemplified by Nairobi; Africa is urbanising rapidly and estimates are that 56% of the population of African will be urban by the middle of the century.

The UrbanARK project aims to generate knowledge and build capacity to support the growing need for disaster risk reduction strategies for urban populations in sub-Saharan Africa. The component of the project is predominantly driven by a physical science perspective, building on computer simulation and other modelling, to investigate physical hazards and impacts. Our trip was really a scoping exercise to refine our methodology, and to meet local collaborators in our case study cities.

Depending on whose estimates one chooses, Nairobi today is around the 12th largest city in Africa. During our three days there – negotiating the traffic which at times can be debilitating – we met with various regional and city officials to discuss hazards experienced in the city, how they are planned for, managed and mitigated against.

Flash flooding in the lower-lying areas of the city as water flows down from the upland areas is a primary hazard, exacerbated by informal settlements as people construct dwellings on the available space rivers and streams. Many of these areas are really slums and on one day of our trip we visited some of these areas, including Kibera, said by some to be the largest slum in Africa covering 4.5 sq km and housing more than half a million people.

A stream running through Kibera
One of the many problems in these informal settlements, and another which increases problems of flooding, is solid waste management. The researchers at the African Population and Health Research Center involved in the UrbanARK project will focus on this issue, and we saw examples of how discarded waste can block what planned (or unplanned) drainage provision exists. Understanding how these elements of physical interactions between human infrastructure and natural processes (such as overland flow) is important if such issues are to be meaningfully addressed.

Whilst in Nairobi we also visited the Kenya Red Cross to discuss hazards they help to deal with in the city and heard about their current work on fires in informal settlements. One project they are currently working on aims to install smart, web-enabled fire (heat) sensors in houses in informal settlements to provide an early warning system. Fires in informal settlements can spread quickly because of the construction materials used and the high density of buildings. These fires frequently cause loss of life and it is hoped that by creating a network of sensors able to send text message alerts to locals, fires can be more effectively dealt with and risk can be reduced.

A final stop in Nairobi before we travelled onwards to Malawi was to visit the Regional Centre for Mapping of Resources for Development to find out what sorts of spatial information is being collected and used across sub-Saharan Africa. Interestingly, while there we found out more there about data and tools for Malawi than for Kenya. For example, we discovered the newly launched Malawi Hazards and Vulnerability Atlas which looks like a very useful tool at the country-level for assessing risks from a variety of hazards. As is often the case, however, the tool does not focus specifically on urban issues, but it was useful to think about on the flight south past Mount Kilimanjaro and crossing Lake Malawi.

From Malawi’s capital Lilongwe, we immediately headed north to Mzuzu to link up with colleagues involved with UrbanARK at Mzuzu University. The Malawi case study city is not actually Mzuzu itself but the smaller town of Karonga on the shore of Lake Malawi yet further north. Before we continued to Karonga to better understand issues in the town, we discussed the most important hazards faced there – flooding, earthquakes, strong winds and lightning.

On reaching Karonga, the ways in which these hazards are manifest in the town became clearer. Karonga is much smaller than Nairobi and although it will never reach the same scale, it is expected to grow over the coming years. Currently with a population of around 50,000 (expected to grow to 72,000 by 2022), the town feels much less dense than parts of Nairobi (like Kibera). The primary means of transport in Karonga is bicycle, meaning the traffic jams experienced in Nairobi are largely absent (although driving past the market in the evening can be slower than walking as pedestrians outnumber cars by probably more than 100 to 1). Houses in town are generally made of brick and are separated by small yards, but the poverty is on a similar level to the deprived areas of our bigger case study city. As a whole Malawi is poorer compared to Kenya (GNP of $715 per capita vs $2,157) with a lower human development index (0.414 vs 0.535) and a greater proportion of the population are in multidimensional poverty (67% vs 48%).

With the North Rukuru River flowing down from hills 20km to the west and forming the northern boundary of the town, flooding has been a long standing issue in Karonga. To mitigate against this, the centre of town was moved away from the lake shore in the early 1990s, meaning there is now ‘new town’ and ‘old town’ (although the more flood-prone old town is still largely populated). The remainder of Karonga is protected by an earthen dyke to the north, but the construction of a higher road embankment at the east end, combined with local removing some parts of the dyke for building materials, means that flood waters can still overtop or circumvent the dyke. We got an interesting look at the original plans for the dyke in the local planning office and walked sections of the dyke with our collaborators (tailed by a large group of local kids – we were the entertainment for the afternoon!)

The dyke at Karonga
Another issue for Karonga is the recurrence of earthquakes (or tremors), situated as it is on the Livingstone fault that forms the Great African Rift valley and Lake Malawi itself. We saw some evidence of the quake that struck in 2009, causing an uplift of the main road through town and cracks in some buildings. Other hazards we discussed with local charity organisations included strong winds and hailstorms.

On reflection, although there are clear differences between our two case study cities there are common issues. In both places, well-meaning plans that aim to reduce risks posed by physical hazards are often confounded by informal settlements that spring up wherever people can best make a living with what little they have. In both urban centres the problem of flooding in lower-lying areas arises as water flowing from upland areas inundates land on which ideally people would not be living but which by necessity (due to lack of space) or convenience (proximity to fertile soils) means that they do. Although Nairobi often felt more chaotic than Karonga, this may simply have been because the population (and motorised traffic) density is so much greater; interactions between uncoordinated actions seem to abound in both, often reinforcing and exacerbating existing risks. These issues seem to be particularly African in the context of physical hazards in urban areas.

It was over 30 years between my first two visits to Nairobi, but my next visit will likely be a lot sooner than 2045. By that year Nairobi (and Karonga) will have continued to change but hopefully for the better for the majority of people, and in ways that mitigate risks from physical hazards.

Photos on Flickr from Nairobi and Malawi

Traditional Fire Knowledge in Spain

When you haven’t done something for a while it’s often best not to rush straight back in at the intensity you were at before. So here’s a nice easy blog to get me going again (not that I was blogging intensely before!).

I didn’t blog about it at the time (unsurprisingly), but back in late June 2013 I went to visit a colleague of mine in Madrid, Dr Francisco Seijo. Francisco and I met back at something I did blog about, the 2009 US-IALE conference in Snowbird. Since then we’ve been discussing how we can use the idea of coupled-human and natural systems to investigate Mediterranean landscapes.

Example of Traditional Fire Knowledge. The ‘pile-burning’ technique involves raking, piling and igniting leaves. This contrasts with ‘a manta’ broadcast burning in which leaves and ground litter are burned across larger areas. Photos by the authors of the paper.

After a brief field visit by me, an interview campaign by Francisco, collection of secondary data from other sources (aerial photography and official fire statistics) and some desk analysis, we recently published our first paper on the work. Entitled Forgetting fire: Traditional fire knowledge in two chestnut forest ecosystems of the Iberian Peninsula and its implications for European fire management policy, and published in the journal Land Use Policy, the article presents the results of our mixed-methods and interdisciplinary approach. Building on Francisco’s previous examination of ‘pre-industrial anthropogenic fire regimes’ we to to investigate differences between the fire regimes and management approaches of chestnut forest ecosystems in two municipalities in central Spain. In the paper we also discuss ideas of Traditional Ecological Knowledge (TEK), the related idea of Traditional Fire Knowledge (TFK), and discuss them in light of contemporary fire management approaches in Europe.

The full abstract is below with links to the paper. I’ll stop here now as this rate of blogging it making me quite dizzy (but hopefully I’ll be back for more soon).


Seijo, Francisco, James DA Millington, Robert Gray, Verónica Sanz, Jorge Lozano, Francisco García-Serrano, Gabriel Sangüesa-Barreda, and Jesús Julio Camarero (2015) Forgetting fire: Traditional fire knowledge in two chestnut forest ecosystems of the Iberian Peninsula and its implications for European fire management policy. Land Use Policy 47 130-144. doi: 10.1016/j.landusepol.2015.03.006
[Online] [Pre-print]


Human beings have used fire as an ecosystem management tool for thousands of years. In the context of the scientific and policy debate surrounding potential climate change adaptation and mitigation strategies, the importance of the impact of relatively recent state fire exclusion policies on fire regimes has been debated. To provide empirical evidence to this ongoing debate we examine the impacts of state fire exclusion policies in the chestnut forest ecosystems of two geographically neighbouring municipalities in central Spain, Casillas and Rozas de Puerto Real. Extending the concept of ‘Traditional Ecological Knowledge’ to include the use of fire as a management tool as ‘Traditional Fire Knowledge’ (TFK), we take a mixed-methods and interdisciplinary approach to argue that currently observed differences between the municipalities are useful for considering the characteristics of “pre-industrial anthropogenic fire regimes” and their impact on chestnut forest ecosystems. We do this by examining how responses from interviews and questionnaire surveys of local inhabitants about TFK in the past and present correspond to the current biophysical landscape state and recent fire activity (based on data from dendrochronological analysis, aerial photography and official fire statistics). We then discuss the broader implications of TFK decline for future fire management policies across Europe particularly in light of the published results of the EU sponsored FIRE PARADOX research project. In locations where TFK-based “pre-industrial anthropogenic fire regimes” still exist, ecosystem management strategies for adaptation and mitigation to climate change could be conceivably implemented at a minimal economic and political cost to the state by local communities that have both the TFK and the adequate social, economic and cultural incentives to use it.

Key words

Fire exclusion policies; traditional ecological knowledge; traditional fire knowledge; Chestnut forest ecosystems; FIRE PARADOX


Morocco Fieldtrip Recon

I spent a couple of weeks this month in Morocco, the majority of which was scouting out a route for a new physical geography fieldtrip for second year undergraduates at King’s College London. For the last several years the physical geography fieldtrip has been based on the Morocco coast at Agadir and Essaouira, visiting nearby sites. The new fieldtrip will take more of a transect approach, starting in Marrakech, traversing the High Atlas mountains and following the River Draa out to the edge of the Sahara (see map below).

As we work our way up and through the High Atlas one of the things we’ll consider is how vegetation changes and what might be driving those changes. In the picture below you can see colleagues on the trip Prof. Drake and Dr Chadwick (@DrMChad) debating (and betting on!) vegetation on the hills over-looking the town of Demnate.

For example, what are the relative influences of climate and human activity on the vegetation we see? In the picture below Prof Drake confronts one potential disturbance.

As this is a new trip and we’ll be staying in a new location each night, one of our tasks was to check the accommodation we’ll be staying in. Here hotel connoisseurs Drake and Chadwick relax in luxury in the gîte at Toufghine.

There’s some impressive geology in the High Atlas and we’ll discuss that as we go too. The scale of some of the tectonic features is illustrated by Prof Drake in the bottom right of the picture below.

We’ll also be surveying rivers, both their geomorphology and ecology. Another of our tasks therefore was to work out what we would examine and where along the various rivers in the region.

Once we get over the High Atlas and the Anti-Atlas beyond we’ll follow the River Draa all the way to the desert. The Draa is a vital life-line for people in the region, with water drawn from the river used to irrigate agriculture (including wheat).

Once the water has all been used up we reach the desert. There we’ll look for evidence of previous flows of the Draa and of climate change. Some of the dunes can be steep.

But the view from the top is usually good, especially at sunset. We’ll stay a night out in the dunes with the students to get a feel for what it might be like living in such hostile environment.

And of course there will be camels! Below, our driver negotiates a herd as we head back north to Marrakech on the final leg of our trip.

So it looks like we’re going to have a great trip with our students in December and following years! The trip will allow us to investigate how climate, geology, geomorphology, ecology and livelihoods change across space and how they have changed through time.

I’ve posted some more of my favourite pictures on Panoramio so that you can see some of the locations we’ll visit.

#ialeuk2014 – Urban landscape ecology: Science, policy and practice

Something else to keep me busy this year is the organisation of the Annual Conference of the International Association for Landscape Ecology (UK). We’ll be hosting the conference at King’s in central London on 1-3 September 2014. We will be having two days of presentations on science, policy, planning and practice, networking events and workshops. We’re still planning them, but we’re hoping that fieldtrips on the final day will include visits to the Thames Barrier and surrounding area and to the top of the Shard, Western Europe’s tallest building.

The theme of the conference this year is ‘Urban landscape ecology: science, policy and practice’. We are keen to hear from researchers, policymakers, and practitioners developing new evidence, policies, strategies, plans or projects on the ground that relate to the landscape ecology of urban and peri-urban areas. The call for abstracts has just gone out; please submit abstracts (300 words) for presentations and posters to by 28 February 2014. We expect selected papers will compose an edited volume on current key issues in urban landscape ecology. The full call for abstracts is copied below.

We’ll be updating the conference website regularly throughout the year as conference planning continues, so keep checking back at: Further details of the conference programme and how to register will be available there soon. We’ll be using the hashtag #ialeuk2014 so please use this on social media. And any questions or queries, don’t hesitate to get in touch via

Call for Abstracts – Urban landscape ecology: Science, policy and practice

Cities are growing rapidly. Across Europe, more than 70 per cent of people already live in urban areas, including 80 per cent of the UK population. The growth of cities poses ever-increasing challenges for the natural environment on which they impact and depend, not only within their boundaries but also in surrounding peri-urban areas. Landscape ecology – the study of interactions across space and time between the structure and function of physical, biological and cultural components of landscapes – has a pivotal role to play in identifying sustainable solutions.

This conference will consider how concepts from landscape ecology can inform the maintenance and restoration of healthy, properly functioning natural environments across urban and peri-urban landscapes, as the foundation of sustained economic growth, prospering communities and personal wellbeing.

Conference themes are likely to include: ecological connectivity of terrestrial and aquatic environments; ecosystem services, including regulation of air quality, urban heat, and water quality and quantity, as well as cultural services; planning for change; and landscape-scale management of terrestrial and aquatic ecosystems.

We are keen to hear from researchers, policymakers, and practitioners developing new evidence, policies, strategies, plans or projects on the ground that relate to the landscape ecology of urban and peri-urban areas.

Please submit abstracts (300 words) for presentations and posters to by 28 February 2014. Selected papers will compose an edited volume on current key issues in urban landscape ecology.

There will be two days of presentations on science, policy, planning and practice, networking events and workshops. We are hoping that fieldtrips on the final day will include visits to the Thames Barrier and surrounding area and to the top of the Shard, Western Europe’s tallest building, from where we can consider connectivity across London and beyond.

Further details of the conference programme and how to register will be available soon.

General enquiries:
Social media: #ialeuk2014

When is a pattern a pattern?

This week I received my copy of ‘Patterns of Land Degradation in Drylands: Understanding Self-Organised Ecogeomorphic Systems’ which I contributed to after participating at a workshop in Potsdam, Germany. It’s a well produced book and as I was flicking through it I came across one of the pieces I wrote. Rather than just leave it hidden away on pages 60 – 61 in the book I thought I’d reproduce it here. It’s less than 500 words and to the point. Just right for a blog post.

“In science, patterns are observations of any non-random structure. In ecology for example, a pattern has long been understood as the “structure which results from the distributions of organisms in, or from, their interactions with their environments” (Hutchinson 1953, p.3, also see Watt 1947, Greig-Smith 1979). However, when identifying patterns in nature, scientists more precisely mean the identification of patterns in data about nature. Important considerations for identifying patterns, therefore, are the means by which data were collected, and most importantly the scales of measurement used to collect data. In particular, two components of scale – grain and extent – are important in determining whether a pattern is identified. Grain is the resolution of measurement (i.e. the smallest unit of measurement at which objects or states can be distinguished), whereas extent is the full scope of observation or total range over which measurements are made. As examples, different spatial patterns will be detectable in maps of vegetation configuration in semi-arid areas depending on the grain and extent of the maps (e.g. compare Figures 3 and 6 in Barbier et al. 2006), and different temporal patterns will be detectable in storm hydrographs depending on the resolution and duration of measurement (e.g. compare drainage for 10 minute intervals with full 80 minute duration, and observed drainage with simulated drainage, in Figure 5 of Mueller et al. 2007). In other circumstances, observed structures may be described as being ‘scale-free’. These structures lack a characteristic length scale and have the same properties across any grain and extent of measurement (e.g. power-law distributions of vegetation patch sizes; Kéfi et al. 2007). These scale-free structures can also be considered to be patterns.

Because patterns are non-random, they have the potential to provide information. In natural science this information is usually understood as being about the processes that caused the pattern. Thus, identifying patterns is useful because they can be used to investigate processes (Levin 1992). Processes are typically assumed to act at a different scale from the patterns they produce, with patterns either emerging from processes at smaller scales (‘bottom-up’ processes) or imposed by constraints at larger scales (‘top-down’ processes). It is also important to consider the reciprocal effects of patterns on processes (Turner 1989). For example, the field of landscape ecology has placed an emphasis on the quantification of spatial pattern using pattern metrics (e.g. McGarigal 2006) and shown how the history of previous ecological processes can increase the strength and extent of spatial pattern (Peterson 2002). The ‘pattern-oriented modelling’ (POM) approach has been developed to use models to help decode the information present in patterns to better understand processes (Wiegand et al. 2003, Grimm et al. 2005). The POM approach iteratively compares empirical and model-output patterns at multiple scales and levels of organization and for multiple models to identify most appropriate models. Approaches like POM, which place pattern at the centre of scientific investigation, are vital for improving understanding about physical processes.”


  • Barbier N, Couteron P, Lejoly J et al (2006) Self-organized vegetation patterning as a fingerprint of climate and human impact on semi-arid ecosystems. J of Ecol 94:537-547
    Greig-Smith P (1979) Pattern in vegetation. J of Ecol 67: 755-779
  • Grimm V, Revilla E, Berger U et al. (2005) Pattern-oriented modeling of agent-based complex systems: Lessons from ecology. Science 310:987-991
  • Hutchinson GE (1953) The concept of pattern in ecology. Proc of the Acad of Nat Sci of Philadelphia 105:1-12
  • Kéfi S, Rietkerk M, Alados, CL et al (2007) Spatial vegetation patterns and imminent desertification in Mediterranean arid ecosystems. Nature 449:213-217
  • Levin SA (1992) The problem of pattern and scale in ecology: The Robert H. MacArthur award lecture. Ecology 73(6):1943-1967
  • McGarigal K (2006) Landscape pattern metrics. In: El-Shaarawi AH and Piegorsch WW (eds) Encyclopedia of Environmetrics. Wiley: Chichester, UK
  • Mueller EN, Wainright J, Parsons, AJ (2007) Impact of connectivity on the modeling of overland flow within semiarid shrubland environments. Water Res Res 43:W09412
  • Peterson GD (2002) Contagious disturbance, ecological memory, and the emergence of landscape pattern. Ecosystems 5:329-338
  • Turner MG (1989) Landscape ecology: The effect of pattern on process. Ann Rev of Ecol and Syst 20:171-197
  • Watt, AS (1947) Pattern and process in the plant community. J of Ecol 35:1-22
  • Wiegand T, Jeltsch F, Hanski I et al (2003) Using pattern-oriented modeling for revealing hidden information: A key for reconciling ecological theory and application. Oikos 100:209-222

Jeltsch, F., Millington, J.D.A., et al. (2014) Resilience, self-organization, complexity and pattern formation In: Mueller, E.N., Wainwright, J., Parsons, A.J. and Turnbull, L. (Eds.) Patterns of Land Degradation in Drylands. Springer, pp. 55-84.

Lecturer in Physical and Quantitative Geography

Things got a bit crazy this month as I made the transition from my Leverhulme Fellowship to a permanent position at King’s as Lecturer in Physical and Quantitative Geography. I’m now Programme Director on the MSc in Environmental Monitoring, Modelling and Management (which I completed 10 years ago this month!) and preparing for of new modules on which I’m teaching this term has kept me busy. Specifically, this term I’m teaching on the postgraduate module ‘Methods for Environmental Research’ and the undergraduate modules ‘Principles of Geographical Inquiry II’ and ‘Current Research in… Ecosystem Services’ (which I taught last year also). So it’s been busy, but also stimulating to be putting thought into how best to communicate and illuminate ideas.

As part of the Intro for our new postgraduate students, and so that can find out more about the research that we do in the department, this week the Earth and Environmental Dynamics research group seminar series was given over to several short presentations by members of staff. The slides from mine is below.

Next month I’ll give a summary of the work I did during my Leverhulme Fellowship. For now, I just need to find some time for some research in amongst all my new teaching commitments!

Writing: Landscape Ecology and Land Degradation

July was a busy month of writing. Unfortunately, it wasn’t busy writing on this blog and I failed on my New Year’s resolution to make at least one blog post each calendar month this year.

The writing I was doing was for my contribution to a new Landscape Ecology textbook I’m co-authoring with Dr Rob Francis. I’ve written and contributed to individual chapters for edited books previously (the latest highlighted below), but a whole book is a larger challenge. In particular, it’s been a useful experience thinking about how to structure the presentation of the ideas we want to address, which order they come in, what goes in each chapter, and so forth. I’ve mainly been working on the chapters on scale and disturbance, but have also been thinking about material for the heterogeneity and landscape evolution chapters. I’ve been learning a lot, revisiting old notes (including from my undergraduate lectures with Dr Perry!) and reviewing the content of others’ books. It’s been good thinking about some of the broader issues – such as the shifting-mosaic steady state and diversity-disturbance relationships – as it helps to frame more focused questions and work I’ve been thinking about and doing (including my ongoing research using Mediterranean disturbance-succession simulation modelling). When I get the chance (in amongst other things) I’ll post more here about the progression of the book, it’s aims and how it will fit in with teaching we have planned.

Just this week another book I have been involved with has become available online. Patterns of Land Degradation in Drylands: Understanding Self-Organised Ecogeomorphic Systems is the edited volume that summarises and develops the discussions we had at a workshop in Potsdam, Germany in the summer of 2010. The workshop and writing of the book, led by Eva Mueller, John Wainwright, Tony Parsons and Laura Turnbull, examine processes at the interface of ecology and geomorphology that are associated with land degradation in drylands. I contributed to the book chapters on the current state of the art in studying land degradation in drylands, on resilience, self-organization, complexity and pattern formation, and on pattern-process interrelationships and the role of ecogeomorphology. The book is the first on ecogeomorphology of drylands and contains four case studies from drylands in Europe, Africa, Australia and North America that highlight recent advances in ecogeomorphic research. It’s available online now and will be out in print soon.

AAG 2013

Last week I was in Los Angeles for my first ever Association of American Geographers Annual Meeting. I think I hadn’t been before because the US-IALE annual meeting is around the same time of year and attending that has made more sense in the last few years given my work on forest modelling in Michigan. As I’d heard previously, the meeting was huge – although not quite as crazy as it could have been.

Most of my participation at the meeting was related to the Land Systems Science Symposium sessions (which ran across four days) and the Agent-Based and Cellular Automata Model for Geographical Systems sessions. It was good to discuss and meet new people wrestling with similar issues to those in my own research. Unfortunately, the ABM sessions were scheduled for the last day which meant it was only late in the conference that I got to properly meet people I’d encountered online (e.g., Mike Batty, Andrew Crooks, Nick Magliocca) and others. Despite being scheduled for the last day there was a good turnout in the sessions and my presentation (below) seemed to go down well. Researchers from the group at George Mason University were most well-represented, with much of their work using the MASON modelling libraries (which I’m going to have to looking into more to continue the work initiated during my PhD).

It’s hard to concentrate on 20-minute paper sessions continuously for five days though, and I found the discussion panels and plenaries a nice relief, allowing a broader picture to develop. For example, David O’Sullivan (whom I’m currently visiting at the University of Auckland) chaired and interesting panel discussion on ABM for Land Use/Cover Change. Participants included, Chris Bone who discussed the need for better representation of model uncertainty from multiple simulation (via temporal variant-invariant analysis – coming soon in IJGIS); Dan Brown who suggested we’re missing mid-level models that are neither abstract ‘toys’ nor beholden to mimetic reproduction of specific empirical data (e.g., where are the ABM equivalents of von Thunen and Burgess type models?); and Moira Zellner who highlighted problems of using ABM for decision-making in participatory approaches (Moira’s presentation in the ABM session was great, discussing the ‘blow-up’ in her participatory modelling project when the model got too complicated and stakeholders no longer wanted to know what the model was doing under the hood).

I also really enjoyed Mike Goodchild’s Progress in Human Geography annual lecture, in which he reviewed the development of GIScience through his long career and where he thought it should go next (‘Old Debates, New Opportunities’). Goodchild argued (I think) that Geography cannot (and should not) be an experimental science in the mold of Physics, and that rather than attempting to identify laws in social (geographical) science, we should aim to find things that can be deemed to be ‘generally true’ and used as a norm for reducing uncertainty. This is possible because geography is ‘neither uniform nor unique’, but it is repeating. Furthermore, he argued it was time for GIScience to rediscover place and that a technology of place is needed to accompany the (existing) technology of space. This technology of place might use names rather than co-ordinates, hierarchies of places rather than layers of coverages, and produce sketch maps rather than planimetric maps. The substitution of names of places for co-ordinates of locations is particularly important here, as names are social constructs and so multiple (local) maps are possible (and needed) rather than a single (global) map. Goodchild exemplified this using Google Maps, which differs depending on which country you view it from (e.g., depending on what the State views as its legitimate borders). He talked about loads of other stuff, including critical GIS, but these were the points I found most intriguing.

Another way to break up the constant stream of 20-minute project summaries would have been organised fieldtrips around the LA area. However, unlike the landscape ecology conference there is no single time set aside for fieldtrips, and while there are organised trips they’re scheduled throughout the week (simultaneous with sessions). Given such a large conference I guess it would be hard to fit all the sessions into a single week if time were set aside. I didn’t make it to any of the formal fieldtrips, but with Ben Clifford (checkout his new book, The Collaborating Planner?) and Kerry Holden I did manage to find time to hit the beach for some sun. It was a long winter in the UK after all! Now I’m in Auckland it’s warm but stormy; an update about activities here to come in May.

Recursion in society and simulation

This week I visited one of my former PhD advisors, Prof John Wainwright, at Durham University. We’ve been working on a manuscript together for a while now and as it’s stalled recently we thought it time we met up to re-inject some energy into it. The manuscript is a discussion piece about how agent-based modelling (ABM) can contribute to understanding and explanation in geography. We started talking about the idea in Pittsburgh in 2011 at a conference on the Epistemology of Modeling and Simulation. I searched through this blog to see where I’d mentioned the conference and manuscript before, but to my surprise, before this post I hadn’t.

In our discussion of what we can learn through using ABM, John highlighted the work of Kurt Godel and his incompleteness theorems. Not knowing all that much about that stuff I’ve been ploughing my way through Douglas Hofstadter’s tome ‘Godel, Escher and Bach: An Eternal Golden Braid’ – heavy going in places but very interesting. In particular, his discussion of the concept of recursion has taken my notice, as it’s something I’ve been identifying elsewhere.

The general concept of recursion involved nesting, like Russian dolls, stories within stories (like in Don Quixote) and images within images:

Computer programmers of take advantage of recursion in their code, calling a given procedure from within that same procedure (hence their love of recursive acronyms like PHP [PHP Hypertext Processor]). An example of how this works is in Saura and Martinez-Millan’s modified random clusters method for generating land cover patterns with given properties. I used this method in the simulation model I developed during my PhD and have re-coded the original algorithm for use in NetLogo [available online here]. In the code (below) the grow-cover_cluster procedure is called from within itself, allowing clusters of pixels to ‘grow themselves’.

However, rather than get into the details of the use of recursion in programming, I want to highlight two other ways in which recursion is important in social activity and its simulation.

The first, is in how society (and social phenomena) has a recursive relationship with the people (and their activities) composing it. For example, Anthony Gidden’s theory of structuration argues that the social structures (i.e., rules and resources) that constrain or prompt individuals’ actions are also ultimately the result of those actions. Hence, there is a duality of structure which is:

“the essential recursiveness of social life, as constituted in social practices: structure is both medium and outcome of reproduction of practices. Structure enters simultaneously into the constitution of the agent and social practices, and ‘exists’ in the generating moments of this constitution”. (p.5 Giddens 1979)

Another example comes from Andrew Sayer in his latest book ‘Why Things Matter to People’ which I’m also progressing through currently. One of Sayer’s arguments is that we humans are “evaluative beings: we don’t just think and interact but evaluate things”. For Sayer, these day-to-day evaluations have a recursive relationship with the broader values that individuals hold, values being ‘sedimented’ valuations, “based on repeated particular experiences and valuations of actions, but [which also tend], recursively, to shape subsequent particular valuations of people and their actions”. (p.26 Sayer 2011)

However, while recursion is often used in computer programming and has been suggested as playing a role in different social processes (like those above), its examination in social simulation and ABM has not been so prominent to date. This was a point made by Paul Thagard at the Pittsburgh epistemology conference. Here, it seems, is an opportunity for those seeking to use simulation methods to better understand social patterns and phenomena. For example, in an ABM how do the interactions between individual agents combine to produce structures which in turn influence future interactions between agents?

Second, it seems to me that there are potentially recursive processes surrounding any single simulation model. For if those we simulate should encounter the model in which they are represented (e.g., through participatory evaluation of the model), and if that encounter influences their future actions, do we not then need to account for such interactions between model and modelee (i.e., the person being modelled) in the model itself? This is a point I raised in the chapter I helped John Wainwright and Dr Mark Mulligan re-write for the second edition of their edited book “Environmental Modelling: Finding Simplicity in Complexity”:

“At the outset of this chapter we highlighted the inherent unpredictability of human behaviour and several of the examples we have presented may have done little to persuade you that current models of decision-making can make accurate forecasts about the future. A major reason for this unpredictability is because socio-economic systems are ‘open’ and have a propensity to structural changes in the very relationships that we hope to model. By open, we mean that the systems have flows of mass, energy, information and values into and out of them that may cause changes in political, economic, social and cultural meanings, processes and states. As a result, the behaviour and relationships of components are open to modification by events and phenomena from outside the system of study. This modification can even apply to us as modellers because of what economist George Soros has termed the ‘human uncertainty principle’ (Soros 2003). Soros draws parallels between his principle and the Heisenberg uncertainty principle in quantum mechanics. However, a more appropriate way to think about this problem might be by considering the distinction Ian Hacking makes between the classification of ‘indifferent’ and ‘interactive’ kinds (Hacking, 1999; also see Hoggart et al., 2002). Indifferent kinds – such as trees, rocks, or fish – are not aware that they are being classified by an observer. In contrast humans are ‘interactive kinds’ because they are aware and can respond to how they are being classified (including how modellers classify different kinds of agent behaviour in their models). Whereas indifferent kinds do not modify their behaviour because of their classification, an interactive kind might. This situation has the potential to invalidate a model of interactive kinds before it has even been used. For example, even if a modeller has correctly classified risk-takers vs. risk avoiders initially, a person in the system being modelled may modify their behaviour (e.g., their evaluation of certain risks) on seeing the results of that behaviour in the model. Although the initial structure of the model was appropriate, the model may potentially later lead to its own invalidity!” (p. 304, Millington et al. 2013)

The new edition was just published this week and will continue to be a great resource for teaching at upper levels (I used the first edition in the Systems Modeling and Simulation course I taught at MSU, for example).

More recently, I discussed these ideas about how models interact with their subjects with Peter McBurney, Professor in Informatics here at KCL. Peter has written a great article entitled ‘What are Models For?’, although it’s somewhat hidden away in the proceedings of a conference. In a similar manner to Epstein, Peter lists the various possible uses for simulation models (other than prediction, which is only one of many) and also discusses two uses in more detail – mensatic and epideictic. The former function relates to how models can bring people around a metaphorical table for discussion (e.g., for identifying and potentially deciding about policy trade-offs). The other, epideictic, relates to how ideas and arguments are presented and leads Peter to argue that by representing real world systems in a simulation model can force people to “engage in structured and rigorous thinking about [their problem] domain”.

John and I will be touching on these ideas about the mensatic and epideictic functions of models in our manuscript. However, beyond this discussion, and of relevance here, Peter discusses meta-models. That is, models of models. The purpose here, and continuing from the passage from my book chapter above, is to produce a model (B) of another model (A) to better understand the relationships between Model A and the real intelligent entities inside the domain that Model A represents:

“As with any model, constructing the meta-model M will allow us to explore “What if?” questions, such as alternative policies regarding the release of information arising from model A to the intelligent entities inside domain X. Indeed, we could even explore the consequences of allowing the entities inside X to have access to our meta-model M.” (p.185, McBurney 2012)

Thus, the models are nested with a hope of better understanding the recursive relationship between models and their subjects. Constructing such meta-models will likely not be trivial, but we’re thinking about it. Hopefully the manuscript John and I are working on will help further these ideas, as does writing blog posts like this.

Selected Reference
McBurney (2012): What are models for? Pages 175-188, in: M. Cossentino, K. Tuyls and G. Weiss (Editors): Post-Proceedings of the Ninth European Workshop on Multi-Agent Systems (EUMAS 2011). Lecture Notes in Computer Science, volume 7541. Berlin, Germany: Springer.

Millington et al. (2013) Representing human activity in environmental modelling In: Wainwright, J. and Mulligan, M. (Eds.) Environmental Modelling: Finding Simplicity in Complexity. (2nd Edition) Wiley, pp. 291-307 [Online] [Wiley]

Wrapping up 2012

Nearing the end of 2012 and the total number of posts on this blog has been even fewer this year than in 2011. At least I have been tweeting a bit more of late. Here’s a quick round-up of activities and publications since my last post with a look at some of what’s going on in 2013.

The Geoforum paper on narrative explanation of simulation modelling is now officially published, as is the first of two Ecological Modelling papers on the Michigan forest modelling work. Citations and abstract for both are below, and are included on my updated publications list. I’ll post more details and info on each in the New Year (promise!). I’ll likely wait to summarise the Michigan paper until the second paper of that couplet is published – hopefully that won’t be too long as it’s now going through the proofs stage.

The proceedings for the iEMSs conference I attended in Leipzig, Germany, this summer are now online. That means that the two papers I presented there are also available. One paper was on the use of social psychology theory for modelling farmer decision-making, and the model I discuss in that paper is available for you to examine. The other paper was a standpoint contribution to a workshop on the place of narrative for explaning decision-making in agent-based models. From that workshop we’re working on a paper to be published in Environmental Modelling and Software about model description methods for agent-based models. More on that next year too hopefully.

In one of my earlier posts this year I talked about agent-based modelling spatial patterns of school choice (I’ll get the images for that post online again soon… maybe). I’ve managed to write up the early stages of that work and have submitted it to JASSS. We’ll see how that goes down. I hope to continue on that work in the new year also, possibly while in New Zealand at the University of Auckland. I’ll be in Auckland visiting and working with George Perry and David O’Sullivan, with whom I published the recent Geoforum paper (highlighted above). On the way to New Zealand I’ll be stopping off in Los Angeles for the Association of American Geographers conference which I haven’t been to previously and which should be interesting.

So that’s it for 2012. A New Year’s resolution for 2013 – post at least once every month on this blog! Especially from Down Under.

Happy Holidays!

Millington, J.D.A., O’Sullivan, D., Perry, G.L.W. (2012) Model histories: Narrative explanation in generative simulation modelling Geoforum 43 1025–1034
The increasing use of computer simulation modelling brings with it epistemological questions about the possibilities and limits of its use for understanding spatio-temporal dynamics of social and environmental systems. These questions include how we learn from simulation models and how we most appropriately explain what we have learnt. Generative simulation modelling provides a framework to investigate how the interactions of individual heterogeneous entities across space and through time produce system-level patterns. This modelling approach includes individual- and agent-based models and is increasingly being applied to study environmental and social systems, and their interactions with one another. Much of the formally presented analysis and interpretation of this type of simulation resorts to statistical summaries of aggregated, system-level patterns. Here, we argue that generative simulation modelling can be recognised as being ‘event-driven’, retaining a history in the patterns produced via simulated events and interactions. Consequently, we explore how a narrative approach might use this simulated history to better explain how patterns are produced as a result of model structure, and we provide an example of this approach using variations of a simulation model of breeding synchrony in bird colonies. This example illustrates not only why observed patterns are produced in this particular case, but also how generative simulation models function more generally. Aggregated summaries of emergent system-level patterns will remain an important component of modellers’ toolkits, but narratives can act as an intermediary between formal descriptions of model structure and these summaries. Using a narrative approach should help generative simulation modellers to better communicate the process by which they learn so that their activities and results can be more widely interpreted. In turn, this will allow non-modellers to foster a fuller appreciation of the function and benefits of generative simulation modelling.

Millington, J.D.A., Walters, M.B., Matonis, M.S. and Liu, J. (2013) Modelling for forest management synergies and trade-offs: Northern hardwood tree regeneration, timber and deer Ecological Modelling 248 103–112
In many managed forests, tree regeneration density and composition following timber harvest are highly variable. This variability is due to multiple environmental drivers – including browsing by herbivores such as deer, seed availability and physical characteristics of forest gaps and stands – many of which can be influenced by forest management. Identifying management actions that produce regeneration abundance and composition appropriate for the long-term sustainability of multiple forest values (e.g., timber, wildlife) is a difficult task. However, this task can be aided by simulation tools that improve understanding and enable evaluation of synergies and trade-offs between management actions for different resources. We present a forest tree regeneration, growth, and harvest simulation model developed with the express purpose of assisting managers to evaluate the impacts of timber and deer management on tree regeneration and forest dynamics in northern hardwood forests over long time periods under different scenarios. The model couples regeneration and deer density sub-models developed from empirical data with the Ontario variant of the US Forest Service individual-based forest growth model, Forest Vegetation Simulator. Our error analyses show that model output is robust given uncertainty in the sub-models. We investigate scenarios for timber and deer management actions in northern hardwood stands for 200 years. Results indicate that higher levels of mature ironwood (Ostrya virginiana) removal and lower deer densities significantly increase sugar maple (Acer saccharum) regeneration success rates. Furthermore, our results show that although deer densities have an immediate and consistent negative impact on forest regeneration and timber through time, the non-removal of mature ironwood trees has cumulative negative impacts due to feedbacks on competition between ironwood and sugar maple. These results demonstrate the utility of the simulation model to managers for examining long-term impacts, synergies and trade-offs of multiple forest management actions.