
Oliver J. Walther
· Professor of African StudiesUniversity of Florida · African Studies
Active 1984–2024
Research topics
- Computer Science
- Sociology
- Political Science
- Law
- Geography
- Economic geography
- Business
- Psychology
- Criminology
Selected publications
Uncovering the internal structure of Boko Haram through its mobility patterns
Applied Network Science · 2020 · 36 citations
- Political Science
- Sociology
- Computer Science
Abstract Boko Haram has caused nearly 40,000 casualties in Nigeria, Niger, Cameroon and Chad, becoming one of the deadliest Jihadist organisations in recent history. At its current rate, Boko Haram takes part in more than two events each day, taking the lives of nearly 11 people daily. Yet, little is known concerning Boko Haram’s internal structure, organisation, and its mobility. Here, we propose a novel technique to uncover the internal structure of Boko Haram based on the sequence of events in which the terrorist group takes part. Data from the Armed Conflict Location & Event Data Project (ACLED) gives the location and time of nearly 3,800 events in which Boko Haram has been involved since the organisation became violent 10 years ago. Using this dataset, we build an algorithm to detect the fragmentation of Boko Haram into multiple cells, assuming that travel costs and reduced familiarity with unknown locations limit the mobility of individual cells. Our results suggest that the terrorist group has a very high level of fragmentation and consists of at least 50–60 separate cells. Our methodology enables us to detect periods of time during which Boko Haram exhibits exceptionally high levels of fragmentation, and identify a number of key routes frequently travelled by separate cells of Boko Haram where military interventions could be concentrated.
Network analysis of regional livestock trade in West Africa
PLoS ONE · 2020 · 71 citations
- Computer Science
- Geography
- Economic geography
In West Africa, long and complex livestock value chains connect producers mostly in the Sahel with consumption basins in urban areas and the coast. Regional livestock trade is highly informal and, despite recent efforts to understand animal movement patterns in the region, remains largely unrecorded. Using CILSS' database on intraregional livestock trade, we built yearly and overall weighted networks of animal movements between markets. We mapped and characterized the trade networks, identified market communities, key markets and their roles. Additionally, we compared the observed network properties with null-model generated ensembles. Most movements corresponded to cattle, were made by vehicle, and originated in Burkina Faso. We found that live animals in the central and eastern trade basins flow through well-defined, long distance trade corridors where markets tend to trade in a disassortive way with others in their proximity. Modularity-based communities indicated that both national and cross-border trade groups exist. The network's degree and link distributions followed a log-normal or a power-law distribution, and key markets located primarily in urban centers and near borders serve as hubs that give peripheral markets access to the regional network. The null model ensembles could not reproduce the observed higher-level properties, particularly the propinquity and highly negative assortativity, suggesting that other possibly spatial factors shape the structure of regional live animal trade. Our findings support eliminating cross-border impediments and improving the condition of the regional road network, which limit intraregional trade of and contribute to the high prices of food products in West Africa. Although with limitations, our study sheds light on the abstruse structure of regional livestock trade, and the role of trade communities and markets in West Africa.
Frequent coauthors
- 49 shared
Denis Retaillé
Institut national de l’information géographique et forestière
- 16 shared
Allen M. Howard
- 16 shared
Christian Leuprecht
Royal Military College of Canada
- 12 shared
Laurent Matthey
University of Geneva
- 11 shared
Steven M. Radil
United States Air Force Academy
- 11 shared
David B. Skillicorn
- 10 shared
Christophe Sohn
Luxembourg Institute of Socio-Economic Research
- 9 shared
Bernard Reitel
Université d'Artois
Education
- 2006
Ph.D. in Geography
University of Lausanne
- 2004
Master of Advanced Studies in Development Studies
University of Geneva
- 2001
Master of Arts in Geography
University of Lausanne
- 1999
Bachelor of Arts
University of Lausanne
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