ICSU Dark Nature


Aims, scope and workplan

IGCP 490

MEETING: Megafloods

Date: November 1 - 5, 2004

Place: Bobole, Mozambique


Throughout the geological history mega-floods have occurred in a great many places. The floods have had major impact on geomorphology, and during the Quaternary also on human societies. The cause of the floods varies, from drainage of ice-dammed lakes to the huge rainfalls associated with tropical cyclones.

In January 2000, coastal and lowland Mozambique experienced a period of catastrophic floods. Local settlements were destroyed, with disastrous consequences for the local population. Afterwards, many flood victims were offered new properties in safer localities. The experience has been, however, that many of them later preferred to move back to their old homesteads, which will be at risk during future flood events.

Many other parts of the world have experienced mega-floods during the past decades. Whether or not these are related to global warming is a question that is much debated. In order to understand this question it is important also to look at palaeorecords: Have mega-floods been more frequent during warm than cool climate episodes, and if so, in which part of the world is this to be expected during a possible future global warming?

The meeting in Mozambique addressed these questions, and focused in particular on the frequency and impact of recent and sub-recent mega-flood and flood action programmes:

The full programme of the meeting, abstracts, abstract volume (pdf) and list of participants is attached.

Achievements of Meeting

Meeting declaration

The workshop was organized by a group of four local geologists from the National Directorate of Geology and Department of Geology, University of Eduardo Mondlane. It was participated in by 29 scientists from 9 countries: Canada, India, Kenya, Mozambique, Norway, Poland, Uganda, UK and USA. For the local organizers it was in itself a capacity building to plan and carry out such an international meeting. The paper meeting and field trips were organized in an excellent way. The workshop had a very strong training component. 19 persons attended the full training programme, most of them from Africa.

The paper session included data from recent and sub-recent floods in North America, Europe and Africa, all of them focusing on sediment sequences and/or the impact on the societies. It did in particular give a very broad overview of the factors that cause mega-floods in different climate regions, and how a climate change will affect different climate regions in different ways, One lecture addressed actions plans based on the experiences from flood in Mozambique, which was a topic especially relevant for the other third world participants present.

The training course lectures by Dr. John Ridgway, Prof. Jim Teller, and Dr. Marek Graniczny in particular focused on how to analyze fluvial records in order to identify large floods. Dr. John Ridgway linked his talk to the Geoindicator initiative, and showed how to use geochemistry in the study of megafloods. Prof. Jim Teller focused his talk on where to find sediments from a flood and which methods and parameters could be used. He used a mega-flood from Manitoba as an example and showed how patchy the sediments may become, already some few years after a flood. Dr Graniczny addressed the application of satellite images and ground-motion monitoring in flood studies, using data from before during and after a flood.

The field trips gave all the participants, also the senior international scientists, a comprehensive and new insight into the mega - flood in 2000, including: the origin, duration and magnitude of the flood, its impact on the people living on the floodplains in the towns affected by the flood. Also the magnitude of the 2000 flood compared to earlier floods in the same areas was discussed, and the flood frequency related to climate was addressed. This was of great interest in order to discuss the flood frequency in different other countries in eastern and southern Africa. The discussions in the field were very important for the understanding of past flood events: Where to look for sediments, and which sediments to look for.

Outcome of Meeting

All papers presented at the meeting will be published in a special, high-quality volume of the Bulletin of the National Directorate of Mozambique, written in English and with abstracts also in Portuguese. The volume will also include a report from the training course. This volume will in particular be spread to a large number of African countries, where it will become an important contribution to joint African geoscience initiatives.

The organizers plan to publish papers related to Holocene flood history in a volume of Quaternary International. They have encouraged the participants to submit other papers (those that were related to the impact of recent floods on the societies) to Environmental Geology.

A summary of the highlights of the meeting will be published in the joint volume of the IGCP490 and ICSU Dark Nature projects.

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