Dryland Rivers: Process & Product 2002

This BSRG-supported conference was held at the University of Aberdeen between August the 7th and 10th 2002. The conference set out to promote cross discipline discussion, combining expertise from a wide range of academic and industrial workers. A total of 81 people attended 40 from industry, 41 from academia, including a number PhD students. Attendees were drawn from 10 Countries (GB, Norway, USA, Germany, Israel, Canada, Australia, Netherlands, Spain, France). Over a four day program including core workshops, presentations, field classes and the ensuing discussions, several key points were higlighted:

• Possible process misinterpretation in the rock record and the need to refine facies models to enhance understanding of core data sets and assist reservoir prediction.
• Importance of in-channel and bank vegetation in modern systems: would this have been as influential in ancient systems? For example, the propensity of pre-Devonian dryland sheet flood facies may be attributed to the lack of sediment binding grassy vegetation. How applicable, therefore, are models derived from modern analogue studies?
• Incorporation of dryland soil characteristics and their spatial variation to increase understanding of floodplain development and highlight the significance of palaeosols in the rock record; palaeosols can be used to infer local conditions, in contrast to channel facies which tend to reflect up stream tectono-climatic fluctuations.
• In addition, the application of recently defined dryland ichnofacies, with emphasis not only on intensity but specific type of bioturbation, will further enhance palaeoclimatic and geographic reconstructions.
• Definition of what constitutes a key surface in dryland systems to make regional correlations more reliable and aid construction of sequence stratigraphic frameworks is needed. This will contribute to the further enhancement of predictive facies models in reservoir evaluation.
• The preservation potential of present day dryland geomorphological systems is poor due to the dominance of high magnitude, low frequency events. A preservation bias towards high magnitude, low frequency flood events also exists in the rock record, with a proportionate lack of higher frequency "regular" flow regime deposits.
• Need for more analogue studies from the entire range of dryland settings: criteria for classification as a dryland river cannot be defined from one environmental setting only, or inferred from another.
• The need to increase understanding of tectonic and climatic signatures, not discounting subtle effects, thus addressing the key controlling factors of process magnitude and frequency. Cannot lose sight of the combined influence of tectonics and climate.

In conclusion, a suite of characteristics specific to dryland systems has not, as yet, been identified; there is therefore a pertinent need for greater cross discipline discussion and agreement upon definitive terminology, in addition to further collaborative research. The conference was very successful mixing a broad range of expertise and interests, and hopefully the contacts made will lead to increased collaboration between geomorphologists, academic geologists and petroleum geologists. We would like to thank BP, Shell, Conoco, Anadarko Algeria, Exxonmobil and TotalFinaElf for sponsoring the core workshop and the conference.

Alex Fordham & Gail Warwick