INTERNATIONAL HYDROLOGICAL PROGRAMME Ecohydrological processes in small basins Sixth Conference of the European Network of Experimental and Representative Basins (ERB) Strasbourg (France), 24-26 September 1996 IHP/UNESCO - ERB - CEREG (ULP/CNRS) PROCEEDINGS Edited by D. Viville and I.G. Littlewood IHP-VI Technical Documents in Hydrology I No. 14 UNESCO, Paris, 1997 I. The designations employed and the presentation of material throughout the publication do not Imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or of its authorities, or concerning the delimitation of its frontiers or boundaries. Preface To mark the tenth anniversary of the Experimental and Representative Basin (ERB)Network, it is timely to give a brief review of ERB achievements before introducing the Proceedings of the Strasbourg Conference. The ERB Network was founded in 1986. The main aims of the Network are to bring together European scientists involved in catchment and hydrological processes research, to ’ stimulate the exchange of information and results, and to encourage co-operation in research projects. Pursuit of these objectives is achieved through biennial ERB Conferences, the publication of a biannual Newsletter and the maintenance of a register of ERE3 catchments (ICARE - see later) operated by participating countries for long-term water balance studies and research into physical, hydrogeochemical and ecohydrological processes. Much of the work of ERB relates to small natural catchments but the development of methods for measuring, monitoring and assessing the impacts of environmental changes (e.g. afforestation, acidification, climate, land-use) on ecohydrological processes and systems at larger scales is a motivation for many of the projects carried out in ERB basins. For the tenth anniversary of the ERB Network, which was founded in Aix en Provence in 1986, it was most appropriate that the Conference returned to France. Previous Conferences were: 0 Aix-en-Provence (F), October 1986; 0 ‘Erosion and sediment transport’, Perugia (I) October 1988 (Proceedings published in: Quad. Idronomia Montana [Special Issue], A.I.D.I.,Fac. Di Agraria Univ. Padova); 0 ‘Hydrologicalresearch basins and the environment’, Wageningen (NL) September 1990 (TNOComm. on Hydrol.Res., Proc. and Informat.no. 44, The Hague, 347 pp); 0 ‘Methods of hydrological basin comparison’, Oxford (UK)September 1992 (Institute of Hydrology Rep. no. 120, Wallingford, 198 pp); a ‘Assessment of hydrological temporal variability and changes’, Barcelona (SP) September 1994 (Acta Geol. Hisp. [Special Issue] vol. 28 no. 2-3 [1993], Barcelona, 138 pp). Copies of the Wageningen, Oxford and Barcelona conference proceedings are still available on request. Each participating country provides a National Correspondent for the EFU3 whose nomination is supported and confirmed by the relevant Unesco International Hydrological Programme (IHP) Committee. Currently, the team of National Correspondents comprises: Belgium F.de Troch Czech Republic M.Tesar France D.Viville Germany A.Herrmann (ERB Coordinator, 1994 - 1998) Italy V.Anselmo Poland B.Wiezik Romania P.Mita Russia S. Zhuravin Slovakia P. Miklanek Spain F.Gallart Switzerland M.Spreafico The Netherlands P .Warmerdam United Kingdom I.G.Littlewood V The ERJ3 Newsletter is published approximately twice yearly and distributed widely among hydrologists throughout Europe. The Newsletter provides information about national and international activities, projects, research findings and publications, as well as progress with the ERB Inventory of -Catchments for Research in Europe (ICARE).ICARE provides a computer database of ERE3 Network basins (currently about 100 catchments in 13 countries), including their physical characteristics, instrumentation, available data, research aims and key publications. The database is maintained and continually updated by CEMAGREF in Lyon, France with information provided by the National Correspondents. Details of ICARE and ERB are available from http://wwwhh.lyon.cemagref.fr. ERB Conference “Ecohydrological Processes in Small Basins” These proceedings include 30 papers out of 29 oral and 15 poster presentations at the conference which were all invited for inclusion in this volume. The contributions cover current research carried out across south-west to Central Europe on ecohydrological processes in small basins and related topics. They focus mainly on the monitoring and modelling of soil-atmosphere interactions, runoff generation processes and water pathways, and water quality and hydrobiogeochemical behaviour at small basin scale. In this context, regionalisation and scale effects remain important unsolved problems which are frequently being discussed here, and probable effects of climate change on hydrological behaviour and mass budgets also. Accordingly, the selected Conference results published here largely fit many relevant discussions undertaken elsewhere, but they strictly concentrate on the process scale, with preference of both agricultural and forested basins. The main examples come from Spain, southern France, and Central Europe. ERB Network is encouraging working groups to get into contact and co-operate on joint scientific problems. Therefore, it is hoped that these Proceedings are of broad interest and help to establish new contacts. It may also encourage contributions to the next ERB Conference, “Catchment Hydrological and Biogeochemical Processes in Changing Environment”, to be held in Liblice, Czech Republic, September 22-24,1998. Finally, I should like to thank the local organisers of the Conference from CEREG-CNRS at Louis Pasteur University in Strasbourg, including the scientific and technical staff for the excellent organisation, and especially Daniel Viville who played his co-ordinating role perfectly, and was always a most co-operative counterpart. These proceedings were possible due to the commendable efforts of authors, referees and of course of both co-editors Daniel Viville, Strasbourg and Ian Littlewood of the Institute of Hydrology in Wallingford. Andreas Herrmann, ERB Coordinator (1994-1998) vi Note from the Editors These Proceedings comprise 30 papers presented orally as either full Papers or Posters at the Sixth Conference of the Experimental and Representative Basin (EM)network, “Ecohydrological Processes in Small Basins”, Strasbourg, September 24* - 26*, 1996. The Papers are grouped under four broad thematic headings corresponding to the four Sessions of the Conference: Evapotranspiration components and modelling; Surface water quality; Runoff formation, discharge generation and water pathways; and Runoff modelling. Manuscripts were refereed for their technical and scientific suitability for publication by the Chairman of the Session in which the Paper or Poster was presented orally at Conference. The Editors are greatly indebted to the following Session Chairman for undertaking the review procedure: A.Herrmann, Technical University, Braunschweig, Germany; P .M. M. Warmerdam, Wageningen Agricu 1tu ral University, The Netherlands; P.Chevalier, ORSTOM,France; and P. Miklanek, Institute of Hydrology SAS, Slovakia. AAer the technical and scientific review of the Papers, the Editors prepared the Proceedings for camera-ready printing and publication by Unesco. Readers of the Proceedings are requested to bear in mind that the Papers are all by authors whose first language is not English. While this is a noteworthy achievement in itself, the Editors believe that the authors might agree that the written English was better in some manuscripts than in others. Editing for the readability of the written English was undertaken without returning the manuscripts to authors for final proof-reading, spending about the same amount of time on each Paper. While care has been taken to introduce a uniformity of style throughout the Proceedings, the editorial result may still be a little uneven in places. If, for example, non-standard phrases are still encountered in the Proceedings, readers are requested to bear in mind the practical limits on resources which could be made available for such aspects of preparing the Papers for publication. Any technical errors introduced at this stage of preparation of the Proceedings are the responsibility of the Editors. Ian G.Littlewood, Institute of Hydrology, Wallingford, UK Daniel Viville, CEREG (CNRS - Louis Pasteur University), Strasbourg, France vii Conference "Ecohydrological Processes in Small Basins", Strasbourg,24 - 26 September 1996 Contents Evapotranspiration components and modelling Monitoring evapotranspiration and interception from grassland and forest patches overgrown in abandoned terraces at the Cal Parisa basin. LLORENS,P., ABRIL, M.,SALVANY, M.C., POW, R. AND GALLART,F. 1 A new concept for canopy water storage simulation in a 30-yearsold spruce stand (Strengbach catchment,Vosges, France) PFISER,L., VIVILLE, D., NAJJAR, G.,BRON, P., RICHARD, S. AND FISCHER,L. 7 Sap flow and micrometeorological measurements in the Strengbach catchment (Vosges mountains) for SVAT model validation BIRON,P., NAJJAR, G.,VIVILLE, D., GRANIER, A.AND DAMBRINE,E. 13 Sap flow measurement of floodplain forest of the Danube river MESZAROS,I. AND MOLNAR,L. 21 Evapotranspiration from the plant cover in the vegetation season TESAR,M., SIR, M.,PRAZAK, J. ANDBUCEK, J. 27 Soil water balance at a high-elevation site in the southern Black Forest Zmm,L.AND FEGER,K.H. 31 Development of an evapotranspiration model