ORIGINAL ARTICLE Evaluation of water resources in a high-mountain basin in Serra da Estrela, Central Portugal, using a semi-distributed hydrological model J. Espinha Marques • J. Samper • B. Pisani • D. Alvares • J. M. Carvalho • H. I. Chamine ´ • J. M. Marques • G. T. Vieira • C. Mora • F. Sodre ´ Borges Received: 15 June 2009 / Accepted: 11 June 2010 / Published online: 6 July 2010 Ó Springer-Verlag 2010 Abstract High-mountain basins provide a source of valuable water resources. This paper presents hydrological models for the evaluation of water resources in the high- mountain Ze ˆzere river basin in Serra da Estrela, Central Portugal. Models are solved with VISUAL BALAN v2.0, a code which performs daily water balances in the root zone, the unsaturated zone and the aquifer and requires a small number of parameters. A lumped hydrological model fails to fit measured stream flows. Its limitations are overcome by considering the dependence of the temperature and precipitation data with elevation and the spatial variability in hydrogeomorphological variables with nine sub-basins of uniform parameters. Model parameters are calibrated by fitting stream flow measurements in the Ze ˆzere river. Computed stream flows are highly sensitive to soil thick- ness, whereas computed groundwater recharge is most sensitive to the interflow and percolation recession coeffi- cients. Interflow is the main component of total runoff, ranging from 41 to 55% of annual precipitation. High interflows are favored by the steep relief of the basin, by the presence of a high permeability soil overlying the fractured low permeability granitic bedrock and by the extensive subhorizontal fracturing at shallow depths. Mean annual groundwater recharge ranges from 11 to 15% of annual precipitation. It has a significant uncertainty due to uncertainties in soil parameters. This methodology proves to be useful to handle the research difficulties regarding a complex mountain basin in a context of data scarcity. Keywords High-mountain hydrology  Groundwater recharge  Water balance  Semi-distributed hydrological model  Serra da Estrela Introduction Mountain areas are the source of many large river systems. They usually represent some of the blackest ‘‘black boxes’’ in the hydrological cycle. The UNESCO International Hydrological Programme envisions high mountains as country’s water towers and considers the hydrology of mountain areas as one of the most essential water-related research issues (Aureli 2002). Although mountainous areas occupy a significant portion of the Earth land surface, water resources and groundwater systems in high-mountain regions are generally poorly understood (Forster and Smith 1988). J. Espinha Marques (&)  F. Sodre ´ Borges Dep. de Geocie ˆncias, Ambiente e Ordenamento do Territo ´rio, Faculdade de Cie ˆncias da Universidade do Porto, Centro de Geologia da Universidade do Porto (CGUP), Rua do Campo Alegre, 687, 4169-007 Porto, Portugal e-mail: jespinha@fc.up.pt J. Samper  B. Pisani  D. Alvares E.T.S. de Ingenieros de Caminos, Canales y Puertos, Universidad de La Corun ˜a, La Corun ˜a, Spain J. M. Carvalho  H. I. Chamine ´ Laborato ´rio de Cartografia e Geologia Aplicada (LABCARGA), Dep. de Engenharia Geote ´cnica, Instituto Superior de Engenharia do Porto and Centro GeoBioTec|UA, Porto, Portugal J. M. Marques Dep. de Engenharia de Minas e Georrecursos, Centro de Petrologia e Geoquı ´mica (CEPGIST), Instituto Superior Te ´cnico, Universidade Te ´cnica de Lisboa, Lisbon, Portugal G. T. Vieira  C. Mora Centro de Estudos Geogra ´ficos, Instituto de Geografia e Ordenamento do Territo ´rio, Universidade de Lisboa, Lisbon, Portugal 123 Environ Earth Sci (2011) 62:1219–1234 DOI 10.1007/s12665-010-0610-7