Browsing by Author "Samper, Javier"
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- Avaliação de recursos hídricos através de modelação hidrológica: aplicação do programa VISUAL BALAN v2.0 a uma bacia hidrográfica na Serra da Estrela (Centro de Portugal)Publication . Espinha Marques, Jorge; Samper, Javier; Pisani, B. V.; Alvares, D.; Vieira, Gonçalo; Mora, Carla; Carvalho, C.; Chaminé, Helder; Marques, J. M.; Sodré Borges, F.Numerical models are needed to evaluate complex hydrological systems. VISUAL BALAN v2.0 is a lumped hydrological code which performs daily water balances in the soil, the unsaturated zone and the aquifer requiring a small number of parameters. VISUAL BALAN has been used to model the river Zêzere catchment upstream of Manteigas (Serra da Estrela, Central Portugal), in order to assess its water resources. Modelling started with the definition of sub-basins based on hydrogeomorphological units. Then, daily temperature and precipitation data from Manteigas meteorological station were extrapolated to each sub-basin considering vertical gradients. Finally, modelling with VISUAL BALAN was performed in four stages: (i) physical characterisation of each sub-basin; (ii) preliminary calculations of the daily water balance; (iii) model calibration by means of flow measurements in the river Zêzere; (iv) result analysis. This basin exhibits complex patterns in hydrometeorological variables such as rainfall and temperature. Several sub-basins have been defined in order to account for the spatial variability in hydrometeorological and geomorphological variables. The model reproduces observed flowrates while its results are coherent with the conclusions of previous studies in similar basins.
- Evaluation of water resources in a high-mountain basin in Serra da Estrela, Central Portugal, using a semi-distributed hydrological modelPublication . Marques, Jorge Manuel Espinha; Samper, Javier; Pisani, B.; Alvares, D.; Carvalho, José Martins; Chaminé, Helder I.; Marques, José Manuel V. Barbosa; Vieira, Goncalo; Mora, Carla; Borges, Frederico SodréHigh-mountain basins provide a source of valuable water resources. This paper presents hydrological models for the evaluation of water resources in the highmountain Zezere 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 failsto 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 Zezere river. Computed stream flows are highly sensitive to soil thickness, whereas computed groundwater recharge is most sensitive to the interflow and percolation recession coefficients. 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.