Modelización en Geografía Física.-Preliminary results on uncertainties in rainfall interception estimation

ABSTRACT This work deals with some aspects of rainfall interception estimation uncertainty in a deciduous forest. The importance of interception loss measurement error is stressed. Confidence limits of Rutter original and sparse interception model parameters obtained from regressions for leafed and leafless period are presented, as well as free throughfall coefficient variability with event weather conditions

A review of rainfall interception modelling

This paper is a review of physically-based rainfall interception modelling. Fifteen models were selected, representing distinct concepts of the interception process. Applications of these models to field data sets published before March 2008 are also analysed. We review the theoretical basis of the different models, and give an overview of the models’ characteristics. The review is designed to help with the decision on which model to apply to a specific data set. The most commonly applied models were found to be the original and sparse Gash models (69 cases) and the original and sparse Rutter models (42 cases). The remaining 11 models have received much less attention, but the contribution of the Mulder model should also be acknowledged. The review reveals the need for more modelling of deciduous forest, for progressively more sparse forest and for forest in regions with intensive storms and the consequent high rainfall rates. The present review also highlights drawbacks of previous model applications. Failure to validate models, the few comparative studies, and lack of consideration given to uncertainties in measurements and parameters are the most outstanding drawbacks. Finally, the uncertainties in model input data are rarely taken into account in rainfall interception modellin

Morfología Fluvial.-Hidrología de un ambiente Mediterráneo de montaña. Las cuencas de Vallcebre (pirineo oriental) III. Vegetación y flujos de agua

ABSTRACT The Vallcebre research catchments are located in a Mediterranean mountain area (Pyrenean range, NE Spain). These catchments were originally covered by Quercus pubescens Willd. and deforested for agricultural use in the past. Nowadays they are covered by mesophyle grasses with spontaneous afforestation by Pinus sylvestris L. In this context, different investigations studying water fluxes in the soil-vegetation-atmosphere continuum have been performed. The main objective of these studies is the analysis and modelling of the role of vegetation cover on the catchment water balance in a framework of climate and land use changes. The dynamics of rainfall interception and transpiration by Scots pines and pubescens oaks, are investigated in terms of their dependence on meteorological conditions, on soil moisture and water table depth. Furthermore, the role of vegetation on catchment water balance is analysed. The results underline: (i) the importance of rainfall interception losses by both tree species and the high temporal variability of this flux, (ii) the effect of forest covers on soil moisture and (iii) the differences in transpiration between species, showing Scots pines a strong reduction of transpiration during droughts. Modelling results indicate that TOPBAL model (a developed version of TOPMODEL for an improved simulation of the response of catchments with diverse vegetation covers and high climatic seasonality) improved the simulation of the catchment water balance

Morfología Fluvial.-Hidrología de un ambiente Mediterráneo de montaña. Las cuencas de Vallcebre (Pirineo Oriental) I. 20 años de investigaciones hidrológicas

ABSTRACT The Vallcebre research catchments are located in a Mediterranean mountain area (Pyrenean range, NE Spain). These catchments were originally covered by Quercus pubescens Willd. and deforested for agricultural use in the past. Nowadays they are covered by mesophyle grasses with spontaneous afforestation by Pinus sylvestris L. In this context, different investigations studying water fluxes in the soil-vegetation-atmosphere continuum have been performed. The main objective of these studies is the analysis and modelling of the role of vegetation cover on the catchment water balance in a framework of climate and land use changes. The dynamics of rainfall interception and transpiration by Scots pines and pubescens oaks, are investigated in terms of their dependence on meteorological conditions, on soil moisture and water table depth. Furthermore, the role of vegetation on catchment water balance is analysed. The results underline: (i) the importance of rainfall interception losses by both tree species and the high temporal variability of this flux, (ii) the effect of forest covers on soil moisture and (iii) the differences in transpiration between species, showing Scots pines a strong reduction of transpiration during droughts. Modelling results indicate that TOPBAL model (a developed version of TOPMODEL for an improved simulation of the response of catchments with diverse vegetation covers and high climatic seasonality) improved the simulation of the catchment water balance

Global canopy interception from satellite observations

A new methodology for estimating forest rainfall interception from multisatellite observations is presented. The Climate Prediction Center morphing technique (CMORPH) precipitation product is used as driving data and is applied to Gash's analytical model to derive daily interception rates at global scale. Results compare well with field observations of rainfall interception (R = 0.86, n = 42). Global estimates are presented and spatial differences in the distribution of interception over different ecosystems analyzed. According to our findings, interception loss is responsible for the evaporation of approximately 13% of the total incoming rainfall over broadleaf evergreen forests, 19% in broadleaf deciduous forests, and 22% in needleleaf forests. The product is sensitive to the volume of rainfall, rain intensity, and forest cover. In combination with separate estimates of transpiration it offers the potential to study the impact of climate change and deforestation on the dynamics of the global hydrological cycle