Water availability is essential for the appropriate analysis of its sustainable management. We performed a comparative study of six hydrological balance models (Témez, ABCD, GR2M, AWBM, GUO-5p, and Thornthwaite-Mather) in several basins with different climatic conditions within Spain in the 1977–2010 period. We applied six statistical indices to compare the results of the models: the Akaike information criterion (AIC), the Bayesian information criterion (BIC), Nash–Sutcliffe model efficiency coefficient (NSE), coefficient of determination (R2), percent bias (PBIAS), and the relative error between observed and simulated run-off volumes (REV). Furthermore, we applied the FITEVAL software to determine the uncertainty of the model. The results show that when the catchments are more humid the obtained results are better. The GR2M model gave the best fit in peninsular Spain in a UNEP aridity index framework above 1, and NSE values above 0.75 in a 95% confidence interval classify GR2M as very good for humid watersheds. The use of REV is also a key index in the assessment of the margin of error. Flow duration curves show good performance in the probabilities of exceedance lower than 80% in wet watersheds and deviations in low streamflows account for less than 5% of the total streamflow.

Abstract:The availability of precipitation data is the key driver in the application of hydrological models when simulating streamflow. Ground weather stations are regularly used to measure precipitation. However, spatial coverage is often limited in low-population areas and mountain areas. To overcome this limitation, gridded datasets from remote sensing have been widely used. This study evaluates four widely used global precipitation datasets (GPDs): The Tropical Rainfall Measuring Mission (TRMM) 3B43, the Climate Forecast System Reanalysis (CFSR), the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), and the Multi-Source Weighted-Ensemble Precipitation (MSWEP), against point gauge and gridded dataset observations using multiple monthly water balance models (MWBMs) in four different meso-scale basins that cover the main climatic zones of Peninsular Spain. The volumes of precipitation obtained from the GPDs tend to be smaller than those from the gauged data. Results underscore the superiority of the national gridded dataset, although the TRMM provides satisfactory results in simulating streamflow, reaching similar Nash-Sutcliffe values, between 0.70 and 0.95, and an average total volume error of 12% when using the GR2M model. The performance of GPDs highly depends on the climate, so that the more humid the watershed is, the better results can be achieved. The procedures used can be applied in regions with similar case studies to more accurately assess the resources within a system in which there is scarcity of recorded data available.

Abstract. The assessment of inflows in a water resources system is essential for the appropriate analysis of its management.These inflows can be obtained from hydrological balance models. In this paper, we intend to perform a comparative study of six lumped hydrological balance models in several basins with different climatic conditions within Spain. Lumped models enable the estimation of catchment resources without using spatially distributed information that would not be available in 10 many cases. We have selected basins where long time series of climatic and hydrological data are available (more than 30 years) to calibrate parsimonious models, taking into account the stochastic behaviour of the natural streamflow and the climatic variables. The study period comprises 34 years . The explored models are Témez, ABCD, GR2M, the Australian water balance model (AWBM), GUO-5 parameters (Guo-5p) and Thornthwaite-Mather. Six statistical indices are applied to compare the results of the models: Nash-Sutcliffe model efficiency coefficient (NSE), root-mean-square deviation (RMSE), 15Pearson's correlation coefficient (R), percent bias (PBIAS), RMSE-observations standard deviation ratio (RSR) and the relative error between observed and simulated runoff volumes (REV). The results show that although lumped models can be employed in humid and sub-humid regions, the more humid the catchments are, the better the results obtained. Témez models provide the worst results in dry sub-humid and semi-arid regions. Guo-5p estimates runoff volumes with errors below 10% despite the unsatisfactory results provided according to the Bressiani classification. The Bressiani classification takes into 20 account different comparison criteria to help in the decision-making process when selecting a model. Nevertheless, the assessment of the margin of error in total runoff volume using REV is also a key index. The usefulness of Pearson's correlation when selecting a model is quite low but can be helpful in the analysis of models' weaknesses.

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El estudio de la dinámica de los cauces efímeros mediterráneos (CEM) resulta de gran interés, al tratarse de sistemas geomorfológicos expuestos a importantes fluctuaciones recientes en los factores extrínsecos e intrínsecos que los gobiernan. Para obtener una aproximación a su modelo dinámico y comprender su adaptación a diferentes perturbaciones resulta vital el desarrollo de estudios a una escala temporal adecuada (décadas). En este trabajo, se analiza el potencial de los fotogramas aéreos históricos y la fotogrametría automatizada para generar modelos 3D y ortofotografías de CEM en diferentes fechas y tratar de analizar cambios morfológicos a partir de ellos. Se seleccionaron, a modo de ejemplo, varios tramos de dos ramblas en la cuenca del Segura (Rambla de Algeciras y Rambla de Valdelentisco) y otros tres en un curso efímero de la Cuenca del Ebro (Barranco de Tudela). Se emplearon fotogramas de los denominados vuelo americano B (1956) y vuelo interministerial (1973-1986), junto con puntos de apoyo naturales registrados con un sistema de posicionamiento global (GNSS) para alimentar técnicas de fotogrametría automatizada (Structure-from-Motion & Multi-View Stereo) y producir nubes de puntos, modelos digitales de superficie y ortofotografías. Fue necesario llevar a cabo algunas adaptaciones del flujo de trabajo fotogramétrico convencional a las características de los fotogramas (inclusión de marcas fiduciales, utilización de máscaras, uso de puntos naturales, etc.). Los resultados arrojaron un error cuadrático medio de los productos cartográficos que osciló entre 0,62 y 0,85 m con densidades volumétricas de las nubes de puntos resultantes de 1,03 a 4,47 pts·m-3. Por lo tanto, este enfoque metodológico podría emplearse en el análisis de cambios relevantes (>1 m) y para la descripción morfológica de los cauces e integrarse con cartografía reciente para una mejor compresión de su dinámica.