The water yield component of the SWRRB model was validated in a watershed of 125 ha, permanent stream flow, 35 percentage of steep gradient, sandy loam soils, seasonal rainfall and grassland vegetation, in Macapo, Cojedes State, Venezuela. Water yield was measured with a Stevens water level recorder installed in a gauge channel, and compared to the predicted water yield by the model. Using directs inputs, the model underestimated water yield (with relative differences between -100 and +800 percentage). In almost all cases, as well as rainy days, surface runoff was ignored. Base flow was ignored by the model. Subsurface runoff was the more important flow in terms of model perfomance. Flows behavior can be caused by the underestimation of the CN at the high values of retention constants. Using indirect inputs, it was obtained a higher, but more variable, water yield. Water yield was found very sensitive to Curve Number, Saturated Hydraulic Conductivity and Available Water Content, this shows the involved risk in the application of the model when estimated inputs are used. SWRRB must not be used for detailed planning and design in small watershed, but it may be useful to evaluate watershed degradation and response trends in terms of land use and management changes.

A partir de 18 variables características del hábitat actual de Quercus suber L. en el centro-oeste de España (Salamanca y Zamora), se ha cartografiado el área potencial climática para la especie así como los límites máximos de las áreas potenciales considerando no sólo los factores climáticos sino tres variables edafoclimáticas para dos hipótesis extremas de capacidad de retención de agua (CRA): CRA baja (50 mm) y CRA elevada (250 mm). Por último, se han tenido en cuenta las posibles limitaciones derivadas de la reacción del suelo. Los resultados obtenidos muestran la notable potencialidad climática de la zona para el alcornoque. Asimismo, se ha constatado que las áreas climática y edafoclimáticamente aptas para el alcornoque en el área española occidental de la cuenca del Duero presentan una notable dependencia de la CRA que condiciona no sólo su carácter central o marginal sino, en buena medida, su extensión. En la cuenca del Tajo, al sur de Salamanca, esta dependencia es notablemente menor.

Se analiza la forma y la intensidad de la contaminacion de caracter organico que experimenta el cauce del rio Mino a su paso por la comarca lucense de Terra Cha. Ademas se prueba que el nivel de precipitacion esta estrechamente relacionado con el grado de contaminacion humica registrada tanto en las aguas superficiales como en las subterraneas. La practica de riego con purin es la causa principal de la contaminacion detectada en las aguas de algunos pozos de aquella region. Por ultimo se deducen mejores correlaciones entre los paramentros de precipitacion-color del agua, precipitacion-oxidabilidad y color-oxidabilidad en los rios que en las aguas subterraneas.

Methods that use diurnal groundwater-level fluctuations are commonly used for shallow water-table environments to estimate evapotranspiration (ET) and recharge. The key element needed to obtain reliable estimates is the specific yield (Sy), a soil-water storage parameter that depends on unsaturated soil-moisture and water-table fluxes, among others. Soil-moisture profile measurement down to the water table, along with water-table-depth measurements, can provide a good opportunity to calculate Sy values even on a sub-daily scale. These values were compared with Sy estimates derived by traditional techniques, and it was found that slug-test-based Sy values gave the most similar results in a sandy soil environment. Therefore, slug-test methods, which are relatively cheap and require little time, were most suited to estimate Sy using diurnal fluctuations. The reason for this is that the timeframe of the slug-test measurement is very similar to the dynamic of the diurnal signal. The dynamic characteristic of Sy was also analyzed on a sub-daily scale (depending mostly on the speed of drainage from the soil profile) and a remarkable difference was found in Sy with respect to the rate of change of the water table. When comparing constant and sub-daily (dynamic) Sy values for ET estimation, the sub-daily Sy application yielded higher correlation, but only a slightly smaller deviation from the control ET method, compared with the usage of constant Sy.