Runoff characteristics in forest plots before and after wood ash fertilization

Spreading wood ash on forest and agricultural lands has been used for years to correct pH in acid soils and as a source of plant nutrients. However, it is necessary to enhance the knowledge of potential hazards derived from such a practise. Surface runoff pollution is one of these possible hazards. In this work we studied the quality of runoff water collected in two sloped forest plots before and after wood ash spreading, with the aim of checking potential undesirable effects of ash use. We have not found environmental pollution problems in runoff derived from the ash application zones. These results encourage further research and use of wood ash as an amendment in acid sloped forest soils.S

Effects of soil hydraulic properties on simulated hydrological response generated by LISEM 5.0

[Abstract] LISEM model (Limburg Soil Erosion Model) is actually being developped in order to perform dynamic simulations of surface runoff and erosion in catchments. This model is also proposed as analysis support system for soil erosion problems derived from agricultural management practices, which can be used as a kernel of an expert system for agricultural and environmental planning. Hydrological response of LISEM 5.0 is analysed on the basis of soil water flow parameter values of the Green-Ampt sub-model, which estimates infiltration rates. Observed hydrographs in the stream gauge installed in a catchment were tested with those simulated by LISEM 5.0. Observed hydrographs shows that the hydrological response of experimental catchment corresponds to a variable source type. By contrast, given the assumptions of LISEM 5.0 for calculating runoff , the calculated hydrological response is always hortonian.Results showed that, for any set of infiltration parameters, Green-Ampt infiltration submodel is not able to simulate the observed streamflow discharge (variable source). This occurs because the rainfall intensity-infiltration ratii do not allow a generalized hortonian surface runoff as predicted by LISEM 5.0. Hortonian runoff only may be possible at short times and limited to small areas, and does not appear to be significant in the observed hydrographs

Uso de un modelo basado en eventos para evaluar la conductividad hidráulica en una cuenca de pequeñas dimensiones

Los suelos de cultivo situados en pendiente y desarrollados sobre esquistos del Complejo de Órdenes en Galicia, se consideran sensibles a la acción de la escorrentía y a la erosión hídrica. Ello se debe al efecto conjunto de un clima húmedo con precipitaciones elevadas durante la estación invernal, a suelos de textura franca o franco-limosa que pueden encostrarse y a la topografía ondulada. Para luchar eficazmente en contra de los efectos adversos de la erosión y la escorrentía es importante conocer aquellos períodos de la estación húmeda en que la intensidad de la infiltración es de menor cuantía, en ausencia de cubierta vegetal. En este contexto se utilizó un modelo determinista con base física (LISEM), que funciona asociado a un SIG de tipo raster (PCRaster), para predecir la erosión y la escorrentía. Mediante el modelo LISEM se estimó la conductividad hidráulica a saturación (Ks) en una pequeña cuenca agrícola mediante el método de prueba y error, usando datos de precipitación y caudal. Las series de datos experimentales corresponden a ocho eventos medidos en la cuenca de 10,7 ha denominada Abelar durante el período 1997/1998. Dado que LISEM requiere una cantidad importante de parámetros de entrada, se utilizaron diferentes fuentes de información para obtener estos datos, incluyendo el calibrado del modelo, experiencia previas y nuevas observaciones de campo. En los ocho eventos estudiados la conductividad media de la cuenca se obtuvo usando un procedimiento de prueba y error. Para ello se activó una opción del modelo que permite estimar para cada evento la fracción de la conductividad hidráulica saturada considerada como óptima. De este modo, mediante la interfaz de LISEM, se modificó el porcentaje Ks con respecto al valor de referencia, hasta alcanzar un ajuste visual razonable entre el caudal medido y el simulado. Tras los ajustes, el valor del parámetro E de Nash-and-Sutcliffe (1970) obtenido fue de 0,51 y el valor medio del coeficiente de correlación entre datos medidos y simulados en r2 = 0,69. El valor más bajo de Ks fue 2,48 mm/h y se obtuvo durante un evento considerado como excepcional. En los restantes siete eventos este óptimo osciló entre 3,73 y 12,01 mm/h. La conductividad hidráulica puede presentar una disminución importante en otoño. Sin embargo, las menores intensidades de infiltración a escala de cuenca tienden a ocurrir a finales de invierno y comienzos de la primavera. En base a estos resultados, se recomienda que las acciones que puedan contribuir a reducir la escorrentía y por tanto la erosión del suelo apliquen durante dicho período, dado que en él los valores de conductividad hidráulica se alejan del óptimo durante un intervalo importante / The combination of a wet climate with elevated winter precipitation, loamy-silt or loamy soils prone to crusting and rolling terrain makes the cultivated slopes of soils developed over Ordenes schist parent material in Galicia sensible to soil erosion and overland flow. To efficiently counteract erosion and runoff, it is important to know when the infiltration rate in the winter season is lowest, in the absence of soil cover. For this purpose, a deterministic, physically-based soil erosion and runoff model (LISEM) coupled to a raster GIS (PCRaster) was used. With the aid of the LISEM model, saturated hydraulic conductivity (Ks) in a small agricultural catchment was estimated by the trial-and-error method from precipitation and discharge data. Experimental data sets were measured during eight events in the 10,7 ha-sized catchment of O Abelar in the winter season of 1997/1998. Since LISEM demands a number of input data, they were retrieved from several sources, including calibration, literature and additional field observations. The catchmentaveraged saturated hydraulic conductivity was inversely modelled by trail-and-error for all eight events. For this purpose a model option to estimate the fraction of the optimal saturated hydraulic conductivity was used. The effective percentage of saturated hydraulic conductivity within the LISEM interface was adjusted until a reasonable visually fit was reached between measured and modelled discharge. The model fits had an average Nash-and- Sutcliffe (1970) E of 0,51 and an average r2 of 0,69 between measured and simulated data was obtained. The lowest value of Ks was 2,48 mm/h which was reached during an event considered to be exceptional. For seven out of eight events this figure was between 3,73 and 12,01 mm/h. The hydraulic conductivity can already drop significantly during late-autumn events. However, in general late winter-early spring is the time with the lowest infiltration rate on catchment level. Thus, management measures to mitigate runoff and erosion are recommend to be applied especially during this period, since hydraulic conductivity is least optimal for a more prolonged timeGalicia. Consellería de Economía e Industria; PGIDT01 AGR10302 PRMinisterio de Ciencia y Tecnología; REN2000-04445-C02-01-H

Runoff characteristics in forest plots before and after wood ash fertilization

Spreading wood ash on forest and agricultural lands has been used for years to correct pH in acid soils and as a source of plant nutrients. However, it is necessary to enhance the knowledge of potential hazards derived from such a practise. Surface runoff pollution is one of these possible hazards. In this work we studied the quality of runoff water collected in two sloped forest plots before and after wood ash spreading, with the aim of checking potential undesirable effects of ash use. We have not found environmental pollution problems in runoff derived from the ash application zones. These results encourage further research and use of wood ash as an amendment in acid sloped forest soils

Freshwater biodiversity loss in urbanised rivers

Since the second half of the 20th century, when monitoring programmes were implemented as a measure to improve the water quality of rivers, numerous advantages have been achieved. one of the most remarkable advances was the integration of bioindicators as a suitable and quick tool to complement the assessment based on the evaluation of physical and chemical parameters. This paper evaluated which of the already used water quality indices based on macroinvertebrates would be more suitable to assess the ecological status of 6 rivers (Barxas, Deva, Tea, Manco, Louro and Furnia rivers) within the Mino ˜ River international basin (NW Spain and N Portugal) applying the methodology proposed by the Water Framework Directive (WFD). In addition, the relationship between the water quality and the land uses within a buffer zone of 100 along the watershed of each river was studied. Our findings demonstrate that the IBMWP (Iberian Biomonitoring Working Party) is the most suitable index to evaluate the water quality of rivers from this geographical zone. Nevertheless it is necessary to use other more sensitive index like EPT and PT indices to identify any potential pressures that might be concealed by IBMWP. The tributaries of the Mino ˜ River generally presented a good ecological status according to the IBMWP. Nevertheless, the Louro River had the lowest score for all the indices being the worst preserved among all within the basin. On the contrary Barxas, Deva and Furnia rivers showed the higher values. The results indicated that the most urbanised river was the Louro River (13 %) followed, to a lesser extent, by Manco River (7 %) and Tea River (2 %). Consequently, the Louro River had the worst water quality (poor quality) and a less diverse benthic macroinvertebrate community, in which more generalist taxa such as Chironomids, Ceratopogonids, or Crustaceans were found. On the other hand, the rivers with the best water quality were the Barxas, Deva, and Furnia, all of them with a negligible proportion of artificial cover surface (<1 %) within the delimited buffer zone. This would suggest a negative influence of the proportion of artificial areas over diversity and quality indices.Universidade de Vigo/CISU

Machine learning applied to the oxygen-18 isotopic composition, salinity and temperature/potential temperature in the Mediterranean sea

This study proposed different techniques to estimate the isotope composition (δ18O), salinity and temperature/potential temperature in the Mediterranean Sea using five different variables: (i–ii) geographic coordinates (Longitude, Latitude), (iii) year, (iv) month and (v) depth. Three kinds of models based on artificial neural network (ANN), random forest (RF) and support vector machine (SVM) were developed. According to the results, the random forest models presents the best prediction accuracy for the querying phase and can be used to predict the isotope composition (mean absolute percentage error (MAPE) around 4.98%), salinity (MAPE below 0.20%) and temperature (MAPE around 2.44%). These models could be useful for research works that require the use of past data for these variables.Universidade de Vigo | Ref. 0000 131H TAL 641Xunta de Galicia | Ref. ED431C 2018/42Xunta de Galicia | Ref. POS-B / 2016/00

Copper retention kinetics in acid soils

Retention and release kinetics of Cu on four acid Typic haplumbrepts developed on two different types of parent rock material (granite and amphibolite) were studied with a stirred-flow chamber (SFC) method. The granitic soils were lower in organic material and lower in Fe and Al oxides than the soils formed in amphibolite. The kinetic parameters were assessed in four consecutive Cu retention–release cycles by alternately applying pulses of solutions with and without Cu. Granite soils showed lower total Cu retention (7–12 mmol kg−1) than amphibolite soils (16–21 mmol kg−1) after one single pulse application of 0.0787 mmol Cu L−1 at pH 5.5, which may be due to differences in their organic and oxides compositions. The amount of Cu retained diminished to 40 to 25% in the third retention cycle relative to the first, suggesting that the soils’ Cu retention depends on the previous metal loading. Conversely, the released Cu was approximately 20% of that retained in the first cycle, but the amounts released were similar for all cycles and all soils. The results obtained were fitted using a first-order equation for both retention and release of Cu. In the first cycle, first order rate coefficients of retention ranged from 0.084 to 0.56 min−1, and increased by about a factor of two in the next cycle. Release rate coefficients were more than 10 times lower than those of retention, and less dependent on the previous metal loading. The process of retention and release of Cu was found to be hysteretic, which suggest that the desorption mechanism or path is not an exact opposite of the adsorption mechanism or path.Ministerio de Educación y Ciencia | Ref. AGL2006-04231/AG

The soil use conflict and food quality

Se discuten los problemas derivados de la intensificación del conflicto de los usos del suelo en base a las tres amenazas que pueden comprometer la calidad y seguridad alimentaria. Este trabajo se centra en analizar: A) la importancia de la conservación del suelo como protector de los recursos hídricos y las consecuencias de la mala ordenación de usos del suelo sobre la calidad del agua y los alimentos, B) el problema del empleo del suelo como receptor final de residuos orgánicos y la compatibilidad con su uso agrícola, C) finalmente se abordará el problema de la competencia del uso del suelo para la producción de energía, destacando el conflicto entre la producción de biocombustibles y alimentosWe discuss the problems arising from the intensification of the land use conflict on the basis of three main threats that may compromise the food safety and its quality. We focused on: (A) the importance of soil conservation to protect the water resources and the consequences of inadequate soil use planning on the water quality and food, (B)the problem of soil as destination of organic wastes and its use in agriculture, (C) finally we discuss the problem of the competence for energy production, highlighting the conflict between biofuels and food productionS