Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2008)

This data set contains measurements of dissolved organic carbon in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

Collection of data on particulate and dissolved soil nitrogen in the Jena Experiment (Main Experiment, time series since 2002)

This data set contains four time series of particulate and dissolved soil nitrogen measurements from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. 1. Total nitrogen from solid phase: Stratified soil sampling was performed every two years since before sowing in April 2002 and was repeated in April 2004, 2006 and 2008 to a depth of 30 cm segmented to a depth resolution of 5 cm giving six depth subsamples per core. In 2002 five samples per plot were taken and analyzed independently. Averaged values per depth layer are reported. In later years, three samples per plot were taken, pooled in the field, and measured as a combined sample. Sampling locations were less than 30 cm apart from sampling locations in other years. All soil samples were passed through a sieve with a mesh size of 2 mm in 2002. In later years samples were further sieved to 1 mm. No additional mineral particles were removed by this procedure. Total nitrogen concentration was analyzed on ball-milled subsamples (time 4 min, frequency 30 s-1) by an elemental analyzer at 1150°C (Elementaranalysator vario Max CN; Elementar Analysensysteme GmbH, Hanau, Germany). 2. Total nitrogen from solid phase (high intensity sampling): In block 2 of the Jena Experiment, soil samples were taken to a depth of 1m (segmented to a depth resolution of 5 cm giving 20 depth subsamples per core) with three replicates per block ever 5 years starting before sowing in April 2002. Samples were processed as for the more frequent sampling but were always analyzed independently and never pooled. 3. Mineral nitrogen from KCl extractions: Five soil cores (diameter 0.01 m) were taken at a depth of 0 to 0.15 m (and between 2002 and 2004 also at a depth of 0.15 to 0.3 m) of the mineral soil from each of the experimental plots at various times over the years. In addition also plots of the management experiment, that altered mowing frequency and fertilized subplots (see further details below) were sampled in some later years. Samples of the soil cores per plot (subplots in case of the management experiment) were pooled during each sampling campaign. NO3-N and NH4-N concentrations were determined by extraction of soil samples with 1 M KCl solution and were measured in the soil extract with a Continuous Flow Analyzer (CFA, 2003-2005: Skalar, Breda, Netherlands; 2006-2007: AutoAnalyzer, Seal, Burgess Hill, United Kingdom). 4. Dissolved nitrogen in soil solution: Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for nitrate (NO3-), ammonium (NH4+) and total dissolved nitrogen concentrations with a continuous flow analyzer (CFA, Skalar, Breda, The Netherlands). Nitrate was analyzed photometrically after reduction to NO2- and reaction with sulfanilamide and naphthylethylenediamine-dihydrochloride to an azo-dye. Our NO3- concentrations contained an unknown contribution of NO2- that is expected to be small. Simultaneously to the NO3- analysis, NH4+ was determined photometrically as 5-aminosalicylate after a modified Berthelot reaction. The detection limits of NO3- and NH4+ were 0.02 and 0.03 mg N L-1, respectively. Total dissolved N in soil solution was analyzed by oxidation with K2S2O8 followed by reduction to NO2- as described above for NO3-. Dissolved organic N (DON) concentrations in soil solution were calculated as the difference between TDN and the sum of mineral N (NO3- + NH4+).

Seasonally aggregated values of dissolved inorganic phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2003)

This data set contains measurements of inorganic phosphorus in samples of soil solution collected in 2003 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below) that have been aggregated to seasonal values. In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved inorganic P (PO4P). Here volume-weighted mean values are provided as aggregated seasonal values (spring = March to May, summer = June to August, fall = September to November, winter = December to February) for 2003 in spring, fall, and winter. To calculate these values, the sampled volume of soil solution is used as weight for P concentrations of the respective sampling date. Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (CFA SAN++, Skalar [Breda, The Netherlands]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.02 mg P l-1 (CFA, Skalar).

Seasonally aggregated values of dissolved inorganic phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2005)

This data set contains measurements of inorganic phosphorus in samples of soil solution collected in 2005 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below) that have been aggregated to seasonal values. In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved inorganic P (PO4P). Here volume-weighted mean values are provided as aggregated seasonal values (spring = March to May, summer = June to August, fall = September to November, winter = December to February) for 2005 in spring, and winter. To calculate these values, the sampled volume of soil solution is used as weight for P concentrations of the respective sampling date. Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (CFA Autoanalyzer [Bran&Luebbe, Norderstedt, Germany]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.04 mg P l-1 (Autoanalyzer, Bran&Luebbe).

Dissolved phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2002)

This data set contains measurements of dissolved phosphorus (total dissolved nitrogen: TDP, dissolved inorganic phosphorus: PO4P and dissolved organic phosphorus: DOP) in samples of soil water collected in 2002 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled bi-weekly, in 2002 at the 23.10.2002; 05.11.2002; 20.11.2002; 05.12.2002; and 28.12.2002, and analyzed for dissolved inorganic P (PO4P) and total dissolved phosphorus (TDP). Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (CFA SAN++, Skalar [Breda, The Netherlands]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. Total dissolved P in soil solution was analyzed by irradiation with UV and oxidation with K2S2O8 followed by reaction with ammonium molybdate (Skalar catnr. 503-553w/r). As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.02 mg P l-1 (CFA, Skalar). Dissolved organic P (DOP) in soil solution was calculated as the difference between TDP and PO4P. In a low number of samples, TDP was equal to or smaller than PO4P; in these cases, DOP was assumed to be zero.

Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of dissolved organic carbon in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

Dissolved nitrogen in soil solution of the Jena Experiment (Main Experiment, year 2002)

This data set contains measurements of dissolved nitrogen (total dissolved nitrogen: TDN, dissolved organic nitrogen: DON, dissolved ammonium: NH4+, and dissolved nitrate: NO3-) in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for nitrate (NO3-) and ammonium (NH4+) concentrations with a continuous flow analyzer (CFA, Skalar, Breda, The Netherlands). Nitrate was analyzed photometrically after reduction to NO2- and reaction with sulfanilamide and naphthylethylenediamine-dihydrochloride to an azo-dye. Our NO3- concentrations contained an unknown contribution of NO2- that is expected to be small. Simultaneously to the NO3- analysis, NH4+ was determined photometrically as 5-aminosalicylate after a modified Berthelot reaction. The detection limits of NO3- and NH4+ were 0.02 and 0.03 mg N L-1, respectively. Total dissolved N in soil solution was analyzed by oxidation with K2S2O8 followed by reduction to NO2- as described above for NO3-. Dissolved organic N (DON) concentrations in soil solution were calculated as the difference between TDN and the sum of mineral N (NO3- + NH4+). In 5% of the samples, TDN was equal to or smaller than mineral N. In these cases, DON was assumed to be zero.

Dissolved nitrogen in soil solution of the Jena Experiment (Main Experiment, year 2003)

This data set contains measurements of dissolved nitrogen (total dissolved nitrogen: TDN, dissolved organic nitrogen: DON, dissolved ammonium: NH4+, and dissolved nitrate: NO3-) in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for nitrate (NO3-) and ammonium (NH4+) concentrations with a continuous flow analyzer (CFA, Skalar, Breda, The Netherlands). Nitrate was analyzed photometrically after reduction to NO2- and reaction with sulfanilamide and naphthylethylenediamine-dihydrochloride to an azo-dye. Our NO3- concentrations contained an unknown contribution of NO2- that is expected to be small. Simultaneously to the NO3- analysis, NH4+ was determined photometrically as 5-aminosalicylate after a modified Berthelot reaction. The detection limits of NO3- and NH4+ were 0.02 and 0.03 mg N L-1, respectively. Total dissolved N in soil solution was analyzed by oxidation with K2S2O8 followed by reduction to NO2- as described above for NO3-. Dissolved organic N (DON) concentrations in soil solution were calculated as the difference between TDN and the sum of mineral N (NO3- + NH4+). In 5% of the samples, TDN was equal to or smaller than mineral N. In these cases, DON was assumed to be zero.

Nonlinear and Scaling Processes in Hydrology and Soil Science

Hydrology is the study of the properties, distribution and effects of water on the Earth?s soil, rocks and atmosphere. It also encompasses the study of the hydrologic cycle of precipitation, runoff, infiltration, storage, and evaporation, including the physical, biological and chemical reaction of water with the earth and its relation to life?.

Caracterización de los parámetros de resistencia al corte y erosionabilidad del suelo para su aplicación en los problemas de estabilidad de taludes en obras lineales

La tesis se organiza en un volumen de Memoria integrada por once capítulos que constituyen el cuerpo de la tesis y otro volumen de Apéndices titulado “Caracterización geotécnica de Base de los suelos de España” que reúne en forma de cuadros las características de textura, permeabilidad, humedad-succión, erosionabilidad y resistencia al corte de los cuarenta y dos perfiles de suelos representativos de los tipos del Mapa de suelos De España. Estos cuadros han sido elaborados originalmente por la doctorando durante sus estudios para la obtención del DEA de la Suficiencia Investigadora, excepto los de resistencia al corte que lo han sido también por la doctorando de forma original, pero ya en la etapa de redacción de la tesis. En el Capítulo 1 “Introducción” se describe la motivación, antecedentes, alcance y contenido de la tesis, ordenado según el índice que en él se incluye. Los Capítulos 2 “Meteorización, 3 “Balance Hídrico” y 4 “Humedades características” constituyen el “estado del arte” en el momento actual de los temas de geotecnia ambiental relacionados con la degradación de la superficie terrestre y la estabilidad de taludes. El Capítulo 2, tras matizar algunas generalidades, aporta elementos para la cuantificación de la alteración de rocas como el “índice climático de Weinert” y de la erosión de suelos como la “ecuación universal de pérdida de suelo (U.S.L.E.)” El Capítulo 3, partiendo de los fenómenos de precipitación y evapotranspiración, plantea el balance hídrico en vertientes con instrumentos para evaluar la infiltración y la escorrentía, conceptos imprescindibles para adentrarse en los de resistencia y erosionabilidad del conjunto suelo-agua. En los Apéndices A1 y A2, se recogen valores de coeficientes de infiltración en condiciones saturadas y no saturadas de los perfiles de suelos del Mapa de España. El Capítulo 4 se dedica al estudio de este conjunto suelo-agua con la definición de conceptos que lo caracterizan, basados en la relación entre los contenidos de ambos elementos o “humedad”, sus valores máximos y mínimos y la forma en la que es retenida el agua por el suelo. Este capítulo acaba con el concepto de “Curva característica Suelo-Agua/Soil Water Characteristic curve (SWCC)”, que liga el contenido de agua de un suelo con la tensión a la que está retenida (uauw) “succión” o con su expresión más usual “pF”. En el Apéndice A 3 se adjuntan las SWCC de los perfiles de suelos del Mapa de suelos de España. En el Capítulo 5 “Resistencia al corte de los suelos”, se detalla la influencia que tienen sobre la resistencia de los suelos factores como el paso del tiempo, el contenido de humedad y la presencia y tipo de vegetación en la superficie del suelo estudiado. El Capítulo 6 “Evaluación de la erosión”, analiza el factor de erosionabilidad del suelo “factor K” de la U.S.L.E., su evaluación en función de la textura, estructura y permeabilidad del suelo, con la estimación hecha para los cuarenta y dos perfiles de suelos del Mapa de España, contenida en el Apéndice 4. En el Capítulo 7 “Metodología de diseño” se hacen en su primera parte unas consideraciones geoambientales de diseño aplicables al estudio de los problemas de inestabilidades en taludes. La segunda parte constituye el núcleo de la tesis con la propuesta de “estimación de los parámetros de resistencia al corte del suelo”, consecuente con las teorías y metodología de análisis expuesta en los capítulos anteriores. En el Apéndice A 5 se presentan los valores de los parámetros coulombianos de resistencia al corte, ”c y Ф” estimados según la caracterización climática a partir del índice de Thornthwaite, en condicionesde diseño para humedades naturales máxima y mínima de los cuarenta y dos perfiles de suelos del Mapa de suelos de España. El Capítulo 8 “Aplicación a casos reales” se considera de gran interés al constituir una auténtica continuación de la segunda parte del capítulo anterior, desarrollando la metodología expuesta en él a cuatro problemáticas de infraestructuras de obras lineales, relacionadas con problemas de erosión y deslizamientos en taludes. El Capítulo 9 “Ensayos de referencia” se incluye como punto de apoyo (referencia) a las teorías expuestas, valorando la idoneidad de los tipos de ensayos y tipos de suelos seleccionados (Laboratorio de Geotecnia del CEDEX y Laboratorio Hong-Kong University of Science and Technology), utilizados para la obtención, por correlaciones deducidas, de las curvas SWCC de los perfiles de suelos del Mapa de España, incluídas en el Apéndice A 3, como se ha citado antes. En el Capítulo 10 “Conclusiones y Futuras Líneas de Investigación”se apuntan en primer lugar unas conclusiones que, a juicio de la doctorando, se pueden extraer con interés de esta tesis y a continuación se esbozan unas posibles líneas de investigación, fundamentalmente de tipo experimental, que complementarían los avances derivados de esta tesis o podrían esclarecer y abrir nuevas interpretaciones de los fenómenos naturales de erosión y estabilidad de taludes en los que ésta se ha centrado. Finalmente, en el Capítulo 11 “Bibliografía” se han reunido 328 referencias que reflejan una visión amplia y bastante completa del tema tratado, obtenida complementando las de tesis anteriores sobre esta singular materia (“Efecto estabilizador de la vegetación en taludes”, L Fort 1975 y “Determinación de las características de fricción en el contacto suelo-geotextil a diferentes succiones, mediante equipos de laboratorio singulares”, E Asanza 2009), con propias de la doctorando (9) y las consideradas de mayor interés de los últimos Congresos sobre Suelos no saturados,”Unsat 95”, “Unsat 2002” y “Unsat 2011” entre otros. ABSTRACT The thesis is organized in a volume of Memory composed of eleven chapters that make up the body of the thesis and other Appendices volume entitled "Geotechnical characterization of basis of the soils of Spain" that combines the characteristics of texture, permeability, moisture-suction, erosionability, and shear strength of forty-two profiles of soils representative of the types of the soil of Spain map in the form of pictures. These pictures have been produced originally by the student during their studies to obtain the DEA of the research, except those of the shear strength, also been done by the PhD student in an original way, but already at the stage of drafting of the thesis. Chapter 1 "Introducción" describes the motivation, background, scope and content of the thesis, ordered according to the index that is included. The Chapters: 2 "Weathering, 3 “Water Balance” and 4 “moisture characteristics" are the "State of the art" at the present time of geotechnical environmental issues related to the degradation of the Earth's surface and the slope stability. Chapter 2 after clarify some general information, provides elements for the quantification of the alteration of rocks as "Weinert climate index" and soil erosion as the "universal equation of loss of soil (U.S.L.E.)" Chapter 3, on the basis of the phenomena of precipitation and evapotranspiration, raises the water balance in sheds with instruments to evaluate infiltration and runoff, essential concepts into the resistance and erosionability water-soil joint. Values of soils coefficients of infiltration in saturated and unsaturated conditions from the Spain map of profiles are collected in the Appendices A1 and A2. Chapter 4 is dedicated to the study of this joint “soil-water”, with the definition of concepts that characterize it, based on the relationship between the contents of both elements or “moisture”, their maximum and minimum values and the way in which water is retained by the soil. This chapter ends with the concept of “Soil Water Characteristic curve (SWCC)", which linked the water content of a soil with the stress that it is retained (ua-uw) "suction" or its expression more usual "pF". The SWCC of the profiles of soils of the Spain soils Map are attached in the Appendix 3. In Chapter 5 “Soils shear strength”,is detailed the influence that they have on the resistance of soils factors such as the passage of time, the content of moisture and the presence and type of vegetation on the surface of the studied soil. Chapter 6 "Assessment of erosion", analyses the soil erodibility factor "Kfactor" of the U.S.L.E., its evaluation based on texture, structure and permeability of the soil, with the estimate for forty-two profiles of soils on the Spain Soils Map, contained in Appendix 4. Chapter 7 "Design methodology" some considerations are made in the first part geo-environmental design applicable to the study of the problems of instabilities in slopes. The second part constitutes the core of the thesis with the proposal of “estimation of parameters of shear strength”, of the soils consistent with theories and analytical methodology outlined in the previous chapters. Appendix A 5 presents the values of the coulombians parameters of shear strength, "c and Ф" according to the characterization of climate from the index of Thornthwaite, in design for natural moisture conditions maximum and minimum of forty-two profils of Spain Soils Map Chapter 8 "Application to real cases" is considered of great interest to constitute a true continuation of the second part of the previous chapter, developing the methodology exposed it to four problems of civil-works infrastructure, related to problems of erosion and landslides in slopes. Chapter 9 "Tests of reference" is included as point of support (reference) to the theories exposed, assessing the suitability of the types of tests and types of selected soils (Geotechnical laboratory of CEDEX and laboratory Hongkong University of Science and Technology), used to obtain, by deduced correlations, of curves SWCC of soils profiles on the Spain Soils Map, included in Appendix A. 3, as it was mentioned before. Chapter 10 "Conclusions and future research lines" are running first conclusions which, in the opinion of the candidate, can be extracted with interest of this thesis, and then, it outlines some possible lines of research, mainly experimental, which would complement the advances arising from this thesis or could clarify and open new interpretations of natural phenomena of erosion and slope stability in which it has focused. Finally, in Chapter 11 "Bibliography" 328 references have been included which reflect a broad and fairly comprehensive view of the subject matter, obtained complementing those of the previous theses on this singular issue ("Vegetation stabilizing effect on slopes", L Fort 1975, and "Determination of the characteristics of friction in the contact soil-geotextile to different-suctions, through special laboratory equipment", E Asanza 2009) with some of them from of the candidate (9) and the others from of the considered as the most interesting of recent conferences on unsaturated soils, "Unsat 95", "Unsat2002" and "Unsat 2011" among others.

Dispersivity Determination Through a Modeling Approach From a Tracer Test Based on Total Br Concentration in Soil Samples

Determination of reliable solute transport parameters is an essential aspect for the characterization of the mechanisms and processes involved in solute transport (e.g., pesticides, fertilizers, contaminants) through the unsaturated zone. A rapid inexpensive method to estimate the dispersivity parameter at the field scale is presented herein. It is based on the quantification by the X-ray fluorescence solid-state technique of total bromine in soil, along with an inverse numerical modeling approach. The results show that this methodology is a good alternative to the classic Br− determination in soil water by ion chromatography. A good agreement between the observed and simulated total soil Br is reported. The results highlight the potential applicability of both combined techniques to infer readily solute transport parameters under field conditions.

Investigations of evaporation from a screened pan and development of a coefficient for the conversion of pan evaporation to lake evaporation /

Mode of access: Internet.

Quantifying effects of soil heterogeneity on groundwater pollution in four sites in the USA

Four sites located in the north-eastern region of the United States of America have been chosen to investigate the impacts of soil heterogeneity in the transport of solutes (bromide and chloride) through the vadose zone (the zone in the soil that lies below the root zone and above the permanent saturated groundwater). A recently proposed mathematical model based on the cumulative beta distribution has been deployed to compare and contrast the regions' heterogeneity from multiple sample percolation experiments. Significant differences in patterns of solute leaching were observed even over a small spatial scale, indicating that traditional sampling methods for solute transport, for example the gravity pan or suction lysimeters, or more recent inventions such as the multiple sample percolation systems may not be effective in estimating solute fluxes in soils when a significant degree of soil heterogeneity is present. Consequently, ignoring soil heterogeneity in solute transport studies will likely result in under- or overprediction of leached fluxes and potentially lead to serious pollution of soils and/or groundwater. The cumulative beta distribution technique is found to be a versatile and simple technique of gaining valuable information regarding soil heterogeneity effects on solute transport. It is also an excellent tool for guiding future decisions of experimental designs particularly in regard to the number of samples within one site and the number of sampling locations between sites required to obtain a representative estimate of field solute or drainage flux.

Process, performance, and pollution potential: A review of septic tank-soil absorption systems

On-site wastewater treatment and dispersal systems (OWTS) are used in non-sewered populated areas in Australia to treat and dispose of household wastewater. The most common OWTS in Australia is the septic tank-soil absorption system (SAS) - which relies on the soil to treat and disperse effluent. The mechanisms governing purification and hydraulic performance of a SAS are complex and have been shown to be highly influenced by the biological zone (biomat) which develops on the soil surface within the trench or bed. Studies suggest that removal mechanisms in the biomat zone, primarily adsorption and filtering, are important processes in the overall purification abilities of a SAS. There is growing concern that poorly functioning OWTS are impacting upon the environment, although to date, only a few investigations have been able to demonstrate pollution of waterways by on-site systems. In this paper we review some key hydrological and biogeochemical mechanisms in SAS, and the processes leading to hydraulic failure. The nutrient and pathogen removal efficiencies in soil absorption systems are also reviewed, and a critical discussion of the evidence of failure and environmental and public health impacts arising from SAS operation is presented. Future research areas identified from the review include the interactions between hydraulic and treatment mechanisms, and the biomat and sub-biomat zone gas composition and its role in effluent treatment.

Artificial pumping errors in the Kool-Parker scaling model of soil moisture hysteresis

Hysteresis models that eliminate the artificial pumping errors associated with the Kool-Parker (KP) soil moisture hysteresis model, such as the Parker-Lenhard (PL) method, can be computationally demanding in unsaturated transport models since they need to retain the wetting-drying history of the system. The pumping errors in these models need to be eliminated for correct simulation of cyclical systems (e.g. transport above a tidally forced watertable, infiltration and redistribution under periodic irrigation) if the soils exhibit significant hysteresis. A modification is made here to the PL method that allows it to be more readily applied to numerical models by eliminating the need to store a large number of soil moisture reversal points. The modified-PL method largely eliminates any artificial pumping error and so essentially retains the accuracy of the original PL approach. The modified-PL method is implemented in HYDRUS-1D (version 2.0), which is then used to simulate cyclic capillary fringe dynamics to show the influence of removing artificial pumping errors and to demonstrate the ease of implementation. Artificial pumping errors are shown to be significant for the soils and system characteristics used here in numerical experiments of transport above a fluctuating watertable. (c) 2005 Elsevier B.V. All rights reserved.