Congreso Internacional sobre Desertificación.

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Open Access
El uso de parámetros edáficos como indicadores de riesgo de erosión. Rambla de Las Moreras, Murcia, SE de España
(2020-03-30) Romero Díaz, María Asunción; Quiñonero Rubio, J.M; Ortiz Silla, R.; Sánchez Navarro, Antonio; Fernández-Delgado Juárez, M.; Gil Vazquez, J.M.; Departamento de Geografía, Universidad de Murcia, Campus de La Merced; Centro de Edafología y Biología Aplicada del Segura (CEBAS), CSIC; Departamento de Química Agrícola, Geología y Edafología, Universidad de Murcia
Uno de los factores que más interviene en la erosión del suelo es su erodibilidad, es decir, la vulnerabilidad que el suelo tenga a la erosión. En este trabajo se estudian varios parámetros (textura, estructura, materia orgánica, profundidad, pedregosidad y cobertura vegetal) en la cuenca de la Rambla de Las Moreras (Murcia) con el objetivo de determinar si algunos de ellos pudieran servir de indicadores de riesgo de erosión. Los resultados muestran como la materia orgánica y la estabilidad de agregados pueden ser buenos indicadores de ello.
Open Access
Estimación de volúmenes de suelo perdido por procesos de erosión por piping. Sureste de España.
(2020-03-30) Romero Díaz, María Asunción; Plaza Martínez, J.F; Sánchez Soriano, A.; Belmonte Serrato, F.; Ruiz Sinoga, J.D; Departamento de Geografía, Universidad de Murcia, Campus de La Merced; Departamento de Geografía, Universidad de Málaga, Campus de Teatinos
Piping processes have been widely studied in many countries and regions, but especially in arid environments, on marl soils, reach a great development. We studied eight areas affected by piping, located in the Basin of Mula (Murcia), on terraced farmlands and abandoned about 40 years ago. Have been evaluated sediments mobilized by this process and erosion rates. The erosion rate per plot is 287 t/ha/year, undoubtedly, a very high value of soil losses. For this it is necessary soil conservation practices when these fields are abandoned.
Open Access
African and local wind-blown dust contributions at three rural sites in SE Spain: the aerosol size distribution
(2020-04-03) Orza, J.A.G.; Cabello, M.; Lidón, V.; Martínez, J.; SCOLAb, Física Aplicada, Universidad Miguel Hernández; Aeolian Erosion Research Group, Universidad Miguel Hernández
The entrainment of particulate material into the atmosphere by wind action on surface soils both disturbed and natural, as well as directly due to human activities like agricultural practices, mineral industry operations, construction works and traffic, is a significant contribution to the aerosol load in Mediterranean semi-arid areas. A further crustal contribution in the region comes from the frequent arrival of African mineral dust plumes. We summarize some of the results obtained after 4-6 -month campaigns at three rural sites in SE Spain where the aerosol number size distribution (31 size bins between 0.25 and 32 μm) was continuously measured. The influence of both local wind speed and the arrival of air masses loaded with African dust on the airborne particulate distribution is assessed. Similarities and differences between the three locations give information that allows a better understanding of the influence of both local wind speed and African dust outbreaks (ADO), while highlight what is mostly related to local features.
Open Access
Aplicación de técnicas hiperespectrales de imagen al estudio de la degradación de suelos en ambientes áridos (Los Monegros, España)
(2020-04-03) Gumuzzio Such, A.; Palacios Orueta, A.; Schmid, T.; Dominguez, J.A.; Gumuzzio, J.; E.T.S.I Montes de Madrid. Departamento de Silvopascicultura, Ciudad Universitaria; CIEMAT, Departamento de Medioambiente, Avda. Complutense; Centro de Estudios Hidrográficos CEDEX; Departamento de Geología y Geoquímica. Universidad Autónoma de Madrid
The aim of this work is to identify characteristics associated to soils affected by degradation within an arid area of Spain using optical hyperspectral airborne data. The methodological approach was developed to determine the spatial distribution of selected soils affected by degradation processes. A satisfactory spatial distribution is obtained where the corresponding soil characteristics are closely related to degradation processes.
Open Access
An evaluation of the MEDALUS ESA index (environmental sensitivity to land degradation), from regional to plot scale
(2020-04-03) Lavado Contador, J. F; Schnabel, S; Gómez Gutiérrez, A.; Grupo de Investigación GeoAmbiental, Universidad de Extremadura
An assessment of the sensitivity to land degradation have been carried out for the region of Extremadura, SW Spain, by means of the modelling approach developed in the European Commission funded MEDALUS project (Mediterranean Desertification and Land Use) which identifies such areas on the basis of an index (ESA index) that incorporates data on environmental quality (climate, vegetation, soil) as well as on anthropogenic factors (management). Two maps of environmental sensitivity to degradation with different legend resolution (4 and 8 classes of sensitivity) have been made. The results of the model were validated at different spatial scales, i.e.; regional and farm scales. True field data on degradation-related variables at the different spatial scales have been used in order to undertake the validation procedures. Selected farms covering different physiographical and socioeconomic characteristics were used to gather data at farm scale. Data gathered from the National Inventory of Soil Erosion was also used to validate the model at the regional scale.
Open Access
Analysing the factors affecting gully development and their relationships with land-use changes in the east Alentejo (Portugal)
(2020-04-03) Roxo, M. J.; Calvo-Cases, A.; Departamento de Geografia e Planeamento Regional, Universidade Nova de Lisboa; Departament de Geografia, Universitat de Valencia
The land abandonment and land-use changes as a consequence of the implementation of the European Union Common Agricultural Policy (C.A.P.), in the SE of Portugal, have been generating, differences in the equilibrium of the geomorphic processes. The head waters catchments of some of the Guadiana River tributaries show in the study area several degrees of gully initiation and development both on the hillsides and valley bottom infill. This gully generation process is closely related with the changes in the soil and cover properties occurring when agricultural practises have been replaced by intensive grazing areas or by abandoned land. High resolution panchromatic and Landsat images, dating from the last 40 years have been analysed in combination with field observations and the analysis of the data from soil erosion plots series in the Estação Experimental de Vale Formoso, in order to establish and parameterise the sequence of changes in soil surface properties and vegetation cover and distribution. The results show the connection between the different degrees of gully development and their morphological characteristics with the land cover properties at different times and after different sequences of land-use changes
Open Access
A procedure to derive intra- and inter-annual changes on vegetation from NDVI time series. A case study in Spain.
(2020-04-03) Gilabert, M.A.; Martínez, B.; Meliá, J.; Departament de Física de la Terra i Termodinàmica, Universitat de València.
The NDVI time series are characterized by patterns like seasonality, trends and localized abrupt changes or discontinuities resulting from disturbance events. Therefore, they allow us to characterize vegetation dynamics on the basis of different temporal scales. In particular, the subtle, long-term changes convey relevant information on land degradation. The objective of this work is to study the spatial patterns of vegetation activity over Spain and its temporal variability throughout the period 1989-2002. A multi-resolution analysis (MRA) based on the wavelet transform has been implemented on NDVI time series from the MEDOKADS database. The MRA decomposes the original signal as a sum of series associated with different temporal scales. Specifically, the intra-annual series is processed to define several key features in relation with the vegetation phenology. In contrast, the interannual component of the signal is used to detect trends by means of a Mann-Kendall test and map the magnitude of the land-cover change. Finally, a comprehensive identification of the areas presenting a negative value of the magnitude of change is carried out to select those linked to land degradation processes. Results show a major presence of these areas the Southeast of Spain.
Open Access
Aportaciones de la teledetección y los SIG para la mejora de los modelos de evaluación de las pérdidas de suelo en Andalucía
(2020-04-03) Moreira Madueño, J.M.; Rodríguez Surián, M.; Ojeda Zújar, J.; Dirección General de Desarrollo Sostenible e Información Ambiental. Consejería de Medio Ambiente.; Departamento de Geografía Física y Análisis Geográfico Regional, Universidad de Sevilla,
The Regional Ministry of the Environment, through the Environmental Information Network (REDIAM), monitors the annual rate of land loss in Andalusia. This phenomenon, which is characterised by a high level of spatial and temporal variance, is particularly influenced by the amount and intensity of rainfall and land uses. The use of high and low resolution satellite images and regional ortophotographs has enabled continuous updating of information on plant cover and land uses, whilst the daily climate information from a network of automated weather and rainfall stations are used to generate monthly rain erosivity maps. This information on land loss is a useful tool for direct analysis or modelling, and provides the basis for identifying and implementing preventive and corrective actions enshrined in the various strategic plans developed by this agency.
Open Access
Agua y agricultura en sistemas áridos: un modelo dinámico del regadío de Mazarrón y Águilas
(2020-04-03) Martínez Fernández, j.; Esteve Selma, Miguel A.; Departamento de Ecología e Hidrología. Universidad de Murcia; Departamento de Ecología e Hidrología. Universidad de Murcia
The intensive use of groundwater resources in the new irrigated lands of Mazarron-Aguilas has led to the over-exploitation of the local aquifers and thus, to seawater intrusion, water salinization and falling off water tables, all of them key processes of desertification. The simulation results show that the unrealistic perceptions about the relationships between irrigated land and water resources constitutes a key factor to explain the highly unsustainable dynamics of irrigated lands in Mazarrón and Aguilas and the whole SE Spain. The increase in water resources does not eliminate the problem because the feedback loops and endogenous factors of the system lead to a further increase in irrigated land and continuation of the water deficit, which shows a highly counter-intuitive behaviour.
Open Access
Morfología Fluvial.-Morpholgical change in a stream channel as consequence of the fluvial dynamics (Vallcebre)
Soler, M.; Nord, G.; Latron, J.; Gallart, F.; Universidad de Murcia
ABSTRACT This study shows the morpholgical changes observed in a stream channel as consequence of the fluvial dynamics in an experimental research basin (Vallcebre,Eastern Pyrenees). Three cross sections were surveyed along a 100 metres distance near the basin outlet. The cross sections were measured 21 times from 2003 to 2008. Along the study period, higher deposition rates were observed in summer whereas higher erosion rates were observed in April. Considering the whole period, an average resulting deposition of 7 cm has been measured. At the flood scale, correlation analysis, revealed weak correlations between the magnitude of the changes in the stream bed and the main hydrometeorological variables
Open Access
Erosión y desertificación.-Los procesos de erosión hídrica en el retroceso erosivo de acantilados sobre rocas blandas en la provincia de Cádiz
Rendón Aragón, J.J.; Gracia Prieto, F.J.; Del Río Rodríguez, L.; Universidad de Murcia
ABSTRACT The littoral cliffs on soft materials of the Atlantic Cadiz coast show an important activity of the fresh water erosion processes, sometimes even more significant than the marine erosion processes. The connection of the lower cliffs with sandy beaches favours aeolian sand invasion, which fills previous rills and reduces the water erosion intensity by increasing infiltration. Cliff retreat and rill erosion measurement by using erosion sticks has shown very variable values, most of them higher than the estimated error of the employed methods. This indicates the existence of other factors influencing the distribution of water erosion processes along these cliffs, which have to be studied through different techniques.
Open Access
Relaciones agua-suelo-vegetación.-Efficiency assessment of runoff harvesting techniques using a 3D coupled surface-subsurface hydrological model
Verbist, K.; Cornelis, W.M.; McLaren, R.; Gabriels, D.; Soto, G.; Universidad de Murcia
ABSTRACT In arid and semi-arid zones runoff harvesting techniques are often applied to increase the water retention and infiltration on steep slopes. Additionally, they act as an erosion control measure to reduce land degradation hazards. Both in literature and in the field, a large variety of runoff collecting systems are found, as well as large variations in design and dimensions. Therefore, detailed measurements were performed on a semi-arid slope in central Chile to allow identification of the effect of a simple water harvesting technique on soil water availability. For this purpose, twenty two TDR-probes were installed and were monitored continuously during and after a simulated rainfall event. These data were used to calibrate the 3D distributed flow model HydroGeoSphere, to assess the runoff components and soil water retention as influenced by the water harvesting technique, both under simulated and natural rainfall conditions. Preliminary results show important design flaws that do not take into account local soil and climatic conditions adequately, resulting in a low water harvesting efficiency. The proposed methodology can be used to improve the design of water harvesting techniques, to optimally apply scarce financial sources in order to obtain maximal efficiency from runoff harvesting techniques in semi-arid regions.lengua.es
Open Access
Morfología Fluvial.-Activación de los procesos de edafización en la rehabilitación de zonas degradadas por actividades mineras. Un caso de estudio
García Álvarez, A.; Mejuto Mendieta, M.; Del Riego, L.; Cardona, A.I.; Díaz Puente, F.J; Rodríguez Gallego, V.; Schmid, T.; Millán Gómez, R.; Universidad de Murcia
RESUMEN Se está realizando un experiencia piloto para la rehabilitación de escombreras que proceden de la minería del carbón en la comarca de El Bierzo, para la que se ha diseñado un protocolo que pone un énfasis especial en activar los procesos de formación de suelo, como parte esencial en su evolución, que culmine con su integración en la dinámica global del paisaje que tiene lugar en ese territorio.
Open Access
Erosión y desertificación.-Environmental risks associated to wind erosion in a metal mining area from SE Spain
Garcia Fernández, G.; Romero Díaz, A.; Universidad de Murcia
ABSTRACT Soils and mining wastes from the Mediterranean mining area placed in the Sierra Minera Mountains are highly enriched in heavy metals such as lead and zinc, but also other metals such as cadmium and arsenic. Wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in this wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns. In order, to study these wind erosion processes over these mining materials, some experiments for the evaluation of the transportation of soil particles were carried out. Erosion rates in this realm is particularly important during spring months, when increased activity of the eastern winds brings intense soil dragging, with strong effects on the metals dispersion, including the massive removal of sediments.
Open Access
El impacto de la ganadería y la agricultura en los ecosistemas terrestres.-The availability of water in ranches of mediterranean type climate
S. Schnabel; Pulido Fernández, M.; Lavado Contador, J.F.; Universidad de Murcia
ABSTRACT A preliminary study on water resources for livestock rearing in SW Spain is presented. The objectives of this work were to assess the availability of water for domestic animals in farms and to explain whether water shortages are controlled by environmental factors or are also related with land management. The study was carried out in 54 private farms of wooded and treeless rangelands in Extremadura. Field work, digital topographic maps and aerial photographs were used to assess the potential hydrological resources of each farm. The water needs of livestock were estimated considering the number and species of animals per farm, as well as other factors influencing their water consumption. Furthermore, semistructured interviews were carried out in order to gather information about water management. Results indicate that almost 20% of the farms suffer problems of water availability in summer and almost 50% during droughts. Different solutions are adopted by the farmers, including construction of infrastructure, bringing water from outside or moving the animals to other areas. Data indicate a positive relationship between problems of water supply and the degree of aridity. Data also point to a relationship with water consumption by livestock and the availability of water by artificial ponds.
Open Access
Erosión y desertificación.-Contribution to the edaphic component definition in the desertification susceptibility index
Sampaio, E.P.; Corte-Real, J.A; Universidad de Murcia
ABSTRACT Many of the biophysical processes involved in the scope of desertification depend on the hydric characteristics of the soils that impact on vegetation cover. To protect soils against desertification, it is necessary to understand how some of these characteristics (such as water storage) interact in a complex and integrated chain of degradation processes. Several works have been developed to contribute to the definition of a Index of Desertification Susceptibility (DSI) expressed as a function of several components, climatic, edaphic, vegetative and slope. However, the various built-in edaphic components already defined, leave aside the water retention in soil. Furthermore, these components only focus on the characteristics of the uppermost surface soil layer (A-layer). In fact, desertification is simultaneously cause and consequence of the depleted soil water retention with a positive feedback on the plant life and on the hydrological cycle. This work intends to respond to the question of assessing if the B-layer exerts a significant influence in the definition of the edaphic component of the DSI. This may reflect the influence of the B-layer on the soil resilience to external factors. An experimental study has been performed on several profiles (n = 50) of representative soil units at Mértola, Southern Portugal (a region classified as having high DSI). Soil columns, have been delimited having at the upper and lower boundaries respectively the soil surface and the C-layer. The total volume (VT) of the Soil Available Water Content (AWC) was calculated as the sum of the elementary volumes (in the case, VA and VB) stored in each layer of the prospected soil column. Furthermore, volumetric ratios VA/VT and VB/VT have been determined. A possible existing empirical relationship between the ratios VA/VT and VB/VT, was investigated aiming to establish the relative importance of each term to the total volume VT. The results reveal a clear linear trend between VA/VT and VB/VT suggesting that the B-layer assumes the greater importance in terms of the holding water capacity of soil. It was found that except for soils constituted only by the A-layer, or when this layer is deeper than 45 cm, the relative weight of the B-layer is preponderant. For the most representative soil units of the study area, the referred relationship is persistent and is dependent on the layer thickness. To conclude, the foregoing relationship allowed identifying the soil units with greater desertification susceptibility through their inability to store sufficient water to maintain vegetation. It also allowed one to identify soil units whose B-layer assumes the greater importance in this soil function, and therefore should be take into account in defining the edaphic component of DSI. Thus, it is understood that the results of the present exercise have contributed to a better understanding of desertification processes, allowing to outlining strategies of action and implementing technologies for soil and water conservation, more appropriate to each situation. A more extended and detailed study will have to be done in order to more effectively contribute to upscale the results to the regional level.
Open Access
Erosión y desertificación.-Valorización de purines de cerdo en rehabilitación de espacios mineros: ensayos en condiciones de campo
Carmona, D.M.; Faz Cano, A.; Zanuzzi, A; Acosta, J.A.; Martínez-Martínez, S.; Muñoz, M.A.; Universidad de Murcia
ABSTRACT The intense mining activity carried out in Cartagena-La Unión Mountain, in Murcia region, has provoked extremely high accumulation of heavy metals in the environment. Due to the absence of vegetation cover, these soils are very liable to erosion, either wind or water, and they represent the major source of heavy metals pollution for the local environment due to dust blow and leaching of the results of mineral weathering into nearby watercourses. After 4 years of experiments in plots (4 m2), it has been demonstrated the potential use of pig manure to rehabilitate degraded and polluted soils, increasing carbon content and nutrients, promoting aggregates stability, decreasing mobility of heavy metals and establishing plant cover. In this study we pretend to extrapolate the results obtained in these plot previous experiments to field large scale scenarios using pig manure to amend the polluted soil and phytostabilization technique with native species in order to allow spontaneous colonization by plants and minimise the risks associated to those mining areas.
Open Access
Erosión y desertificación.-Influencia de la cubierta vegetal arbustiva y la longitud de la ladera sobre la densidad aparente del suelo
Bienes, R.; Jiménez, R.; Ruiz, M.; García-Estríngana, P.; Marqués, M. J.; Universidad de Murcia
Open Access
Erosión y desertificación.-Influencia de los procesos de sofusión (Piping) en la evolución del modelado. Bardenas Reales (Navarra)
Desir, G.; Marín, C.; Gutiérrez, M.; Universidad de Murcia
ABSTRACT Piping processes are controlled by many interacting factors, such as the index of dispersion and the sodium content, SAR and ESP. To it is necessary to join the density of cracking and the slope of the hillsides on which it develops. In the study area climatic characteristics together with soil structure and chemical and mineralogical composition of the substrate has a key role in Piping's formation. Cracking is linked to the presence of dispersive clays with high contents in SAR and ESP, which give the rates of swelling until 12%. The process presence of piping is linked to two concrete situations: the massive intermediate levels of the intermediate Holocene filling sediments and the sediments deposited by the gullies; whereas in the tertiary materials it does not manage to develop. The size and scale of the pipes studied show a clear relationship among the level thickness, slope and hydraulic gradient. In the Holocene landfills the principal bounding factor is the levels thickness since the lower laminated levels do not facilitate the continuity in depth of the process due to the high number of discontinuities, generating centimeter-scale conduits that are always on duty to the drainage network.
Open Access
Erosión y desertificación.-Índices de Fournier modificado y de concentración de la precipitación, como estimadores del factor de riesgo de la erosión, en Sinaloa, México
Cortés, G.; Universidad de Murcia
ABSTRACT Some of the parameters which characterize the climatic zones, identified as Hydric Régime Indices are the rainfall concentration index (ICP), and the Modified Fournier index (IFM), which allow to evaluate, in terms of the rainfall behavior, the risk of soil erosion. The conventional ICP rank of variation goes from uniforms to irregular (8 to 100%). The calculation of this index must be done for every year and then the average is the value to use. IFM considers the monthly rainfall of the most humid month of the year in relation to the other months. This index characterizes the rainfall aggressiveness, and their conventional values go from very low (0 to 60), until very high (more than 160), and mainly mean the vulnerability and risk to soil loss. It must be calculated for every year and its annual average is then used. Altogether with ICP, these indices give a very objective idea of the possible rainfall effect in soil erosion. In this work the estimation of these two indices for the Sinaloa State (NW of Mexico) is made; ICP shows a high seasonality, and IFM depends strongly on the topography. The potential consequences of soil erosion in then estimated, through conventional values of the indices.