La geomorfología en los estudios del medio físico y planificación territorial : propuesta metodológica y aplicación a un sector del Sistema Central

El trabajo de investigación se apoya en un postulado básico: la planificación territorial con bases ecológicas, o planificación integrada, es la herramienta mas adecuada para abordar los denominados "problemas ambientales". Entre las metodologías que abordan esa temática, los procedimientos fisiograficos se muestran adecuados para definir "usos vocacionales" en tanto sintetizan la historia natural y social del territorio; por su carácter de ciencia puente entre la geología y la geografía, la geomorfología se presenta como un campo de conocimientos ideal para abordar este tipo de estudios a través de las "clasificaciones del relieve". Esas clasificaciones deben tener un carácter científico y no exclusivamente configuracional, y adecuarse a los objetivos que intenta resolver: en este caso, problemas derivados del uso del territorio. En base a esas tesis y a partir de los conocimientos derivados de las ciencias de la tierra, se propone como jerarquía básica los niveles: geológico (regiones fisico-geologicas), geográfico (regiones geomorfologicas), genético (dominios del relieve) y dinámico- configuracional (elementos del relieve). La clasificación se aplica a un sector del sistema central español, simulando su aportación a procesos de planificación territorial a distintos ámbitos politico-administrativos y normativos; se completa además con ejemplos concretos: restauración de paisaje y caracterización-cuantificación de "el hombre como agente geomorfológico"

Erosión minera en la cuenca del arroyo Peñalén (Parque Natural del Alto Tajo, Guadalajara)

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Geological factors of the Guadalajara landscapes (Central Spain) and their relevance to landscape studies

The landscapes of a territory are the consequence of its history; overlapped geological, vegetable and cultural histories usually exist on a landscape. At the Mediterranean domain, however, a translucent vegetation exists, and its history is closely related to the geologic and cultural histories, because low-technology agricultural uses on a different hardness rock background control vegetation. Thus, in areas like the Guadalajara province, the geologic composition and the human activities can be considered the primary conditions for landscape configuration. Both condition the typologies, distribution and relative importance of the geotic, biotic and anthropogenic components of landscapes. A complex network of interrelations among all them exists but, in the base of which lie the geology of the territory, included relief, because it has amore independent influence since man cannot modify the geologic factors; such as the colour of the rocks, the size and distribution of rock bodies, the palaeogeographic domains and the tectonic structure all which control landscape development and configuration. Moreover, geology influences conditions and even limit, the presence, typologies and development of the biotic and anthropogenic elements. These factors also have a major relevance for environmental management, educational and economic policy, and, in some cases, for environmental impact assessment.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Geological factors of the Guadalajara landscapes (Central Spain) and their relevance to landscape studies

The landscapes of a territory are the consequence of its history; overlapped geological, vegetable and cultural histories usually exist on a landscape. At the Mediterranean domain, however, a translucent vegetation exists, and its history is closely related to the geologic and cultural histories, because low-technology agricultural uses on a different hardness rock background control vegetation. Thus, in areas like the Guadalajara province, the geologic composition and the human activities can be considered the primary conditions for landscape configuration. Both condition the typologies, distribution and relative importance of the geotic, biotic and anthropogenic components of landscapes. A complex network of interrelations among all them exists but, in the base of which lie the geology of the territory, included relief, because it has amore independent influence since man cannot modify the geologic factors; such as the colour of the rocks, the size and distribution of rock bodies, the palaeogeographic domains and the tectonic structure all which control landscape development and configuration. Moreover, geology influences conditions and even limit, the presence, typologies and development of the biotic and anthropogenic elements. These factors also have a major relevance for environmental management, educational and economic policy, and, in some cases, for environmental impact assessment

Hacia una Minería Sostenible en el 95 entorno del Parque Natural del Alto Tajo. La escombrera experimental de la mina ‘El Machorro’(Poveda de la Sierra, Guadalajara)

Por su situación en el entorno de un espacio natural protegido, y sobre una ladera de pendiente y longitud elevadas, la restauración de la mina El Machorro constituye un importante reto científico y profesional. La empresa propietaria de esta mina, CAOBAR S.A., tiene entre sus objetivos demostrar la compatibilidad de la actividad minera con la conservación del medio ambiente. Por todo ello está acometiendo sucesivas revisiones de su Plan de Restauración del Espacio Natural (PREN), tratando de incorporar las mejores prácticas internacionales al respecto. Todo ello en colaboración con las universidades Complutense y de Alcalá (Madrid) y bajo la supervisión de la Dirección del Parque Natural del Alto Tajo. Una de las acciones más destacadas a ese respecto ha sido la construcción de una escombrera experimental, específicamente diseñada para mejorar la restauración de los terrenos afectados por la mina. En ella se estudia el comportamiento erosivo que tienen diferentes diseños de escombreras mediante la combinación de: (a) distintas topografías (cóncava y en terrazas); (b) distintos tipos de sustrato (estériles, coluviones y suelos originales); y (c) distintos tipos de revegetación (como hidrosiembras). En la comunicación se describen los detalles de la puesta en funcionamiento de esta escombrera experimental, así como los resultados obtenidos para el periodo 1 de noviembre de 2008 a 31 de marzo de 2009

Procesos geomorfológicos activos en cárcavas del borde del piedemonte norte de la Sierra de Guadarrama (Provincia de Segovia, España)

Dos localizaciones situadas cerca del borde del piedemonte norte de la Sierra de Guadarrama (provincia de Segovia) ofrecen formas erosivas en cárcavas bien desarrolladas: (a) un conjunto de barrancos encajados sobre arenas arcósicas del Mioceno, en un relieve de lomas y vaguadas del suroeste provincial; (b) cárcavas sobre arenas silíceas del Cretácico Superior, en un relieve de laderas de mesas y cuestas de la zona centro sur de la Provincia. En este trabajo se caracteriza la actividad geomorfológica de esos barrancos y cárcavas, y se inicia su cuantificación. El objetivo está encaminado a conocer qué procesos movilizan sedimentos, y a evaluar sus tasas de actuación, intensidad, frecuencia de ocurrencia y conectividad entre los mismos. Los procesos de erosión hídrica por salpicadura, arroyada laminar y concentrada en rills, junto con la actividad gravitacional observada, movilizan materiales desde las cabeceras de las cárcavas hasta los colectores, rellenándolos; éstos son evacuados mediante procesos de encajamiento en los canales efímeros, y sedimentados en pequeños conos aluviales. En los barrancos sobre arcosas, los eventos de precipitación poco intensos y de alta frecuencia tienden a rellenar los lechos arenosos, mientras que la fusión nival y las precipitaciones de alta intensidad y baja frecuencia vacían los canales, sedimentando en zonas apicales de los conos aluviales. En las cárcavas sobre arenas silíceas, los primeros datos obtenidos apuntan a unas tasas de erosión y producción de sedimentos muy elevadas, ya que sobre ellas se produce escorrentía y erosión hídrica de manera casi instantánea; por ello, los eventos de precipitación de baja intensidad son capaces de sedimentar en las zonas apicales de los conos, mientras que los eventos de alta intensidad originan lóbulos telescópicos sobre conos aluviales existentes en pedimentos. [ABSTRACT] Two areas located at the edge of the North piedmont of the Guadarrama Mountains (province of Segovia) show a conspicuous development of gullies. A series of valley side gullies, or ravines, cut on arkosic sand sediments of Miocene age at the Río Chico Valley (southwest of the Segovia province); and slope gullies, cut on silica sand, shale and gravel sediments of Upper Cretaceous age, on the slopes of a set of mesas and cuestas at the río Cega piedmont (Pedraza region, south centre of the Segovia province). This paper characterizes the geomorphic activity of both types of gullies. In addition, the quantification of their current activity is initiated. The objectives are: to know which processes are eroding and mobilizing the sediments within the gullies, and to evaluate their rates, intensity, frequency and connectivity. A detailed field survey shows that weathering processes (sandstone sheeting, and the formation of popcorn structures on shale layers), and splash, sheet and rill erosion, along with sand and mud falls, slides and flows move sediment from the gully slopes and internal divides to the dry washes. These materials are temporary stored in ephemeral stream channels (filled with sandy bed material), evacuated by stream-bed scour and fill processes, and deposited in alluvial cones. In order to get a first approximation of the amount of erosion and sediment movement, a set of field methods have been applied to these areas. These methods include: erosion pins, measurement of pedestals, system of rods and washers, pit traps (box and gabion check-dam types), and topographic surveys after extensive sedimentation on alluvial cones, along with the installation of pluviographs. The results show how on the arkosic valley side gullies, the precipitation events of low intensity and high frequency tend to fill the sandy stream-beds, whereas the snowmelt and the high intensity and low frequency precipitation events scour the sandy stream-beds. The sedimentation occurs here at the apex part of the alluvial cones, which rest directly on the nearby floodplain of the Chico River. On the silica sand slope gullies, the first gathered data point at very high rates of erosion and sedimentation (44.1 tons/ha for a single event), which is interpreted due to the fact that runoff and water erosion occurs here almost instantaneously after precipitation. Here, the precipitation events of low intensity and high frequency produce sedimentation at the apex part of the alluvial cones, whereas the high intensity and low frequency precipitation events sediment in the form of telescopic lobes, on existing alluvial cones, which rest on pediments

The Ribagorda sand gully (east-central Spain): Sediment yield and human-induced origin

Gullies are developed under different climatic conditions and lithologies; however, those formed on sands have been scarcely described. This paper reports the study of the Ribagorda sand gully, 2.57 ha in area (east-central Spain). The main objectives were to characterize and quantify its geomorphic dynamics and to trace its origin. We described the landforms of the gully and measured the surface strength of the sand. We monitored, for six years, the filling of the storage areas of three check dams built downstream from the gully, and related it with rainfall characteristics. We also described the nature of the sediments trapped by the dams and estimated the amount of sediment eroded since the gully formation. Finally, we consulted historical records and maps to determine past land uses and transformations that may have affected the origin of the gully. The study shows a high diversity of landforms, denoting active processes, consistent with a measured mean annual sediment yield of 114 Mg ha−1 yr−1. A statistically significant relationship exists between the mass of sediment (Mg) and: 1) the total rainfall (mm) (P = 0.0007) or 2) the analysed rainfall intensities. Among five identified facies in the sedimentarywedge, the sandy ones are predominant. The total amount of sediment eroded by the Ribagorda gully since its originwas 962,800Mg. The results are unequivocal signs of an intense geomorphic activity within the gully, with an alluvial-fan type deposition in the dams.We interpret that the Ribagorda gully was initiated by deforestation after the 13th century, when forests began to be intensively logged, and before the 18th century,when the gullywas first indirectly described in print. The age, origin, evolution and dynamics of this gully indicate that this landscape is currently evolving towards a new steady state, after human disturbances over centuries. Given the gully evolution and local extent, we suggest that no correction measures are needed for its management

Los paisajes de la región de Milmarcos: sistemática y cartografía (Cordillera Ibérica, Provincias de Guadalajara, Soria y Zaragoza)

Landforms constitute the physical framework of the landscape, whether it is considered in a territorial or in a visual approach. The composition, tectonic structure and geologic history of a territory determine the topographic development of the landscape and its textures. Here, we summarize the study o f the landscape's structure of a region o f 600 km2 located in the centre of the Iberian Peninsula, characterised by an alternance o f rock strata with different consistency and erosionability. The Mesozoic materials are folded and faulted because o f the alpine movements, and flattened to Neogene planation surfaces. The Cenozoic materials are in a horizontal disposal. During the Quaternary, the river system of the Mesa River was incised and developed. As a consequence of these circumstances, a wide variety of landforms is displayed. A typological classification o f the structures o f the landscapes of this region and their mapping has been made

Perspective: The historical reference in restoration ecology: Re-defining a cornerstone concept

Ecological restoration aims to revitalize ecosystem integrity and functionality following severe damage or degradation. Often, however, efforts are hampered by an incomplete or flawed concept of historical ‘reference’ used when choosing or constructing a target ecosystem or landscape to restore ‘to’. This problem may stem from a culturally-skewed interpretation of history or from misunderstanding or underestimation of the role that humans have played in a given ecosystem’s historical development and dynamics. While strongly confirming the importance of the reference concept in restoration ecology, we argue for the need to refine it, and to broaden the ways it can be conceived, developed, and applied. Firstly, the historical reference system informing a given restoration project should be grounded in both latent and active ‘ecological memories’, encoded and stored across relevant geographical and temporal scales. Further, the generally neglected geomorphic component of reference-building should also be addressed, as well as the contributions of human cultures to current ecosystem and landscape condition. Thirdly, ecosystems are historically contingent and multi-layered. Pre-versus post-disturbance comparisons are insufficient. Instead, restoration scenarios should be seen as tapestries of multiple and successive states. In sum, a well-conceived reference model helps promote and ensure the recovery and subsequent maintenance of historical continuity, i.e., the reestablishment of an impaired ecosystem to its historic ecological trajectory. We use case studies from pain and Peru to illustrate how this approach can provide better goalposts and benchmarks, and therefore better guide the planning, implementation, and evaluation of effective restoration projects

Environmental assessment: Landform Classification for Land Use Planning in Developed Areas: An Example in Segovia Province (Central Spain)

Landform-based physiographic maps, also called land systems inventories, have been widely and successfully used in undeveloped/rural areas in several locations, such as Australia, the western United States, Canada, and the British ex-colonies. This paper presents a case study of their application in a developed semi-urban/suburban area (Segovia, Spain) for land use planning purposes. The paper focuses in the information transfer process, showing how land use decision-makers, such as governments, planners, town managers, etc., can use the information developed from these maps to assist them. The paper also addresses several issues important to the development and use of this information, such as the goals of modem physiography, the types of landform-based mapping products, the problem of data management in developed areas, and the distinctions among data, interpretations, and decisions.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu