Authors:J.C. González-Hidalgo, D. Peña-Angulo, S. Beguería Pages: 345 - 369 Abstract: Variations in trend rates of annual values of the Central England Temperature series (CET) over the period1659-2017 were analysed using moving windows of different length, to identify the minimum period in which the trend expresses a climate signal not hidden by the noise produced by natural variability. Trend rates exhibit high variability and irregular shifting from positive to negative values unless very long window lengths (of 100 years or more) are used. In general, as the duration of the length of the temporal window analysed increases, the absolute range of the trend rates decreases and the signal-to-noise (S/N) ratio increases. The relationship between the S/N ratio and the window length also depended on the total length of the series, so high S/N values are achieved faster when shorter time series are considered. This prevents suggesting a minimum window length for undertaking trend analyses.A comparison between CET and the average continental series in the Berkeley Earth Surface Temperature (BEST) database in their common period (1753-2017) repeats the patterns described for 1659-2017, although the average values of the rates, ranges and the "threshold period" in years change, and are more variable in CET than in BEST.Analysis of both series suggests that the recent warming started early and can be linked to the recovery of temperatures after the Little Ice Age. This process has characterised by progressively increasing trend rates, but also includes periods of deceleration or even negative trends spanning less than 50 years. The behaviour of the two long-term temperature records analysed agrees with a long-term persistence (LTP) process. We estimated the Hurst exponent of the CET series to be around 0.72 and 0.8, which reinforces the LTP hypothesis. This implies that the currently widespread statistical framework assuming a stationary, short-memory process in which departures from the norm can be easily assessed by monotonic trend analysis should not be accepted for long climatic series. In brief, relevant questions relative to the recent evolution of temperatures such as the distinction between natural variability and departures from stationarity; attribution of the causes of variability at different time scales; determination of the shortest window length to detect a trend; and other similar ones have still not been answered and may require adoption of an alternative analytical framework. PubDate: 2020-09-15 DOI: 10.18172/cig.4377 Issue No:Vol. 46, No. 2 (2020)
Authors:J.L. Peña-Monné, L.A. Longares-Aladrén, V. Rubio-Fernández, M.M. Sampietro-Vattuone, M. Sánchez-Fabre Pages: 371 - 393 Abstract: The lower Gállego River has been strongly degraded since the 1960s due to human activity (gravel mining, dump accumulation, channeling works), which has produced a deep channel incision. Although these human-driven processes are usually reported in fluvial bibliography, in this case, more complex results are observable. For instance, regarding the depth and incision rates, we observed no relationship between the most anthropically impacted areas and the sections with the deepest incisions; moreover, the deepening process continues 40 years after the human interventions ceased. The reason for this maladjustment is the role played by the exhumation of the underlying Pleistocene substrate, affected by the synsedimentary processes of karstification. The appearance of paleodolines filled with fine sediments on the incision bottom and sides is the main factor conditioning the continuity and magnitude of the process. Besides, these paleodepressions direct the river dynamics and course, thus favoring its widening when they appear and causing the development of a new riverbed (Qt13) while the 1960s floodplain (Qt12) is becoming an old terrace located between 5 and 11 m above the new alluvial bottom. There are no previous records about this kind of consequences in the regional fluvial dynamics. PubDate: 2020-09-15 DOI: 10.18172/cig.4409 Issue No:Vol. 46, No. 2 (2020)
Authors:E. Serrano, A. Pisabarro, J.I. López-Moreno, M. Gómez-Lende, R. Martín-Moreno, I. Rico Pages: 395 - 411 Abstract: This paper shows the creation of a map of frozen ground potential for the Tucarroya valley in Ordesa National Park. To create this map, it was necessary to combine the identified landforms associated to the presence of frozen ground by fieldwork, ground temperature data continuously recorded during two years by automatic loggers, a Basal Temperature of Snow (BTS) survey, and predictor variables derived from a high resolution Digital Elevation Model (DEM). Four environments have been differentiated: unfrozen ground, seasonal frozen ground, possible permafrost and probable permafrost. The map confirms a very limited variety and extension of permafrost, above 2700 m a.s.l. on gentle and shadowed slopes. Seasonal frozen ground is the most common thermal regime, as it can be developed above 2500 m a.s.l. Snow-pack duration and thickness tightly control the duration of frozen ground and the freezing-thawing cycles. Frost activity and unfrozen ground is restricted from 2570 to 2750 m a.s.l. PubDate: 2020-09-15 DOI: 10.18172/cig.4414 Issue No:Vol. 46, No. 2 (2020)
Authors:J. Ventura-Roca Pages: 413 - 446 Abstract: The application of the paleogeographic method to the study of glacial landforms and rock glaciers allows their morphometric and sedimentological characterization, the establishment of a detailed morphostratigraphic sequence and a chronological proposal for the identified glacial phases. This study analyzes 86 landforms (57 glacial deposits, 21 rock glaciers and 8 protalus ramparts) in the Bonaigua Valley (Noguera Pallaresa Basin, Central Pyrenees), with special attention to the differentiation between debris-covered glaciers and rock glaciers. Other subjects studied concerning rock glaciers are: distinguish its glacial or periglacial origin; the possible current activity of some landforms, and the detection of rock glaciers located at low altitudes (in the current forest environment) through the use of high-resolution digital elevation model (2x2 m) from LIDAR data. The chronological hypothesis elaborated by correlation with other high Pyrenean valleys (with absolute ages available) includes 7 phases (6 glacial phases and 1 periglacial phase) in which co-exist and/or evolve, in a paraglacial dynamic, glaciers, debris-covered glaciers and rock glaciers, and that we temporarily place between the end of the Oldest Dryas and the Little Ice Age. PubDate: 2020-09-15 DOI: 10.18172/cig.4395 Issue No:Vol. 46, No. 2 (2020)
Authors:E. Lannutti, M.G. Lenzano, J. Barón, S. Moragues, L. Lenzano Pages: 447 - 476 Abstract: Puente del Inca is a natural monument standing over the Cuevas river in Mendoza, Argentina. The bridge currently exhibits structural deterioration due to natural and anthropic factors. This article seeks to offer a contribution to the conservation and restoration works of Puente del Inca by integrating instruments and technologies that allow the assessment of the health state of the natural bridge. The study relied on visual inspection, accretion-erosion rate measurements, hydrothermal flow characterization, ground-penetrating radar, soil dielectric sensor, Global Navigation Satellite System, laboratory testing, Structure from Motion, the Finite Element Method and ambient vibration testing. The results show that the morphology and health of the natural bridge depend on the dynamic balance between the erosion and the geobiological system intervening in the formation of the travertine constituting the natural bridge. The computational structural modeling demonstrates that there is a controversy between the benefit of irrigating the geological formation with thermal water and the loss of stability of the bridge under saturation conditions. Nevertheless, a continuous monitoring and an efficient administration of thermal water may ensure the deceleration of most of the erosive processes as well as the improvement of the geobiological system health. PubDate: 2020-09-15 DOI: 10.18172/cig.4390 Issue No:Vol. 46, No. 2 (2020)
Authors:D.R.A. Quiroga, A. Coronato, G. Scioscia, A. Raya-Rey, A. Schiavini, J. Santos-González, C.R. Lopez, J.M. Redondo-Vega Pages: 477 - 496 Abstract: An active Magellanic penguin (Spheniscus magellanicus) colony has been established on Martillo Island, Beagle Channel (54°54´26” S; 67°22´58” W) since 1976. It is located in remnants of eroded drumlins placed in both ending and joined by gravel terraces of glaciofluvial and marine origin. Forest patches occupy the eastern side of the island while most of the island is covered by bushes, tussocks and grasses. This paper presents penguins as bio-erosion agents on glacial and marine landforms. An analysis of multiple criteria surveyed in the field was performed, using Quantum GIS® 3.2.1 with remote sensing images and a digital model terrain of 12 m resolution. The morphometric data and multicriterial evaluation were collected during 2016-2017 austral summer. Soils and sediments of each landform (drumlin, glaciofluvial terrace, raised beach and beach) were sampled for particle size analysis, to determine if there is any relationship between the morphometric parameters of the cave and the sediments. Four bio-erosion classes were defined based on the erosion features observed in the field. “Moderate” was the prevailing erosion class recorded, in the E-NE part of the island. Bio-erosion features are mainly developed on the N facing slope of the east of the island, where a natural gully drains rainfall water, and over the glaciofluvial and marine terrace surfaces. Erosive features such as caves and bridges are mainly developed in silty drumlins. Pedestals are developed on bare soils and tussocks. Trails and cracks were also described as bio-erosion. No erosive features were recorded in the W part of the island. The bio-erosion map is one of the inputs for environmental degradation analysis and population dynamic research which is being done in the Magellanic penguin colony on Martillo Island, Beagle Channel. PubDate: 2020-09-15 DOI: 10.18172/cig.4337 Issue No:Vol. 46, No. 2 (2020)
Authors:T. Bullón Pages: 497 - 519 Abstract: This research assesses the close relationship between river history and human adaptation by combining the study of the migration of channels on the floodplain, the temporal distribution of floods, and human adaptation to the fluvial environment during the Little Ice Age (LIA) period on the Jarama River section situated between the mouths of two tributaries, the Henares and Manzanares. The methodology consists of the employment of abundant documentary records from the 14th to 19th centuries related to the response of society to hydrological dynamics within changing river patterns. The management and delimitation of land ownership, along with the readjustments and modifications therein, allow the inference of the changes that have taken place in the river throughout history. These changes include meander cut-offs, the abandonment of a channel fragment and aggradation in the alluvial plain, all of them located in different areas within the study area and with different historical timeframes. A relationship exists between changes in fluvial dynamics and the times of the greater abundance of floods. An initial change in the alluvial plain occurred in the Middle Ages as a result of the abandonment of the medieval channel and the creation of a new channel. The second change occurred between the 15th and 17th centuries and affected the properties on the right-hand bank of the river. Since the 18th century, the abandonment of and reduction in meanders and the aggradation at the Manzanares-Jarama mouth have created a new alluvial plain of the river. The different phases of the LIA defined herein coincide with much of the palynological and dendrochronological research conducted in other areas of the southwestern fringe of Europe. From the historical point of view, critical changes appear to be associated with some LIA phases. Furthermore, the progressive transformation of communal lands into public or private property could be promoted by the intense floods recorded since the 15th century. The Maunder and Dalton Minimums occurred together with an increase in the area assigned for agriculture on the alluvial plain; this land use type continued to grow during the 19th and 20th centuries. PubDate: 2020-09-15 DOI: 10.18172/cig.4276 Issue No:Vol. 46, No. 2 (2020)
Authors:J.M. Senciales-González, J. Rodrigo-Comino, P. Smith Pages: 521 - 543 Abstract: The main aim of this research was to detect a possible urban heat island (UHI) in the tourist city of Málaga (Spain). To achieve this goal, different methods to validate annual and monthly temperature data have been used, and the internal variability of the UHI with respect to the topographical changes was also surveyed. Our results showed two types of atmospheric thermal gradients: one characterized by a positive gradient according to an elevation above sea level, and another with a negative gradient related to rural areas. The maximum impact of the UHI was found to be 9.1 ºC for an instantaneous event, 4.4 ºC for daily minimum temperatures in August, with a maximum weighted average difference of 2.3 ºC between data from urban and rural stations. We conclude that the detection of UHI is useful as a tool to help urban planners, in order to reduce the intensity of possible climate changes in cities. It is also concluded that UHI is not only a meteorological phenomenon in Málaga city but a climatic phenomenon, present during most days and across the transect of increasing intensity from the sea to the city.
Authors:F.S. Rodrigo Pages: 545 - 561 Abstract: This work presents a new source of documentary data on the Spanish climate from 1792 to 1808 coming from the periodical Correo Mercantil de España y sus Indias, in which weekly summaries of Spanish weather conditions were published. The potential of this data source for historical climatology studies is analysed, focusing on information related to the south of the Iberian Peninsula.
Authors:P. Echeverría, Ch. Domínguez, M. Villacís, S. Violette Pages: 563 - 580 Abstract: The Galapagos Archipelago is a semiarid zone scarce of superficial water resources. Due to its geographic location and the presence of oceanic currents, these islands are covered by fog during seven months along the year which could represent a potential source of water supply. In this study, the feasibility of fog collection for domestic rural use and irrigation was investigated using two Standard Fog Collectors (SFC) of 50% and 35% shade coefficient of 1 m2 and a cylindrical fog net (CFN) of 0.15 m2 at 600 m of elevation in the windward side of San Cristobal Island (Galapagos). The methodology applied consists in the quantification of the monthly and annual water balance at different altitudes in an average and dry years, using the orographic gradients of rainfall, evapotranspiration and cloud water interception. The latter was used to estimate the fog water availability to satisfy any water deficit. Fog water interception was estimated using a geometric model and the use of different climatic variables. On the other hand, water demand in the rural zone for domestic consumption and livestock was estimated with the quota method, and the water demand for agriculture was estimated through the water balance. Results show that the amount of fog captured reaches 7.9, 5.9 and 3.4 mm/d with 50-SFC, 35-SFC and CFN, respectively. Comparing these results with other locations in the world, fog water collection in Galapagos is above the average. A fog gauge system of 50-SFC was designed at different elevations to cover the 25% and 15% of the water deficit in the average and dry year, respectively. PubDate: 2020-09-15 DOI: 10.18172/cig.4382 Issue No:Vol. 46, No. 2 (2020)
Authors:B. Lara, M. Gandini, P. Gantes, S.D. Matteucci Pages: 581 - 602 Abstract: Understanding the interaction between land surface and atmosphere processes is fundamental for predicting the effects of future climate change on ecosystem functioning and carbon dynamics. The objectives of this work were to analyze the trends in land surface phenology (LSP) metrics from remote sensing data, and to reveal their relationship with precipitation and ENSO phenomenon in the Argentina Pampas. Using a time series of MODIS Normalized Difference Vegetation Index (NDVI) data from 2000 to 2014, the start of the growing season (SOS), the annual integral of NDVI (i-NDVI, linear estimator of annual productivity), the timing of the annual maximum NDVI (t-MAX) and the annual relative range of NDVI (RREL, estimator of seasonality) were obtained for the Argentina Pampas. Then, spatial and temporal relationships with the Multivariate ENSO Index (MEI) and precipitation were analyzed. Results showed a negative trend in annual productivity over a 53.6% of the study area associated to natural and semi-natural grassland under cattle grazing, whereas a 40.3% of Argentina Pampas showed a significant positive trend in seasonality of carbon gains. The study also reveals that climate variability has a significant impact on land surface phenology in Argentina Pampas, although the impact is heterogeneous. SOS and t-MAX showed a significant negative correlation with the precipitation indicating an earlier occurrence. 23.6% and 28.4% of the study area showed a positive correlation of the annual productivity with MEI and precipitation, respectively, associated to rangelands (in the first case) and to both rangeland and croplands, in the second case. Climate variability did not explain the seasonal variability of phenology. The relationships found between LSP metrics and climate variability could be important for implementation of strategies for natural resource management. PubDate: 2020-09-15 DOI: 10.18172/cig.4310 Issue No:Vol. 46, No. 2 (2020)
Authors:M. Tabares-Mosquera, E. Zapata-Caldas, O. Buitrago-Bermúdez Pages: 603 - 631 Abstract: The aim of this research was to assess–based on spatial analysis techniques and expert knowledge–the capacity of land covers to provide ecosystem services (ES) in the socioecological system (SES) “metropolitan area of influence of Cali”. In this manner, it was possible to identify the metropolitan ecological structure of said SES in order to establish a baseline from which its level of conservation or fragmentation can be identified in the future. The application of the methodology required the use of mixed research methods. In this regard, i) the SES area was defined from the combination of urban-functional and ecological-biophysical criteria; ii) criteria were defined to establish the unit of analysis and the land cover classification of the defined area at 1:25,000 scale; and iii) the assessment of ES was made based on a consultation with experts from academic, administrative and scientific institutions about the capacity to supply and demand ES present in the land covers that make up the SES. It was found that the metropolitan ecological structure is composed of ten natural and semi-natural land covers, which have the capacity to provide cultural ES (high level), regulation ES (high and medium levels) and supply ES (low level). In addition, as expected, the perception was validated that the flat area of the SES–which concentrates productive, economic and service activities–is clearly the demanding one, while the areas located in the periphery–i.e. piedmonts and the Eastern and Western mountain chains–are the suppliers. Finally, the results of this research once again demonstrate that, from the academic angle, there are novel ways to strengthen the processes of formulating guidelines for planning and environmental management of metropolitan SES, from the combination of spatial analysis and expert knowledge. PubDate: 2020-09-15 DOI: 10.18172/cig.3952 Issue No:Vol. 46, No. 2 (2020)
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