The objective of this study was to compare two different methods for the calculation of the soil quality index for agricultural land in the province of Salamanca in the semiarid ecosystem of the ...Northern Plateau, Spain. The integrated quality index (IQI) and Nemoro quality index (NQI) were applied using the following indicator selection methods: total data set (TDS) and minimum data set (MDS). A total of 16 soil parameters were used for the TDS method. The evaluation of the soil quality index using only the properties of surface soil provides incomplete information because crop productivity is influenced by both the surface and subsoil properties e.g. lithic contact, petrocalcic horizon, clayey horizon (Bt). The quality indexes were calculated using data from 75 soil profiles considering the soil surface properties (between 0 and 25 cm depth) and control section properties (between 0 and 100 cm).
The results show that the consideration of soil properties of both the surface and subsurface horizons is very important to establish a good relationship between soil quality, soil functions, and agricultural management.
The results based on the IQI index provide a better estimate of the soil quality compared with the NQI index; higher values were obtained with the TSD than with the MSD. However, the results obtained from the IQIMSD method provide an adequate evaluation of the soil quality. This is relevant because the use of a limited number of indicators reduces the analysis cost and increases the sampling density.
•The Integrated and Nemoro Quality Indexes were applied to assess soil quality.•A factorial analysis was used to define minimum data set from total data set.•Digital maps of the soil quality indexes and the soil loss rate have been made.•Quality indexes have been linked to the vertical distribution of soil properties.•Soil quality indexes based on the properties of all soil horizons (0–100 cm).
Concentrations of seven heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and one metalloid (As) as well as various parameters (pH, organic carbon, granulometric analysis and cation exchange capacity) ...were analyzed in 77 soil samples collected in the mining areas of La Zanja and Colquirrumi (Department of Cajamarca) and Julcani (Department of Huancavelica). Our study proposed geochemical baseline values for heavy metals in a natural region (La Zanja) from samples collected during the period of the environmental impact study (2006), that is, from an earlier period which occurred at the beginning of the exploitation of the current gold mine. The baseline values obtained were as follows: 8.26 mg kg-1 for Cr; 56.97 mg kg-1 for Ni; 22, 20 mg kg-1 for the Cu; 47.42 mg kg-1 for Zn; 27.50 mg kg-1 for As; 4.36 mg kg-1 for Cd; 4.89 mg kg-1 for Hg, and 44.87 mg kg-1 for Pb. Through the use of different indices of heavy metal contamination (geo-accumulation index (Igeo), improved Nemerow index (IIN) and potential ecological risk index (RI)), the degree of pollution caused by mining activities in two areas, Colquirrumi and Julcani, which have a high density of mining sites in operation, was determined. The values obtained from these indices indicated that the Colquirrumi region was the most contaminated, followed by Julcani. The area of La Zanja, despite being free of mining operations, presented slight diffuse pollution. Several positive correlations were obtained, with a high level of significance, between pH, organic carbon content, cation exchange capacity, and the Cr, Pb and Ni concentrations of the soils. The spatial distribution of the heavy metals was realized by means of the interpolation method of ordinary kriging. The results obtained and the experience gained in this work were necessary to facilitate the identification of soil contamination processes in high altitude areas of the Andes Western Cordillera (Peru) as a basis for taking appropriate measures when restoring soils, during mine closure processes, and to protect the quality of soil resources.
The sustainable management of fluvial systems requires reliable knowledge of the mechanisms that control the basins and their drainages, which in turn must be prioritized for the application of ...measures for flood-risk reduction. Thus, given the need to develop methodological frameworks capable of integrating remote sensing technologies at different scales, as well as traditional metrics and anthropic variables, in this study, a multiscale method is proposed for the characterization and prioritization of river stretches for fluvial risk management. This methodology involves the study of drivers at the watershed level, and a detailed morphometric and hydrogeomorphological analysis of the main channel for fluvial landscape classification, segmentation, and aggregation into units, considering also anthropic variables. Therefore, it includes the use of LiDAR data and exploration GIS tools, whose results are corroborated through fieldwork, where ephemeral and topographic evidence of fluvial dynamics are collected. The procedure is validated in the Carrión river basin, Palencia, Spain, where a high degree of maturity and geomorphological development are determined. Hence, the main channel can be classified into eight geomorphic units and divided into homogeneous segments, which, according to categorical elements such as urban interventions, are prioritized, obtaining, as a result, six stretches of main interest for river risk management.
Display omitted
•Hydrogeomorphological method for flood analyses in narrow rivers.•Integration of geomorphological knowledge and hydrologic-hydraulic modelling.•Study of flood events and hazards ...associated with probabilities of occurrence.•Analyses at high spatiotemporal resolutions at local scale.•Predictions of flood extents at different flows to define management strategies.
Fluvial flood risk management requires precise knowledge of flooding processes; thus, there is a need to carry out a detailed hydrological, hydraulic, and geomorphologic analysis to understand floods and the factors that influence them. Although the integration of geomorphological methods and hydrological-hydraulic modelling is known to be crucial for flood risk analysis, it remains a challenge to apply these approaches to the understanding of floods in small and medium-sized catchments, focusing on complex fluvial systems that have been highly modified. In this work, a hydrogeomorphological methodology was developed to analyse fluvial floods in narrow rivers with broad complex alluvial plains. The procedure comprises different phases that combine hydrologic-hydraulic modelling and a geomorphological break-down. Critically, this allows for a detailed analysis of existing relationships among erosional and depositional fluvial landforms and hydraulic parameters, comprising geometric sections, discharges, depths, flood extents and, therefore, flood hazards. The approach involves the analysis of specific flood events beforehand and the study of fluvial floods associated with different probabilities of occurrence afterwards. The information employed in the present study incorporates high- detailed inputs comprising hourly time series of hydrometeorological data, LiDAR data to extract high-precision terrain information, fluvial geomorphic maps and flood event extents based on Sentinel-2 imagery. We demonstrate this methodology in the Carrión River, located in the province of Palencia, Spain, whose characteristics include a wide complex alluvial plain, reaches highly modified by anthropic interventions and recurrent flood episodes. This hydrogeomorphological approach allowed the integration of geomorphological knowledge and hydrologic-hydraulic modelling in flood analysis. As a result, it led to a deeper comprehension of the processes of inundation, which would be challenging to thoroughly understand without incorporating a holistic method, an essential factor for defining effective flood management strategies.
Fluvial spaces have a marked reduction at a global level because of anthropic processes, which have generated an increase in elements exposed to flooding. These spaces include natural flow courses ...and flood-prone lands. In Spain, natural channels are defined as Hydraulic Public Domain assets, whose delimitation is essential for their protection and flood risk management. However, demarcation of these areas with independent hydrological-hydraulic approaches has generated underestimates in the extension of water-covered lands, thus in recent years it has become clear that there is a need to integrate other variables, such as geology and fluvial geomorphology, which allow comprehension of river dynamics from processes that occurred in the past. Therefore, this study aims to contribute to a better understanding in the definition of areas belonging to natural channels through the development of a detailed hydrogeomorphological-historical method applied to Carrión river (Palencia, Spain). For this purpose, Digital Terrain Models were generated from high spatial resolution LIDAR data, on which erosive and sedimentary forms generated by water circulation were delimited, whose process was also supported in ephemeral and topographic evidences collected in field. With this input, depending on dynamic characteristics and river land vegetation, limits of the Hydraulic Public Domain were drawn. The products obtained are made up as optimized elements both for management of natural courses and for delimitation and zoning of new flooding areas by incorporating hydrogeomorphological criteria.
On 3 June 2018, a strong eruption of the Fuego volcano in Guatemala produced a dense cloud of 10-km-high volcanic ash and destructive pyroclastic flows that caused nearly 200 deaths and huge economic ...losses in the region. Subsequently, due to heavy rains, destructive secondary lahars were produced, which were not plotted on the hazard maps using the LAHAR Z software. In this work we propose to complement the mapping of this type of lahars using remote-sensing (Differential Interferometry, DINSAR) in Sentinel images 1A and 2A, to locate areas of deformation of the relief on the flanks of the volcano, areas that are possibly origin of these lahars. To determine the trajectory of the lahars, parameters and morphological indices were analyzed with the software System for Automated Geoscientific Analysis (SAGA). The parameters and morphological indices used were the accumulation of flow (FCC), the topographic wetness index (TWI), the length-magnitude factor of the slope (LS). Finally, a slope stability analysis was performed using the Shallow Landslide Susceptibility software (SHALSTAB) based on the Mohr–Coulomb theory and its parameters: internal soil saturation degree and effective precipitation, parameters required to destabilize a hillside. In this case, the application of this complementary methodology provided a more accurate response of the areas destroyed by primary and secondary lahars in the vicinity of the volcano.
The present study deals with the morphometric quantification of erosion and illustrates the uplift component triggered by denudation (isostasy) in the growth and evolution of a rising orogeny by the ...application of Airy isostasy concepts. The Gibraltar Arc, located in the Western–Central sector of the Betic Cordillera, developed an exceptional geological scenario during the Messinian Salinity Crisis since the thin emerged fringe of the uprising Cordillera disconnected the Atlantic and Mediterranean basins, generating a relevant misbalance and asymmetry in the fluvial erosion between the two slopes of the emergent orogeny. Our analysis was applied to 50 individual drainage basins (spatial isostatic units) in the Western–Central Betic Cordillera, allowing us to obtain individual and bulk estimates for these isostatic parameters. GIS-based numerical estimations were obtained using LiDAR Digital Elevation Models (DEMs) provided by the Spanish Geographical Institute and reconstructed pre-incision surface models obtained from proxy paleo-elevation data, estimated from stratigraphic and geomorphological littoral to shallow marine markers. The obtained values for geophysical relief, denudation plates, erosion/uplift rates and computed accumulated uplift (245–407 ±20 m) are higher for the ancient Mediterranean slope of the orogen. On the contrary, the Atlantic slope presents an accumulated uplift of only 138–236 ±20 m, indicating the strong control of the ancient Messinian Atlantic–Mediterranean water divide. The temporal study of erosion indicates that most of the difference in uplift in the Mediterranean slope was achieved during or soon after the Messinian Salinity Crisis, resulting in mean uplift rates of 0.21 mm/y, but practically null (0.01 mm/y) for the Atlantic slope. The comparison of the geophysical relief models with proxy paleo-elevation data allowed us to assess the current state of the denudation process in the range. The results indicate that, towards the west of the range denudation compensated elevation, and is actively back-feeding isostatic rebound. Therefore, the contribution of external processes to mountain range elevation through isostasy is quantitatively estimated using elevation data. In this case, a relevant part of the surface uplift (50-55%) is undertaken by the orogen. Ultimately, the Messinian Salinity Crisis-related isostatic response to differential denudation may be behind the quaternary westward tilting of Iberia, causing more than 70% of the Peninsula to drain towards the Atlantic.
The assessment of flood disasters is considered an essential factor in land use management, being necessary to understand and define the magnitude of past events. In this regard, several flood ...diagnoses have been developed using Sentinel-2 multispectral imagery, especially in large water bodies. However, one of the main challenges is still related to floods, where water surfaces have sizes similar to the spatial resolution of the analyzed satellite images, being difficult to detect and map. Therefore, the present study developed a combined methodology for flood mapping in small-sized water bodies using Sentinel-2 MSI imagery. The method consisted of evaluating the effectiveness of the application and combination of (a) a super-resolution algorithm to improve image resolution, (b) a set of seven spectral indices for highlighting water-covered areas, such as AWE indices, and (c) two methods for flood mapping, including a machine learning method based on unsupervised classification (EM cluster) and 14 thresholding methods for automatic determination. The processes were evaluated in the Carrión River, Palencia, Spain. It was determined that the approach with the best results in flood mapping was the one that combined AWE spectral indices with methods such as Huang and Wang, Li and Tam, Otsu, moment preservation, and EM cluster classification, showing global accuracy and Kappa coefficient values higher than 0.88 and 0.75, respectively, when applying the quantitative accuracy index.
While determining the uranium concentration in the rock (background level) and soils on the Iberian Massif of western Spain, several geochemical anomalies were observed. The uranium concentration was ...much higher than the geochemical levels at these locations, and several uranium minerals were detected. The proposed uranium background levels for natural soils in the west of Salamanca Province (Spain) are 29.8 mg kg−1 in granitic rock and 71.2 mg kg−1 in slate. However, the soil near the tailings of abandoned mines exhibited much higher concentrations, between 207.2 and 542.4 mg kg−1.
The calculation of different pollution indexes (Pollution Factor and Geo-accumulation Index), which reveal the conditions in the superficial horizons of the natural soils, indicated that a good percentage of the studied samples (16.7–56.5%) are moderately contaminated. The spatial distribution of the uranium content in natural soils was analysed by applying the inverse distance weighted method.
The distribution of uranium through the horizons of the soils shows a tendency to accumulate in the horizons with the highest clay content. The leaching of uranium from the upper horizons and accumulation in the lower horizons of the soil could be considered a process for natural attenuation of the surface impacts of this radiogenic element in the environment. Environmental restoration is proposed in the areas close to the abandoned mining facilities of this region, given the high concentration of uranium. First, all the tailings and other mining waste would be covered with a layer of impermeable material to prevent leaching by runoff. Then, a layer of topsoil with organic amendments would be added, followed by revegetation with herbaceous plants to prevent surface erosion.
Display omitted
•Uranium geochemical anomaly compared to the world geochemical background level.•Natural soils with diffuse pollution by mining activities.•The geochemical baseline of uranium in soils is greater on slates than on granites.•The vertical distribution of uranium in soil is concentrated in subsurface horizons.
This work analyses the chronology of fluvial terrace sequences of the two most important fluvial basins from central Spain draining to the Atlantic Ocean (Upper Tagus and Duero drainage basins). Both ...basins evolved under similar Mediterranean climatic conditions throughout the Pleistocene and present comparable number of fluvial terraces (16–17) after excluding the higher terrace levels of the Tagus (T1–T5) entrenched in the Raña surface. These higher “rañizo terraces” was formed in response to fan-head trenching in this high alluvial piedmont (+220 m) and therefore not properly controlled by Quaternary fluvial downcutting. The study accomplishes the implementation of multiple regression analyses for terrace height-age relationships. To transform relative terrace heights above the present river thalwegs (i.e. +100 m) in numerical ages a “height-age transference function” has been developed on the basis of preliminary statistical geochronological approaches proposed for Central Spain. The resultant height-age transference function gather 73 published geochronological data for terrace sequences, featuring a 3rd Order Polynomial Function (R2 0.90). This function describes the overall trend of valley downcutting for the last c. 2.3 Ma in Central Spain and is used to assign numerical ages to terrace levels at different relative elevation.
•Is analysed the chronology of fluvial terrace sequences in central Spain summarising existent Geochronological, faunal and Palaeolithic data.•3rd Order Polynomial Functions describe the overall trend of valley downcutting for the last c. 2.3 Ma in Central Spain.•The obtained Height-Age transference functions can be used to assign numerical ages to terrace levels at different relative elevation.
PDF
