A. Navas

• Doctor of Geology
• Professor at Spanish National Research Council

Global climate change has most significantly affected the Polar Regions. The increase in air temperature has stimulated the melting of glaciers in the Arctic and Antarctic, which has contributed to changes in the formation of water and sediment runoff. However, there are very few quantitative estimates of the sediment redistribution in the periglac...

This study examined phosphorus (P) delivery and transport in flood events in an agroforestry catchment, with cropland and forestland as the main land uses. Sediments were collected in artificial‐lawn mats (MATs) distributed in five locations across the catchment (MAT1 to MAT5) along 20 seasonal campaigns during 5 years, in which rainfall with diffe...

To ensure sustainable agricultural management, there is a need not only to quantify soil erosion rates but also to obtain information on the status of soil water content and soil loss under different soil types and land uses. A clear understanding of the temporal dynamics and the soil moisture spatial variability (SMSV) will help to control soil de...

The impact of particle size on elemental content in soils is difficult to predict because the positive linearity between them does not apply equally to all elements. This assumption needs to be constantly examined and considered for fingerprinting studies. Overall, higher element enrichment in the fine fractions reflects the increasing adsorption p...

Erosion exerts control on soil organic carbon (SOC) and both erosion and SOC are affected by climate. To what extent temperature controls the coupling between these erosion–C interactions remains unclear. Using ¹³⁷Cs and SOC inventories from catchments spanning different climates, we find that increasing decomposition rates with temperature result...

Recent land use changes, the absence of soil protection between crop periods, and extreme precipitation events have been highlighted as major influential factors in the fluctuations of sediment export in the last decades at the catchment scale worldwide. In this regard, soil erosion and fine-particle export are two of the major concerns of soil nut...

In slopes of Mediterranean mid-mountain areas, land use and land cover changes linked to the abandonment of cropland activity affect soil quality and degradation and soil redistribution; however, limited attention has been paid to this issue at catchment scale. This paper evaluates the effects of cropland abandonment and post-land abandonment manag...

Erosion causes significant soil and nutrient losses that can reach streams and degrade habitats. Phosphorus (P) is among the nutrients of greatest concern for water pollution. Due to the increase in the number of storm events over the last decade, which could rise further under climate change scenarios, a more in-depth analysis of the effect of rai...

The effects of human activity on geomorphic processes, particularly those related to denudation/sedimentation, are investigated by reviewing case studies and global assessments covering the past few centuries. Evidence we have assembled from different parts of the world, as well as from the literature, show that certain geomorphic processes are exp...

In the Cordillera Blanca, the glaciers delineated by some of the highest peaks in the tropical Peruvian Andes have experienced a fast retreat over the last few decades. At the foot of Artesonraju Peak, the glacier‐fed river conveys fine sediments to Parón Lake, which is enclosed in the proglacial area created by the retreating glaciers of the uniqu...

Soil erosion is especially severe in areas affected by intermittent heavy rainfalls after dry periods, and human practices such as deforestation. Mediterranean mountain environments underwent conversion of rangelands into croplands during the previous centuries to increase agricultural production but this process was reversed after land abandonment...

Sediment fingerprinting has emerged as a valuable tool for elucidating soil erosion processes and assessing the sources of sediment and particle-bound chemicals. Due to its upward trend in popularity and the parallel advances in analytical methods, different types of tracers such as Compound-Specific Stable Isotopes (CSSIs) have been incorporated t...

Sediment fingerprinting experiments have been used to demonstrate the sensitivity of numerical mixing model outputs to different particle size distributions in source materials and experimental sediment mixtures. The study aims to examine further grain size effects in the distribution of geochemical elements by soils through a laboratory experiment...

The mineral composition of soils and weathering processes are known to control the natural radioactivity of soils but research on the influence of water erosion and of main soil properties in the spatial variability of lithogenic and fallout radionuclides remains little investigated in heterogeneous agroecosystems with complex landscape. An extensi...

A Compound Specific Stable Isotope (CSSI) sediment tracing approach is applied for the first time in a Mediterranean mountain agroforestry catchment subjected to intense land use changes in the past decades. Many Mediterranean mountain environments underwent conversion of rangelands into croplands during the previous centuries to increase agricultu...

Fingerprinting technique is a widely used tool to assess the sources of sediments and particle bound chemicals within a watershed, and the results obtained from unmixing models are becoming valuable data to support soil and water resources monitoring and conservation. Nowadays, numerous studies have used fingerprinting techniques to examine specifi...

Denudation and land cover change are of high relevance for Earth surface and landscape dynamics and the transfer of solutes and sediments from headwater systems through main stem of drainage basin systems to the world oceans. Denudational hillslope and fluvial processes, associated source-to-sink fluxes and sedimentary budgets are controlled by a r...

Soil erosion and fine particle exports are two of the major concerns of soil nutrient loss and water quality decrease nowadays. In Mediterranean mountainous environments, agricultural practices during different cropland stages likely increase sediment supplies and the export of fertilisers and pesticides out into the drainage system. In this study,...

Soil loss by erosion processes is one of the largest challenges for food production and reservoir siltation around the world. Information on sediment, nutrients and pollutants is required for designing effective control strategies. The estimation of sediment sources is difficult to get using conventional techniques, but sediment fingerprinting is a...

Sediment export rates are sensitive to different parent materials, changes in land use, human impact and climate, but the landscape response to such changes is difficult to interpret, and more knowledge of soil erosion hot spots is still needed. Special focus should be directed to examine the role of the erosional impact of water movement in mobili...

In the changing glacierized areas of the maritime Arctic region, fluxes of sediments are of high intensity during the Arctic melting season. On the Western Spitsbergen Island around Grønfjord, several glaciers have declined rapidly over the last century. The Aldegonda Glacier has retreated about 2 km since 1911 when the glacier tongue reached the s...

Soil erosion induced by runoff is a main hydrological pathway for lateral soil carbon movement in terrestrial landscapes. Consequences of accelerated soil erosion have led to the degradation of soil resources and reduction of soil productivity. Water erosion includes detachment, soil transport and sedimentation processes. The dynamics of soil erosi...

Soil erosion induced by runoff is a main hydrological pathway for lateral transport of carbon in terrestrial landscapes. More information about how water erosion influences the carbon gains and losses at different erosional and depositional landform positions is critical, especially in fragile agroecosystems with a variety of land uses and ephemera...

In this study, the potential effect of the selective transport and deposition by interrill erosion on the spatial distribution of eroded soil and associated soil organic (SOC) and inorganic carbon (SIC) in carbonate-rich soils was investigated in Mediterranean cultivated Calcisols. Particular attention was paid to the role of calcium carbonate in t...

Soil erosion and fine particle transport are two of the major challenges in food security and water quality for the growing global population. Information of the areas prone to erosion is needed to prevent the release of pollutants and the loss of nutrients. Sediment fingerprinting is becoming a widely used tool to tackle this problem, allowing to...

This paper reports work exploring the potential for using the natural fallout radionuclide 210Pbex to date moraine soils for tracing glacier retreat. Based on the physical processes of 210Pbex deposition, decay and losses due to runoff, a 210Pbex accumulation-decay model (A_n=I[(1-λ^(n+1))/(1-λ)-(b(c^(n+1)-λ^(n+1)))/(c-λ)] ) was developed, where A_...

The aim of this research was to analyse the effect of rainfall intensity and slope on soil and nutrient losses by hydric erosion in soils with different hydrological characteristics. This research was carried out on soils collected from slopes with different land uses/covers (LU/LC)-forest, scrub, agricultural, afforested and barren land-, from a m...

Patterns of erosion, transport and deposition of soil particles not only affect the distribution of mineral fraction of the soil but their organic components. The spatial variability of soil nutrients in Mediterranean mountain agroecosystems that combine complex land uses and abrupt topography is poorly documented despite emerging concerns on nutri...

Fallout radionuclides, such as Caesium-137, were proven to be a valuable means for studying medium-term (c.a. 50 years) soil erosion processes. In order to gain knowledge on the spatial distribution of ¹³⁷Cs in volcanic soils of Andean Patagonia, ¹³⁷Cs reference inventories were established along a precipitation gradient. At the subhumid sector, pa...

In Mediterranean mountain agroecosystems, soil erosion associated with the development of ephemeral gullies is a common environmental problem that contributes to a loss of nutrient‐rich topsoil. Little is known about the influence of ephemeral gully erosion on particle size distribution and its effect on soil organic (SOC) and inorganic (SIC) carbo...

In the Mediterranean region, floods are expected to increase as a result of climate change and knowledge of soil erosion hot spots during exceptional rainfalls is required to support mitigation measures. This study quantifies the main sediment sources during an exceptional rainfall event in 2012 (235 mm) at the outlet of two catchments located in N...

The loss of fertile topsoil is one of the principal soil degradation problems in mountain agroecosystems worldwide. Soil erosion rates reach their maximum during exceptional storm events that remove soil particles, especially from unprotected topsoil. In Mediterranean mountainous environments, several centuries of non-irrigated agriculture and the...

Soil organic carbon (SOC) is a useful indicator of soil fertility that plays an important role in improving soil quality, increasing agronomic productivity and maintaining sustainability of agricultural systems. The use of hyperspectral data for SOC estimation offers a fast, cost-effective, and non-destructive alternative to conventional soil analy...

Soil salinization is one of the biggest challenges for food production worldwide and an important threat to farming activities, water quality, land degradation and sustainable development in arid and semi-arid areas. Soil saliniza-tion is mainly characterized by significant spatiotemporal dynamics. The salt-affected soils are predominant in the Ebi...

As in other regions of the world, glaciers in South America like in Torres del Paine National Park are shrinking. The trends of increasing temperatures would accelerate melting process that will affect not only populations but also natural resources as water and soil that support life. Recent works in other polar and cold regions have shown the use...

Soil tillage and erosion promote the break up of soil structure and loss of carbon. Soil structure is one of the main factors controlling the ability of soil to support plant growth, the movement of water and the cycling of carbon and nutrients. Therefore soil aggregation is an important soil property for farmers. Soil aggregation affects soil orga...

Sediment source fingerprinting is increasingly used to provide insight into the dynamics of catchment sediment transfer processes, yet relatively few studies seek to validate source apportionments obtained from unmixing models. Our work focuses on simulating natural processes to test the accuracy of source apportionments obtained using a multivaria...

Several decades of intensive rainfed, farming in Mediterranean mountains and later land abandonment has led to rapid land use and land cover changes. During recent centuries, the conversion of rangelands into croplands has increased the surfaces prone to erosion. In the southern Pre-Pyrenees, the process was reversed during the middle of the twenti...

Implementation of socially acceptable and environmentally desirable solutions to soil erosion challenges in the Global South is often limited by (1) fundamental gaps between the evidence bases of different disciplines and (2) an implementation gap between science-based recommendations, policy makers and practitioners. We present an integrated, inte...

The lateral and vertical variations of SOC (soil organic carbon) contents were examined in combination with the 137Cs profiles to gain information on the nutrient content in the soils under the most characteristic land uses existing in the catchment. In general the SOC contents are low but the mean contents in the croplands are much lower than in t...

The present dominant trend of retreating and shrinking glaciers is leading to the formation of new soil in proglacial zones. The Cordillera Blanca located in the Peruvian Andes includes the Lake Parón catchment known for the Artesonraju Glacier and its rapid retreat, forming the largest proglacial lake in the region. This work aims to gain knowledg...

Increasing complexity in human-environment interactions at multiple watershed scales presents major challenges to sediment source apportionment data acquisition and analysis. Herein, we present a step-change in the application of Bayesian mixing models: Deconvolutional-MixSIAR (D-MIXSIAR) to underpin sustainable management of soil and sediment. Thi...

This paper aimed to identify indicators of soil degradation in volcanic soils developed in the ecotone between the Andean Forests and the Patagonian steppe. The study area is located in the Percy River Basin, Argentine, on alluvial fans with volcanic soils. Sampling was conducted in two adjacent hillslopes where native forest was replaced by a rang...

Changes in land use due to human activities on soils and vegetation are a widespread problem that often leads to land degradation and are of considerable concern worldwide in the context of environmental degradation and global climate change. Over last centuries, the conversion of rangelands into croplands had increased the surfaces prone to erosio...

Land degradation by water erosion is one of the main problems in Mediterranean areas. This problem is of particular relevance in mountain areas, where intensive farming and land use changes including land abandonment and changes in soil cover occur. This research analysed the contribution of different land uses to soil and nutrient losses in an eph...

Soil magnetic susceptibility (MS) is a rapid and cost-effective technique that has been applied in environmental studies for monitoring soil pollution by heavy metals and soil redistribution and to infer soil forming processes. Few studies involved magnetic research in arable soils and limited information is available about the use of field magneti...

In Mediterranean mountainous environments, the removal of natural vegetation for developing agriculture increased the surface areas prone to erosion in the past centuries. In Southern Pre-Pyrenees, the process was inverted during the middle of the 20th century. This work aims to assess how land-use changes after widespread land abandonment affect s...

Many ice-free environments in Maritime Antarctica are undergoing rapid and substantial environmental changes in response to recent climate trends. This is the case of Elephant Point (Livingston Island, South Shetland Islands, SSI), where the glacier retreat recorded during the last six decades exposed 17% of this small peninsula, namely a moraine e...

Oxygen depletion (temporal or permanent) in freshwater ecosystems is a widespread and globally important environmental problem. However, the factors behind increased hypolimnetic anoxia in lakes and reservoirs are often diverse and may involve processes at different spatial and temporal scales. Here, we evaluate the combined effects of different an...

Soils in ice‐free areas of Elephant Island (South Shetland Islands) have been forming since the last deglaciation following the glacial retreat that started in the area probably later than 9.7‐5.5ka. In paraglacial landscapes landforms and processes in transition from glacial to non‐glacial conditions, are experiencing rapid environmental adjustmen...

Lake Enol, a mountain lake in Northern Spain, is located at 1,070 m a.s.l. in Picos de Europa National Park (PENP), an emblematic area of limestone formations, Atlantic forests, mountain meadows and a varied and rich wildlife which led to its declaration as National Park (first one in Spain) in 1918. The Enol Lake is one of the most visited places...

The characteristics and distribution of unsupported radioactive lead‐210 ( ²¹⁰ Pb ex ) in soil and the relations between the radionuclide and soil properties determine its fate within the environment. We have explored the distribution of ²¹⁰ Pb ex in stony soil profiles near the edge of the Ebro basin in northern Spain, the role played by vegetatio...

Land use conversion from cropland to natural vegetation can be an effective mechanism to reduce soil C losses and promote soil C recovery affecting the storage of C in soils. Understanding how anthropogenic land use changes lead to implications for soil C storage and how it affects the distribution of total carbon provide information that will supp...

Soils are the largest C reservoir of terrestrial ecosystems and play an important role in regulating the concentration of CO 2 in the atmosphere. The exchange of CO 2 between the atmosphere and soil controls the balance of C in soils. The CO 2 fluxes may be influenced by climate conditions and land use and cover change especially in the upper soil...

Soil redistribution processes play an important role influencing the spatial distribution patterns of soil and associated soil organic carbon (SOC) at landscape scale. Information on drivers of SOC dynamics is key for evaluating both soil degradation and SOC stability that can affect soil quality and sustainability. 137Cs measurements provide a ver...

The spatial variability of soil organic carbon (SOC) and nitrogen (SON) can be affected by environmental factors such as land use change, type of vegetation, topographic characteristics, soil management practices and specially soil redistribution processes. The use of fallout 137Cs derived from nuclear testing in the past century has been widely us...

Rainfall simulation experiments were carried out in order to study soil crust formation and its relation with soil infiltration parameters—sorptivity (S) and hydraulic conductivity (K)—on four common agricultural soils with contrasted properties; namely, Cambisol, Gypsisol, Solonchak, and Solonetz. Three different rainfall simulations, replicated t...

Fine-grained sediment is an important pollutant and determining its provenance is an important issue for reservoir management and river quality. Sediments accumulated in reservoirs have greatly decreased water storage capacities and are a major threat to the sustainability of water resources around the world. Using fingerprinting procedures is now...

Increased sediment erosion levels can lead to degraded water and food quality, reduced aquatic biodiversity, decrease reservoir capacity and restrict recreational usage but determining soil redistribution and sediment budgets in watersheds is often challenging. One of the methods for making such determinations applies sediment fingerprinting method...

Soil aggregate stability is one of the main factors of soil physics and structure. Formation and stabilization of soil aggregates facilitates soil carbon sequestration and reduces the susceptibility of soil to erosion. The gain or loss of C in agricultural systems is largely influenced by aggregate–associated soil organic carbon that affects the se...

In Maritime Antarctica important environmental changes are affecting ice-free environments of the South Shetland Islands and the northern Antarctica Peninsula. In the Elephant Point Peninsula (Livingstone Island) a rapid glacier retreat during the last decades has exposed already around 20% of its 1.16 km2 surface. Despite soil development is taken...

Abstract The purpose of this study is to understand and quantify the relationships between current 137Cs inventories and the soil properties and the physiographic characteristics. A total of 36 cores were taken in seven transects with different slopes, lithology and land use. The analysis focused on the 137Cs mass activity as well as inventories an...

The project involves the study of Enol and Marboré lakes in order to study the current state, the assessment of the impact of the global change, and the changes of the last 3000 years. Lake Enol is subjected to a high-anthropic pressure since the nineteenth century: mining, water regulation, erosion, tourism and livestock. A hypolimnetic anoxia is...

Fallout caesium-137 has been used to trace soil redistribution in abandoned fields located in the Central Spanish Pyrenees. A total of 28 fields with different lengths, slope angles and time since abandonment were selected on a representative south facing slope of the Estarrún valley. The local reference inventory and the magnitude and spatial dist...

In the Mediterranean region, the long history of cultivation is associated with significant changes in the original landscape. Agricultural intensification and subsequent land abandonment and reforestation have significantly affected the hydrological behaviour and connectivity patterns of hydrological systems. Thus, information on the spatial distr...

The Ebro river gypsum scarp shows a high density of inactive and currently active mass movements. An analysis of the numerous factors and processes which control the evolution of this scarp, his geomorphological landforms and a 3D diagram explaining his evolution was performed. Both, uploading in a family of joints parallel to the scarp, and the pr...

Grain-size analysis is a key analysis in soil studies, so accurate determinations are needed for this variable. However, different analytical methods could show different results, even more in volcanic soils with high organic matter contents. The aim of this study was to compare the granulometric fractions of non-allophanic volcanic soils of the An...

Grain-size analysis is a key analysis in soil studies, so accurate determinations are needed for this variable. However, different analytical methods could show different results, even more in volcanic soils with high organic matter contents. The aim of this study was to compare the granulometric fractions of non-allophanic volcanic soils of the An...

The new challenges in assessment of water resources demand new approaches and tools, such as the use of hydrologic models, which could serve to assist managers in the prediction, planning and management of catchment water supplies in view of increased demand of water for irrigation and climatic change. Good characterization of the spatial patterns...

No. 0088 Categories Symposium 19: Erosion threats in mountain environments: processes, impacts and mitigation Title Using roughness and C-factor in a connectivity index to evaluate the impact of land use/cover changes in a Mediterranean mountain catchment Abstract Sediment connectivity has an important effect on the development of morphological lan...

Land management in agricultural lands has important effects on soil organic carbon (SOC) dynamics. These effects are particularly relevant in the Mediterranean region, where soils are fragile and prone to erosion. Increasing interest of modelling to simulate SOC dynamics and the significance of soil erosion on SOC redistribution have been linked to...

Understanding how organic carbon (OC) moves with sediments along the fluvial system is crucial to determining catchment scale carbon budgets and helps the proper management of fragile ecosystems. Especially challenging is the analysis of OC dynamics during fluvial transport in heterogeneous, fragile, and disturbed environments with ephemeral and in...

Information on sediment contribution and transport dynamics from the contributing catchments is needed to develop management plans to tackle environmental problems related with effects of fine sediment as reservoir siltation. In this respect, the fingerprinting technique is an indirect technique known to be valuable and effective for sediment sourc...

The elevated supply and transfer of sediment in river systems can impact on water resource infrastructure, water quality and ecosystem health around the world. Moreover, the loss of reservoir capacity due to siltation is of particular concern in regions that experience water scarcity, such as the Mediterranean. Therefore, quantifying the sediment p...

Land use/cover changes since 1957 by human intervention have probably increased connectivity and runoff in Barués Catchment, mostly due to tillage and geomorphological processes such as landsliding, gullying incised streams and severe soil erosion whilst abandoned arable lands and reforested areas seems to be very efficient in reducing runoff and c...

In Elephant Point Peninsula the glacier retreat recorded during the second half of the XX century has exposed 17% of its 1.16 km2 surface (Oliva & Ruiz-Fernández, 2016). This study aims at characterizing the upper soil layers of recently formed soils developed on different geomorphic features to investigate the properties that can reveal features r...

The estimation of soil redistribution rates is necessary to evaluate the environmental impact of soil erosion including the loss of fertile topsoil which is one of the main soil degradation problems in agricultural landscapes. Modelling approach offers a potential tool for quantifying soil redistribution and to propose site-specific control measure...

Mediterranean mountain agroecosystems are prone to soil loss mainly due to the accelerated erosion as a consequence of human induced changes from agriculture and grazing practices over the last centuries and the climatic conditions (i.e. irregular and scarce precipitations and drought periods). Soil erosion leads to soil degradation inducing the lo...

The loss of fertile topsoil is one of the principal soil degradation problems in agricultural landscapes worldwide. Mediterranean agroecosystems are particularly threatened to soil degradation because of the climate, a higher sensitivity to soil erosion and the intensification of human activities and agricultural practices during centuries. The sev...

Loss of soil and subsequent export of sediments to streamflows by water erosion constitute significant environmental threats because of the areal extent typically involved and the agricultural activities that they support. Climate change is expected to impact on the availability of water and therefore on soil resources. In this context, hydrologica...

Topsoil water content (TSWC) is a key factor for crop establishment and subsequent production, runoff generation, soil detachment, and other soil processes. TSWC is one of the most variable soil properties due to the complexity of water fluxes in the unsaturated zone. The studies about TSWC in cultivated Calcisols are limited and almost inexistent...

Se presenta una fauna de briozoos queilostomados hallados en un depósito diamictítico localizado en el Cabo Lamb, Isla Vega, Antártida, que constituye un nuevo registro fósil de este grupo en rocas sedimentarias del Cenozoico tardío de la Cuenca James Ross. Estos briozoos provienen de los mismos horizontes y del mismo perfil estratigráfico donde fu...

Mediterranean mountain agroecosystems are sensitive areas to soil degradation due to climatic conditions and anthropogenic pressure from agriculture and grazing practices. Soil redistribution processes affect the spatial variability of soil properties and nutrients, as soil organic carbon and nitrogen (SOC and SON) are linked to soil quality and so...

Information on sediment sources in river catchments is required for effective sediment control strategies, to understand sediment, nutrient and pollutant transport, and for developing soil erosion management plans. Sediment fingerprinting procedures are employed to quantify sediment source contributions and have become a widely used tool. As finger...