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The effectiveness of conservation agriculture (CA) and other soil management strategies implying a reduction of tillage has been shown to be site-dependent (crop, clime and soil), and thus any new soil and crop management should be rigorously evaluated before its implementation. Moreover, farmers are normally reluctant to abandon conventional practices if this means putting their production at risk. This study evaluates an innovative soil and crop management (including no-tillage, cover crops and organic amendments) as an alternative to conventional management for rainfed cereal cropping in a calcareous soil in a semi-arid Mediterranean climatic zone of Navarra (Spain), based on the analysis of soil water retention curves (SWRCs) and soil structure. The study was carried out in a small agricultural area in the municipality of Garínoain (Navarre, Spain) devoted to rainfed cereal cropping. No other agricultural area in the whole region of Navarre exists where soil and crop management as proposed herein is practiced. Climate is temperate Mediterranean, and the dominant soil is Fluventic Haploxerept. Within the study area there is a subarea devoted to the proposed soil and crop management (OPM treatment), while there is another subarea where the soil and crop management is conventional in the zone (CM treatment). OPM includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments. CM involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Undisturbed soil samples from the topsoil and disturbed samples from the tilled layer were collected for both systems. The undisturbed samples were used to obtain the detailed SWRCs in the low suction range using a HYPROP©device. From the SWRCs, different approaches found in the literature to evaluate soil physical quality were calculated. The pore-size distribution was also estimated from the SWRCs. Disturbed samples were used in the laboratory to assess soil structure by means of an aggregate-size fractionation and to perform complementary analysis from which other indicators related to soil functioning and agricultural sustainability were obtained. The approaches evaluated did not show clear differences between treatments. However, the differences in soil quality between the two forms of management were better observed in the pore size distributions and by the analysis of the size distribution and stability of soil aggregates. There was an overabundance of macropores under CM, while the amount of mesopores (available water) and micropores were similar in both treatments. Likewise, more stable macroaggregates were observed in OPM than in CM, as well as more organic C storage, greater microbial activity, and biomass. The proposed management system is providing good results regarding soil physical quality and contributing also to the enhancement of biodiversity, as well as to the improvement in water-use efficiency. Finally, our findings suggest that the adoption of the proposed practice would not result in a loss in yields compared to conventional management. This study was partially supported by the Ministerio de Economía y Competitividad (Government of Spain) via research project CGL2015-64284-C2-1-R and PID2020-112908RB-I00 funded by 568 MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa”.

In 1993, the Government of Navarre (northern Spain) began the installation and operation of a network of experimental watersheds in order to assess, among other aspects, soil erosion in representative agricultural areas of the territory. Initially, sediment sampling at the outlet of each of the five basins was performed on a daily basis, despite which it was possible to get a highly fruitful and novel knowledge on sediment export (Merchán et al., 2019). However, in the last 16 years, with the aim of studying sediment export in more detail, the sampling frequency was increased so that the behavior of the sedimentogram at the event level could be known. In these cases, when the amount of sediment was large enough, the sediment texture was also determined. In addition, from the beginning of the observations, a turbidimeter was used to record turbidity data every 10 minutes. The aim of this work is to deepen the knowledge of sediment export dynamics in representative agricultural watersheds of Navarre by analyzing the database described above and focusing in specific events. To do this, first, the entire database was represented in graphs that include variables such as sediment texture, samples taken per event, daily mean precipitation, turbidity, flow rate, etc. Next, events with a minimum of six samples were selected and the linear relationship between turbidity and sediment concentration was analyzed using simple linear regressions, as this is the method used in similar works. Subsequently, these same event data were added to set up monthly samples where again linear regressions were performed. Apart from the simple linear analysis, where the linear relationship with turbidity was analyzed as the only predictor variable, different artificial intelligence methods have been explored, such as the generalized linear model (GLM), support vector machine (SVM), multivariate adaptive regression splines (MARS) and random forest (RF), adding additional variables such as accumulated precipitation, and season or water level in the analysis. The results from all these statistical studies have been disappointing, since no pattern or generalization has been found to predict sediment concentration from the variables considered. These results suggest that the sediment export behavior of small agricultural watersheds is particularly complex and controlled by spatially and temporally varying variables. It is evident that at least some of these variables have not been taken into account in the study. The high variability found in sediment textures supports the hypothesis that the erosive behavior of watersheds is of great complexity. We believe that the consideration of variables such as vegetation on slopes and channels and its evolution can be helpful in the analysis. Merchán, D., Luquin, E., Hernández-García, I., Campo-Bescós, M. A., Giménez, R., Casalí, J., & Del Valle de Lersundi, J. (2019). Dissolved solids and suspended sediment dynamics from five small agricultural watersheds in Navarre, Spain: A 10-year study. CATENA, 173, 114–130. https://doi.org/10.1016/J.CATENA.2018.10.013

Nitrate pollution adversely affects water quality, making it unsafe for human consumption and contributing to increased eutrophication. Nitrate exportation in agricultural areas is inevitable; however, climate change introduces great uncertainty into an already very complex problem. Thus estimating the effects of climate change on streamflow and nitrate dynamics would significantly contribute to the management of the affected areas. This research aimed to predict the impacts of climate change on streamflow and nitrate exportation in a Mediterranean rainfed agricultural watershed using the Soil Water Assessment Tool (SWAT). The model was first evaluated for its suitability to simulate streamflow and nitrate loads under rainfed agricultural conditions in the 477 km2 Cidacos River Watershed in Navarre, Spain. The model was then used to analyze the climate change impacts on streamflow and nitrate load in the short-term (2011-2040), medium-term (2041-2070), and long-term (2071-2100) climate projections compared to a historical baseline period (1971-2000) using the RCP4.5 and RCP8.5 CO2 emission scenarios. The model evaluation showed a good model performance during calibration (2000-2011) and validation (2011-2020) for streamflow (NSE = 0.82/0.83) and nitrates load (NSE = 0.71/0.68), indicating its suitability for adoption in the watershed. The climate change projection results showed a steady decline in streamflow and nitrate load for RCP4.5 and RCP8.5 in all the projections, with the long-term projection scenario of RCP8.5 significantly affected. Autumn and winter saw the greatest seasonal declines compared to spring and summer. The decline in streamflow was attributed to the projected decrease in precipitation and increase in actual evapotranspiration due to increasing temperatures, while the nitrate load decline was consistent with the projected streamflow decline. Based on these projections, the long-term projection scenarios of RCP8.5 indicate severe situations requiring urgent policy changes and management interventions to minimize and mitigate the negative consequences. Therefore, better agricultural management practices are needed to ensure sustainable water resource utilization and efficient nitrogen fertilizer application rates in the watershed to reduce pollution.

The effectiveness of conservation agriculture (CA) and other soil management strategies implying a reduction of tillage has been shown to be site-dependent (crop, clime and soil), and thus any new soil and crop management should be rigorously evaluated before its implementation. Moreover, farmers are normally reluctant to abandon conventional practices if this means putting their production at risk. This study evaluates an innovative soil and crop management (including no-tillage, cover crops and organic amendments) as an alternative to conventional management for rainfed cereal cropping in a calcareous soil in a semi-arid Mediterranean climatic zone of Navarra (Spain), based on the analysis of soil water retention curves (SWRCs) and soil structure. The study was carried out in a small agricultural area in the municipality of Garínoain (Navarre, Spain) devoted to rainfed cereal cropping. No other agricultural area in the whole region of Navarre exists where soil and crop management as proposed herein is practiced. Climate is temperate Mediterranean, and the dominant soil is Fluventic Haploxerept. Within the study area there is a subarea devoted to the proposed soil and crop management (OPM treatment), while there is another subarea where the soil and crop management is conventional in the zone (CM treatment). OPM includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments. CM involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Undisturbed soil samples from the topsoil and disturbed samples from the tilled layer were collected for both systems. The undisturbed samples were used to obtain the detailed SWRCs in the low suction range using a HYPROP©device. From the SWRCs, different approaches found in the literature to evaluate soil physical quality were calculated. The pore-size distribution was also estimated from the SWRCs. Disturbed samples were used in the laboratory to assess soil structure by means of an aggregate-size fractionation and to perform complementary analysis from which other indicators related to soil functioning and agricultural sustainability were obtained. The approaches evaluated did not show clear differences between treatments. However, the differences in soil quality between the two forms of management were better observed in the pore size distributions and by the analysis of the size distribution and stability of soil aggregates. There was an overabundance of macropores under CM, while the amount of mesopores (available water) and micropores were similar in both treatments. Likewise, more stable macroaggregates were observed in OPM than in CM, as well as more organic C storage, greater microbial activity, and biomass. The proposed management system is providing good results regarding soil physical quality and contributing also to the enhancement of biodiversity, as well as to the improvement in water-use efficiency. Finally, our findings suggest that the adoption of the proposed practice would not result in a loss in yields compared to conventional management.

Agriculture intensification, such as irrigation, creates a lot of pressure on the available water resources and the environment. This paper explored the water quality dynamics, specifically nitrates, before and after transformation from rainfed to irrigation agriculture within the Cidacos River Watershed in Navarra, Spain. The watershed occupies 477 km2, of which approximately 260 km2 have been traditionally rainfed cultivated, whereas 77 km2 were transformed from rainfed to pressurized irrigation between 2009 and 2011. The newly irrigated area is located in the watershed's lower region, close to the river's mouth. Water quality data sampling has been taken at several points along the watershed from 2000 to date, up to the outlet of the Cidacos River in Traibuenas, where it joins with the Aragón River. Streamflow and nitrate concentration data have been measured at the watershed's outlet in Traibuenas since 2017. A previous baseline study by Merchán et al. (2020) showed an increase in the electrical conductivity and nitrate concentration in the river's lower reaches affected by irrigation. However, no information about the effect on streamflow, nitrate loads, and yields resulting from the irrigation was explored. The aim of this study was therefore to fill this research gap by using hydrological models such as the Soil Water Assessment Tool (SWAT) model, to recreate, simulate and understand the behaviour of the Cidacos River in the irrigated area from 2017 to the present, if the transformation from rainfed to irrigation had not occurred; and then compare those simulated variables with the measured ones since 2017. Simulation of streamflow and nitrate loads were done using the SWAT model until Olite from 2000 to 2020 under rainfed conditions. This was later extended for the entire watershed up to the mouth of the Cidacos River from 2017 to the present when the transformation to irrigation was fully completed and the Traibuenas outlet gauging station started operating. The results were then compared to the measured data for the irrigated region before and after the transformation to irrigation. For the simulations, the model was calibrated from 2000 to 2010 and validated from 2011 to 2020, and its sensitivity and uncertainties were analyzed for streamflow and nitrates at the Olite gauging station. The model evaluation results were satisfactory for both streamflow and nitrate loads, with streamflow having values of NSE = 0.82/0.83 and R2 = 0.83/0.84 during calibration and validation periods, respectively. Similarly, the statistical evaluation values for nitrate loads were NSE = 0.71/0.68 and R2 = 0.72/0.79 during calibration and validation periods, respectively. Subsequently, the calibrated parameters were used to simulate the entire watershed, considering all the territorial variables specific to each zone. Comparative analysis between the periods before and after the implementation of irrigation indicated a 6.6% and 43.2% increase in streamflow and nitrate loads, respectively, which subsequently increased the nitrate concentrations. The results from this study could provide useful information and guidance on nitrate pollution control, thus contributing to the management of the effects of agriculture on water quality and enhancing sustainable agricultural practices.

Dense time series of Sentinel-1 imagery are an invaluable information source for agricultural applications. Multiple orbits can observe a specific area and their combination could improve the temporal resolution of the time series. However, the orbits have different acquisition geometries regarding incidence and azimuth angles that need to be considered. Furthermore, crops are dynamic canopies and the influence of incidence and azimuth angles might change during the agricultural season due to different phenological stages. The main objective of this letter is to evaluate the influence of different acquisition geometries in Sentinel-1 backscatter time series over wheat canopies, and to propose a strategy for their correction. A large dataset of wheat parcels (∼40,000) was used and 344 Sentinel-1 images from three relative orbits were processed during two agricultural seasons. The first analysis was a monthly evaluation of the influence of incidence angle on backscatter (σ0) and terrain flattened backscatter (γ0). It showed that terrain flattening significantly reduced the backscatter dependence on incidence angle, being negligible in VH polarization but not completely in VV polarization. Incidence angle influence in VV backscatter changed in time due to wheat growth dynamics. To further reduce it, an incidence angle normalization technique followed by an azimuthal anisotropy correction were applied. In conclusion, γ0 enabled a reasonable combination of different relative orbits, that may be sufficient for many applications. However, for detailed analyses, the correction techniques might be implemented to further reduce orbit differences, especially in bare soil periods or winter months. This work was supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (MINECO/FEDER-UE) through projects [CGL2016-75217-R and PID2019-107386RB-I00 / AEI / 10.13039/501100011033] and doctoral grant [BES-2017-080560].

In this paper, the assessment of multiple scenario cases for large-scale farm monitoring using Low-Power Wide-Area Network (LPWAN) based near-ground sensor nodes with the interaction of both tractors and farmers are presented. The proposed scenario under analysis considers multiple communication links, namely nodes to infrastructure, nodes to tractor, nodes to farmer, tractor to infrastructure and farmer to infrastructure communications. Moreover, these scenarios are proposed for tractors and agricultural equipment performance improvement and tracking, as well as resources management within the farm field. Different link type configurations are tested in order to consider the impact of ground, spatial distribution as well as infrastructure elements. The results show that LPWAN-based WSNs can provide better performance in terms of coverage and radio link quality results than ZigBee for a non-flat large-scale farm field in both cases of near-ground fixed nodes and moving tractor and farmer. The proposed systems are validated by cloud-based platforms for LoRaWAN, Sigfox and NB-IoT communications, providing flexible and scalable solutions to enable interactive farming applications. This research is supported by the 2017 Predoctoral Research Grant supported by the Xunta de Galicia and the research projects TEC2017-85529-C03-3R and RTI2018-095499-B-C31, funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU, AEI, FEDER, UE), as well as from European Union's Horizon 2020 research and Innovation programme under grant agreement N°774094 (Stardust-Holistic and Integrated Urban Model for Smart Cities).

ispartof: EARTH SURFACE PROCESSES AND LANDFORMS vol:44 issue:14 pages:2731-2740 status: published

A precise estimation of transversal gully limits is a prerequisite for accurate gully volume assessment. This step has been typically performed by operators through visual interpretation of gully cross-sections (XSs), based on assumptions which have not been reported. The aim is of this study is to evaluate how much uncertainty is involved in the human definition of XS limits and to propose an alternative, automated approach which can avoid this subjectivity. For this purpose, we designed the Optimal Lid Method (OLid), a non-threshold-dependent approach for the definition of XS limits and dimensions in ephemeral gullies (EGs). It works by maximizing the sum of three topographic characteristics: a prominent elevation, good margin alignment and a smooth pre-erosion surface. The OLid model has been evaluated using a series of accuracy and precision tests on a number of datasets: a) a screening stage on one-cycle (XSynOne) and two-cycles (XSynTwo) of erosion synthetic XSs; b) a calibration stage on field EG XSs (XSCorCal); c) a validation stage on a different subset of field XSs (XSCorVal); and d) a comparison with the expert panel approach on 60 XSs of EG in Navarre (XSNav). Major differences were found in how the dimensions were estimated by the different experts, revealing a high degree of subjectivity. The calibrated OLid model produced a good fit with the reference technique (relative errors in XS dimensions below 7%), and performed similarly in the validation stage. In addition, the OLid results were in line with the median-expert estimates. The OLid method is believed to be applicable to larger channels than EGs, although further research is required in this area. An OLid executable which is compatible with Windows platforms is available at http://www.uco.es/users/ccastillo/OLid.html .

Traditionally, distribution uniformity has been obtained by using rain gauges, which makes it a very expensive process. This paper sought to create a simulation strategy using QGIS and EPANET, both free software, that allowed the simulation of the water application results of all the emitters of an irrigation installation. In this way, it was possible to obtain the geospatial representation of the applied water and finally to know the distribution uniformity in the whole installation. The simulation finally fulfilled its objective and was compared with a study of distribution uniformity with rain gauges. The biggest difference between the measured and simulated data was a difference of 5.76% among the sectors. The simulated uniformity was very similar to the measured uniformity, which allowed us to affirm that the proposed simulation methodology was adequate. We believe that the methodology proposed in this article could be very useful in improving the management of sprinkler irrigation systems, particularly those in which distribution uniformity is of special importance. These improvements in management can also result in savings in water and other inputs, which are becoming increasingly important in the current context of climate change and the reduction in the impact of agriculture on the environment. Finally, similar studies could be carried out with the same tools for other pressurized irrigation systems, such as sprinkler irrigation outside greenhouses and drip irrigation. Research Initiation Grant of the Public University of Navarra for master's students who develop their Master's Thesis (TFM) in the field of research institutes and in Navarrabiomed, academic year 2021-2022 (Res 602/2022)

Ephemeral gully (EG) erosion has an important impact on agricultural soil losses and increases field surface hydrology connectivity and transport of pollutants to nearby water bodies. Watershed models including an EG component are scarce and not yet properly evaluated. The objective of this study is to evaluate the capacity of one such tool, AnnAGNPS, to simulate the evolution of two EG formed in a conservation tillage system. The dataset for model testing included runoff measurements and EG morphological characteristics during 3 years. Model evaluation focused on EG evolution of volume, width, and length model outputs, and included calibration and testing phases and a global sensitivity analysis (GSA). While the model did not fully reproduce width and length, the model efficiency to simulate EG volume was satisfactory for both calibration and testing phases, supporting the watershed management objectives of the model. GSA revealed that the most sensitive factors were EG depth, critical shear stress, headcut detachment exponent coefficient b, and headcut detachment leading coefficient a. For EG outputs the model was additive, showing low sensitivity to interactions between the inputs. Prediction of EG spatial evolution on conservation tillage systems requires improved development of gullyerosion components, since many of the processes were developed originally for traditional tillage practices or larger channel systems. Our results identify the need for future research when EG form within conservation tillage systems, in particular to study gully headcut, soil erodibility, and width functions specific to these practices. Eduardo Luquin was funded by a scholarship from the Public University of Navarre and received a travel grant from the Government of Navarre for the purpose of the research. This work received funding from the Ministerio de Economía y Competitividad (Government of Spain) via the Research Project CGL2015-64284-C2-1-R.

Continuous soil moisture content monitoring is key to understand the soil and water flow and transport processes and their impact on a wide range of environmental change and quality processes. Nowadays, there are a wide variety of electromagnetic sensors for estimating soil volumetric content. These include those from established manufacturers (>50€) and low-cost (3/cm3, and the sensing volume of the different probes exhibited a large variability, ranging from 0.5 to 1500 cm3. Importantly, the probes evaluated in laboratory conditions showed different errors for each soil type. The loamy soil readings presented the smallest errors, followed by sandy and clayey soils. No statistically significant differences were found in measurement accuracy between low-cost and higher-priced probes. From the study of the sensing volume explored, with the exception of one case, it can be concluded that the low-cost probes generally explore a smaller volume than the established probes. The selection of the appropriate probe based on its sensing value could be important for different types of risk analysis and management applications.

This study was partly financed by the Spanish Government ’ s ‘ National Plan for Research, Development and Techno- logical Innovation ’ (projects CGL2011-24336 (MICIN/FEDER) and CGL2015-64284-C2-1-R (MINECO/FEDER)). The authors thank the Public University of Navarre (UPNA) for funding this work with a grant awarded to the principal author. In addition, the authors are grateful for the support and assistance given by Dr Antonina Capra and Dr Carmelo La Spada from the Universita degli Studi Mediterranea di Reggio Calabria (Italy).

This study was partly financed by the Spanish Government’s National Plan for Research, Development and Technological Innovation [projects CGL2011-24336 (MICIN/FEDER) and CGL2015-64284-C2-1-R (MINECO/FEDER)]. The authors thank the Public University of Navarre (UPNA) for funding this work with a grant awarded to the principal author.

Crop classification provides relevant information for crop management, food security assurance and agricultural policy design. The availability of Sentinel-1 image time series, with a very short revisit time and high spatial resolution, has great potential for crop classification in regions with pervasive cloud cover. Dense image time series enable the implementation of supervised crop classification schemes based on the comparison of the time series of the element to classify with the temporal signatures of the considered crops. The main objective of this study is to investigate the performance of a supervised crop classification approach based on crop temporal signatures obtained from Sentinel-1 time series in a challenging case study with a large number of crops and a high heterogeneity in terms of agro-climatic conditions and field sizes. The case study considered a large dataset on the Spanish province of Navarre in the framework of the verification of Common Agricultural Policy (CAP) subsidies. Navarre presents a large agro-climatic diversity with persistent cloud cover areas, and therefore, the technique was implemented both at the provincial and regional scale. In total, 14 crop classes were considered, including different winter crops, summer crops, permanent crops and fallow. Classification results varied depending on the set of input features considered, obtaining Overall Accuracies higher than 70% when the three (VH, VV and VH/VV) channels were used as the input. Crops exhibiting singularities in their temporal signatures were more easily identified, with barley, rice, corn and wheat achieving F1-scores above 75%. The size of fields severely affected classification performance, with ~14% better classification performance for larger fields (>1 ha) in comparison to smaller fields (

This paper disentangles the ethnic drivers of the effect of food-related income shocks on African conflict employing geo-localized information. We consider diversity and political ethnic variables and several conflict definitions. We find that differentiating between organized armed-force and non-organized conflict can be more informative than between factor and output conflict. We show evidence that conflict is driven by the opportunity cost and state capacity mechanisms. Furthermore, ethnic cleavages have a large role in the transmission process of income shocks on organized armed-force conflict; whereas their role in non-organized violence is more limited. The sensitivity to ethnic heterogeneity for producer-price and droughts shocks is much larger than for consumer-price changes. Financial support from the Spanish Ministry of Economy and Competitiveness (Projects PGC2018-093542-B-I00 and PID2019-111208GB-I00) is gratefully acknowledged.

Nutrient dynamics and factors that control nutrient exports were observed in two watersheds, namely Latxaga and La Tejería, with similar climatic and management characteristics throughout 10 years (2007–2016). Similar patterns were observed in intra-annual and inter-annual dynamics with higher NO3 − concentration and NO3 −-N yield during the humid seasons (i.e., winters and hydrological year 2013). Regarding concentration, Latxaga showed a higher decrease of nitrate due to a higher development of vegetated areas. High discharge events produced nitrate dilution due to the presence of tile-drainage at La Tejeria. At Latxaga, where tile-drainage was not observed, an increase in concentration occurred as a response to high discharge events. Comparing both watersheds, La Tejería presented ca. 73 ± 25 mg NO3 − L−1 while at Latxaga, the concentration observed was almost three times lower, with ca. 21 ± 15 mg NO3 − L−1 throughout the study period. Similar patterns were observed for the NO3 −-N yield, with 32 kg NO3 −-N ha−1 year−1 and 17 kg NO3 −-N ha−1 year−1 at La Tejería and Latxaga, respectively. Regarding phosphorous, the observed concentrations were 0.20 ± 0.72 mg PO4 3− L−1 and 0.06 ± 0.38 mg PO4 3− L−1 at La Tejería and Latxaga, respectively, with PO4 3−-P yields being 71 kg PO4 3−-P ha−1 year−1 and 33 kg PO4 3−-P ha−1 year−1. Annual phosphate-P yield distribution in both watersheds followed similar patterns to those observed for the nitrate-N yield, with higher yields in the humid season. Regarding concentration, highly erosive rainfall that occurred in summer, mobilizing sediments and probably generating desorption of phosphorous in the stream channel, increased phosphate concentration. This research adds to the knowledge base regarding the dynamics of nutrients and the controlling factors in complex agricultural systems with Mediterranean characteristics. The authors wish to acknowledge the funding received from the Ministry of Economy and Competitiveness (Research Project CGL2015-64284-C2-1-R), and research grants from the FPI program (BES-2016-078786) and Juan de la Cierva program (FJCI-2015-24920).

La agricultura de regadío es una de las actividades que más agua utiliza, de hecho, según indica la ONU, el 70% del agua dulce disponible es utilizada por este sector. Esto convierte al regadío en uno de los ámbitos donde mayor esfuerzo se debe de realizar para optimizar el uso de los recursos hídricos. Uno de los elementos que proporciona información valiosa para ayudar a ajustar la dosis y frecuencia de riego son los sensores de medición del contenido de agua en el suelo. Si bien existe una amplia variedad de productos/dispositivos existentes en el mercado dedicados a esta labor, su coste supone una limitación para su uso extensivo. Por el contrario debido a su sencillo funcionamiento y facilidad de implementación las sondas capacitivas se presentan como una adecuada alternativa. Al igual que diversas sondas de bajo coste procedentes del mundo maker. Pero estas últimas aun sin una adecuada evaluación.En este trabajo se ha llevado a cabo una evaluación de 20 sondas capacitivas de humedad de suelo de reconocidas casas comerciales y prototipos de sondas de bajo coste, con un doble objetivo: por un lado, evaluar la calibración de cada una de las sondas en suelos de textura contrastante, y por otro lado determinar el volumen explorado por cada una de ellas. La experimentación se ha llevado a cabo instalaciones a Universidad Pública de Navarra (UPNA).La calibración de cada sonda, se han realizado en tres suelos de clases texturales contrastantes en un amplio rango de humedad. Mediciones directas de la humedad del suelo fueron tomadas como valores de referencia. Se ha evaluado asimismo el volumen efectivo de medición de cada sonda.Los primeros resultados indican, que existen diferencias significativas en el comportamiento de las sondas dependiendo de los tipos de suelo analizados, así como en el volumen de suelo explorado por cada una de ellas.

Dissolved solids (DS) and suspended sediment (SS) loads are considered relevant environmental problems. They are related to a wide range of on-site and off-site impacts, such as soil erosion or salinization of water bodies. In this study, the dynamics of DS and SS concentrations and loads were assessed in five small watersheds covering representative agricultural land uses in Navarre (Spain). To this end, discharge, DS and SS concentration data were collected during ten hydrological years at each watershed outlet, and loads were computed from discharge and concentration values. DS concentration followed a seasonal pattern imposed by the availability of water, with higher concentrations recorded in low-flow periods and lower concentration in the high-flow period. SS concentration was extremely variable, with a range of 2–4 orders of magnitude in concentration for any specific discharge. Temporal variations (both intra- and inter-annual) in DS loads were explained by differences in runoff, whereas those of SS were not, being the SS loads associated mainly with specific high flow events. These temporal patterns were observed for both agricultural (this study) and non-agricultural (literature) watersheds. From the data in the Navarrese watersheds and those available in the literature, we inferred that agricultural land use, in general, tends to increase the concentration of both DS and SS. Regarding DS and SS yields, the effects of agricultural land use on DS yields are controlled by the changes in runoff rather than the (small) changes in DS concentration. In this sense, land uses changes expected to increase runoff (i.e., a shift from forested to arable or from rainfed to irrigated agriculture) would increase DS yields. On the other hand, agricultural land use tends to increase SS yields, although the effect is highly variable depending on site-specific factors, both natural (e.g., watershed shape) and anthropogenic (e.g., degree of soil conservation practices). In the Navarrese watersheds, DS yields ranged from 1.1 to 2.2 Mg ha−1 year−1 whereas SS yields ranged from 0.3 to 4.3 Mg ha−1 year−1. DS yields seem to dominate under non-agricultural conditions and in most agricultural land uses at the small watershed scale. On the other hand, SS yields dominate in watersheds with increased soil erosion as a consequence of arable land use over erosion-prone watersheds. This work received funding from “Ministerio de Economía y Competitividad” via the Research Project CGL2015-64284-C2-1-R and support to D. Merchán (“Juan de la Cierva - Formación” program, FJCI-2015-24920) and I. Hernández García (FPI program, BES-2016-078786). E. Luquin was funded by a scholarship from the Public University of Navarre.

Este artículo contiene 16 páginas, 6 figuras, 2 tablas., Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) Wand SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures., This research was supported by projects funded by the MINECOFEDER: CGL2014-52135-C3-3-R, CGL2014-59946-R, CGL2015-65569- R, CGL2015-64284-C2-2-R, and PCIN-2017-061/AEI. When this manuscript was first submitted Estela Nadal-Romero and Damià Vericat received a “Ramón y Cajal” postdoctoral contract (RYC-2013-14371 and RYC‐2010‐06264, Spanish Ministry of Economy and Competitiveness, MEC). Damià Vericat is now a Serra Húnter Fellow at the University of Lleida. María Fernández-Raga received a “José Castillejo” postdoctoral grant (Spanish Ministry of Education, Culture and Sports). Carla Ferreira was supported by a post-doctoral research grant from the Portuguese Science and Technology Foundation (SFRH/ BPD/120093/2016). Mariano Moreno-de las Heras received a Juan de la Cierva postdoctoral contract (IJCI-2015-26463) from the MEC. José Andrés López-Tarazón received a Vicenç Mut postdoctoral fellowship from the Autonomous Balearic Government (CAIB PD/038/2016). José Andrés López-Tarazón and Ramon Batalla also acknowledge the Secretariat for Universities and Research of the Department of the Economy and Knowledge of the Autonomous Government of Catalonia for supporting the Consolidated Research Group 2014 SGR 645 (RIUSFluvial Dynamics Research Group), and the CERCA Programme. This paper has benefited from the Lab and Field Data Pool created within the framework of the COST action CONNECTEUR (ES1306).

Soil moisture content has always been an important parameter to control because it is a deterministic factor for site-specific irrigation, seeding, transplanting, and compaction detection. In this work, a discrete sensor that is based on a SnO2&ndash, FP (Fabry-P&eacute, rot) cavity is presented and characterized in real soil conditions. As far as authors know, it is the first time that a microstructured optical fiber is used for real soil moisture measurements. Its performance is compared with a commercial capacitive soil moisture sensor in two different soil scenarios for two weeks. The optical sensor shows a great agreement with capacitive sensor&rsquo, s response and gravimetric measurements, as well as a fast and reversible response, moreover, the interrogation technique allows for several sensors to be potentially multiplexed, which offers the possibility of local measurements instead of volumetric: it constitutes a great tool for real soil moisture monitoring.

Surface irrigated agriculture in arid and semi-arid regions contributes to downstream environmental degradation. Changes in irrigation system operational scenarios (ISOS) can represent an economic alternative to reduce surface runoff impacts. At the same time the use of vegetative filter strips (VFS) can have a positive impact on the ecological health of rural landscapes by reducing erosion, improving water quality, increasing biodiversity, and expanding wildlife habitat. The goal of this paper is, using a combination of field data and mechanistic modeling results, to evaluate and compare the spatial effectiveness of improvements in ISOS and introduction of VFS to reduce surface runoff pollution in the semi-arid/arid furrow irrigation agroecosystem that exceeds current regulatory turbidity limits (25 NTU). Five main factor interactions were studied: four soil textures, two field slopes, three ISOS, six filter vegetation types, and ten filter lengths. Slope and runoff volume were identified as the two main drivers of sediment export from furrows. Shifting from current ISOS to less water consumptive irrigation practices reduce runoff in addition to sediment delivery to comply with environmental regulations. The implementation of 3 to 9 m vegetative buffers on experimental parcels were found to mitigate sediment delivery (greater than 90% sediment reduction) on tail drainage ditches but had limited effect in the reduction of runoff flow that can transport other dissolved pollutants. These findings were insensitive to filter vegetation type. Thus, introduction of improved ISOS is desirable while VFS may be targeted to specific hot spots within the irrigation district. This study shows that the adoption of dense vegetation buffers in vulnerable semi-arid irrigated regions can be effective to mitigate agricultural impacts and provide environmental protection. However, it should not be adopted as an alternative to proper on-site irrigation practices, rather as a complementary off-site pollution control practice. This study was funded through the USDA National Integrated Water Quality Program (NIWQP) under the grant entitled “Protecting Water Resources by Engaging Stakeholders in Targeted Implementation of Filter Strips” (Grant No. 2009-51130-06098). The authors wish to thank Elaine Brouillard (Roza-Sunnyside Board of Joint Control, Sunnyside, Washington) and R. Troy Peters (Washington State University)for their assistance in providing data and information on irrigation practices

Trabajo presentado a la 26th International Conference on Optical Fiber Sensors. Suiza, 2019 A discrete sensor based on a Sn0₂-FP (Fabry-Pérot) cavity is presented and characterized in real soil conditions. Results are compared, for the first time to our knowledge, with a commercial capacitive sensor and gravimetric measurements. The Spanish Government projects TEC 2016-76021-C2-1-R, TEC2016-78047-R, TEC2016-79367-C2-2-R, Innocampus and the Cost Action MP 1401, as well as to the AEI/FEDER Funds are acknowledged.

The high revisit time of Sentinel-1 (S1) observations enables the design of crop type mapping approaches exploiting the backscatter time series observed for the different crops. The objective of this study is to propose a supervised crop classification methodology based on the temporal signature of crops. With this aim 29 dual-pol S1 observations acquired over an agricultural area of Spain, where ground truth was available, were processed. The classification approach was based on the temporal signatures obtained for each polarization channel (VH, VV and the cross-pol ratio) for the different crops. Highest accuracies were obtained when fields were assigned to the class that minimized the RMSE, with an overall accuracy of 79% and best results for rapeseed, sunflower, alfalfa and barley. This work was partly funded by project CGL2016-75217-R (MINECO/FEDER, EU) and project PyrenEOS EFA 048/15, the latter has been 65% cofinanced by the European Regional Development Fund (ERDF) through the Interreg V-A Spain-France Andorra programme POCTEFA 2014-2020).

Infrastructure development, specifically road paving, contributes socio-economic benefits to society worldwide. However, detrimental environmental effects of road paving have been documented, most notably increased deforestation. Beyond deforestation, we hypothesize that road paving introduces “unseen” regional scale effects on forests, due to changes to vegetation dynamics. To test this hypothesis, we focus on the tri-national frontier in the southwestern Amazon that has been subject to construction of the Inter-Oceanic Highway (IOH) between 1987 and 2010. We use a long-term remotely sensed vegetation index as a proxy for vegetation dynamics and combine these with field-based socio-ecological data and biophysical data from global datasets. We find 4 areas of shared vegetation dynamics associated with increasing extent of road paving. Applying Dynamic Factor Analysis, an exploratory dimension-reduction time series analysis technique, we identify common trends and covariates in each area. Common trends, indicating underlying unexplained effects, become relatively less important as paving increases, and covariates increase in importance. The common trends are dominated by lower frequency signals possibly embodying long-term climate variability. Human-related covariates become more important in explaining vegetation dynamics as road paving extent increases, particularly family density and travel time to market. Natural covariates such as minimum temperature and soil moisture become less important. The change in vegetation dynamics identified in this study indicates a possible change in ecosystem services along the disturbance gradient. While this study does not include all potential factors controlling dynamics and disturbance of vegetation in the region, it offers important insights for management and mitigation of effects of road paving projects. Infrastructure planning initiatives should make provisions for more detailed vegetation monitoring after road completion, with a broader focus than just deforestation. The study highlights the need to mitigate population-driven pressures on vegetation like family density and access to new markets. This work was supported by funding from NSF CNH Award number 1114924, USA.

The environmental impact of irrigated agriculture on water quality was assessed in Landazuria watershed (Navarre, northeast Spain), a 479.5 ha watershed with 53% of irrigated agricultural land. In the framework of a long-term monitoring program, precipitation and discharge were measured at 10-min intervals and compound daily water samples were collected during the agricultural years (September to August) 2007–2016, and analysed for nitrate (NO3−), phosphate (PO43−), sediment and total dissolved solids (TDS) concentrations. Typical agricultural management (including crop surfaces, irrigation and fertilization rates) was obtained from inquiries to farmers. Concentration and yield of the studied variables presented a high degree of variation, both intra- and inter-annual. Median concentration for the entire study period were 185

[1] A large fraction of soil erosion in temperate climate systems proceeds from gully headcut growth processes. Nevertheless, headcut retreat is not well understood. Few erosion models include gully headcut growth processes, and none of the existing headcut retreat models have been tested against long-term retreat rate estimates. In this work the headcut retreat resulting from plunge pool erosion in the Channel Hillslope Integrated Landscape Development (CHILD) model is calibrated and compared to long-term evolution measurements of six gullies at the Bardenas Reales, northeast Spain. The headcut retreat module of CHILD was calibrated by adjusting the shape factor parameter to fit the observed retreat and volumetric soil loss of one gully during a 36 year period, using reported and collected field data to parameterize the rest of the model. To test the calibrated model, estimates by CHILD were compared to observations of headcut retreat from five other neighboring gullies. The differences in volumetric soil loss rates between the simulations and observations were less than 0.05 m3 yr−1, on average, with standard deviations smaller than 0.35 m3 yr−1. These results are the first evaluation of the headcut retreat module implemented in CHILD with a field data set. These results also show the usefulness of the model as a tool for simulating long-term volumetric gully evolution due to plunge pool erosion.

Understanding the drivers of large-scale vegetation change is critical to managing landscapes and key to predicting how projected climate and land use changes will affect regional vegetation patterns. This study aimed to improve our understanding of the role, magnitude, and spatial distribution of the key environmental and socioeconomic factors driving vegetation change in a southern African savanna. This research was conducted across the Kwando, Okavango and Zambezi catchments of southern Africa (Angola, Namibia, Botswana and Zambia) and explored vegetation cover change across the region from 2001–2010. A novel coupled analysis was applied to model the dynamic biophysical factors then to determine the discrete / social drivers of spatial heterogeneity on vegetation. Previous research applied Dynamic Factor Analysis (DFA), a multivariate times series dimension reduction technique, to ten years of monthly remotely sensed vegetation data (MODIS-derived normalized difference vegetation index, NDVI), and a suite of time-series (monthly) environmental covariates: precipitation, mean, minimum and maximum air temperature, soil moisture, relative humidity, fire and potential evapotranspiration. This initial research was performed at a regional scale to develop meso-scale models explaining mean regional NDVI patterns. The regional DFA predictions were compared to the fine-scale MODIS time series using Kendall’s Tau and Sen’s Slope to identify pixels where the DFA model we had developed, under or over predicted NDVI. Once identified, a Random Forest (RF) analysis using a series of static social and physical variables was applied to explain these remaining areas of under- and over- prediction to fully explore the drivers of heterogeneity in this savanna system. The RF analysis revealed the importance of protected areas, elevation, soil type, locations of higher population, roads, and settlements, in explaining fine scale differences in vegetation biomass. While the previously applied DFA generated a model of environmental variables driving NDVI, the RF work developed here highlighted human influences dominating that signal. The combined DFRFA model approach explains almost 90% of the variance in NDVI across this landscape from 2001–2010. Our methodology presents a unique coupling of dynamic and static factor analyses, yielding novel insights into savanna heterogeneity, and providing a tool of great potential for researchers and managers alike. This research was funded by NASA grant NNX09AI25G to JS: Understanding and predicting the impact of climate variability and climate change on land use and land cover change via socioeconomic institutions in southern Africa May 2009- May 2013.

There are increasing calls to audit decision-support models used for environmental policy to ensure that they correspond with the reality facing policy makers. Modelers can establish correspondence by providing empirical evidence of real-world behavior that their models skillfully simulate. Since real-world behavior-especially in environmental systems-is often complex, credibly modeling underlying dynamics is essential. We present a pre-modeling diagnostic framework based on Nonlinear Time Series (NLTS) methods for reconstructing real-world environmental dynamics from observed data. The framework is illustrated with a case study of saltwater intrusion into coastal wetlands in Everglades National Park, Florida, USA. We propose that environmental modelers test for systematic dynamic behavior in observed data before resorting to conventional stochastic exploratory approaches unable to detect this valuable information. Reconstructed data dynamics can be used, along with other expert information, as a rigorous benchmark to guide specification and testing of environmental decision-support models corresponding with real-world behavior. A pre-modeling Nonlinear Time Series (NLTS) framework presented.Framework reconstructs real-world system dynamics from observed data.Reconstructed dynamics inform model specification and auditing.

Much of the research on (ephemeral) gully erosion comprises the determination of the geometry of these eroded channels, especially their width and depth. This is not a simple task due to uncertainty generated by the wide range of variability in gully cross section shapes found in the field. However, in the literature, this uncertainty is not recognized so that no criteria for their measurement are indicated. The aim of this work is to make researchers aware of the ambiguity that arises when characterizing the geometry of an ephemeral gully and similar eroded channels. In addition, a measurement protocol is proposed with the ultimate goal of pooling criteria in future works. It is suggested that the geometry of a gully could be characterized through its mean equivalent width and mean equivalent depth, which, together with its length, define an “equivalent prismatic gully” (EPG). The latter would facilitate the comparison between different gullies. This study was partly funded by the Spanish Ministry of Science and Innovation (project CGL2011-24336).

Background: Understanding the drivers of large-scale vegetation change is critical to managing landscapes and key to predicting how projected climate and land use changes will affect regional vegetation patterns. This study aimed to improve our understanding of the role, magnitude and spatial distribution of the key environmental factors driving vegetation change in southern African savanna, and how they vary across physiographic gradients. Methodology/Principal Findings: We applied Dynamic Factor Analysis (DFA), a multivariate times series dimension reduction technique to ten years of monthly remote sensing data (MODIS-derived normalized difference vegetation index, NDVI) and a suite of environmental covariates: precipitation, mean and maximum temperature, soil moisture, relative humidity, fire and potential evapotranspiration. Monthly NDVI was described by cyclic seasonal variation with distinct spatiotemporal patterns in different physiographic regions. Results support existing work emphasizing the importance of precipitation, soil moisture and fire on NDVI, but also reveal overlooked effects of temperature and evapotranspiration, particularly in regions with higher mean annual precipitation. Critically, spatial distributions of the weights of environmental covariates point to a transition in the importance of precipitation and soil moisture (strongest in grass-dominated regions with precipitation,750 mm) to fire, potential evapotranspiration, and temperature (strongest in tree-dominated regions with precipitation.950 mm). Conclusions/Significance: We quantified the combined spatiotemporal effects of an available suite of environmental drivers on NDVI across a large and diverse savanna region. The analysis supports known drivers of savanna vegetation but also uncovers important roles of temperature and evapotranspiration. Results highlight the utility of applying the DFA approach to remote sensing products for regional analyses of landscape change in the context of global environmental change. With the dramatic increase in global change research, this methodology augurs well for further development and application of spatially explicit time series modeling to studies at the intersection of ecology and remote sensing. This study was funded by National Aeronautics and Space Administration Land-Cover/Land-Use Change Program (NASA LCLUC) Project # NNX09AI25G, titled ‘‘The Role of Socioeconomic Institutions in Mitigating Impacts of Climate Variability and Climate Change in Southern Africa’’, and National Science Foundation Integrative Graduate Education and Research Traineeship (NSF-IGERT) 0504422 Adaptive Management of Water, Wetlands and Watershed.

Producción Científica, Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations., Ministerio de Economía y Competitividad - FEDER (CGL2014 52135-C3-3-R; ESP2017-89463-C3-3-R; CGL2014-59946-R; CGL2015-65569-R; CGL2015-64284- C2-2-R; CGL2015-64284-C2-1-R; CGL2016-78075-P; GL2008-02879/BTE; LEDDRA 243857; RECARE-FP7; CGL2017-83866-C3-1-R y PCIN-2017- 061/AEI), Ministerio de Economía y Competitividad (FJCI-2017-33652), Organización para la Cooperación y el Desarrollo Económicos (TAD/CRP JA00088807), Junta de Castilla y León - FEDER (CLU-2018-04)