Person: Giménez Díaz, Rafael
Loading...
Email Address
person.page.identifierURI
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
Giménez Díaz
First Name
Rafael
person.page.departamento
Ingeniería
person.page.instituteName
IS-FOOD. Research Institute on Innovation & Sustainable Development in Food Chain
ORCID
0000-0003-3210-0578
person.page.upna
6698
Name
9 results
Search Results
Now showing 1 - 9 of 9
Publication Open Access Assessment of soil factors controlling ephemeral gully erosion on agricultural fields(Wiley, 2017) Ollobarren del Barrio, Paul; Campo-Bescós, Miguel; Giménez Díaz, Rafael; Casalí Sarasíbar, Javier; Landa Ingeniaritza eta Proiektuak; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Proyectos e Ingeniería Rural; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaThe soil factor is crucial in controlling and properly modeling the initiation and development of ephemeral gullies (EGs). Usually, EG initiation has been related to various soil properties (i.e. sealing, critical shear stress, moisture, texture, etc.); meanwhile, the total growth of each EG (erosion rate) has been linked with proper soil erodibility. But, despite the studies to determine the influence of soil erodibility on (ephemeral) gully erosion, a universal approach is still lacking. This is due to the complex relationship and interactions between soil properties and the erosive process. A feasible soil characterization of EG erosion prediction on a large scale should be based on simple, quick and inexpensive tests to perform. The objective of this study was to identify and assess the soil properties – easily and quickly to determine – which best reflect soil erodibility on EG erosion. Forty‐nine different physical–chemical soil properties that may participate in establishing soil erodibility were determined on agricultural soils affected by the formation of EGs in Spain and Italy. Experiments were conducted in the laboratory and in the field (in the vicinity of the erosion paths). Because of its importance in controlling EG erosion, five variables related to antecedent moisture prior to the event that generated the gullies and two properties related to landscape topography were obtained for each situation. The most relevant variables were detected using multivariate analysis. The results defined 13 key variables: water content before the initiation of EGs, organic matter content, cation exchange capacity, relative sealing index, two granulometric and organic matter indices, seal permeability, aggregates stability (three index), crust penetration resistance, shear strength and an erodibility index obtained from the Jet Test erosion apparatus. The latter is proposed as a useful technique to evaluate and predict soil loss caused by EG erosion.Publication Open Access Factors controlling sediment export in a small agricultural watershed in Navarre (Spain)(Elsevier, 2012) Giménez Díaz, Rafael; Casalí Sarasíbar, Javier; Grande Esteban, Ildefonso; Díez Beregaña, Javier; Campo-Bescós, Miguel; Álvarez Mozos, Jesús; Goñi Garatea, Mikel; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Gestión de Empresas; Enpresen Kudeaketa; Gobierno de Navarra / Nafarroako GobernuaIt is recognised that the hydrological and erosion processes in watersheds are very much conditioned by the (inter)action of a number of variables. This paper covers a 15-year period of studying those factors that have a major influence on the sediment yield and transport during individual hydrological events in a small Mediterranean agricultural watershed. Multivariate statistical techniques such as cluster analysis and principal component analysis were applied for the interpretation of datasets. In addition, the relationships between suspended sediment concentration and discharge (hysteretic loops) were also analysed. The hydrological response of the studied watershed is mainly controlled by the antecedent condition of the flow. Most of the runoff and sediment are generated during the wet season when vegetation cover is scant and saturation overland flow occurs promptly as a response to almost any rainfall events. In contrast, during the dry seasons even if high-intensity rainfalls normally occur, very scant runoffs are, however recorded, at the exit of the watershed. Most of the eroded sediment seems to come from riparian areas. The discharge registered at the watershed outlet up to 1 h prior to the flood is a very good surrogate for antecedent soil moisture.Publication Open Access Evaluation of 2D models for the prediction of surface depression storage using realistic reference values(Wiley, 2016) Giménez Díaz, Rafael; Mezkiritz Barberena, Irantzu; Campo-Bescós, Miguel; Álvarez Mozos, Jesús; González de Audícana Amenábar, María; Martínez de Aguirre Escobar, Alejandro; Casalí Sarasíbar, Javier; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta ProiektuakDepression storage (DS) is the maximum storage of precipitation and runoff in the soil surface at a given slope. The DS is determined by soil roughness that in agricultural soils is largely affected by tillage. The direct measurement of DS is not straightforward because of the natural permeability of the soil. Therefore, DS has generally been estimated from 2D/3D empirical relationships and numerical algorithms based on roughness indexes and height measurements of the soil surface, respectively. The objective of this work was to evaluate the performance of some 2D models for DS, using direct and reliable measurements of DS in an agricultural soil as reference values. The study was carried out in experimental microplots where DS was measured in six situations resulting from the combination of three types of tillage carried out parallel and perpendicular to the main slope. Those data were used as reference to evaluate four empirical models and a numerical method. Longitudinal altitudinal profiles of the relief were obtained by a laser profilometer. Infiltration measurements were carried out before and after tillage. The DS was largely affected by tillage and its direction. Highest values of DS are found on rougher surfaces mainly when macroforms cut off the dominant slope. The empirical models had a limited performance while the numerical method was the most effective, even so, with an important variability. In addition, a correct hydrological management should take into account that each type of soil tillage affects infiltration rate differently.Publication Open Access Evaluación de la producción de sedimentos y calidad de las aguas en cuencas agrarias de Navarra(Universidad de La Rioja, 2012) Giménez Díaz, Rafael; Casalí Sarasíbar, Javier; Díez Beregaña, Javier; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Gobierno de Navarra / Nafarroako GobernuaThe Government of Navarre (Spain) established a series of experimental watersheds on different sites of its territory in order to assess the impact of the agricultural activities on the environment. Hydrological/meteorological and water quality data are continuously monitored. In this paper, data recorded –precipitation, runoff, sediment, nitrate and phosphate– in two grain-sown watersheds (La Tejería and Latxaga) and in a third one (Oskotz) covered with forest and pasture (cattle-breeding) with a sub-watershed almost entirely under forest, are analyzed; the information covers a period of ca. 15 years. The inter/intra annual variability of the involved processes are studied as well as their impact on the water quality and on the ecosystem. The majority of the sediments yielded in the watersheds are registered during winter, though most of the erosive rainfalls occurred in summer. This is because of the easy-prone runoff that prevailed during winter due to the (much) higher water content of the soils in this period. The grain-sown watersheds –roughly similar at first view– present however important differences regarding sediment yield: 1800 kg/ha year at La Tejería and only 450 kg/ha year at Latxaga. This could be mainly due to differences in morphology, topography, and amount of stream channel vegetation between both sites. At Oskotz this figures are as a whole lower than those registered in the cultivated watersheds but eventually larger than those at Latxaga; this depending on the forest management (logging). Water quality is seriously affected at La Tejería with nitrate concentration constantly over critical threshold. By contrast, nitrate values are much lower in Latxaga watershed. However, phosphate concentrations were similar in both grain-sown watersheds corresponding to water with a significant risk of eutrophication. The cattle-breeding activity at Oskotz generated unexpected levels of phosphate much higher than those registered in the cultivated wathersheds.Publication Open Access Runoff, nutrients, sediment and salt yields in an irrigated watershed in southern Navarre (Spain)(Elsevier, 2018) Merchán Elena, Daniel; Casalí Sarasíbar, Javier; Valle de Lersundi, Jokin del; Campo-Bescós, Miguel; Giménez Díaz, Rafael; Preciado, Beatriz; Lafarga, Alberto; Landa Ingeniaritza eta Proiektuak; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Proyectos e Ingeniería RuralThe 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, <0.05, 31 and 2284 mg L−1 for NO3−, PO43−, sediment and TDS, respectively. NO3−-N and PO43−-P yields averaged 74 and 0.04 kg ha−1 year−1, respectively. NO3 −-N yield was higher than in other agricultural land uses in Navarre and in the order of magnitude of other irrigated areas in the Middle Ebro Valley. PO43−-P yield was in the same order of magnitude than in rainfed watersheds in Navarre but lower than in intensively grazed watersheds. Sediment yield was extremely variable, averaging 360 kg ha−1 year−1, with 44% of the total measured load recorded in a few days. It was in the lower range of those measured in Navarre for rainfed agriculture and similar to those estimated in other irrigated areas of the Middle Ebro River. TDS concentration presented a significant decreasing trend since available salts were being washed out, while TDS yield averaged 1.8 Mg ha−1 year−1. Long-term monitoring of irrigated areas is required to understand pollution processes in these agroecosystems and to adequately characterize the environmental impact of current agricultural practices on water quality, in order to implement, and adequately assess, measures to reduce agricultural pollution.Publication Open Access Dissolved solids and suspended sediment dynamics from five small agricultural watersheds in Navarre, Spain: a 10-year study(Elsevier, 2019) Merchán Elena, Daniel; Luquin Oroz, Eduardo Adrián; Hernández García, Iker; Campo-Bescós, Miguel; Giménez Díaz, Rafael; Casalí Sarasíbar, Javier; Valle de Lersundi, Jokin del; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaDissolved 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.Publication Open Access Hydrological signatures based on event runoff coefficients in rural catchments of the Iberian Peninsula(Wolters Kluwer, 2017) Taguas, Encarnación V.; Nadal-Romero, Estela; Ayuso, José L.; Casalí Sarasíbar, Javier; Cid, Patricio; Dafonte, Jorge; Canatário-Duarte, Antonio; Ferreira, Carla S.S.; Giménez Díaz, Rafael; Giráldez Cervera, Juan Vicente; Gómez-Macpherson, Helena; Gómez, Jose A.; González-Hidalgo, J. Carlos; Lana Renault, Noemí; Lucía, Ana; Mateos, Luciano; Pérez, Rafael; Rodríguez-Blanco, M. Luz; Schnabel, Susanne; Serrano-Muela, M. Pilar; Taboada-Castro, M. Mercedes; Zabaleta, Ane; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta ProiektuakHydrological signatures are indices that help to describe the behavior of catchments. These indices can also be used to transfer information from gauged to ungauged catchments. In this study, different approaches were evaluated to determine volumetric runoff coefficients in 18 small/ medium experimental gauged catchments of the Iberian Peninsula and to fit runoff calculations based on precipitation data for gauged and ungauged catchments. Using data derived from 1962 events, rainfall-runoff relationships were characterized and compared in order to evaluate the various hydrological response patterns. Volumetric runoff coefficients and cumulative runoff and precipitation ratios of the events that generated runoff (Rcum) minimized the root mean square error. A linear fit for the estimation of Rcum in ungauged atchments was based on mean annual precipitation, rates of infiltration, the fraction of forest-land use, and the catchment channel length. Despite high catchment heterogeneity, Rcum resulted in a suitable parameter to evaluate hydrological variability in rural gauged and ungauged catchments. In 50% of the catchments, the precipitation accounted for less than 50% of the runoff variation. Annual precipitation, antecedent rainfall, and base flow did not have a high significance in rainfall-runoff relationships, which illustrates the heterogeneity of hydrological responses. Our results highlight the need for signature characterizations of small/medium rural catchments because they are the sources of runoff and sediment discharge into rivers, and it is more economical and efficient to take action to mitigate runoff in rural locations.Publication Open Access Gully geometry: what are we measuring?(European Geosciences Union, 2015) Casalí Sarasíbar, Javier; Giménez Díaz, Rafael; Campo-Bescós, Miguel; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta ProiektuakMuch 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.Publication Open Access Assessing hillslope-channel connectivity in an agricultural catchment using rare-earth oxide tracers and random forests models(Universidad de la Rioja, 2017) Masselink, Rens Hein; Temme, A.J.A.M.; Giménez Díaz, Rafael; Casalí Sarasíbar, Javier; Keesstra, Saskia D.; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Institute on Innovation and Sustainable Development in Food Chain - ISFOODSoil erosion from agricultural areas is a large problem because of off-site effects like the rapid filling of reservoirs. To mitigate the problem of sediments from agricultural areas reaching the channel, reservoirs and other surface areas it is important to understand hillslope-channel connectivity and catchment connectivity. To determine the functioning of hillslope-channel connectivity and the continuation of transport of these sediments in the channel, it is necessary to obtain data on sediment transport from the hillslopes to the channels. Simultaneously, the factors that influence sediment export out of the catchment need to be studied. For measuring hillslope-channel sediment connectivity, rare-earth oxide (REO) tracers were applied to a hillslope in an agricultural catchment in Navarre, Spain, preceding the winter of 2014-2015. The results showed that during the winter no sediment transport from the hillslope to the channel was detected. To test the implication of the REO results at the catchment scale, two contrasting conceptual models for sediment connectivity were assessed using a random forest (RF) machine learning method. The RF method was applied using a 15-year period of measured sediment output at the catchment scale. One model proposes that small events provide sediment for large events, while the other proposes that only large events cause sediment detachment and small events subsequently remove these sediments from near and in the channel. For sediment yield prediction of small events, variables related to large preceding events were the most important. The model for large events underperformed and, therefore, we could not draw any immediate conclusions whether small events influence the amount of sediment exported during large events. Both REO tracers and RF method showed that low intensity events do not contribute any sediments from the hillslopes to the channel in Latxaga catchment. Sediment dynamics are dominated by sediment mobilization during large (high intensity) events. Sediments are for a large part exported during those events, but the system shows a memory of the occurrence of these large events, suggesting that large amounts of sediments are deposited in and near the channel after these events. These sediments are gradually removed by small events. To better understand the delivery if sediments to the channel and how large and small events influence each other, more field data on hillslope-channel connectivity and within-channel sediment dynamics is necessary.