Runoff Generation in Badlands

Capítulo 5.

Rainfall timing and runoff: The influence of the criterion for rain event separation

Abstract Rain is not uniform in time and space in semiarid areas and its distribution is very important for the runoff process. Hydrological studies usually divide rainfall into events. However, defining rain events is complicated, and rain characteristics vary depending on how the events are delimited. Choosing a minimum inter-event time (MIT) is a commonly used criterion. Our hypothesis is that there will be an optimal MIT that explains the maximum part of the variance of the runoff, with time to runoff used as a surrogate. The objective is to establish a procedure in order to decide upon this optimal MIT. We developed regressions between time to runoff (T0) and three descriptive variable…

Tectonic beheading of fluvial valleys in the Maestrat grabens (eastern Spain): Insights into slip rates of Pleistocene extensional faults

Abstract Interaction between faulting and landscape evolution in regions of active tectonics allows us to use subtle geomorphological markers for estimating fault slip rates. Geomorphic features of two valleys connected with the bottom of the Alcala de Xivert graben, at the Maestrat graben system (eastern Spain), suggest that they correspond to the lowest segments of ancient valleys whose original heads were located at the axis of the neighbouring Irta range. They were beheaded owing to displacement of the Torreblanca and Irta faults during a period of active extensional faulting in Middle Pleistocene times. These faults produced a negative inversion of the relief, sinking a narrow graben (…

Eco-geomorphological connectivity and coupling interactions at hillslope scale in drylands: Concepts and critical examples

The diagnosis of land degradation requires a deep understanding of ecosystem functioning and evolution. In dryland systems, in particular, research efforts must address the redistribution of scarce resources for vegetation, in a context of high spatial heterogeneity and non-linear response. This fact explains the prevalence of eco-hydrological perspectives interested in runoff processes and, the more recent, focused on connectivity as an indicator of system resource optimisation. From a geomorphological perspective and reviewing the concepts of eco-hydro-geomorphological interactions operating in ecosystems, this paper explores the effects of erosion on vegetation configuration through two …

Runoff generation, sediment movement and soil water behaviour on calcareous (limestone) slopes of some Mediterranean environments in southeast Spain

Abstract An interpretation of soil hydrology and erosion data obtained from limestone areas in southeast Spain is presented in the framework of recent hypotheses on runoff generation mechanisms in Mediterranean environments. The main objective is to synthesise and harmonise the data in theoretical concepts or behavioural models of hydrological functioning of Mediterranean limestone slopes. For this purpose, data were collected in a typical limestone area, with climatic characteristics ranging from subhumid to semiarid. Several sites were chosen with comparable slopes, vegetation and soils along a transect of 20 km to carry out several research projects. The data discussed in this paper cons…

MORPHOLOGY AND DEVELOPMENT OF SELECTED BADLANDS IN SOUTHEAST SPAIN: IMPLICATIONS OF CLIMATIC CHANGE

Four areas were selected to represent a range of processes characteristic of badland surfaces in southeast Spain: Petrer and Monnegre in Alicante, Vera and Tabernas in Almeria. At Petrer, rilling and swelling processes produce a deeply cracked surface drained by a finely textured network of shallow rills. At Monnegre, piping and rilling are differentially developed on slopes ultimately controlled by basal incision. At Vera, aspect-controlled lichen and vegetation cover produce a sequence of badland development within which the relative importance of piping, mass movement and rilling varies through the sequence. At Tabernas, simple overland flow is the dominant process, but aspect influences…

Analysis of soil surface component patterns affecting runoff generation. An example of methods applied to Mediterranean hillslopes in Alicante (Spain)

Spatial patterns of soil surface components (vegetation, rock fragments, crusts, bedrock outcrops, etc.) are a key factor determining hydrological functioning of hillslopes. A methodological approach to analyse the patterns of soil surface components at a detailed scale is proposed in this paper. The methods proposed are applied to two contrasting semi-arid Mediterranean hillslopes, and the influence of soil surface component patterns on the runoff response of the slopes was analysed. A soil surface components map was derived from a high resolution photo-mosaic obtained in the field by means of a digital camera. Rainfall simulation experimental data were used to characterise the hydrologica…

Post-fire hydrological response and suspended sediment transport of a terraced Mediterranean catchment

In July 2013, a wildfire severely affected the western part of the island of Mallorca (Spain). During the first three post-fire hydrological years, when the window of disturbance tends to be more open, the hydrological and sediment delivery processes and dynamics were assessed in a representative catchment intensively shaped by terracing that covered 37% of its surface area. A nested approach was applied with two gauging stations (covering 1.2 km2 and 4.8 km2) built in September 2013 that took continuous measurements of rainfall, water and sediment yield. Average Suspended Sediment Concentration (1,503 mg l-1) and the maximum peak (33,618 mg l-1) were two orders of magnitude higher than tho…

Effects of agricultural drainage systems on sediment connectivity in a small Mediterranean lowland catchment

Traditional drainage systems combining man-made channels and subsurface tile drains have been used since Roman times to control water excess in Mediterranean lowland regions, favouring adequate soil water regime for agriculture purposes. However, mechanization of agriculture, abandonment or land use changes lead to a progressive deterioration of these drains in the last decades. The effects of these structures on hydrological and sediment dynamics have been previously analyzed in a small Mediterranean lowland catchment (Can Revull, Mallorca, Spain, 1.4 km2) by establishing an integrated sediment budget with a multi-technique approach. Moreover, the recent advances in morphometric techniques…

Influence of soil properties on the aggregation of some Mediterranean soils and the use of aggregate size and stability as land degradation indicators

Abstract Soil aggregation in relation to other soil properties was studied along a climatological transect in the Southeast of Spain. Three sites were selected along this transect ranging from semiarid to subhumid climatological conditions. The aggregate size distribution, the macro and microaggregate stability of the superficial soil horizon and their relations with other soil properties were analysed. Large aggregates (>10, 10–5, 5–2 mm) were present in highest proportions in the most arid of the studied areas. These large aggregates were associated with high values of water-stable microaggregates; however, they did not improve soil structure and are related to high bulk densities and low…

Effective run-off flow length over biological soil crusts on silty loam soils in drylands

This study was undertaken in the context of the research projects PECOS (REN2003-04570/GLO) and PREVEA (CGL2007-63258/BOS), both funded by the Spanish National Plan for RD&I and by the European ERDF Funds (European Regional Development Fund), as well as the projects COSTRAS (Excellence project RNM-3614) funded by the Junta de Andalucia (Autonomous Government of Andalusia, Spain), and SCIN (Soil Crust Inter-National, PRI-PIMBDV-2011-0874, European project of ERA-NET BIODIVERSA, the Spanish team being funded by the Spanish Ministry of Economy and Competitiveness)

Carreras por montaña en la Comunitat Valenciana (1995-2019). Evolución, distribución territorial e incidencia en áreas naturales protegidas

El rápido crecimiento de las carreras por montaña, ha motivado durante los últimos años su estudio. Aun son pocas las referencias bibliográficas que podemos encontrar a escala local, aunque algunas a nivel de España. Existen diferencias regionales, que demandan la necesidad de examinar este tipo de pruebas a una escala detallada. La Comunitat Valenciana, dada su extensión forestal y porcentaje de territorio montañoso (56 %), el número de espacios naturales (646) y superficie total protegida (40 %), se convierte en un buen ámbito de estudio. Una revisión bibliográfica y un análisis de la información recogida ha permitido determinar el número y la evolución de esta práctica en los últimos 25 …

Causes and underlying processes of measurement variability in field erosion plots in Mediterranean conditions

Published online 25 May 2006

Badlands in the Tabernas Basin, Betic Chain

The complex badland landscape at Tabernas results from a combination of relief amplitude generated by tectonic uplift since the Pliocene and reactivated several times during the Pleistocene, the properties of the Tortonian sedimentary rocks and a predominantly arid climate. The landscape is dominated by deep incision of the main river systems, which continues in part of the headwater tributaries, and characterized by contrasting slope morphologies and a variety of microecosystems. The Tabernas badlands exhibit a diversity of landforms resulting from the combination of multi-age soil surface components that allow a variety of processes to operate at different rates. These are dominated by ri…

Cárcavas y regueros generados en suelos sódicos : Petrer (Alicante, España)

Este articulo pretende mostrar las interacciones entre los procesos de piping y la formacion de carcavas y regueros en diferentes sub-sistemas (laderas y rellenos de fondo de valle) de una pequena cuenca del SE espanol. Se analiza la influencia de diversas propiedades del los suelos y regolitos en el desarrollo de formas asociadas al piping. Los sistemas reguero-tunel de las laderas de badlands estan principalmente relacionados con la ratio de absorcion de sodio (SAR) y la conductividad electrica (CE) de los suelos. En contraste, en los rellenos de fondo de valle estas propiedades quimicas interactuan con las discontinuidades en el gradiente hidraulico introducidas por las terrazas de culti…

Concise review of interrill erosion studies in SE Spain (Alicante and Murcia): erosion rates and progress of knowledge from the 1980s

From the 1980s onward studies on interrill soil erosion were intensified in SE Spain. The main achievements of the research carried out in the field areas of Alicante and Murcia concern: first, (1) the estimation of erosion rates directly in the field under a wide range of methodologies, different scales and different environmental conditions; (2) estimations based on existing models, such as the USLE, carried out for different subcatchments of the Segura and Júcar catchments; and (3) other parametric and physical event-based models have also been calibrated and validated. Second, the progress of the knowledge in understanding erosion mechanisms. New and reviewed concepts regarding mainly h…

Evaluating functional connectivity in a small agricultural catchment under contrasting flood events by using UAV

Defining minimum runoff length allows for discriminating biocrusts and rainfall events

This study was started in the context of the research projects PECOS (REN2003-04570/GLO) and PREVEA (CGL2007-63258/BOS) , both funded by the Spanish National Plan for RD&I and by the European ERDF Funds (European Regional Development Fund) , and continued during the project SCIN (Soil Crust In-terNational, PRI-PIMBDV-2011-0874, European project of ERA-NET BIODIVERSA, the Spanish team being funded by the Spanish Ministry of Economy and Competitiveness) . The work was finally supported and culminated by the DINCOS project (CGL2016-78075-P, Spanish State Programme for Scientific Research) and by the European ERDF Funds (Euro-pean Regional Development Fund) . Consuelo Rubio's partici-pation was…

A review of runoff generation and soil erosion across scales in semiarid south-eastern Spain

Climate, lithology, soil and especially, intense land use/cover changes, make SE Spain very vulnerable to runoff generation and water erosion leading to loss of nutrients and organic matter and to infrequent but devastating floods, reservoir siltation and mass failures. This susceptibility has led to heavy economic investment and research efforts since the 1980s, making this region a worldwide reference for understanding the hydrology and geomorphology of semiarid ecosystems. Runoff and soil erosion have been intensively studied throughout the last decades in various natural ecosystems as well as in abandoned farmlands. Research has considered a wide range of methods and spatial and tempora…

Características de las costras físicas y biológicas del suelo con mayor influencia sobre la infiltración y la erosión en ecosistemas mediterráneos

28 páginas, 4 figuras, 5 tablas.

Spatial patterns of sediment connectivity in terraced lands: Anthropogenic controls of catchment sensitivity

In recent decades the dynamics of global change in developed countries has led to significant alterations in the hydrological and sediment dynamics of terraced land. Agricultural terraces were built to control overland flow and prevent erosion, acting as buffers and barriers throughout the sediment cascading system. Their abandonment and degradation increase the sensitivity of the catchment, promoting the collapse of dry-stone walls and the reworking of stored sediment. In this study, a geomorphometric Index of Connectivity (IC) –derived from high-resolution LiDAR data (0.9 pt m-2, RMSE Q8). This spatial matching was related to feedback dynamics between structural and functional connectivit…

Chapter 3 patterns and thresholds of runoff generation and sediment transport on some Mediterranean hillslopes

Abstract Runoff and sediment transport data obtained from hillslopes in two limestone areas in southeast Spain are analysed in order to define spatial and temporal thresholds for sediment movement at the patch scale under Mediterranean semiarid and subhumid climatological conditions. The data discussed in this paper include a 7-year series of runoff and sediment collection in open Gerlach plots. The 136 events are analysed in relation to characteristics of rainfall, soil and soil surface components. In both cases slopes behave as a patchwork of runoff and runon areas and the size of the runoff or runon patches being dependent on the climatological conditions. These control the hydrological …

Multi-temporal Forest Cover Change and Forest Density Trend Detection in a Mediterranean Environment

The loss of forests along with the various types of shrubs in the Mediterranean region is seen as an important driver of climate change and has been repeatedly related with the observed land degradation and desertification in the region. Nevertheless, the extent of woody perennial vegetation cover (WPVC) and its density remain largely unclear. Here, we apply a series of algorithms and methods operationally used in Australia for large-scale WPVC mapping and monitoring and demonstrate their applicability in the Mediterranean region using a Spanish area as the trial site. Five Landsat TM and ETM+ images from various dates spanning 14 years are used to map changes in the extent of WPVC and to i…

Erosion and stabilisation sequences in relation to base level changes in the El Cautivo badlands, SE Spain

Abstract The complex multiple-age badlands at El Cautivo are cut in upper Miocene marls of the uplifted and dissected Tabernas Basin, Almeria, in semi-arid SE Spain. Previous work identified six episodes of erosion and subsequent stabilisation, with ages ranging from the late Pleistocene to the present day. This paper uses newly-acquired digital elevation models, orthorectified aerial photographs, and field survey data to illustrate the development sequence of a series of gullies which drain into the Rambla de Tabernas. Changing drainage directions and phases of incision and stabilisation are related to the filling and subsequent dissection of the Tabernas lower lake sediments, differential…

Spatial and short-term temporal variations in runoff, soil aggregation and other soil properties along a Mediterranean Climatological Gradient.

Abstract Physical and chemical soil properties were measured along a mountainous climatological gradient in the province of Alicante (Spain). The objective was to evaluate how the climate affects certain soil properties at different temporal and spatial scales. These properties include infiltration, runoff and sediment concentrations resulting from rainfall simulation experiments performed in winter and in summer. Chemical soil properties like carbonate content, organic matter content and CEC were analysed in reference soil profiles along the gradient. Physical soil properties like soil moisture content, macroaggregation and waterstable microaggregation were measured at monthly intervals du…

Biocrusts and catchment asymmetry in Tabernas Desert (Almeria, Spain)

Abstract Catchment asymmetry is a fairly frequent phenomenon on a global scale but the main causes leading to its formation are still not well understood. Where the intervention of structural or tectonic causes is not relevant, asymmetry seems to result from differential erosion between opposite slopes that flow into the same channel, which is frequently associated with contrasted biocrust and/or vegetation covers. Biocrusts are known to be important surface stabilizing agents. However, their geomorphological consequences at the landscape scale are little known. In this study we combined field measurements with digital elevation models and image analysis to determine whether catchment asymm…

Measuring soil erosion by field plots: Understanding the sources of variation

Soil erosion plots of different types and sizes are widely used to investigate the geomorphological processes related to soil erosion. This field method has provided a variety of results, depending on the characteristics of the plots, on their suitability to reflect the ecosystem's characteristics and on the objectives of each particular research. The coupling of real soil loss at patch and slope scale within a landscape and the values obtained by field plots depend, among other things, on how good the methodology performs over a set of ecosystem properties, such as those related with temporal and spatial scale issues, disturbance and representation of natural conditions, and the ability to…

Monthly precipitation and runoff series of Begura de Salma River (Mallorca, Spain): January 2015-October 2018

Here we provide the data set obtained as described in detail in Estrany et al. (2020, doi:10.5194/nhess-2019-304); a brief description is presented below. A hydrometric gauging station is located where the Begura de Salma River enters Sant Llorenç des Cardassar, a village located in the northeastern part of Mallorca island (Spain). The station was built by the water authority in the 1970s. After years of abandonment, in 2015 the MEDhyCON Research Group installed within the gauge house a Hobo Water Level U20L-04, which measures the water stage by 1-minute readings, accumulating 15-minute average values. The station is located at the very beginning of the concrete channel that takes the river…

Discharge data series of Begura de Salma River (Mallorca, Spain): January 2015-October 2018

Here we provide the data set obtained as described in detail in Estrany et al. (2020, doi:10.5194/nhess-2019-304); a brief description is presented below. A hydrometric gauging station is located where the Begura de Salma River enters Sant Llorenç des Cardassar, a village located in the northeastern part of Mallorca island (Spain). The station was built by the water authority in the 1970s. After years of abandonment, in 2015 the MEDhyCON Research Group installed within the gauge house a Hobo Water Level U20L-04, which measures the water stage by 1-minute readings, accumulating 15-minute average values. The station is located at the very beginning of the concrete channel that takes the river…