unsaturated hydraulic conductivity in limestone dolines influence of vegetation and rock fragments abstract vegetation and rock fragments have a profound impact on runoff generation in the dolines of the sierra de gador southeastern spain this study investigated the effect of vegetation and rock fragments on unsaturated hydraulic conductivity k h in three limestone dolines and examined whether variation in k h was consistent with differences in runoff from simulated rainfall tension infiltrometers were used to measure unsaturated hydraulic conductivity at three pressure heads h of 30 60 and 120 mm at 70 locations within the three dolines generally the trends of the k h were consistent with the simulated rainfall data and accounted for difference in runoff for the vegetated surfaces vegetation resulted in high infiltration with unsaturated hydraulic conductivities at 30 and 60 mm are significantly greater for the vegetated surface than for the rock fragment covered surface and bare soil surface rock fragments had no obvious effect on soil hydraulic conductivity as compared with bare soils the k h of the non crusted soil were 2 5 times higher than that of the crusted soil the k h decreased with increasing tensions k 60 and k 120 were only 8 4 and 0 89 respectively of k 30 for the vegetated surfaces and were about 30 and 8 7 respectively of k 30 for both rock fragment covered surfaces and bare soils suggesting that pores in the 0 5 to 1 mm diameter range dominate flow under unsaturated conditions there were significant differences in k h among the different topographic units of the dolines and k h tended to be higher in the upper position than in the lower position of the doline

seasonal changes in the hydrological and erosional response of a hillslope under dry mediterranean climatic conditions montes de malaga south of spain the mediterranean eco geomorphological system was analysed at one representative hillslope of the geological unit of montes de malaga province of malaga spain under dry mediterranean climatic conditions the research was divided into two stages first the eco geomorphological pattern of the slope and some physical properties of the soil were analysed second the hydrological and erosional response of the eco geomorphological system was analysed by applying simulated rainfall to the main elements of the system and using closed plots with different lengths this hydrodynamic analysis was carried out during two periods crucial for the mediterranean environment in hydrological terms the end of the dry season or the beginning of the active hydrodynamic season and the middle of the wet season the results show that i the hydrophobic behaviour of soil is the predominant runoff generation mechanism that accounts for sediment movement ii once soil was moistened in the wet season it lost its hydrophobicity and the saturation of soil became a predominant runoff generation mechanism and iii there was high variability in hillslope runoff with evident hydrological disconnections which made the hydrodynamic response of the eco geomorphological system complex due to the absence of a clear predominance of abiotic or biotic factors

subsurface flow in a soil mantled subtropical dolomite karst slope a field rainfall simulation study abstract soil and epikarst co evolve resulting in complex structures but their coupled structural effects on hydrological processes are poorly understood in karst regions this study examined the plot scale subsurface flow characteristics from an integrated soil epikarst system perspective in a humid subtropical cockpit karst region of southwest china a trench was excavated to the epikarst lower boundary for collecting individual subsurface flows in five sections with different soil thicknesses four field rainfall simulation experiments were carried out under different initial moisture conditions dry and wet and rainfall intensities 114 mm h 1 high and 46 mm h 1 low on average the soil epikarst system was characterized by shallow soil overlaying a highly irregular epikarst surface with a near steady infiltration rate of about 35 mm h 1 the subsurface flows occurred mainly along the soil epikarst interface and were dominated by preferential flow the subsurface flow hydrographs showed strong spatial variability and had high steady state coefficients 0 52 and 0 36 for high and low rainfall intensity events irregular epikarst surface combining with high vertical drainage capacity resulted in high threshold rainfall depths for subsurface flows 67 mm and 263 mm for initial wet and dry conditions respectively the above results evidenced that the irregular and permeable soil epikarst interface was a crucial component of soil epikarst architecture and consequently should be taken into account in the hydrological modeling for karst regions

the erosional response of calcareous soils along a climatological gradient in southeast spain abstract the erosional response of calcareous soils along a climatological gradient in alicante se spain was studied the erosional response was defined in terms of indicators obtained from field rainfall simulation experiments and laboratory studies of soil aggregation measurements were made at seven sites on limestones and marls between benidorm with an annual average rainfall of 400 mm yr 1 and coll de rates annual rainfall 900 mm yr 1 the sites were on matorral vegetation affected to varying intensities by grazing and fire at the seven locations soil aggregation was studied by sieving by the single water drop test and by a microscan particle sizer rainfall simulation experiments were made on circular 55 cm diameter target area plots using the calvo simulator at an intensities between 35 and 59 mm h 1 on limestone it was found that on bare surfaces the coarse soil aggregation increases with depth at the highest sites and decreases at the lower sites the benidorm surface soil has the highest erodibility the least stable soils are at the lower intermediate sites on marls the aggregate stability is generally high in contrast to those under cultivation simulated runoff from the wetter limestone sites is very low the driest areas have the highest runoff and sediment yields trends with climate suggest that the erosional responses of the soils indeed increase with aridity and temperature but local factors have a large effect particularly at intermediate altitudes a clear relationship like that found in israel by lavee on a similar lithology does not exist

soil loss and soil water content affected by land levelling in penedes vineyards ne spain abstract this paper analyses the differences in soil moisture runoff and sediment concentration resulting from land levelling works carried out before new vineyard establishment in a reference wine region of ne spain in low disturbed soils low differences in soil moisture were observed while in high disturbed soils soil moisture and water infiltration of the surface were always lower than in the low disturbed ones while soil sealing was higher in high disturbed than in the low disturbed soils differences in runoff and sediment concentrations were also observed the most disturbed plot showed a higher sediment concentration in runoff which together with higher runoff volumes gave higher erosion rates and soil losses than the low disturbed one the differences within the most disturbed soils were high after high intensity rainfall events while no significant variations were observed in the least disturbed ones

effects of soil surface components on soil hydrological behaviour in a dry mediterranean environment southern spain abstract various researchers have studied the spatial pattern of soil surface components such as vegetation rock fragments bare soil litter and surface crusts as a key factor of hydrological behaviour in mediterranean settings with heterogeneous patches of vegetation cover and strong human impact the studies indicate that there is a mosaic of patches that generate run off or infiltrate overland flow distributed in various ways along hillslopes few of these studies however have looked at areas underlain by metamorphic rocks such as phyllites or schists this study analysed the temporal and spatial variability of the effects of soil surface components on hydrological processes in a small dry mediterranean catchment underlain by metamorphic rocks a systematic sampling of multiple sites throughout a hydrological year was carried out we related the hydrological behaviour of soil surface components to 1 their position along the hillslope 2 the distance of existing vegetation tussocks from the line of run off 3 rainfall intensity and 4 the main physical chemical soil properties affecting infiltration processes statistical analysis was used to check the validity of the relationships the results show that soil surface components have highly variable effects in both space and time on soil hydrological behaviour these effects particularly depend on the location along the line of maximum slope and the intensity of preceding rainfall whose interaction defines soil hydrological status these results are similar to those for other mediterranean settings with different lithology in that the succession of contributing patches are hydrologically interconnected along a hillslope the variables used and the grouping of explanatory variables through principal component analyses were found to be suitable for discussing the spatial distribution of soil surface components in the hydrologically dynamic environment of the study area

human impacts on fluvial systems in the mediterranean region the long history of substantial human impacts on the landscape of the mediterranean region and their effects on fluvial systems is documented these effects have included impacts of deforestation and other land use changes agricultural terracing on a wide scale water transfers and irrigation schemes during the 20th century major changes were made directly to channels through channelisation construction of dams of various sizes and extraction of gravel and indirectly by reforestation these changes have caused a major phase of incision on some rivers runoff and soil erosion have been affected by types of crops and agricultural practices as well as by the varying extent of cultivation and grazing some recent agricultural practices involve wholescale relandscaping of the topography and alteration of surface properties of material the importance of analysing the connectivity within different land units and of the spatial position of human activity within a catchment is illustrated the analysis of connectivity is the key to understanding the variability of impact and the extent of propagation of effects

effects of erosion degree rainfall intensity and slope gradient on runoff and sediment yield for the bare soils from the weathered granite slopes of se china abstract soil erosion caused by rainfall is a dominant driving force of ecosystem degradation and has become a worldwide environmental issue however few studies have been conducted to investigate the effect of erosion degree on the characteristics of soil erosion this study aims to investigate the effects of erosion degree rainfall intensity and slope gradient on erosion processes on bare weathered granite slopes of southeast china the method of simulated rainfalls was applied with two soil tanks under three slope gradients 8 15 25 four rainfall intensities 60 90 120 150 mm h and three erosion degrees slight e1 moderate e2 severe e3 the rainfall time lasted 90 min and the paddy samples were collected at every 3 min to determine the runoff rate for surface flow rr s and interflow rr i sediment rate sr sediment concentration sc and particle size distribution psd the enrichment ratio er and mean weigh diameter mwd of different particles were finally calculated and evaluated the occurring time of surface flow tr s and interflow tr i presented a negative relationship with rainfall intensity and slope gradient while tr s presented an order of e2 e1 e3 and tr i was negatively related to erosion degree rr s increased with runoff duration and was positively correlated to rainfall intensity and slope gradient but negatively correlated to erosion degree but rr i displayed single peak curves with runoff duration and was positively related to erosion degree sr showed an increasing deceasing trend with runoff duration and was positively correlated to rainfall intensity and slope gradient sr on different slopes displayed an order of e1 e2 e3 at the 60 and 90 mm h rainfalls while it reversed at heavier rainfalls sc decreased with runoff duration with light fluctuations it was found that sediment psd was corresponding to original soils to a definite extent while mwd and er were positively correlated to erosion degree these results facilitate the understandings of runoff and soil erosion processes in the weathered granite regions and erosion degree should be considered in future erosion prediction and modeling

analysis of soil surface component patterns affecting runoff generation an example of methods applied to mediterranean hillslopes in alicante spain abstract 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 hydrological behaviour of areas with a specific pattern of soil surface components by means of the parameters of the horton equation plot runoff data were extrapolated at the hillslope scale based on the soil surface component maps and their hydrological characterisation the results show that in both slopes runoff generation is concentrated up and downslope with a water accepting area in the centre of both slopes disrupting the hydrological connectivity at the slope scale this reinfiltration patch at the centre of the slope is related to the type of soil surface component and its spatial pattern herbaceous vegetation and on top rock fragments increase the infiltration capacity of soils at the centre of the slope in contrast embedded rock fragments rock outcrops as well as crusted surfaces located in the upper and lower slopes favour runoff generation in these areas in addition a general pattern of water contribution areas downslope is apparent on both slopes the south facing slope shows a higher hydrological connectivity and more runoff 55 of the surface of the south facing slope produces runoff at the end of a 1 hour rainfall event and 17 3 of the surface is covered by a runoff depth between 0 5 and 1 mm while on the north facing slope only 38 of the surface produces runoff under the same conditions longitudinal connectivity of runoff is higher at the south facing slope where more runoff generating surfaces appear and where the vegetation pattern favours the connectivity of bare areas

effects of soil and vegetation on runoff along a catena in semi arid spain runoff and infiltration were investigated on abandoned fields of patchy vegetation in semi arid spain during 15 months of natural rainfall and by rainfall simulations the aim was to ascertain sources and sinks of runoff and the effects of soils and plant cover soils of the catena developed from mica schists of the upper hillslopes fan deposits of the lower hillslopes and an alluvial terrace at the bottom runoff from natural events were from three sets of three pairs each of 10 2 m runoff plots the pairs of each set had different densities of plant cover the sets were vegetated with tussock grass stipa tenacissima a shrub anthyllis cytisoides and a bush retama sphaerocarpa nineteen natural rainfall events of intensities up to 18 mm h produced 400 mm of rain during the study period because the rainfall threshold for runoff production was about 20 mm only eight events produced runoff the rainfall simulations used a sprinkler that produced 50 mm h of rain for 30 minutes runoff was recorded each minute in 0 24 m2 bounded plots the depth and structure of the soil mantle provide the main controls on runoff rates which are lowest on the lower fan deposits and highest on the thin upslope soils the river bank terrace with a surface covered by crusts and mosses also yields relatively high runoff in general vegetation density varies inversely with runoff nevertheless shrub and bush litter favor runoff as does a particular spatial distribution of individual plants on the hillslope settling of the upper few centimeters of soils of the alluvial fan following cessation of cultivation 15 to 40 years ago has produced a near surface compacted layer favoring shallow subsurface runoff apparently contradictory results between runoff plots and rainfall simulations are the result of differing processes

the effect of rock fragment size and position on topsoil moisture on arid and semi arid hillslopes abstract rock fragments on arid hillslopes affect rainwater redistribution and overland flow through various hydrological processes the present study focuses on the evolution of topsoil moisture content under rock fragments following rain events measurement was taken under rock fragments in various sizes large and small and positions on top of the soil surface and partially embedded within the soil surface at north and south facing hillslopes in arid and semi arid areas the main findings 1 the topsoil moisture content under rock fragments was higher over time than that of bare soil areas 2 rock fragments affect the topsoil moisture content for a longer time in semi arid areas than in arid areas and 3 large rock fragments and partially embedded ones are favorable micro environments for accepting and retaining rainwater and overland flowing water this may have eco geomorphic implications regarding the mosaic like patterns of source and sink areas on arid hillslopes

modelling runoff and erosion for a semi arid catchment using a multi scale approach based on hydrological connectivity runoff and erosion processes are often non linear and scale dependent which complicate runoff and erosion modelling at the catchment scale one of the reasons for scale dependency is the influence of sinks i e areas of infiltration and sedimentation which lower hydrological connectivity and decrease the area specific runoff and sediment yield the objective of our study was to model runoff and erosion for a semi arid catchment using a multi scale approach based on hydrological connectivity we simulated runoff and sediment dynamics at the catchment scale with the lapsus model and included plot and hillslope scale features that influenced hydrological connectivity the semi arid carcavo catchment in southeast spain was selected as the study area where vegetation patches and agricultural terraces are the relevant sinks at the plot and hillslope scales respectively we elaborated the infiltration module to integrate these runoff sinks by adapting the parameters runoff threshold and runoff coefficient which were derived from a rainfall simulation database the results showed that the spatial distribution of vegetation patches and agricultural terraces largely determined hydrological connectivity at the catchment scale runoff and sediment yield for the scenario without agricultural terraces were respectively a factor four and nine higher compared to the current situation distributed hydrological and erosion models should therefore take account of relevant sinks at finer scales in order to correctly simulate runoff and erosion sedimentation patterns

accuracy constraints of terrestrial lidar data for soil erosion measurement application to a mediterranean field plot abstract applications of terrestrial laser scanning tls to measure soil erosion are yet limited although this topographic mapping method allows for large area coverage with high resolution and reliable precision however restricting factors are accurate and stable references for multi temporal change detection and adverse scanning geometries at agricultural fields the plot is usually situated on gentle slopes provoking low viewing angles of the scanning device onto the surface which inherits the risk of high data noise in this study tls is exploited from a high tripod to measure soil erosion at an andalusian hillslope 2 1000 m2 in the mediterranean sediment yield reveals discontinuous pattern and tls is a promising method to quantify these surface changes a stable reference system is defined resulting in multi temporal registration accuracy better than 7 mm further an mm accurate calibration plot 60 m2 is designed to evaluate scan geometry and radiometry i e incidence angle footprint and intensity in dependence of distance related errors a lookup table is determined to correct systematic errors of the field data the andalusian field plot is captured during a winter season and during single precipitation events estimated erosion rates amount 10 and 2 4 t ha 1 respectively surface changes with magnitudes larger 1 5 cm are reliably measured tls can be implemented to estimate soil erosion with cm resolution if errors are carefully accounted for

shrub mound formation and stability on semi arid slopes in the northern negev desert of israel a field and simulation study in semi arid areas vegetation is scarce and often dominated by individual shrubs on raised mounds the processes of formation of these mounds are diverse and still debated often shrub mound formation is directly related to the formation of vegetation patterns thereby assuming that shrub mound formation is driven by biological interactions we hypothesize that water related erosion and sedimentation are also important drivers of shrub mound formation in the northern negev desert of israel we test this hypothesis by combining field observations with model simulations we studied shrub mounds in the semi arid catchment of sayeret shaked in the northern negev desert 200 mm annual precipitation height and diameter of shrub canopy and shrub mounds were measured and micro morphological techniques were used to reconstruct the formation of the shrub mounds we used landscape evolution model lapsus to simulate shrub mound formation at short single precipitation event and longer 100 years timescales at different slope angles both field and model results indicate that shrub mounds in sayeret shaked are at least partly formed by redeposition of eroded material below the shrubs and by erosion and lowering of the surrounding crust additional model simulations suggest that mounds are formed most under low shrub density and large shrub canopy diameter shrub mound formation increases with slope in dryer and wetter climates than the studied 200 mm rainfall semi arid climate zone shrub mound formation is less likely

pliocene lower pleistocene shallow water mixed siliciclastics and carbonates yanigua and los haitises formations in eastern hispaniola dominican republic the virtually unfolded sedimentary cover of the cordilleras central and oriental in the eastern dominican republic eastern hispaniola tropical north atlantic largely consists of pliocene to early pleistocene mixed siliciclastics and carbonates these deposits have been grouped into two laterally interfingering mapping units the yanigua and los haitises formations the former mainly siliciclastics comprises marl marly limestone and minor conglomerate sandstone lignite and carbonaceous clay and crops out closest to the basement the los haitises formation mainly consists of limestone and intercalating beds of marly limestone and marl lithological mapping at the 1 50 000 scale and facies analysis of twelve measured sections and of additional fourteen outcrops suggest that these deposits mainly formed on a shallow water marine platform fringing the precursor reliefs of the cordillera oriental and the southeastern end of the cordillera central only a limited proportion of sediment formed in floodplains and marshes marl and marly limestone dominated the inner platform sediments terrigenous mud decreased away from the emergent basement and carbonate sedimentation dominated the more external platform corals molluscs echinoids foraminifers bryozoans coralline algae and halimeda are the main components with varying amounts of carbonate mud the platform was generally a low energy environment with seagrass patches in the inner platform corals grew as isolated colonies or as small patch reefs dominated by porites in marly and bioclastic substrates branching corals stylophora and acropora grew in extensive carpets in more distal areas at least in the last stage of its development early pleistocene the platform was rimmed by a reef barrier similar to the holocene caribbean barrier reefs with acropora gr palmata a cervicornis porites montastrea siderastrea and diploria as the main reef builders

significance of preferential flow at the rock soil interface in a semi arid karst environment abstract in many semi arid environments the surface materials are frequently characterized by thin soils and large proportions of bare rock both of which are expected to considerably influence infiltration and groundwater recharge processes in this study small plot scale irrigation experiments in combination with dye tracer application as well as real time and subsequent soil moisture measurements and soil particle size analysis were conducted to investigate the significance of preferential flow at the rock soil interface large scale assessments of soil depth and surface type distribution were used to upscale the findings of the irrigation experiments to the scale of a complete hillslope and further to estimate percolation properties of a hypothetical rainfall event the two experimental plots were each located in the west bank mountains close to ramallah each irrigation experiment was designed with 50 mm of precipitation applied on an area of 1 m 2 during the course of ca 2 5 h each irrigation plot had a surface share of approximately 50 rock outcrop and 50 soil surface percolation properties were investigated by subsequent soil moisture measurements at high spatial resolution on vertical soil profiles on the irrigated plot dye tracer application on the rock outcrop during the sprinkling allowed for tracking of resulting outcrop runoff in the subsurface the soil depth survey included 2100 measurement points on 7 transects which allowed the estimation of local soil depth distribution results of the irrigation experiments showed that precipitation induced runoff from rock outcrops continued below ground as preferential flow along the rock soil interface while water from the soil surface percolated mainly vertically and much more homogeneously this was evident from the high density soil moisture measurements as well as from the dye tracer patterns outcrop runoff percolated faster and to greater depths than water infiltrating directly from the soil surface thus possessing a greater potential for groundwater recharge

interactions of plant growth and sediment movement on slopes in a semi arid environment abstract the morphology and architecture of the tussocks of alpha grass stipa tenacissima as well as its associated micro topography have been described in several sites on the south versant of the filabres range in southern spain the annual rainfall of this area is between 225 and 275 mm and plant cover ranges from 20 to 45 the results show the formation of micro topographic mounds upslope of the tussocks which are interpreted as deposition bodies originating from the interception of downslope sediment movement by the vegetated patches the tussock architecture shows an outer growing zone a middle mature zone and a central senescent zone the outward expansion of the tussock is performed by tillers in the growing zone which bend at the nodes and root when they come into contact with the soil surface the mat of dead leaves inside the tussock may prevent the stems from bending and this factor plays a significant role in controlling tussock growth a similar effect on slopes is produced by the mound of sediments which accumulate upslope of the tussock and press upon the growing stems a simple simulation model has been built from the above field observations the model is able to reproduce the tussock shapes found in nature and predicts that at low plant rates the tussocks become unstable and collapse while at higher levels of plant vigour and sediment movement rates sedimentation occurs upslope of the tussock and erosion downslope these foci of sedimentation and erosion are crescent shaped and their relative importance depends on the splash factor

nonlinearity of ecogeomorphic processes along mediterranean arid transect the study was conducted along a climatic transect extending from the judaean mountains mean annual rainfall 700 mm annual mean temperature 17 c to the dead sea mean annual rainfall 100 mm annual mean temperature 23 c a high correlation was found between climatic conditions and factors and processes of the ecogeomorphological system the values of certain factors and processes such as soluble salt content and overland flow increase with increasing aridity whereas those of others such as soil organic matter content clay content aggregate size and stability and infiltration rate diminish with increasing aridity these trends express the long term effect of the prevailing mean climatic conditions in the research stations conditions that led to the development of various types of soil and of plant communities it was also found that for many of the factors and processes examined such as organic matter content salt concentration aggregate stability infiltration rate and overland flow yield the rates of change with respect to position along the transect are not linear and that a climatic threshold value exists in the zone with a mean annual rainfall of about 300 mm and in which the p t ratio is about 17 which creates a sharp boundary between arid and mediterranean ecogeomorphological systems while in arid systems erosion occurs mainly through physical mechanical processes under mediterranean systems it is governed mainly by chemical and biological processes the significance of the existence of a sharp boundary between the arid and the mediterranean zones is that even a relatively slight increase in the annual mean temperature and or a slight decrease in the mean annual rainfall is liable to shift the boundary towards the mediterranean zone and accelerate desertification processes

role of epikarst in near surface hydrological processes in a soil mantled subtropical dolomite karst slope implications of field rainfall simulation experiments epikarst exerts a strong control on run off generation in karst regions but it is still unclear in karst regions our study aimed to demonstrate the effect of epikarst on near surface hydrological processes in a subtropical cockpit karst region of southwest china using plot scale rainfall simulation experiments with different rainfall intensities low and high and antecedent moisture conditions dry and wet a trench excavated to the epikarst lower boundary allowed identification of flow pathways in the entire soil epikarst architecture system thus facilitating the water balance calculations using a conceptual model with the assumption of a two stage hydrological evolution more than 70 of the total rainfall water moved vertically through the shallow soil layer and then was redistributed by the epikarst as subsurface flow occurring on the soil epikarst interface depression filling on epikarst surface water held by epikarst and deep percolation epikarst water regulation capacity defined as the sum of depression filling on epikarst surface water held by epikarst epikarst seepage flow and deep percolation was 58 mm wet antecedent condition and 223 mm dry antecedent condition total run off from the soil epikarst system was dominated by saturated subsurface flow showing a threshold process controlled by epikarst storage capacity storing as much as 181 mm of rainfall water under dry antecedent condition our study proved that despite the epikarst being relatively poorly developed and covered by a soil mantle it still exerted a strong influence on near surface hydrological processes and thus should be adequately considered in future modelling of water recharge and depletion dynamics in this integrated soil epikarst system copyright 2015 john wiley sons ltd

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 water retention aggregates 1 0 105 mm were positively correlated to medium fine very fine sand and silt fractions and to organic matter aggregates water stability of microaggregates showed a positive correlation with clay content while the stability of the macroaggregates depended on the organic matter content when the organic matter content was greater than 5 or 6 below that threshold the carbonate content was strongly correlated with aggregate stability a general conceptual scheme of associations between aggregate size distribution water stable microaggregation and textural characteristics for the area was developed the land use history affecting soil overlaps the pattern of climatological situations and has to be taken into account aggregate size distribution and stability can be used as indicator of soil degradation but not as a unique parameter

linking spatial patterns of soil organic carbon to topography a case study from south eastern spain a key uncertainty in our understanding of the global carbon cycle is the lateral movement of carbon through the terrestrial system soils are the major storage of carbon in the terrestrial biosphere and the inventory of soil organic carbon soc is required for greenhouse gas inventories and carbon mitigation projects the aim of this study is to characterize spatial patterns of the concentrations of topsoil total organic carbon toc in a semi arid mediterranean area in south eastern spain and to assess their relationship to topography we adopt a remote sensing based approach for the spectral determination and quantification of toc with a complete coverage of bare soil surfaces digital terrain analysis and geostatistical techniques are applied to analyze the spatial patterns of toc at different spatial scales we show that accumulation of topsoil soc is dependent on topographic position at the landscape scale with highest values found in valley bottoms at the hill slope scale differences among terrain classes exist regarding the topographic controls on soc while positive correlation between the topographic wetness index twi and toc can be observed on steep slopes that correlation is not significant on wide pediments small scale spatial variability is large on ridges steep slopes and valley bottoms while soc distribution on pediments is relatively homogeneous these differences are most likely governed by the presence of vegetation patches and variable runoff and sediment transport rates among the terrain classes the successful application of hyperspectral remote sensing for the spatial estimation of soc concentrations suggests that it is a promising technique to advance soc inventories in semi arid and arid regions

effects of crust and shrub patches on runoff sedimentation and related nutrient c n redistribution in the desertified steppe zone of the tengger desert northern china runoff and erosion are critical geomorphic processes in arid ecosystems and they are strongly affected by vegetation patterns little is known about the influence of spot structured vegetation on runoff and erosion in temperate deserts especially the effects of vegetation patterns and human induced disturbances on runoff triggered nutrients redistribution are poorly understood a series of simulated rainfall experiments were conducted in the tengger desert northern china to examine 1 the effects of shrub patches on runoff and erosion and related nutrients redistribution on hillslopes 2 whether different amounts of water and nutrients are stored in the shrub patches compared to open inter patch areas and 3 how the runoff and erosion and related nutrients redistribution processes respond to human induced disturbances the results indicate that in undisturbed plots 53 of the applied water became runoff from crust patches and 55 of this was redistributed to the shrub patches water penetration was significantly deeper in shrub patches than in crust patches and more than 75 of the sediments 63 soil carbon 74 nitrogen and 45 73 dissolved nutrients triggered by runoff from crust patches were delivered to shrub patches the disturbance of crust patches tended to result in the uniform distribution of water over the whole slope and the reduction of flow of vital resources from the crust patches to the shrub patches disturbance of macrophytic patches significantly degraded the capacity for resource capture and retention and thereby decreased resources all of which are crucial for the maintenance of plant productivity and vegetation cover the understanding of the function of patterned vegetation in the study area suggests that it represents an aspect of the ecosystem that requires careful management

effects of land use land cover and rainfall regimes on the surface runoff and soil loss on karst slopes in southwest china abstract surface runoff and soil loss from 2007 to 2010 related to land use and rainfall regimes in karst hill slopes in guizhou province southwest china were analyzed using the hierarchical clustering method sixty one rainfall events under the subtropical monsoon climate condition were classified into 5 types of rainfall regimes according to the depth maximum 30 min intensity and duration of rainfall in our study we first demonstrated that the amounts of surface runoff and soil loss on the karst hill slopes were very small compared to the non karst areas because the dual hydrological structure in the karst region including ground and underground drainage systems could influence the processes of rainfall recharge and runoff generation most rainfall water was transported underground through limestone fissures and fractures while little was in the form of surface runoff second the runoff and soil loss were affected by land use management and vegetation cover soil loss was intensified in a descending order to five types of land uses pastureland burned area cropland combination vegetation land young forestland third the runoff and soil loss exhibited remarkable variances among different rainfall regimes large runoff and soil loss were mainly created by heavy rainfall storms with a rainfall depth of more than 40 mm and a maximum 30 min rainfall intensity of over 30 mm h 1 in addition rainfall storms with large antecedent precipitations could also produce large runoff and soil loss these observations indicated that limestone fissures and fractures play important roles in surface runoff generation on karst limestone slopes due to their large storage capacity and high infiltration rate lastly the soil erosion risk in the karst pure limestone slope is quite high and should be paid particular attention especially in regards to over grazing because the soil loss created by a single heavy rainstorm in pastureland was 5 times the annual soil loss tolerance

effect of catchment properties on runoff coefficient in a karst area of southwest china frequent human activities and climate change in the karst region of southwest china since the 1950s have led to the investigation of response of runoff to climate and catchment properties runoff coefficient rc as an expression variable of the catchment response to rainfall is important to describe runoff dynamics and to estimate available streamflow for utilization in this study the equations of rc associated with its attributors of climate condition and catchment property were derived using the budyko framework the equations were used to estimate relationship between the rc and the attributors in the karst catchments in guizhou province of southwest china analysis in the selected 23 karst catchments demonstrates that the spatial distribution of rc is dominated by the catchment properties such as the catchment properties of geology slope and land use and land cover rather than climate condition of drought index correlation analysis indicates that the catchment with a large slope usually has a high value of rc and a large proportion of carbonate rock in a catchment reduces rc in the study area temporal increasing trend of rc during 1961 2000 was found for most catchments in the study area this increasing trend was primarily resulted from changes of catchment properties e g deforestation in large areas of guizhou province during the 1950s 1980s copyright 2013 john wiley sons ltd

hydrocarbon potential of the zechstein main dolomite in the western part of the wielkopolska platform sw poland new sedimentological and geochemical data abstract the results of identification of facies and microfacies of highstand systems tract hst deposits in the zechstein main dolomite ca2 are presented followed by a critical analysis of the existing views on the paleogeography and facies architecture of the wielkopolska platform eastern part of the fore sudetic monocline sw poland the authors discuss and question the existence in zones that have been treated as basinal flat in the analysed area and an extensive platform margin ooidal barrier in general the facies architecture of the study area resembles the block built of the paleozoic basement on this background analytical geochemical results are presented and their source nature characterized in the context of a new revised model of the ca2 basin paleogeography a new facies classification of carbonates which has not been applied for the polish part of the ca2 basin yet was presented the geochemical characteristic of ca2 rocks indicates that good oil prone source rocks are present only locally and are connected with calcisiltites and dolomudstones of facies ii and dolobindstones of facies iv these facies are mainly present in the slope and toe of slope zones the microbial algal facies abundant in the carbonate platform have a weaker residual potential however the thermal maturity stays within the entire range of the oil window the rocks should be re labeled as good source rocks the presence of oil prone kerogen type ii and locally even type i makes the ca2 beds in this part of the wielkopolska platform a very efficient source rock the character of which is confirmed by numerous hydrocarbon accumulations related to the course of tectonic zones and morphology of the basement the proposed characteristic of source rocks in the new paleogeographic facies system enables their better petroleum evaluation and shall enable future prospecting of the perspective zones

spatial distribution dynamics of topsoil moisture in shrub microenvironment after rain events in arid and semi arid areas by means of high resolution maps understanding the dynamic patch mosaic of topsoil moisture on arid hillsides has implications for understanding eco geomorphic processes the present study used high resolution maps to investigate the spatial distribution of moisture in the topsoil on the shrub microenvironment scale and its dynamics during the first days after rain events these maps were acquired by a thermal infrared tir method based on close range tir imaging and on a model in which spatially consecutive tir data are converted into soil moisture values the main results show that in addition to the general diminishing trend of topsoil moisture content and in spite of the specific differences between the two research sites there was in both arid and semi arid zones a general spatio temporal pattern of topsoil moisture in a shrub microenvironment during the first days after rainfall this pattern is manifested in the presence of a changing moist patch under the shrub and diminishing moisture content gradients from the shrub center towards the bare soil that vary over space and time an improved understanding of surface water resources is gained from investigations of the spatio temporal patterns of soil moisture during and following rainfall events

rainfall influence on plot scale runoff and soil loss from repeated burning in a mediterranean shrub ecosystem valencia spain abstract the effect of a repeated burning on soil hydrology and erosive parameters was studied on a mediterranean forest soil rendzic leptosol with the aim of identifying the effects of the fire and climatic parameters related to the post fire runoff and soil loss the study was carried out in an experimental permanent field station la concordia close to valencia spain this field station is located on a calcareous hillside facing sse and is composed of nine erosion plots 20 4 m firstly experimental fires were performed in june 1995 with two fire treatments t1 or high severity fire and t2 or moderate severity fire and a control one unburnt t3 the repeated fire low severity was carried out in july 2003 the studied period was focused from 18 months before the repeated fire july 2003 until 18 months after it rainfall characteristics of each single event were recorded which allowed us to statistically distinguish four time periods according to the rainfall intensity and duration periods i march 2002 to may 2003 and iii december 2003 to early may 2004 with low intensity and long duration rainfalls and periods ii june 2003 to november 2003 and iv late may 2004 to december 2004 with high intensity and short duration rainfalls before the 2003 fire the partial recovery of soil and vegetation from the previous burning in 1995 led to a diminution in the runoff rates 6 5 l m 2 in burned plots and 1 8 l m 2 in unburnt ones six months later period ii runoff increased in one order of magnitude 23 9 l m 2 in burnt plots and 1 1 l m 2 in the unburnt ones due in part to the short time elapsed from fire until high intensity rainfalls these differences in runoff production were maintained during the whole post fire period fire effects were reflected in the erosion rates soil losses prior to the 2003 fire in both fire treatments and in the control one were scant relative to post fire levels however six months after the repeated fire period ii and almost one year later period iv soil losses increased into two orders of magnitude coinciding with the post fire bare soil augment the repeated fire impact and rainfall intensity magnified runoff and soil loss significant linear relationships between rainfall intensity runoff and soil loss were obtained for the burned plots in the burned areas rain intensities increased to 20 mm h 1 augmenting the runoff and soil loss in one and two orders of magnitude respectively

the influence of geomorphological position and vegetation cover on the erosional and hydrological processes on a mediterranean hillslope soil erosion and runoff rates are assumed to be highly dependent on slope position however little knowledge exists about the hydrogeomorphological processes at the pedon scale that support this idea in order to assess the hydrological and erosional behaviour of soils at different slope positions simulated rainfall experiments 55 mm was applied during one hour were carried out on a south facing slope with underlying limestone in south east spain in the mean terms the erosion rates 9 g m2 hr 1 and the runoff coefficients 12 were very low at the scale of measurement 0 25 m2 the slope position does not affect erosion rates when the measurements are carried out under extreme dry conditions during summer the low runoff rates found in summer under thunderstorms of high intensity 5 year return period and the runon into surfaces with higher infiltration rates resulted in no detectable direct surface runoff hortonian at the slope scale this implies that erosion as a consequence of surface overland flow will only take place during events of high magnitude 55 mm hr 1 and low frequency 5 years vegetation is the most important factor determining the soil erosion and runoff rates within the slope 1998 john wiley sons ltd

key factors controlling the post fire hydrological and erosive response at micro plot scale in a recently burned mediterranean forest abstract the impacts of wildfires on the hydrological and erosive response of forest ecosystems have been extensively studied worldwide nevertheless few studies have measured post fire runoff and erosion over large time scales in mediterranean climate type environments and even fewer studies considered the effects of pre fire land management practices on post fire hydrological and erosive processes in a previous study in the colmeal study area vieira et al 2016 revealed that post fire runoff and erosion may not follow the classic window of disturbance model since the peak of post fire response occurred in the second and third years after fire this previous study also showed that pre fire land management can substantially influence the post fire response since annual runoff and erosion were lower in pre fire unplowed than plowed sites in this follow up work a multiple regression model mrm analysis was performed to understand how several key factors influence the hydrological and erosive response of a burned mediterranean forest taking into account the wildfire pre fire land management practices unplowed downslope plowed and contour plowed and soil moisture conditions based on the results of the present study post fire runoff was largely explained by rainfall amounts and soil water repellency swr related variables whereas erosion processes were better explained by rainfall intensity and ground cover variables fewer factors were found to control the hydrological response of plowed sites when compared to the unplowed site aside from rainfall intensity which was the major factor controlling sediment losses bare soil cover also seems to have been important for erosion processes at the unplowed site whereas at the plowed sites stone cover was the second most relevant factor rainfall related variables rainfall and maximum 30 min rainfall intensity were more important for explaining runoff and erosion under dry conditions than under wet conditions the results of the mrm analysis are an important contribution to understand the dynamics of burned forest areas and should be considered when adapting hydrological and erosion models to post fire environments

the role of crust thickness in runoff generation from microbiotic crusts contrary to humid areas where runoff takes place following the saturation of the soil column runoff in arid and semiarid zones takes place when rain intensities exceed the infiltration capability of the upper soil crust whether physical crust or microbiotic crust mc this type of overland flow known as hortonian overland flow hof is not fully understood especially in the case of mc in particular little is known regarding the effect of crust thickness and its fine silt and clay content on runoff generation with some scholars claiming that runoff generation is positively correlated with crust thickness and fine content in an attempt to determine the effect of crust thickness and to assess the role played by the silt and clay on runoff generation a set of field and lab experiments were undertaken on mcs inhabiting sand dunes in the negev desert israel these included sprinkling experiments coupled with measurements of the physical thickness silt and clay and biological chlorophyll protein total carbohydrates properties of 0 5 10 mm thick crusts the data showed that runoff generation took place on surfaces as thin as 0 5 0 7 mm only and was not correlated with the fine silt and clay content the implications for hof and for arid ecosystems are discussed copyright 2014 john wiley sons ltd

differential responses of hillslope and channel elements to rainfall events in a semi arid area the degree of hydrological connectivity of hillslope elements in a semi arid climate was studied at the season and event timescales field data were obtained in rambla honda a medalus project field site situated in se spain on micaschist bedrock and with 300 mm annual rainfall the season timescale was assessed using correlation analysis between soil moisture and topographic indices the event timescale was studied by a quasi continuous monitoring of rainfall soil moisture runoff and piezometric levels results show that widespread transfers of water along the hillslope are unusual because potential conditions for producing overland flow or throughflow are spatially discontinuous and extremely short lived during extreme events runoff coefficients may be locally high ca 40 on slope lengths of 10 m but decrease dramatically at the hillslope scale 10 on slope lengths of 50 m two mechanisms of overland flow generation have been identified infiltration excess and local subsurface saturation from upper layers the former occurs during the initial stages of the event while the latter which is quantitatively more important takes place later and requires a certain time structure of rainfall intensities that allow saturation of the topsoil and the subsequent production of runoff hillslopes and alluvial fans function as runoff sources and sinks respectively permanent aquifers are lacking in rambla honda variable proportions of hillslope areas may contribute to flash floods in the main channel but their contribution to the formation of saturated layers within the sediment fill is very limited

eco geomorphological system response variability to the 2004 06 drought along a climatic gradient of the littoral betic range southern spain abstract one of the main characteristics of the mediterranean climate is the high frequency of droughts which last for a year or more and the appearance of dry spells within the wet season the littoral betic range in the south of the iberian peninsula shows a significant climatic gradient from the straits of gibraltar 1600 mm year 1 to the cabo de gata 150 mm year 1 these differences in climatic conditions result in variations in the elements of the eco geomorphological system at the hillslope scale this study aimed to analyse the immediate consequences of a two year drought period 2004 06 on several elements of the mediterranean eco geomorphological system on three hillslopes under different climatic conditions sub humid dry mediterranean and semi arid the soil water content the pattern of vegetation and some soil properties organic matter content aggregate stability and permeability were analysed before nov 2003 and during nov 2005 the drought period the most important findings were i a reduction in the soil water content which reached values below the wilting point in the wet seasons affecting negatively the water available for vegetation especially in the wettest sites ii a reduction in vegetation cover and the number of plants especially on semi arid field sites iii changes in the organic matter content which aggravate the loss of stability of soil aggregates a process seen more clearly under more arid conditions and iv a reduction of soil permeability in all situations in the climate gradient studied which supposes a priori an increase in erosive processes due to surface runoff these results indicate increased vulnerability of the eco geomorphological system because of the rainfall drought situation

soil erosion and hydrology of the western mediterranean badlands throughout rainfall simulation experiments a review abstract rainfall simulation experiments are widely used in geomorphological research in badland areas this technique contributed significantly to our understanding of badland geomorphology in the mediterranean belt due to the different types of simulated rainfall applied and the variable size of the plots a review of the state of the art is necessary this study confirmed that rainfall simulations are well suited to i analyse runoff infiltration processes and sediment detachment within badlands and ii to establish the factors determining the hydrological and erosion response at interrill scale in badland areas the hydrological response of badlands is characterized by rapid responses low to moderate infiltration rates ranging from close to 0 to 55 mm h 1 and high runoff coefficients i e 60 positive relationships are observed between antecedent soil moisture content and rainfall intensity on the one hand and runoff coefficients on the other sediment concentration and soil detachment rates are among the highest measured on the mediterranean region i e up to 84 8 g l 1 and 4722 4 g m 2 h 1 results show that rainfall intensity runoff coefficient and slope angle have a positive influence on sediment concentration and sediment detachment in the case of rock fragment cover its influence is variable according to the soil cover percentage rainfall simulations increase our understanding of the temporal and spatial variability of the soil erosion processes however rainfall simulation provides mostly qualitative rather than quantitative information because of the small plot size and the simulated rainfall characteristics due to facility for repeating experiments and recording a high quantity of data in short time however this method allows the comparison amongst different environments and soil conditions as the rainfall properties can be reproduced

differences in hillslope runoff and sediment transport rates within two semi arid catchments in southeast spain this paper focuses on hillslope runoff and sediment transport within two catchments in southeast spain five monitoring sites were established on hillslope concavities throughout the two catchments the techniques used were mini crest stage recorders spray painted lines sediment traps and tipping bucket rain gauges established during previous research results show that a storm event in the rambla nogalte on 30 june 2002 of 83 0 mm was responsible for a maximum runoff depth of 12 cm and a maximum hillslope sediment transport of 1886 cm3 m 1 the same storm in the rambla de torrealvilla produced 53 4 mm of rainfall on the 1 july 2002 had a maximum runoff depth of 26 cm and resulted in 2311 cm3 m 1 of sediment transport there is evidence to suggest that measured sediment transport is related to runoff and a qualitative estimate of morphological runoff zones mrz sediment transport and depth of runoff varied dramatically with lithology marl sites produced most runoff and sediment transport followed by the sites of mixed red and blue schist then blue schist these results are important for understanding the behaviour of slopes and show that for short lived storms with high but not rare rainfall intensities and total rainfall amounts runoff can cause significant hillslope sediment transport in semi arid areas

sediment budget of high mountain stream channels in an arid zone high atlas mountains morocco abstract in an arid zone the sediment budget is predominantly dependent on runoff which is controlled mainly by the type of rainfall sediment budget calculation is one of the indirect methods of estimating channel morphodynamics this method is advised here since it is not possible to directly measure this important hydrological indicator of environmental dynamics this is because in small mountain catchments of an arid zone it is impossible to obtain flow rates due to factors such as the amount and size of transported rock debris as well as the episodic and sudden nature of precipitation events the research was conducted in 3 catchments 2 95 km2 7 39 km2 22 73 km2 situated within the boundaries of the basin of the upper dades on the southern slopes of the high atlas in morocco the rivers of these catchments tributaries to a trunk river dades are ephemeral and mostly bedrock depending on lithology of the geology three automatic weather stations were installed there precipitation events 10 mm 51 rains in 3 catchments were used in the analysis simple rainfall typology 3 types was devised for these events during the research period seasonally repeated 6 times measurements of topography were obtained from 21 cross section profiles of streams of different order these measurements formed a basis for calculating both the intensity of flow in ephemeral rivers max 69 6 m s and the sediment budget in 70 of analysed channel cross sections erosion was dominant the average change of the surface area of the cross section profile is 82 the maximum seasonal between measurements enlargement of the surface cross section erosion is as high as 128 the lower catchment which is predominantly composed of conglomerates distinctly shows the slightest changes of the cross section profile surfaces max 24 the average volume of channel material displaced at the measurement point is 1 07 m3 max 9 81 m3 there is evidence that not only high intensity rains but also less intense but longer lasting rains amounting to high precipitation totals type c may result in the highest channel sediment budgets differences between a catchment lithology composed of limestones and marlstones and that composed of conglomerates have only a minor impact on sediment budgets in the first and second order channels whereas in the channels of the third and fourth order this impact is much higher it was found that sediment budgets calculated for individual channels were higher for the catchments composed of limestones and marlstones than for those composed of conglomerates even though the catchments of different lithology may have had the same number of tributaries this suggests that the sediment supply from slopes is comparatively larger in the catchments dominated by limestones and marlstones

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 consist of information on water redistribution within the soil profiles obtained from long duration up to 5 h rainfall simulation experiments with continuous monitoring of soil moisture at different depths runoff and sediment concentration data were obtained i from rainfall simulation experiments with different antecedent soil moisture conditions and ii as natural results from open gerlach plots on runoff and sediment movement over 4 years three conceptual models of water redistribution during the infiltration process could be observed two of them imply nonuniform water redistribution within the soil profile due mainly to macropore flow caused by specific soil surface characteristics at the plot scale runoff generated in bare patches is mainly hortonian in plots with previously wetted soils or soils with high infiltration capacities the generated runoff implies the saturation of the upper soil both types of runoff are discontinuous through time and space the runoff generation mechanisms at the slope scale have been synthesised into two conceptual models a hortonian discontinuous runoff model that takes place in the most degraded slopes or during high intensity rain events and a mixed runoff generation model in less degraded slopes or in previously wet soils where infiltration excess runoff as well as saturation excess runoff can happen on the same slope in both cases slopes behave as a patchwork of runoff and runon areas the size of the runoff or runon patches is dependent on the climatological conditions these control the hydrological disconnection between different parts of the slopes hortonian and saturation runoff can both be generated and infiltrated downslope

linking environmental regimes space and time interpretations of structural and functional connectivity connectivity as a concept has been increasingly part of discussions or explanations in hydrology geomorphology and ecology we address recent critiques of this approach by demonstrating how a refinement which distinguishes structural connectivity from functional connectivity can be used to explain patterns observed in very different environmental systems these systems are found in linkages between surface and subsurface flowpaths and the hyporheos in the river don a temperate river channel in yorkshire uk in surface and subsurface fluxes in agricultural land in the uk and in vegetation and surface conditions in a degrading environment at the sevilleta lter site in the semi arid southwest usa first we demonstrate long term geological and structural controls mediated by in channel processes second human organization of landscape elements is a significant control on runoff and erosion so that similar events can produce very different responses and vice versa third linkages between the removal of grass vegetation and runoff and erosion produce non linear and path dependent feedbacks which control the subsequent degradation of the landscape making the process difficult to reverse as a result of these studies we argue that even in cases where connectivity cannot be directly quantified at least at present this limitation does not prevent the concept from being a useful heuristic device for exploring responses of complex systems furthermore this result implies that an increasing need exists for disciplinary connectivity to investigate such systems

influence of alpine plants growing on steep slopes on sediment trapping and transport by runoff abstract understanding the interactions between soil and the organisms that are conducive to decreasing sediment runoff is a great concern on high elevation ski trails intense rainfalls on steep slopes combined with soil formed on gypsum result in recurrent erosion this study was conducted in the northern french alps to determine the abilities of species 1 to make mounds and 2 to trap sediment and thereby to control erosion at the slope scale we also investigated relevant above ground plant characteristics related to those abilities sediment runoff or deposition was investigated at small and large spatial scales we assessed whether hoof prints in soil reflect sediment runoff at the slope scale by trapping sediment populations of plants growing on two slope angles 25 and 35 and three vegetation cover densities 15 35 60 were surveyed an experiment was also conducted to measure the sediment deposit upslope of target species and over three months during the autumn small mounds were found upslope of the plant and sediment deposit measurements showed that they resulted from a sedimentation process nevertheless the species differed in their capacity to make mounds sesleria caerulea and festuca alpina had the highest amount of sediment deposition over the experimental period among the plant characteristics plant length was positively correlated with mound area while the roundness index of the canopy was negatively correlated with mound height mound formation was also positively related to the number of tillers or shoots sediment accumulation in cow hoof prints was linked to runoff that occurred at the slope scale low deposition in hoof prints means low sediment runoff or a large deposition on mounds due to the increase in vegetation cover all the findings stressed that understanding the processes in action at larger scales requires studying processes at smaller scales

controls of infiltration runoff processes in mediterranean karst rangelands in se spain semiarid karst landscapes represent an important ecosystem surrounding the mediterranean basin for which little is known on runoff generation knowledge of the sources and patterns of variation in infiltration runoff processes and their controls is important for understanding and modelling the hydrological functions of such ecosystems the objectives of this paper are to determine the infiltration rates and their controls in a representative mountain karst area sierra de gador se spain at micro plots and to investigate the integrated response of rainfall on a typical hillslope rainfall simulations in micro plots and natural rainfall runoff monitoring on a hillslope were carried out complementarily we investigated the role of soil surface components vegetation rock outcrop fracture and soil crust topographic position antecedent soil moisture and rainfall characteristics in regulating infiltration runoff processes results of rainfall simulation revealed the importance of vegetation cover and the presence of rock fractures in promoting the infiltration in the limestone karst landscape while bare patches and rock outcrops acted as sources for runoff all plots with 50 vegetation cover had no runoff with up to 55mmh 1 of simulated rain in contrast nearly all bare plots had runoff under the same simulated rain with runoff coefficients ranging from 3 1 to 20 6 on dry soil surface conditions and from 2 0 to 65 4 on wet soil surfaces runoff coefficients amounted to 59 0 79 5 for rock outcrops without cracks but were drastically reduced by the presence of cracks the surfaces with rock fragments resting on the soil generally located in the middle of the slopes prevented more effectively the runoff generation than those surfaces where rock fragments were embedded in the top soil antecedent soil moisture had significant impact on runoff generation with wet soil having doubled runoff coefficient shortened time to runoff and increased runoff rate compared to the same but dry soil linear regressions indicated that the main controls for constant infiltration rate were the cover percentages of vegetation and litter plus rainfall intensity while the major controls for runoff coefficient were the bare soil and vegetation coverage plus rainfall intensity high infiltration rates measured at the micro plots agreed with low intra event runoff coefficients mostly below 1 observed under natural rainfalls at the hillslope runoff depth and coefficient at the hillslope was significantly correlated with rainfall depth maximum hourly rainfall intensity and antecedent precipitation over 20days ap20 during the 1 5 year monitoring period from sep 2003 to mar 2005 the overall infiltration was 41 of the total rainfall amount and the maximum infiltration rate was almost 94 of the largest single rainfall event the results from this study contribute to improved understanding of the magnitude and controls of the surface runoff in semiarid karst mountain areas 2011 elsevier b v