ephemeral gully erosion in southern navarra spain abstract ephemeral gully erosion is a common type of water erosion in the loamy soils formed on the miocene marls of southern navarra a study has been conducted to describe the different types of ephemeral gullies and to determine their origin evolution and importance as sediment sources three main types were identified according to their origin classic ephemeral gullies formed within the same field where runoff starts drainage ephemeral gullies collecting the runoff from another upstream area and discontinuity ephemeral gullies due to some abrupt slope change in the landscape during 2 consecutive years of normal precipitation ephemeral gully erosion has caused significant soil losses locally over 2 66 kg m 2 yr 1 which is above tolerable levels in each year one short and intense rainfall event has been responsible for almost all soil losses from ephemeral gullies the main cause of gully formation is the lack of any proper waterway for conveying water excess conventional tillage practices provoked gully occurrence while the maintenance of stubble or vegetation cover completely prevented their formation although farmers refill gullies every year they reappear at the same position if no preventive measures are taken early winter has been the most critical period for gully formation when the soil is wetter and the surface cover is scarce but a strong summer thunderstorm also caused severe gully erosion in unprotected soils two simple topographic indices based on the area and the slope of the watersheds are useful to describe total soil losses

fluvial system response to tectonically induced base level change during the late quaternary the rio alias southeast spain abstract the rio alias of southeast spain crosses a major tectonically active structure the carboneras fault zone within the central portion of the drainage basin the fault originated in the mid miocene and has c 40 km of strike slip offset the impact of late quaternary movement along the fault zone on the evolution of the rio alias is addressed geomorphological and sedimentological analysis of the landform assemblage preserved suggests the development of highly sinuous meander loops and laterally incising streams during phases of tectonic activity continued tectonic activity led to the abandonment of the meander loops and a wave of incision that propagated c 2 km upstream the propagation of this incision wave was restricted by the development of a nickpoint itself controlled by an anticlinal structure sub parallel to the fault zone syn sedimentary and post depositional faulting is evident within the late quaternary fluvial sediments and suggests dominantly vertical movement along the fault lines with downthrow to the southeast regional climatic patterns of aggradation and incision resulting in a basinwide terrace sequence were complicated i e an additional terrace was created and meander wavelength was changed through the study reach by tectonic activity this study highlights the importance of tectonically modified sequences when interpreting climatically generated sequences of aggradation and incision

factors influencing the presence or absence of tributary junction fans in the iberian range spain this paper analyses the factors which influence the presence or absence of tributary junction fans in the iberian range northern spain two valleys were selected both characterised by wide variations in lithology altitude land use and plant cover two groups of factors were studied those related to the internal characteristics of the drainage basins which particularly control sediment generation and those related to the characteristics of the depositional area which control accommodation space and main river power among the internal factors the development of alluvial fans was related to i the capacity of the basin to yield large volumes of sediment ii the occurrence of intense human pressure until recent times a good indicator of sediment yield and iii the capacity of the basin to quickly increase discharge during rainstorms discharge density and torrentiality it is suggested that the areas that were intensively cultivated in the past and have therefore been affected by intense erosion have played a decisive role on the development of alluvial fans this would imply that many of these alluvial fans have a relatively recent origin perhaps related to the beginning of a widespread deforestation the basins without alluvial fans are characterised by relatively steep hillslope gradients that is slopes that never were subjected to historical cultivation low drainage densities and dense forest and shrub cover mostly coinciding with high altitude basins composed of quartzite and shale bedrocks regarding the external factors the shape size and longitudinal gradient of the main river to which the fans are tributary are the most relevant conditioning factors determining the development of alluvial fans

diagenetic controls on evolution of porosity and permeability in lower tertiary wilcox sandstones from shallow to ultradeep 200 6700 m burial gulf of mexico basin u s a abstract reservoir quality is a critical risk factor in deep to ultradeep reservoirs at depths 4 5 km analysis of paleogene wilcox sandstones on the upper texas gulf coast provides insight into the evolution of reservoir quality during shallow to ultradeep burial diagenesis reduction of porosity and permeability with burial in wilcox sandstones was evaluated using subsurface samples from 200 to 6700 m at temperatures of 25 230 c diagenesis and petrophysical properties were interpreted from petrographic data and core analyses wilcox sandstones are mostly lithic arkoses and feldspathic litharenites having an average composition of q59f22r19 provenance did not change significantly during wilcox deposition in this area nor does average sandstone composition vary among lower middle and upper wilcox sandstones however composition does vary with sequence stratigraphic position lowstand slope fan deposits contain more rock fragments than do deposits from highstand or transgressive systems tracts given observations from this onshore dataset wilcox sandstones deposited in deepwater environments in the gulf of mexico are likely to contain more rock fragments than their linked highstand equivalents pore types in wilcox sandstones change from a mix of primary and secondary pores and micropores at shallower depths to predominantly secondary pores and micropores in deeper sandstones wilcox sandstones show steady porosity reduction from an average of 33 at 38 c to 12 at 132 c with little additional loss at higher temperatures by 132 c most primary pores have been lost by mechanical compaction or occluded by quartz cementation volume of secondary pores remains nearly constant despite dissolution of 3 5 average potassium feldspar during deep burial volume of this late dissolution of potassium feldspar is offset by precipitation of ankerite albite illite and minor quartz in secondary pores the proportion of microporosity which occurs in authigenic clays altered grains and matrix increases in the deepest sandstones change in proportion of pore types and reduction in total porosity with increasing temperature changes porosity permeability transforms because most deep to ultradeep wilcox sandstones are dominated by secondary pores and micropores porosity permeability transforms have lower slopes than those for shallower sandstones

suspended sediment transport in a highly erodible catchment the river isabena southern pyrenees abstract understanding and quantifying sediment load is important in catchments draining highly erodible materials that eventually contribute to siltation of downstream reservoirs within this context the suspended sediment transport and its temporal dynamics have been studied in the river isabena 445 km 2 south central pyrenees ebro basin by means of direct sampling and turbidity recording during a 3 year dry period the average flood suspended sediment concentration was 8 g l 1 with maximum instantaneous values above 350 g l 1 the high scatter between discharge and suspended sediment concentrations up to five orders of magnitude has not permitted the use of rating curve methods to estimate the total load interpolation techniques yielded a mean annual sediment load of 184 253 t y 1 for the study period with a specific yield of 414 t km 2 y 1 this value resembles those reported for small torrents in nearby mountainous environments and is the result of the high connectivity between the badland source areas and stream courses a fact that maximises sediment conveyance through the catchment floods dominated the sediment transport and yield however sediment transport was more constant through time than that observed in mediterranean counterparts this can be attributed to the role of base flows that entrain fine sediment temporarily stored in the channel and force the river to carry high sediment concentrations i e generally in the order of 0 5 g l 1 even under minimum flow conditions

geomorphology and late holocene climatic change in northeastern spain abstract during the late holocene accumulation and downcutting stages affected the slopes and infilled valleys in the semiarid areas in ne spain the presence of archaeological remains charcoal and ashes within slope deposits and valley fills makes it possible to carry out accurate datings in the case of infilled valleys the different accumulations may be diachronous at a regional level these diachronisms among different infilled valleys may be caused by both human activity and complex responses of the system on the slopes one can distinguish between two accumulation periods separated by an incision period the older accumulation stage has a widespread distribution and developed from the bronze age to the iberian roman epoch the following accumulation period was formed in the post medieval period and is spatially more restricted because of the widespread synchronism shown by these accumulations a climatic cause is put forward as the possible triggering factor for the accumulation incision stages in the slopes the datings obtained indicate that the first accumulation corresponds to the iron age cold epoch 900 300 years b c and the second to the little ice age between both accumulation periods a downcutting stage took place approximately from 300 b c to 1450 a d this downcutting interval can be related to the warm stages of the subatlantic period during which there was a relatively lower percentage of vegetation cover finally the last incision period which is still taking place has affected previous accumulations

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 those obtained in non burned terraced catchments of mallorca this factor may be related to changes in soils and the massive incorporation of ash into the suspended sediment flux during the most extreme post fire event 50 mm of rainfall in 15 minutes reaching an erosivity of 2 886 mj mm ha 1 h 1 moreover hysteretic counter clockwise loops were predominant 60 probably related to the increased sensitivity of the landscape after wildfire perturbation though the study period was average in terms of total annual precipitation even higher in intensities minimal runoff 2 and low sediment yield 6 3 t km 2 y 1 illustrated how the intrinsic characteristics of the catchment i e calcareous soils terraces and the application of post fire measures limited the hydrosedimentary response despite the wildfire impact

surface sediment characteristics and present dynamics in alluvial fans of the central spanish pyrenees three alluvial fans in the ribera de biescas upper gallego valley and central spanish pyrenees have been studied in order to explain the most recent changes and to identify the spatial organization of the sediment in the alluvial fans surveyed the proximal area is dominated by debris flows which pass downslope into transitional and fluvial deposits the relative importance of each type of sediment is closely related to the size and gradient of the alluvial fan as well as to the gradient in the final stretch of the stream in general the size of the sediment decreases from the proximal to the distal area while the roundness increases nevertheless there are noticeable irregularities in the trend both in longitudinal and transverse transects due mainly to the sedimentary dynamics of the debris flows as they advance towards the inner part of each alluvial fan during the most intense peak flows a sudden shrinkage of the most active area and incision along the fan channels has been assessed and related to land use changes in the catchments

causes of 20th century channel narrowing in mountain and piedmont rivers of southeastern france extensive channel narrowing in southeastern france provides an illustration of geomorphic response to land use changes the study region comprises a range of environments from large piedmont and intramountain gravel bed rivers to small mountain streams field measurements and analysis of historical data demonstrate two distinct periods of channel change from 1850 to 1950 channel narrowing is interpreted to be the result of a recovery process in response to widespread channel destabilization induced by major floods during the second half of the 19th century at the time the largely deforested basins were highly responsive to flooding whereas the recovery process was accelerated by floodplain and basin scale land use changes afforestation and torrential control works which in turn reduced sediment delivery and enabled vegetation development in channels from 1950 to 1970 channel narrowing accelerated in most of the studied rivers this recent phenomenon is considered as a human induced fluvial adjustment directly related to forest development on river margins and human abandonment of intensive floodplain land uses at the same time long profile degradation occurred as a result of long term bedload supply decrease in small mountain streams channel narrowing is mainly explained by channel incision which seems to progress from upstream where sediment sources are progressively stabilized by afforestation copyright 2002 john wiley sons ltd

the influence of competition between lichen colonization and erosion on the evolution of soil surfaces in the tabernas badlands se spain and its landscape effects article i nfo badlands often contain a mosaic of soil surface types with contrasting hydrological behaviour which drives their short term geomorphic evolution the tabernas badlands in semiarid se spain show a complex mosaic of bare ground biological soil crusts and plant covered patches and high variability of covers and morphologies previous work has identified the surfaces that act as sources of runoff and sediments and those that act as sinks the pathways of runoff between surfaces and the runoff and erosion at catchment scale however surfaces without vascular plants can be quite dynamic with important effects on geomorphic processes this work aims to generate hypotheses about the dynamics of both bare soil 34 of the area and biological soil crusts 33 and to provide a first estimation of the growth rate of terricolous lichens as increase of coverage and their geomorphological implications the dynamics of ten representative soil surfaces were photographically monitored over 13 years recording the cover and pattern of bare soil and of the two main kinds of biological soil crust brown crust and white crust erosion deposition were measured by erosion pins in unbounded plots and the hydrological and erosional behaviour monitored in bounded plots under natural and simulated rainfall biological colonization and crust growth were studied from 2004 within cleared plots in four crust communities microclimate was continuously monitored in each community after 13 years net erosion was recorded only in previously eroded slopes and divides vegetated sites and those covered by biological soil crust remained more or less invariant or recorded sedimentation in all white crust surfaces whole crust cover increased by 3 on average while macrolichen cover increased by nearly 30 within the driest brown crust macrolichen cover increased by 7 while the whole crust decreased by 3 according to previous work lichen cover particularly of white crust is often greater in north to east facing orientations because of the higher slope stability and the longer duration of moisture however the increase of the whole biological soil crust can depend more on species composition and previous cover and less or not at all on the aspect although certain species do grow faster in particular orientations within the plots cleared in 2004 the greatest increase occurred in the pioneering brown crust which reached an average of 26 cover after one year in spite of it receiving the most insolation significant microclimatic differences exist among the communities mainly in radiation soil moisture and thallus surface temperature terricolous lichen crusts primary colonizers of bare sufficiently stable areas can grow quickly and by increasing soil stability and development and modifying surface hydrology they can influence surface dynamics and ultimately landform dynamics crust growth rate probably decreases as its cover increases and it probably also oscillates with microclimatic oscillations however the high potential growth rate recorded allows detection not only of climatic changes but also short term possibly seasonal periods of stability extensive lichen crusts indicate low erosion rates and particular climatic conditions variations of crust cover could indicate climatic or land use variations

short term changes in the magnitude frequency and temporal distribution of floods in the eastern mediterranean region during the last 45 years nahal oren mt carmel israel short term changes in eastern mediterranean precipitation affecting flow regime were documented in nahal oren a 35 km 2 ephemeral stream in mt carmel a 500 m high mountain ridge located at the nw coast of israel the rainy winter of the mediterranean type climate csa in mt carmel is characterized by average annual rainfall of 550 mm at the coastal plain to 750 mm at the highest elevation while the summer is hot and dry stream flow generates after accumulated rainfall of 120 150 mm while large floods defined as flows with peak discharge of n 5m 3 s 1 and or n150 000 m 3 in volume are generated in response to rainfall of over 100 mm hence large floods in nahal oren stream occur not earlier than december precipitation and flow data were divided into two sub periods 1957 1969 and 1991 2003 and compared to each other the results indicate a clear increase in the frequency of large floods their magnitudes and volumes during the second period with no parallel change in the annual precipitation similarly an increase in storm rainfall runoff ratio from b5 to n15 and a decrease in the threshold rainfall for channel flow by 16 25 were documented these short term variations in flooding behavior are explained by the clear decrease in the length of the rainy season and by the resulting significant shortening in the duration of the dry spells the increase in the number of large rainfall events and the large floods in each hydrological year together with the increasing number of years with no floods indicate strengthening of their uncertainty of behavior

low erosion rates measured for steep sparsely vegetated catchments in southeast spain abstract in order to reduce widespread degradation in desertification prone areas there is an urgent need to understand the mechanisms controlling human induced degradation processes in semi arid ecosystems southeast spain is known as one of the most arid regions of europe and its landscape is marked by sparsely vegetated degraded hillsides large areas of dry cultivation have been abandoned since the early part of the twentieth century and irrigated cultivation is now expanding rapidly in this study modern erosion rates for two mountain ranges belonging to the betic cordillera were assessed by direct measurements of the accumulated sediment volumes behind 20 checkdams the volume of sediment deposited behind the checkdams ranges between 4 and 920 m 3 for catchments with a drainage area varying between 1 5 and 317 ha our measurements indicate that mean annual catchment wide erosion rates in these mountain ranges are generally low the observed erosion rates are well below maximum tolerable annual soil loss rates for the mediterranean region as 90 of the catchments have mean annual erosion rates below 2 t ha 1 y 1 our erosion data from 20 small catchments in the betic range are lower than the results of previous erosion studies in southeast spain that were conducted in the neogene intramontane basins this study deals with erosion rates on thin soils developed on metamorphic rocks which are not often the subject of study in the mediterranean region in the ephemeral stream systems in the betic range the spatial pattern of the vegetation cover within the catchment in relation to the concentrated flow lines appears to be crucial our data question the direct association of steep sparsely vegetated hillsides with enhanced soil erosion rates and suggest that the main erosion problems are currently not located in these steep sparsely vegetated environments of the betic mountain ranges

seasonal patterns of suspended sediment transport in an abandoned farmland catchment in the central spanish pyrenees the suspended sediment response of a small catchment subjected to farmland abandonment and subsequent plant recolonization was studied in relation to its hydrological functioning the analysis of data over a seven year period demonstrated that suspended sediment yield was greatly influenced by the occurrence of intense low frequency events greater amounts of suspended sediment were exported during spring when the catchment was hydrologically more active rainfall intensity and baseflow at the start of a flood event had a strong influence on the sediment response suggesting that several hydrological processes were active within the catchment ssc suspended sediment concentration q hysteretic loop analysis at the event scale aided understanding of the sedimentological and hydrological behaviour of the catchment during the study period the ssc q loops showed a high degree of seasonality and two main patterns strongly related to catchment wetness were distinguished when the catchment was dry mainly during summer and the beginning of autumn the predominant process was infiltration excess runoff over sparsely vegetated areas close to the main channel under these conditions floods exhibited a counter clockwise hysteretic loop and were characterized by a small streamflow response short duration and high ssc under wet conditions mainly during winter and spring saturation excess runoff was increasingly dominant over vegetated areas under these conditions floods exhibited a clockwise hysteretic loop and were characterized by a larger streamflow response longer duration and higher suspended sediment yield the lower ssc during the falling stage of the hydrograph is likely to be due to dilution effects related to the contribution of clean water resulting from enlargement of the saturated areas together with an increase in the baseflow discharge copyright 2009 john wiley sons ltd

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 rill network density and badland evolution the factors controlling badland development can be grouped into those related to gross morphology to surface cover and runoff generation and to material properties these factors are effective over varying timescales implying that morphological response times differ among the selected badlands

diagenesis and reservoir quality evolution of palaeocene deep water marine sandstones the shetland faroes basin british continental shelf abstract the palaeocene deep water marine sandstones recovered from six wells in the shetland faroes basin represent lowstand transgressive and highstand systems tract turbiditic sediments mineralogic petrographic and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution the middle upper palaeocene sandstones subarkoses to arkoses from the shetland faroes basin british continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates quartz and clay minerals carbonate cements intergranular and grain replacive calcite siderite ferroan dolomite and ankerite are of eogenetic and mesogenetic origins the eogenetic alterations have been mediated by marine meteoric and mixed marine meteoric porewaters and resulted mainly in the precipitation of calcite 18 o v pdb 10 9 and 3 8 trace amounts of non ferroan dolomite siderite 18 o v pdb 14 4 to 0 6 as well as smectite and kaolinite in the lowstand systems tract lst and highstand systems tract hst turbiditic sandstone below the sequence boundary minor eogenetic siderite has precipitated between expanded and kaolinitized micas primarily biotite the mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite 18 o v pdb 12 9 to 7 8 and fe dolomite ankerite 18 o v pdb 12 1 to 6 3 at temperatures of 50 140 and 60 140 c respectively quartz overgrowths and outgrowth which post and pre date the mesogenetic carbonate cements is more common in the lst and tst of distal turbiditic sandstone discrete quartz cement which is closely associated with illite and chlorite is the final diagenetic phase the clay minerals include intergranular and grain replacive eogenetic kaolinite smectite and mesogenetic illite and chlorite kaolinite has been subjected to mesogenetic replacement by dickite the k feldspar and plagioclase grains have been albitized dissolution of calcite cement and of framework grain feldspar volcanic fragments and mud intraclasts has resulted in a considerable enhancement of reservoir quality

identification of eroded areas using remote sensing in a badlands landscape on marls in the central spanish pyrenees abstract identification of erosion areas on a regional scale can be very useful for environmental planning and can help reduce land degradation and sediment yield to streams and reservoirs remote sensing techniques were used to determine erosion and erosion risk areas in a badlands landscape in the esera river catchment spanish pyrenees the size sparse vegetation cover and high erosion level in the badlands enabled good visual and digital discrimination relative to other land covers and surfaces the maximum likelihood algorithm was used for obtaining a spectral distance map to the bare soil signature characteristic of badlands on marls the roc receiver operating characteristic curve analysis was applied to this map for obtaining an optimum classification of the badlands two alternative classification thresholds were set to determine erosion areas and areas at risk of erosion two classification performance statistics the model s sensitivity and specificity were calculated as a means of expressing the uncertainty omission and commission errors associated to both maps most erosion risk areas coincided with low vegetation cover surrounding the badland areas

lithology controls the regional distribution and morphological diversity of montane mediterranean badlands in the upper llobregat basin eastern pyrenees abstract badlands are pervasive in a wide range of environmental conditions across the mediterranean region including arid semiarid and humid environments on montane cold subhumid and humid mediterranean landscapes harsh thermal conditions on north facing hillslopes favour intense bedrock weathering by freezing and impose serious constraints on plant colonization the above are the customary arguments to explain the high abundance of montane badlands on north exposed shady aspects we studied the distribution and morphological diversity of badlands in the upper llobregat basin catalan pyrenees ne spain using remote sensing information high resolution orthophotos and complementary landsat 8 imagery digital elevation data and regional information on lithology badlands extend over about 200 ha in the upper llobregat basin and occur on two different parent materials swelling smectite rich continental garumnian lutites of late cretaceous age and nonswelling illitic marine eocene marls vegetation assessed by remote sensed vegetation greenness is less developed on north facing badland slopes however badland slope aspect distribution varies considerably with lithology while badlands on eocene marls show preferential distribution on north facing shady slopes badland occurrence on garumnian lutites does not reveal clear slope aspect anisotropy patterns lithology also affects slope gradient with badlands on eocene marls showing rougher topography 30 40 average slope angle than on garumnian lutites 20 30 badland morphological differences induced by lithology are discussed in terms of the greater weathering susceptibility and slope instability of the swelling smectite rich garumnian lutites than of the nonswelling eocene marls elevation which broadly controls annual precipitation and winter air temperature within the region shows no clear influence on badland distribution overall our results reveal lithology as the main factor controlling badland distribution and morphological diversity under the montane mediterranean conditions of the upper llobregat basin

geomorphological and sedimentological analysis of flash flood deposits the case of the 1997 rivillas flood spain on the basis of the description of the 1997 rivillas flood deposits a morphosedimentary feature classification is proposed mapping of the main morphosedimentary deposits in seven reaches along the basin has provided abundant data for each defined typology and for a better adjustment of their stability fields because of their unstable preservation environment immediate post flood field surveys with descriptions of erosive and depositional features were undertaken up to 18 features were classified as either sedimentary or erosive and mapped according to their genetic environments anthropic interference such as land use changes produce modification of sediment supply and in channel and floodplain erosive processes causing flash floods to be more catastrophic erosive features are dominant over sedimentary ones as the sedimentary budget in the river is negative by means of hec ras hydrologic engineering center modelling we were able to obtain mean values of the main variables limiting feature stability velocity depth stream powers and shear stress these provide information regarding maximum stability threshold and peak flood discharge the ephemeral nature of riverine flash flood deposits in this type of setting does not mean that they are not significant and their interpretation after recent floods can significantly improve interpretation of the event dynamics and its flood hydrology and also be useful for flood risk mapping

connectivity assessment in mediterranean vineyards using improved stock unearthing method lidar and soil erosion field surveys the interaction between processes and landforms is accelerated in vineyards due to bare tilled soils that enhance splash runoff and erosion traditionally in order to assess these processes the stock unearthing method sum is considered a useful methodology that uses the graft union of the vine plant as passive bio indicator of the topsoil level changes however sum assumes that the topography between the rows is planar when development of a model of the current micro topography is performed thus we consider that there is a need to develop a new methodology isum improved sum that by adding new measurements in the inter row areas at least 3 allows inclusion of the absent micro topographical information of sum in this way the main aim of this research was to estimate the micro topographical changes and soil transport at three different slope positions upper middle and lower parts in a 25 years old vineyard in eastern spain lidar data were used to compare the connectivity processes at the catchment with the pedon scale we obtained maps that showed topsoil level changes and detected soil depletion and accumulation signals we estimated soil displacement rates of 1 6mghayr 1 depletion 2 8mghayr 1 and 13 3mghayr 1 accumulation at upper middle and lower slope positions respectively the total average soil erosion rates in the inter rows were 5 7mgha 1 yr 1 in the row areas deposition of 10 5mghayr 1 was measured field erosion marks surveyed after each rainfall event gave insights to the connectivity at the inter row and the slope scale it was found that at the row scale there were sinks of sediments underneath the vines and sources in the inter row parts although they are the highest and lowest local topographical terrain respectively this is due to tillage erosion that redistributed the sediments at the slope scale the lower part of the slope collected sediments from the upper slope positions which were transported along the middle part of the slope as the measurement of isum and the field survey after intense rainfall events demonstrated connectivity of the flows along the whole slope were rare twice and along individual slope parts connectivity was found eight times and 19 at the inter row scale after 8years of field observations

a new empirical model for estimating calanchi erosion in sicily italy abstract calanchi plural of calanco are typical badland landforms of the italian landscape they consist of dense networks of v shaped valleys with a sparse or absent vegetation cover which frequently develop on unconsolidated or poorly consolidated clayey deposits in this paper the dimensional analysis and the incomplete self similarity theory were used to deduce a model relating the volume of sediments eroded from the calanchi area to a set of geometric attributes of their tributary areas the morphometric characteristics of 209 calanchi basins were used to calibrate and validate the model the predictive skill of the model was assessed by calculating the mean square error and the nash sutcliffe model efficiency coefficient the model was found to provide a reliable prediction of eroded volume from basins entirely covered by calanchi landforms as well as from basins only partially affected by badland erosion processes furthermore as the residuals between the calculated and the measured volume of the eroded material are normally distributed the deterministic model may be considered complete meaning that no other variables are necessary to explain the studied physical process in other words the model is able to predict erosion volume in calanchi landforms from a deterministic point of view

the sediment budget of a highly dynamic mesoscale catchment the river isabena the paper presents the sediment budget of the isabena basin a highly dynamic 445 km2 catchment located in the central pyrenees that is patched by highly erodible areas i e badlands the budget for the period 2007 2009 is constructed following a methodology that allows the interpolation of intermittent measurements of suspended sediment concentrations and enables a subsequent calculation of sediment loads data allow specification of the contribution of each subbasin to the water and sediment yield in the catchment outlet mean annual sediment load was 235 000 t y 1 specific sediment yield reached 2000 t km 2 y 1 a value that indicates very high sedimentary activity especially in the case of villacarli and lascuarre subcatchments were most badlands are located the specific sediment yield obtained for the entire isabena is 527 t km 2 y 1 a high value for such a mesoscale basin results show that a small part of the area i e 1 controls most of the catchment s gross sediment contribution sediment delivery ratio ratio between sediment input from primary sources and basin export has been estimated at around 90 while in channel storage represents the 5 of the annual load on average the high connectivity between sediment sources i e badlands and transfer paths i e streamcourses exacerbates the influence of the local sediment production on the catchment s sediment yield a quite unusual fact for a basin of this scale

sequence stratigraphic distribution of diagenetic alterations in coal bearing paralic sandstones evidence from the rio bonito formation early permian southern brazil linking siliciclastic diagenesis to sequence stratigraphy allows a better understanding of the parameters controlling the spatial and temporal distribution of diagenetic alterations and hence of reservoir quality a study of the coal bearing alluvial deltaic estuarine and shallow marine sandstones of the rio bonito formation early permian parana basin southern brazil reveals that the distribution of diagenetic alterations and of related reservoir quality evolution can be constrained within a sequence stratigraphic framework calcite dolomite siderite kaolinite and pyrite cementation is consistently linked to sequence and parasequence boundaries transgressive and maximum flooding surfaces and is systematically distributed within lowstand transgressive and highstand systems tracts diagenesis of coal layers at parasequence boundaries has promoted the formation of stratabound calcite detectable in resistivity wire line logs concretionary pyrite and kaolinite and of silicate grain dissolution in sandstones located above and below these boundaries particularly in the transgressive systems tract meteoric water diagenesis caused grain dissolution and the formation of kaolinite in sandstones below sequence boundaries and in lowstand systems tract sandstones carbonate bioclasts and low sedimentation rates in lag deposits at parasequence boundaries transgressive and maximum flooding surfaces favoured the formation of grain rimming siderite the results of this study are relevant to the exploration of coal bed methane and other coal bearing reservoirs where it is crucial to unravel and predict the distribution and quality of reservoirs and compartments

rates and spatial variations of soil erosion in europe a study based on erosion plot data an extensive database of short to medium term erosion rates as measured on erosion plots in europe under natural rainfall was compiled from the literature statistical analysis confirmed the dominant influence of land use and cover on soil erosion rates sheet and rill erosion rates are highest on bare soil vineyards show the second highest soil losses followed by other arable lands spring crops orchards and winter crops a land with a permanent vegetation cover shrubs grassland and forest is characterised by soil losses which are generally more than an order of magnitude lower than those on arable land disturbance of permanent vegetation by fire leads to momentarily higher erosion rates but rates are still lower than those measured on arable land we also noticed important regional differences in erosion rates erosion rates are generally much lower in the mediterranean as compared to other areas in europe this is mainly attributed to the high soil stoniness in the mediterranean measured erosion rates on arable and bare land were related to topography slope steepness and length and soil texture while this was not the case for plots with a permanent land cover we attribute this to a fundamental difference in runoff generation and sediment transfer according to land cover types on the basis of these results we calculated mean sheet and rill erosion rates for the european area covered by the corine database estimated rill and interrill erosion rates are ca 1 2 t ha 1 year for the whole corine area and ca 3 6 t ha 1 year 1 for arable land these estimates are much lower than some earlier estimates which were based on the erroneous extrapolation of small datasets high erosion rates occur in areas dominated by vineyards the hilly loess areas in west and central europe and the agricultural areas located in the piedmont areas of the major european mountain ranges c 2010 elsevier b v all rights reserved

petrography and reservoir physics ii relating thin section porosity to capillary pressure the association between pore types and throat size porosity in reservoir rocks is configured into a few types of pores whose size and shape are controlled by depositional fabric and postdepositional processes the size shape and abundance of each pore type can be objectively determined from thin section using image analysis and pattern recognition procedures each pore type tends to be associated with a limited range of throat sizes the association between pore type and throat size can be determined using regression procedures linking pore type data obtained from thin section with capillary pressure data to do so a set of samples is required wherein the association between pore type and throat size is fixed but where pore type proportions vary between samples this condition is met by a sample suite representing res rvoir facies from a single core or in many cases from a single field the relationship between pore type and throat size is an effective means to relate reservoirs in terms of the efficiency of the porous microstructure to multiphase flow parameters derived from the relationship can be used to construct accurate physical models that subdivide physical response in terms of the contributions of each pore type

the causes of piping in a set of abandoned agricultural terraces in southeast spain this study aims to identify some of the factors contributing to the piping process in abandoned terraces in seven sites located in the murcia region southeast spain the local landscape has the appearance of badland geomorphology possessing deep valleys which until the 1970s were terraced and cultivated the terraces have now been abandoned to the piping process the research focuses on the relationship between the size and position of pipes and the physical and geochemistry properties of the local highly dispersive marl lithology and the extent to which the reworking of the materials for terrace cultivation has exacerbated piping erosion morphologically the terracing in the stream beds has resulted in a series of gentle benches separated by steeper risers with variable drop riser height a series of flat infiltration surfaces result and because the resculpting produces a reduced bulk density infill with enhanced throughflow infiltrating water is forced along steep hydraulic gradients to a low outfall at the base of the riser paralleling studies of land levelling and terrace abandonment in similar materials elsewhere piping in the study area is shown to be closely related to the physical and chemical characteristics of the materials its sodicity and dispersive character considerable differences in structure texture mineralogical composition and material s surface crust and subsoil geochemical properties emerged from site signature plots and these results suggest that agricultural processes affect the dispersive character of the crust materials presumably because agricultural activity increases the buffering effect of organic acids on the dispersed clay this is supported by the observation that on the one site that was levelled but not used for agriculture a stable organically distinct crust like the abandoned agricultural sites has not formed the changes to the material s aggregate stability and bulk density properties when terracing occurs is examined but insufficient evidence is available from the data collected to unpick the causes of aggregate stability changes in the study plots the way in which differences between crust and subsoil enhance infiltration is discussed and the role of the terrace drop in influencing hydraulic gradients and pipe development is illustrated a possible index to describe the relationship between evacuated material volumes and the controlling parameters discussed above is tested it is concluded that terracing which is intended as a conservation practice has in dispersive materials actually enhanced piping leading to the abandonment of farming

runoff and sediment yield from topsoils with different porosity as affected by rock fragment cover and position abstract interrill runoff and sediment yield from a topsoil having essentially textural pores and from another with structural pores were measured in the laboratory under simulated rain to investigate the effects of cover and positions of rock fragments the results reveal that the relation between the cover of rock fragments and interrill runoff or sediment yield can be negative as well as positive porosity in the soil near rock fragments determines both the type of relation and the degree to which the positions of rock fragments affect this relation rock fragments increase runoff and sediment yield when well embedded in a surface seal i e a top layer with essentially textural pore spaces a negative relation occurs either where rock fragments are partly embedded in a top layer with structural porosity or where the rock fragments rest on the surface of a soil having either textural or structural pore spaces the time at which macropores at the soil surface close is crucial for then the effect of the cover of rock fragments on the generation of runoff switches from reduction to an increase since cover can have an ambivalent effect on the hydrological and erosion response descriptions of topsoils containing rock fragments should include the type of soil porosity as well as the positions of rock fragments

geomorphological evolution of abandoned fields a case study in the central pyrenees abstract by means of geomorphological transects the evolution undergone by cultivated land after abandonment has been studied during the first years diffuse overland flow processes predominate while older fields seem more highly deteriorated incisions stone flows stone pavement the results confirm the important protection role of vegetable covering particularly scrub and the negative influence of soil uses grazing leads to periodic scrub burnings increasing surface stoniness and concentrated overland flow

thirty years of studies on badlands from physical to vegetational approaches a succinct review the scientific subjects addressed in the research into badlands since the publication of bryan and yair s book bryan r b and yair a editors 1982 badland geomorphology and piping geo books norwich 408 pp are briefly analysed with a steadily increasing number of papers per year attention to some aspects such as runoff generation piping and the role of lithology and soils varied whereas the percentage of studies on erosion rates increased steadily over time vegetation was not a subject of research in early papers as most of the papers dealing with vegetation were rather descriptive and published in local or limited diffusion media which contrasts with the present situation when about 40 of papers published in international journals about badlands address some aspect of vegetation however the growth in the attention paid to vegetation and erosion rates was not linked to any increase in papers dealing with badland reclamation badlands are now seen as a group of systems with some common features but diverse dynamics depending mainly on climatic and lithological drivers more attention should be paid in the future to investigating the evolution of these landforms over time mostly through modelling studies whereas emerging technologies foster detailed analyses that were not possible formerly although some badland areas determine on and off site environmental issues others are spots of landscape diversity that merit protection rather than reclamation

climatological features of cutoff low systems in the northern hemisphere this study presents the first multidecadal climatology of cutoff low systems in the northern hemisphere the climatology was constructed by using 41 yr 1958 98 of ncep ncar reanalysis data and identifying cutoff lows by means of an objective method based on imposing the three main physical characteristics of the conceptual model of cutoff low the 200 hpa geopotential minimum cutoff circulation and the specific structure of both equivalent thickness and thermal front parameter fields several results were confirmed and climatologically validated 1 the existence of three preferred areas of cutoff low occurrence the first one extends through southern europe and the eastern atlantic coast the second one is the eastern north pacific and the third one is the northern china siberian region extending to the northwestern pacific coast the european area is the most favored region 2 the known seasonal cycle with cutoff lows forming much more frequently in summer than in winter 3 the short lifetime of cutoff lows most cutoff lows lasted 2 3 days and very few lasted more than 5 days and 4 the mobility of the system with few cutoff lows being stationary furthermore the long study period has made it possible i to find a bimodal distribution in the geographical density of cutoff lows for the european sector in all the seasons with the exception of winter a summer displacement to the ocean in the american region and a summer extension to the continent in the asian region and ii to detect northward and westward motion especially in the transitions from the second to third day of occurrence and from the third to fourth day of occurrence the long term cutoff low database built in this study is appropriate to study the interannual variability of cutoff low occurrence and the links between cutoff lows and jet stream systems blocking or major modes of climate variability as well as the global importance of cutoff low in the stratosphere troposphere exchange mechanism which will be the focus of a subsequent paper

erosion in mediterranean mountain landscapes during the last millennium a quantitative approach based on lake sediment sequences iberian range spain abstract land degradation and soil erosion are key environmental problems in mediterranean mountains characterized by both a long history of human occupation and strong seasonality of hydrological regimes experimental monitored catchments have identified main controlling factors on erosion dynamics but because of the short time span of the instrumental measurements they do not integrate the complete temporal and spatial variability of these environments to obtain some long term series of mediterranean landscape evolution we propose a novel strategy based on multi proxy analyses of lake sediments aimed to quantify sediment delivery and erosion dynamics karstic lakes in the iberian range central spain provide an opportunity to reconstruct the depositional evolution of the watersheds and to evaluate the response to both the variable anthropogenic impacts and climate forcings during the last 1000 years the most significant periods of increased sediment delivery 26 483 t km yr 1 in the iberian range sites took place during the 15th 16th and 18th 19th centuries as a result of large land use changes and land clearing positive synergies between increasing human population and more humid periods led to peaks in sediment deliver during some phases of the little ice age recent changes associated with the rural exodus and land abandonment during mid 20th century are more clearly shown in larger watersheds by decreased sediment delivery to the lakes due to the re vegetation of the landscape 6 200 t km yr 1 this new integrated approach based on long term lake sequences provides a longer perspective of erosion processes in mediterranean watersheds and validates the main factors identified in monitoring surveys land cover and surface formations erodibility in both settings lakes and experimental catchments most sediment delivery occurs during flooding events measured and reconstructed values show comparable large ranges underlying the punctuated nature of sediment dynamics in mediterranean landscapes at decadal and centennial scales

erosion in mediterranean landscapes changes and future challenges abstract intense erosion processes are widespread in the mediterranean region and include sheet wash erosion rilling gullying shallow landsliding and the development of large and active badlands in both subhumid and semi arid areas this review analyses the main environmental and human features related to soil erosion processes and the main factors that explain the extreme variability of factors influencing soil erosion particularly recent land use changes the importance of erosion in the mediterranean is related to the long history of human activity in a region characterized by low levels of annual precipitation the occurrence of intense rainstorms and long lasting droughts high evapotranspiration the presence of steep slopes and the occurrence of recent tectonic activity together with the recurrent use of fire overgrazing and farming these factors have resulted in a complex landscape in which intensification and abandonment wealth and poverty can co exist the changing conditions of national and international markets and the evolution of population pressure are now the main drivers explaining land use changes including farmland abandonment in mountain areas the expansion of some subsidized crops to marginal lands and the development of new terraces affected by landslides and intense soil erosion during extreme rainstorm events the occurrence of human related forest fires affecting thousands of hectares each year is a significant problem in both the northern and southern areas of the mediterranean basin here we highlight the rise of new scientific challenges in controlling the negative consequences of soil erosion in the mediterranean region 1 to reduce the effects and extent of forest fires and restructure the spatial organization of abandoned landscapes 2 to provide guidance for making the eu agricultural policy more adapted to the complexity and fragility of mediterranean environments 3 to develop field methods and models to improve the identification of runoff and sediment contributing areas 4 to contribute to the conservation of landscapes i e bench terraced fields having high cultural and productivity values 5 to improve knowledge of the hydrological and geomorphological functioning of badlands with the aim of reducing sediment yield and accessibility 6 to better understand the effect of climate change on soil erosion in the mediterranean region and 7 to improve quantitative information on long term soil erosion

heavy metal fractionation in sediments from the jarama river central spain concentrations of certain heavy metals are analyzed in sediments from the jarama river in the autonomous region of madrid spain as well as their variation along the river course in addition the distribution of heavy metals among the solid phases present in the samples is studied in accordance with the sequential extraction procedure of the european union described in the standard material and testing smt the second in the middle course of the river and the third group containing the most contaminated sediments were samples from the lower course of the river

overland flow generation mechanisms affected by topsoil treatment application to soil conservation abstract hortonian overland flow is responsible for significant amounts of soil loss in mediterranean geomorphological systems restoring the native vegetation is the most effective way to control runoff and sediment yield during the seeding and plant establishment vegetation cover may be better sustained if soil is amended with an external source four amendments were applied in an experimental set of plots straw mulching sm mulch with chipped branches of aleppo pine pinus halepensis l pm terracottem hydroabsorbent polymer hp and sewage sludge ru plots were afforested following the same spatial pattern and amendments were mixed with the soil at the rate 10 mg ha 1 this research demonstrates the role played by the treatments in overland flow generation mechanism on one hand the high macroporosity of sm and pm together with the fact that soil moisture increased with depth explains weak overland flow and thus low sediment yield due to saturation conditions therefore regarding overland flow and sediment yield ru behaves similarly to sm and pm on the other hand when hp was applied overland flow developed quickly with relatively high amounts this together with the decrease downward in soil moisture along the soil profile proved that mechanisms of overland flow are of the hortonian type

human topographic signatures and derived geomorphic processes across landscapes abstract the earth s surface morphology in an abiotic context is a consequence of major forcings such as tectonic uplift erosion sediment transport and climate recently however it has become essential for the geomorphological community to also take into account biota as a geomorphological agent that has a role in shaping the landscape even if at a different scale and magnitude from that of geology although the modern literature is flourishing on the impacts of vegetation on geomorphic processes the study of anthropogenic pressures on geomorphology is still in its early stages topography emerges as a result of natural driving forces but some human activities such as mining agricultural practices and the construction of road networks directly or indirectly move large quantities of soil which leave clear topographic signatures embedded on the earth s morphology these signatures can cause drastic changes to the geomorphological organization of the landscape with direct consequences on earth surface processes this review provides an overview of the recent literature on the role of humans as a geological agent in shaping the morphology of the landscape we explore different contexts that are significantly characterized by anthropogenic topographic signatures landscapes affected by mining activities road networks and agricultural practices we underline the main characteristics of those landscapes and the implications of human impacts on earth surface processes the final section considers future challenges wherein we explore recent novelties and trials in the concept of anthropogenic geomorphology herein we focus on the role of high resolution topographic and remote sensing technologies the reconstruction or identification of artificial or anthropogenic topographies provides a mechanism for quantifying anthropogenic changes to landscape systems this study may allow an improved understanding and targeted mitigation of the processes driving geomorphic changes during anthropogenic development and help guide future research directions for development based watershed studies human society is deeply affecting the environment with consequences on the landscape therefore establishing improved management measures that consider the earth s rapidly changing systems is fundamental

impact of lithology and soil properties on abandoned dryland terraces during the early stages of soil erosion by water in south east spain soil erosion by water in abandoned dry terraces is one of the most important environmental problems in semiarid areas enhancing biological degradation and reducing possible resources that can be obtained however little is known about the effects of the types of lithology and soil properties on the early stages of soil erosion therefore the main aim of this research was to assess the effect of different lithologies marls limestones and metamorphic phyllites schists and greywackes materials and soil properties on the early stages of soil erosion by water in abandoned dry terraces compared with similar terraces still in agricultural use soil analyses texture aggregate stability and bulk density and 22 rainfall simulations were carried out under dry conditions during the experiments local inclination vegetation and stone cover total organic matter and antecedent soil moisture were also quantified the results showed that the highest soil loss 41 41 g m2 in cultivated plots and 17 05 g m2 in the abandoned plots and runoff 3 79 l m2 in the abandoned plot occurred on marl substrata marls also showed the shallowest infiltration front 9 cm and lowest infiltration rate 4 3 cm min limestones and especially metamorphic areas showed a lower degree of soil erosion higher infiltration rates and deeper infiltration fronts

channel adjustments and vegetation cover dynamics in a large gravel bed river over the last 200 years article i nfo the timing and extent of the morphological changes that occurred in the last 200 years in a large gravel bed river the piave river eastern italian alps that was heavily impacted by human activities training structures hydropower schemes and gravel mining have been analyzed by historical maps aerial photos repeated topographic measurements and geomorphological surveys results show that the channel underwent a strong narrowing during the twentieth century but with a faster pace during the 1970s 1990s and with an associated shift from a dominant braided pattern to a wandering morphology bed incision up to 2 m mostly from gravel mining has been documented for this period large areas of the former active channel were colonized by riparian forests both as islands and as marginal woodlands the ceasing of gravel extraction in the late 1990s seems to have determined a reversal in the evolutionary trend with evidence of vegetation erosion channel widening even though a significant aggradation phase is not present we conclude that alteration of sediment regime has played a major role on the long term channel evolution however only relevant flood events rin10 15 years appear to determine substantial island erosion and therefore the proportion of island vs channel area fluctuates depending on flood history

evolution of the morphology of the river dragonja sw slovenia due to land use changes the effects of increasing agricultural land use on fluvial morphology have received much attention in fluvial research however in several regions in europe a reversing trend of decreasing agricultural activity and land abandonment followed by reforestation is observed the response of fluvial morphology deserves attention because of its large impacts on landscape and riverine habitats with the help of geomorphological mapping multi date aerial photography and a range of dating techniques we reconstructed the evolution of the morphology of the riverbed and the floodplain of the dragonja river in southwestern slovenia the results of this study show that the fluvial morphology in this mediterranean catchment has changed considerably as a result of shifts in agricultural land use in particular large scale land abandonment in the second half of the 20th century until the first half of the 19th century floodplain aggradation prevailed probably around 1870 a large erosion event occurred from which the floodplain did not fully recover a terrace standing 2 5 m above the present floodplain was formed natural reforestation due to depopulation since world war ii caused a reduction in discharge and sediment supply to the river the decreased intensity and frequency of floods allowed invasion of the riverbed by vegetation causing narrowing and incision of the riverbed this resulted in the formation of a terrace which now stands 1 5 m above the present day river this terrace is about 60 years old however the largest increase in forest area occurred since 1975 which intensified this process of riverbed narrowing and incision creating a local terrace at 0 5 m at 0 5 m above the presently meandering river

diagenetic history of eocene wilcox sandstones south central texas abstract sandstones and shales of the lower eocene wilcox group extend from outcrop to depths greater than 5 km where temperatures exceed 200 c eight authigenic minerals have been identified quartz kaolinite calcite ankerite and albitized plagioclase are volumetrically significant whereas chlorite illite albite overgrowths and dolomite are present only in trace amounts quartz kaolinite and ankerite cements are present over the entire depth range sampled 1528 to 4446 m calcite cement occurs only in sandstones shallower than 3300 m albitized plagioclase is the predominant feldspar in samples deeper than 2600 m whereas detrital potassium feldspar has been completely dissolved out of sandstones deeper than about 3200 m no systematic variations in the chemical composition of calcite with depth no zoning within calcite or ankerite and no compositional differences between pore filling and grain replacing calcite or ankerite were found calcite cements have 87 sr 86 sr ratios generally less than 0 708 whereas ankerite cements are significantly enriched in 87sr the oxygen isotopic composition of carbonate cement ranges between 9 and 14 pdb for calcite and between 8 and 12 for ankerite with no systematic variation with depth calculated 18o values for authigenic quartz and kaolinite range from 22 to 31 smow and from 14 to 17 respectively volumetrically important amounts of authigenic quartz and kaolinite precipitated during early burial before calcite cementation secondary porosity generation or smectite to illite transformation in encasing shales the isotopic composition of strontium in calcite cement shows most of it to be of eocene or older marine carbonate origin ankerite cementation followed the generation of secondary porosity and occurred after the products of organic maturation and shale diagenesis plagioclase albitization or potassium feldspar dissolution significantly affected the sandstone pore water system

erosion and sediment transport in the ganges river basin india abstract based on sampling of the entire region of the ganges basin chemical and sediment load supplied at various parts of the basin have been computed annual flux of materials from sub basin into the main basin and input to the hoogly estuary have been calculated and compared to major river systems of the world the total annual load at calcutta mouth of the river was calculated as 411 10 6 t 328 10 6 t sediment load 83 10 6 t chemical load erosion rate 549 t km 2 yr 1 is among the highest in this river system and controlling factors on a global scale such as basin area are discussed in detail annual decrease in basin elevation indicates a rapid process of denudation and such rates have a bearing on rates of shelf sediment accumulation

influence of climate change and human activities on the organic and inorganic composition of peat during the little ice age el payo mire w spain the study of environmental change during the little ice age lia offers a great potential to improve our current understanding of the climate system and human environment interactions here a

assessing space time variations of denudation processes and related soil loss from 1955 to 2016 in southern italy calabria region studies on denudation processes and soil loss rates can provide insight into the landscape evolution climate change and human activities as well as on land degradation risk the aims of this study were to analyze the space time distribution of denudation processes and evaluate the soil loss changes occurred during the period 1955 2016 by using an approach integrating geomorphological geospatial and modeling analysis the study area is a representative stream catchment of the crati valley calabria southern italy which is affected by severe erosion processes the combined use of aerial photographs interpretation field survey geostatistics and gis processing has allowed to characterize the types of denudation processes and land use change in space and time revised universal soil loss equation implemented in gis environment was used to estimate the space time pattern of soil loss and the soil erosion rates for each investigated year the results showed that from 1955 to 2016 the study area was highly affected by denudation processes mainly related to landslides and water erosion slope wash erosion and gully erosion comparison of denudation processes maps showed that the total area affected by erosion processes has increased by about 31 and the distribution of geomorphic processes and their space time evolution resulted from the complex interrelation between geoenvironmental features and human activities the main land use changes concerned a decrease in areas covered by woodland scrubland and pasture and an increase in croplands and barren lands that favored erosion processes the most susceptible areas to soil loss in both years were mapped and the mean soil loss rates for the study area were 6 33 mg ha 1 y 1 in 1955 and 10 38 mg ha 1 y 1 in 2016 furthermore the soil loss in 2016 has increased by about 64 compared to 1955 finally the results showed that integrating multi temporal analysis of denudation processes land use changes and soil loss rates might provide significant information on landscape evolution which supports decision makers in defining soil management and conservation practices

holocene history of fire vegetation and land use from the central pyrenees france located on a mountain pass in the west central pyrenees the col d ech peat bog provides a holocene fire and vegetation record based upon nine 14c ams dates we aim to compare climate driven versus human driven fire regimes in terms of frequency fire episodes distribution and impact on vegetation our results show the mid holocene 8500 5500 cal yr bp to be characterized by high fire frequency linked with drier and warmer conditions however fire occurrences appear to have been rather stochastic as underlined by a scattered chronological distribution wetter and colder conditions at the mid to late holocene transition 4000 3000 cal yr bp led to a decrease in fire frequency probably driven by both climate and a subsequent reduction in human land use on the contrary from 3000 cal yr bp fire frequency seems to be driven by agro pastoral activities with a very regular distribution of events during this period fire was used as a prominent agent of landscape management

studying solute and particulate sediment transfer in a small mediterranean mountainous catchment subject to land abandonment the sediment budget of the small research catchment of cal parisa vallcebre eastern pyrenees was studied by hydrological monitoring and assessment of the erosion rates in the major sediment sources this area is characterized by clayey mudrock prone to landsliding and badland erosion but the catchment was selected in an area free of major badland features as a representative of middle mountain regions where a system of terraces and drainage ditches had been built for agricultural use but is now abandoned streamwater chemistry is dominated by ca 2 and hco 3 at concentrations close to calcite saturation total dissolved solids show dilution during runoff peaks and positive hysteresis loops that support a slow contribution of subsurface water relative dissolved ion concentrations are different for each event analysed particulate sediment yield is very low and represents only about 1 per cent of gross erosion in the catchment mineralogical analysis of suspended sediments shows an enrichment in calcite because of precipitation chemical analysis of suspended sediments using common one litre water samples shows higher contents of ca p and mn in transported sediment than in sediment source areas attributed to the precipitation of calcite and enrichment in organic particulate matter during events respectively for the two first elements whereas enrichment in mn remains uncertain solid matter yield is therefore clearly dominated by dissolved transport as a result of both high calcium bicarbonate concentrations in runoff waters and strong suspended sediment conveyance discontinuities land conservation structures are very effective because they are in good condition whereas the soil is covered by dense permanent vegetation nevertheless this state is unstable because the network of drainage ditches needs maintenance its spontaneous breakdown after abandonment may result in the rearrangement of the elementary stream network and gullying of old fields in hollows 1997 john wiley sons ltd

the fluvial sediment budget of a dammed river upper muga southern pyrenees abstract many rivers in the mediterranean region are regulated for urban and agricultural purposes reservoir presence and operation results in flow alteration and sediment discontinuity altering the longitudinal structure of the fluvial system this study presents a 3 year sediment budget of a highly dammed mediterranean river the muga southern pyrenees which has experienced flow regulation since the 1969 owing to a 61 hm 3 reservoir flow discharge and suspended sediment concentration were monitored immediately upstream and downstream from the reservoir whereas bedload transport was estimated by means of bedload formulae and estimated from regional data results show how the dam modifies river flow reducing the magnitude of floods and shortening its duration at the same time duration of low flows increases the downstream flow regime follows reservoir releases that are mostly driven by the irrigation needs in the lowlands likewise suspended sediment and bedload transport are shown to be notably affected by the dam sediment transport upstream was mainly associated with floods and was therefore concentrated in short periods of time i e 90 of the sediment load occurred in

palaeoflood and floodplain records from spain evidence for long term climate variability and environmental changes abstract palaeoflood chronologies from seven spanish river basins and floodplain aggradation chronologies from thirteen rivers are analysed these fluvial records were divided in to two sub sets namely atlantic 10 ka record and mediterranean 3 ka record river basins which represent distinct modern hydroclimatic conditions in atlantic basins floods result from intense widespread rainfalls associated with atlantic frontal systems transported by westerly airflow mediterranean river flooding is related to heavy rainfall induced by mesoscale convective systems mcss during autumn months evidence from radiocarbon dates in slackwater flood deposits shows six periods of flood clusters at 10 750 10 240 9550 9130 4820 4440 2865 2350 960 790 and 520 290 cal bp despite the different flood producing weather conditions in atlantic and mediterranean rivers the radiocarbon sample clusters overlap and indicate changes in large scale atmospheric circulation and climatic conditions in the iberian peninsula comparison with proxy records of mean temperature for the northern hemisphere demonstrates a relationship between the period of slackwater flood deposition and cold climatic phases e g the 2650 yr bp climatic event or ad 1590 1650 period of the little ice age radiocarbon dates from aggraded floodplain sediments were clustered at 2710 2320 2000 1830 and 910 500 cal bp the first cluster period is in phase with the timing of slackwater deposition whereas the third 910 500 cal bp occurs in between two periods of increased flood frequency as indicated by the palaeoflood and documentary flood records it is argued that the 910 500 cal bp floodplain aggradation period reflects the first post roman evidence of environmental change related to generalised land use changes at the catchment scale which produced high sediment load transported to overbank areas during high flows

historical evolution of slope instability in the calore river basin southern italy abstract there is interest in knowing historical spatio temporal patterns of landslide activity however this is challenging to reconstruct because it is difficult to obtain detailed records for past landslide activity here we deal with hydro geomorphological signatures such as storms downpours floods snowmelt and mass movement to detect annual slope instability events asies over historical times in order to obtain asies for each year a monthly instability density index idi was used and then monthly values were summed up to obtain a yearly value classes of monthly idi varying between 0 no instability and 4 highest instability were determined from historical documents we present an application for the calore river basin southern italy using data from a 313 year long series 1701 2013 ce after 1880 ce the information becomes more valuable with directly observed landslide frequency by this cataloguing 129 asies were obtained their evolution shows slight instability during the 18th century uneven and greater slope instability occurred instead across the 19th century when an important phase of deforestation coincided with intensification of agricultural activities slope instability events continued during the 20th century but their causes are mainly related to anthropisation and the effects of recent climate change it was determined that stormy autumns until the 19th century and successive winter times with enhanced snowmelt may have driven the reactivation of widespread instability events we also found that mountainous and hilly terrains have an acute sensitivity to climate change

hydro geomorphological consequences of the abandonment of agricultural terraces in the mediterranean region key controlling factors and landscape stability patterns abstract traditional cultivation terraces are one of the most ancient and conspicuous agricultural landscapes in mountain and hilly regions of the mediterranean basin spreading out from asia the first terraces in the mediterranean region date from the bronze age and the classical hellenic and roman periods reaching their greatest spatial extent during the eighteenth and nineteenth centuries under optimum management these systems contribute to the conservation of soil and water resources by increasing infiltration and decreasing sediment yield however traditional management and cultivation ceased on many terraced landscapes of the northern shore mediterranean countries during the twentieth century with variable results an extensive bibliographic review and meta analysis was carried out to explore the main effects of land abandonment of mediterranean agricultural terraces on local hydrological and geomorphological processes our results point to the development of vegetation cover and degradation of terraced structures e g walls terrace risers channels as the main critical factors controlling the hydrological behaviour i e runoff production and hydrological connectivity of abandoned terrace systems severe geomorphological problems in the form of intense surface erosion aggressive piping and gullying occurred under special climatic semi arid climate lithologic dispersive marls and structural high vertical hydraulic gradient conditions dense colonization by vegetation proved to be of major importance for controlling surface erosion vegetation however showed a limited capacity to control the activity of mass movements in most cases mass movements in the form of small soil slips primarily affected long abandoned terraces in hillslope concavities and valley bottom positions that concentrate surface and subsurface water fluxes and show recurrent soil saturation in humid terraced landscapes characterized by high hillslope gradients and terrace risers the most devastating effects of mass movements took place in the form of debris slips and terrace cascading landslides triggered by extreme rainfall a variety of management options non intervention stewardship of natural rewilding processes and active rehabilitation can be applied depending on vegetation development potential site hydro geomorphic vulnerability and local socio economic interests effective conservation approaches will be required to preserve the environmental socio cultural and historical values of these ancient anthropogenic landscapes

sediment yield in europe spatial patterns and scale dependency abstract our understanding about the regional variation of sediment yield sy in europe and its scale dependency currently relies on a limited number of data for mainly larger river systems sy is the integrated result of all erosion and sediment transporting processes operating in a catchment and is therefore of high value for environmental studies and monitoring purposes most global assessments of sy consider catchment area a climate and topography as the main explanatory variables however it is still unclear if these factors also control regional variations of sy within europe this paper aims at bridging this gap therefore we i present a large database of sy values which was constructed through an extensive literature review ii describe the spatial patterns of sy across europe and iii explore its relation with a climate and topography in total sediment yield data from 1794 different locations throughout europe were collected 507 reservoirs and 1287 gauging stations representing a minimum of 29 203 catchment year data only sy data measured at gauging stations or derived from reservoir siltation rates over a period of a minimum of one year were included in the database this database comprises a large range of catchment areas a i e from small upland catchments 0 01 km to major european river basins 1 360 000 km an overview of the collected sy data is provided and sources of uncertainty on the available data are discussed despite potentially large uncertainties on several of the individual sy values analysis of this database indicates clear spatial patterns of sy in europe the temperate and relatively flat regions of western northern and central europe generally have relatively low sy values with ca 50 of the sy 40 t km 2 yr 1 and ca 80 of the data 2 yr 1 while mediterranean and mountainous regions generally have higher sy values with around 85 of the sy data 40 t km 2 yr 1 and more than 50 of the data 200 t km 2 yr 1 these differences are attributed to a combination of factors such as differences in climate topography lithology and land use although larger differences in sy were found between the climatic regions than between topographic zones it is currently difficult to identify the individual importance of the various controlling factors of sy sy a relationships were calculated for the entire dataset and for subgroups stratified according to the measurement method gauging stations or reservoir surveys range of the catchment area climatic region topographic zone of the river outlet and major european river system although typically a negative relationship between sy and a is expected due to a decrease in topsoil erosion rates on more gentle slopes and an increase in sediment deposition with an increase in catchment size this relationship was found to be generally very weak and subject to a lot of scatter furthermore results illustrate important differences in scale dependency whereas a weak but significant negative trend is generally observed for the temperate and relatively flat regions no significant or even positive trends were observed in mountain regions and mediterranean europe when only larger river catchments i e 100 km and especially 10 000 km are considered catchment area exerted a larger control on sy these findings confirm previous studies and indicate that the relationship between sy spatial scale and other controlling factors is often complex and non linear

badland dynamics in the central pyrenees temporal and spatial patterns of weathering processes the genesis and development of badlands is controlled by bedrock lithology topography and climate the development of badlands in the central spanish pyrenees is favoured by the presence of marls and a climate with a marked seasonality the combination of these factors results in active hydrosedimentological processes the aim of the present work was to study the dynamics of badlands in the central pyrenees with a focus on the temporal and spatial patterns of the dominant weathering processes the study area was a small mountain catchment and we focussed on the continuous observation of a number of physical parameters that control regolith development and weathering processes samples collected from different depths at sites with different aspects enabled temporal comparisons of the factors involved in the development of surface regolith that can be considered as indicators of the weathering of the marls these indicators were then related to environmental variables moisture and temperature atterberg limits were established and related to moisture content to explain slope dynamics and related processes finally analyses of carbonate content were performed in the laboratory the results validate the employed methodology supporting our description of weathering processes the established chronological sequence and the relation of these processes to climatic and topographic parameters the results obtained since january 2004 show that the chosen indicators are sensitive to seasonal dynamics variations in temperature and water supply and slope aspect the development and dynamics of regolith on north facing slopes is more active than that on south facing slopes freeze thaw is the main weathering process on north facing slopes while south facing slopes are dominated by the development of crusts associated with wetting drying processes washing effects and lower temperatures upon north facing slopes mean that the dissolution of carbonates is more pronounced in such areas compared with south facing slopes especially within the upper layers of the regolith copyright 2006 john wiley sons ltd

deriving indicators of soil degradation from soil aggregation studies in southeastern spain and southern france soil degradation is perceived as a major threat in the mediterranean region due to changes in land use and possible future climate change soil aggregation parameters are used here to demonstrate their potential as a key indicator for land degradation studies the monitoring of these indicators offers a means of establishing the vulnerability and resilience of geo ecosystems soil aggregation stability and distribution were studied on soils with an open shrubby vegetation cover from several places in southeastern spain and southern france by applying drop tests and determining aggregate size distributions aspect and vegetation cover were incorporated in the soil sampling several indices were derived from these analyses to indicate the degree of soil aggregation this was done by referencing to a base level of aggregation bare soil aggregation it was found that soil aggregates were more stable and were often coarser under vegetation when compared to their immediate surrounding bare areas a similar slightly less clear effect was noted on n facing exposed slopes when compared to s facing exposed slopes long term changes were found by studying cultivated land abandoned fields and land covered by semi natural vegetation on comparable substrate and comparable land units it is clear that soil aggregation and aggregate stability increases with time years it is argued that soil aggregation indices can be used as a key indicator for degradation processes at a fine scale with implications for runoff and sediment generating processes at the hillslope scale

rock fragments in top soils significance and processes this introductory paper reviews various aspects of rock fragments in top soils such information is required for various reasons and in particular for predicting the impact of climatic or landuse changes on the response of these soils particular attention is paid to the definition and measurement of rock fragment content in top soils the density of soils containing rock fragments the spatial distribution and movement of rock fragments in top soils the effects of rock fragments on some key hydrological processes thermal properties of top soils physical soil degradation soil erosion and soil productivity

climate and anthropogenic factors affecting alluvial fan development during the late holocene in the central ebro valley northeast spain the late holocene in the central ebro depression is characterized by a number of morphodynamic stages that affected hillslopes and channels climate fluctuations and human activities together caused severe erosion and floods resulting in alternating stages of accumulation and incision in the valley floors seven accumulation levels n6 n0 correlated with ebro river fluvial terraces have been identified in the secondary fluvial network of the central ebro depression the main accumulation level n3 corresponds to a long period of increased hillslope erosion and sedimentation in the valleys from the neolithic to the late roman periods the accumulation levels are evident throughout the valleys and extend to the valley mouths where many connect with alluvial fans the study of several sedimentological profiles 14c ams dating and many archaeological remnants have enabled detailed assessment of sedimentation characteristics in the alluvial fans and the relationship thereof to the presence of human sett

circum mediterranean fire activity and climate changes during the mid holocene environmental transition 8500 2500 cal bp a mid to late holocene synthesis of fire activity from the mediterranean basin explores the linkages among fire climate variability and seasonality through several climatic and ecological transitions regional fire histories were created from 36 radiocarbon dated sedimentary charcoal records available from the global charcoal database during the mid holocene thermal maximum around 7500 4500 cal bp charcoal records from the northern mediterranean suggest an increase in fire while records from the southern mediterranean indicate a decrease associated with wetter than present summers a north south partition between 40 and 43 n latitude is apparent in the central and western mediterranean relatively abrupt changes in fire activity are observed c 5500 5000 cal bp records of holocene fire activity appear sensitive to both orbitally forced climate changes and shorter lived excursions which may be related to north atlantic cold events possibly modulated by an nao like climate mechanism in cases wh

effects of check dams reforestation and land use changes on river channel morphology case study of the rogativa catchment murcia spain this work has been financially supported by the project respuesta hidrologica y geomorfologica de los sistemas fluvio torrenciales afectados por proyectos de restauracion hidrologico forestal en cuencas semiaridas del sureste peninsular of the fundacion instituto euromediterraneo de hidrotecnia ce the first author was financially supported by an i3p postdoc contract csic ce and a ramon y cajal contract from the education and science ministry spain gonzalo g barbera also was supported by i3p postdoc contract

gully head morphology and implications for gully development on abandoned fields in a semi arid environment sierra de gata southeast spain in this paper we examine whether gully head morphology can be used as an indicator for gully development and hence for sediment production a survey was conducted at five hillslopes in the sierra de gata where different types of channel heads occur close to each other the survey included measurements of morphologic and pedologic properties ground surface channel and catchment characteristics of every gully head present n 59 on the basis of the observed morphologies the heads were subdivided into four types gradual transitional a short inclined section abrupt and rilled abrupt the analyses showed that it is possible to explain the differences of gully heads and the role of some environmental factors on the basis of their morphologies at least for the gradual and the abrupt types the results suggested that steep headcuts abrupt were formed from secondary headcuts in the channel which migrated upstream the abrupt headcuts were always formed in more than one soil layer of which one was a resistant stony layer however shear strength measurements at saturation showed that the top layer was not always the most resistant one width depth relationships indicated that gradual type headcuts were controlled by fluvial processes and abrupt headcuts by a combination of fluvial and mass wasting processes gradual types occurred more downslope than the abrupt types suggesting that the incisions started by fluvial processes and migrated upwards when knickpoints developed in the channel the rilled abrupt types are still actively retreating thus the abrupt types correspond to slower retreat rates abrupt gully heads may deteriorate into transitional types when plunge pool erosion becomes less effective the conceptual model is supported by data from ephemeral gullies in two other study areas sierra de la torrecilla spain and alentejo portugal copyright 1999 john wiley sons ltd

suspended sediment dynamics in a large regulated river over a 10 year period the lower ebro ne iberian peninsula this paper presents a comprehensive assessment of the suspended sediment load for the period 1998 2008 in the lower river ebro ne iberian peninsula one of the most regulated large rivers in europe sediment load estimates are based on continuous discharge and turbidity records calibrated with direct suspended sediment samples covering a wide range of river s hydraulic conditions the temporal variability of the sediment load and the role of the effective discharge at different temporal scales are specifically examined at the log term the study period can be considered as dry mean annual load is estimated at around 0 092 106 t a value that represents less than the 1 of what was transported at the beginning of the twentieth century in the absence of dams and under different land uses in general sediment concentrations observed between 1998 and 2008 are low mean was 9 mg l 1 and maximum was 240 mg l 1 specific sediment yield was in the order of 1 t km2 y 1 also much lower than values reported in other western european rivers of the same scale and impact at the annual scale large floods were responsible for most of the transported suspended sediment up to 80 nevertheless when the effective discharge is calculated for the whole study period floods of moderate magnitude and high frequency are responsible for the largest amount of sediment transport the temporal scale used to calculate the effective discharge thus determines the final results load estimates derived from continuous suspended sediment and discharge data and from the flow duration method yielded similar values this suggests that the latter method is also appropriate when sediment samples cover a large proportion of the observed discharges and statistical significant relations can be obtained and applied to long periods of record this study provides further insights into the sedimentary status of one of the largest rivers in europe results corroborate previous studies highlighting sediment deficit downstream from large dams this type of information constitutes a key element to inform and improve current management and restoration actions

factors affecting eco geomorphological dynamics in two contrasting mediterranean environments abstract southern spain is characterized by a longitudinal pluviometric gradient over a distance of approximately 260 km where the annual rainfall ranges from 1668 mm y 1 in the west sierra de grazalema to only 150 mm y 1 in the east cabo de gata along this gradient during the last 70 years there have been trends of increasing rain in the west and increasing aridity in the east the threshold annual rainfall level separating these regions is approximately 500 mm for this study we selected two experimental basins having different geo morphodynamic variables each representing one side of this threshold we used these basins for analysis of changes in land use and characterization of physiographic soil cover physical chemical and hydrological variables we developed a database applied statistical normalization and then performed principal component analysis to identify the main geomorphological components explaining the variance our quantitative and cartographic results identified particular factors vegetated areas water resources and soil degradation that most control geomorphological processes and explain the landscape dynamics in this region over recent decades

assessment of channel changes due to long term bedload supply decrease roubion river france this paper presents the observations made in the watershed of the upper roubion river which drains a submediterranean mountainous environment and in two of its main tributaries the soubrion and bine creeks our aim was to analyze contemporary morphological and sedimentary changes in response to a progressive decrease in bedload supply this decrease is linked to an increase of forest cover in the watershed during the 20th century following rural depopulation and to a correlated decrease in peak flows several variables were systematically measured width slope bed level change sediment size along 23 km of river whereas dendrochronological data floodplain cross sections and estimated recurrence intervals of sediment entrainment based on critical shear stress calculations were also produced for specific sites to complete our analysis evidence of three major phenomena was obtained on both the roubion and its tributaries i bed degradation ii development of stable pavement in incised reaches and iii channel narrowing associated with the development of alluvial forest on recently abandoned portions of the pre existing active channel forest development began in the 1950s these three phenomena show positively covariant relationships that lead us to propose a descriptive model of mountain fluvial system adjustments to progressive decrease of bedload

from plot to regional scales interactions of slope and catchment hydrological and geomorphic processes in the spanish pyrenees the hydrological and geomorphic effects of land use land cover changes particularly those associated with vegetation regrowth after farmland abandonment were investigated in the central spanish pyrenees the main focus was to assess the interactions among slope catchment basin and fluvial channel processes over a range of spatial scales in recent centuries most mediterranean mountain areas have been subjected to significant human pressure through deforestation cultivation of steep slopes fires and overgrazing depopulation commencing at the beginning of the 20th century and particularly since the 1960s has resulted in farmland abandonment and a reduction in livestock numbers and this has led to an expansion of shrubs and forests studies in the central spanish pyrenees based on experimental plots and catchments in large basins and fluvial channels have confirmed that these land use changes have had hydrological and geomorphic consequences regardless of the spatial scale considered and that processes occurring at any particular scale can be explained by such processes acting on other scales studies using experimental plots have demonstrated that during the period of greatest human pressure mainly the 18th and 19th centuries cultivation of steep slopes caused high runoff rates and extreme soil loss large parts of the small catchments behaved as runoff and sediment source areas whereas the fluvial channels of large basins showed signs of high torrentiality braided morphology bare sedimentary bars instability and prevalence of bedload transport depopulation has concentrated most human pressure on the valley bottoms and specific locations such as resorts whereas the remainder of the area has been affected by an almost generalized abandonment subsequent plant recolonization has resulted in a reduction of overland flow and declining soil erosion at a catchment scale this has caused a reduction in sediment sources and channel incision in the secondary streams at the regional scale the most important consequences include a reduction in the frequency of floods reduced sediment yields increasing stabilization of fluvial channels colonization of sedimentary bars by riparian vegetation and a reduction in the braiding index and stabilization of alluvial fans these results demonstrate the complexity and multiscalar nature of the interactions among land use and runoff generation soil erosion sediment transport and fluvial channel dynamics and highlight the need to adopt a multiscale approach in other mountain areas of the world

temporal distribution of suspended sediment transport in a humid mediterranean badland area the araguas catchment central pyrenees abstract this paper analyses the temporal patterns of suspended sediment yield in the araguas catchment central spanish pyrenees a small experimental catchment with extensive badlands the catchment has been monitored since 2004 to study weathering erosion and hydrological and sediment responses to understand the superficial dynamics of a badland area in a relatively humid environment the development of badlands in the central spanish pyrenees is favoured by the presence of marls and a markedly seasonal climate the continuous observation of selected physical parameters and environmental variables enables us to establish seasonal patterns of weathering processes and identify those factors that control regolith development freeze thaw cycles in winter and wetting drying in spring summer are the main processes involved in regolith weathering thereby controlling slope development in combination with rainfall related erosion processes the 64 floods recorded during the study period december 2005 to january 2007 were used for a hydrosedimentological analysis the main observed features indicate that the araguas catchment reacts to all rainfall events resulting in steep rising and recession limbs on the hydrograph and a very short time lag floods show high suspended sediment concentrations and a heterogeneous temporal distribution related to seasonal variations in surface runoff production these differences increase the degree of complexity involved in studying sediment response suspended sediment concentration and transport mainly depend on rainfall volume maximum rainfall intensity peak flow and runoff occurrence finally the similarities among the obtained hydrographs sedigraphs and hyetographs in combination with the rapid response of most of the floods suggest a large contribution of overland flow derived mainly from infiltration excess runoff upon badland areas accordingly the significant correlations obtained between rainfall intensity and sediment concentration mainly during the dry season which suggest a single source area for both runoff and sediment also support the hypothesis of hortonian hydrological response within badland areas

holocene fire activity and vegetation response in south eastern iberia since fire has been recognized as an essential disturbance in mediterranean landscapes the study of long term fire ecology has developed rapidly we have reconstructed a sequence of vegetation dynamics and fire changes across south eastern iberia by coupling records of climate fire vegetation and human activities we calculated fire activity anomalies faas in relation to 3 ka cal bp for 10 8 ka cal bp 6 ka cal bp 4 ka cal bp and the present for most of the early to the mid holocene uneven but low fire events were the main vegetation driver at high altitudes where broadleaved and coniferous trees presented a highly dynamic post fire response at mid altitudes in the mainland segura mountains fire activity remained relatively stable at similar levels to recent times we hypothesize that coastal areas both mountains and lowlands were more fire prone landscapes as biomass was more likely to have accumulated than in the inland regions triggering regular fire events the wet and warm phase towards the mid holocene between ca 8 and 6 ka cal bp affected the whole region and promoted the spread of mesophytic forest co existing with pinus as faas appear strongly negative at 6 ka cal bp with a less important role of fire mid and late holocene landscapes were shaped by an increasing aridity trend and the rise of human occupation especially in the coastal mountains where forest disappeared from ca 2 ka cal bp mediterranean type vegetation evergreen oaks and pinus pinaster halepensis types showed the fastest post fire vegetation dynamics over time

metal fractionation in topsoils and bed sediments in the mero river rural basin bioavailability and relationship with soil and sediment properties abstract comprehensive studies that examine the transfer of metals across soil river bed sediment systems at the basin scale are scarce an understanding of the distribution of metals among various fractions of soils and sediments within a basin is fundamental to understand their environmental behavior and thus to define watershed management plans this study aims to determine the distribution of metals fe mn cu and zn in topsoils under different land uses cultivation pastures and forests and river surface sediments in the upper mero river basin nw spain and to assess these metals mobility and bioavailability in both environmental compartments to detect potential threats to crops and the water quality sequential extraction is used to fractionate the four metals into six fractions soluble exchangeable specifically adsorbed metals that are bound to mn oxides amorphous compounds metals that are bound to organic matter crystalline al and fe oxides and residual metals metals within the crystal lattices of minerals the fractionation results for both soils and sediment indicate an abundance of metals in the residual fraction except for mn in soils followed by relatively high percentages of oxide bound fractions mostly crystalline fe oxides for both fe and zn amorphous for cu and mn oxides for mn on average the mn residual fraction in soils 30 2 is only slightly exceeded by the mn oxide fraction 34 7 the land uses do not affect the sequence of metal binding phases in soils except for mn which is only slightly altered the results also suggest that fe mn cu and zn in both soils and sediments are not readily mobile under current environmental condition and hence pose no threat to crops or the water quality in overall terms the mobility and bioavailability of the four metals considering the sum of the three least mobile fractions namely organic matter crystalline al and fe oxides and residual in the soils decrease in the following order mn cu fe zn the same sequence occurs in the sediments but the order between fe and zn is reversed the soils and sediments that are studied cannot be considered polluted in terms of these metals because of their low levels and prevalence in the residual fraction which is typical of contributions from natural sources and indicates the pedogenic lithologic origin of these metals

timing of compaction and quartz cementation from integrated petrographic and burial history analyses lower cretaceous fall river formation wyoming and south dakota abstract integrated petrographic and burial history studies of fall river sandstones from outcrop and the subsurface provide insight into the timing of compaction and quartz cementation the two main porosity reducing processes in quartzose sandstones petrographic study of 95 thin sections of fall river fluvial valley fill sandstones from outcrop donkey creek field at 2 km burial depth and buck draw field at 3 8 km indicates that reservoir quality differs significantly in these three areas fall river sandstones at the surface contain an average of 31 intergranular volume igv and 2 quartz cement in both donkey creek and buck draw fields the sandstones average 22 igv but quartz cement volume averages 8 in the shallower field and 12 in the deeper geometric mean permeability at the urface is 4700 md compared with 42 md at 2 km and 2 md at 3 8 km burial history of the fall river sandstone differs greatly in the three areas the outcropping sandstones were buried to 2 km and had reached 80 c by the end of the cretaceous they were then uplifted and have remained at near surface temperatures since the paleocene the calculated time temperature index tti of these sandstones is 1 fall river sandstones at donkey creek were also buried to 2 km and had reached 80 c by the end of the cretaceous but remained at that depth during the tertiary tti is 14 in buck draw field fall river sandstones were buried to 2 5 km during the cretaceous and then continued to subside during the tertiary reaching depths of 4 km and temperatures of 140 c tti is 512 much of the compaction of fall river sandstones had occurred by burial depths of 2 km but additional time at that depth was required for completion of mechanical compaction and for minor chemical compaction although greater depth and higher temperatures did not increase chemical compaction increasing thermal maturity resulted in more quartz cementation internal sources of silica from stylolitization and intergranular pressure solution account for only 10 25 of the volume of quartz cement in fall river sandstones imported silica may have come from clay mineral transformations in cretaceous shales loss of porosity and permeability was greatest between tti of 1 and 14 but continued at a reduced rate as tti increased

relationship between diagenesis and reservoir quality in sandstones of the garn formation haltenbanken mid norwegian continental shelf a quantitative model is proposed for the dependence of porosity and permeability on diagenesis in subarkosic arenites of the middle jurassic garn formation porosity variation is controlled by the combined effects of compaction and quartz cementation in general more porosity has been lost by compaction than by quartz cementation but compactional porosity loss appears to have occurred relatively early in the burial history before burial below 2 km below the sea floor thus progressive reduction of the total porosity with increasing burial below 2 km results mainly from quartz cementation permeability is a function of the abundance of intergranular macroporosity which is interpreted to be a measure of effective porosity at depths less than 3 5 km below the sea fl or intergranular macroporosity generally comprises more than 50 percent of the total porosity but at greater depth as total porosity decreases below about 16 percent the ratio of effective to ineffective porosity drops below one this depth corresponds to the onset of extensive illitization and grain dissolution which results in major reorganization of the pore system generation of secondary porosity by feldspar dissolution appears not to have been beneficial to reservoir quality in the garn formation but it is regarded as an intrinsic part of the overall process of porosity destruction with increasing diagenesis

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

potassium leached zones at the contacts of the garn formation mid norwegian continental shelf evidence for the role of shale in sandstone diagenesis abstract

the 1996 biescas campsite disaster in the central spanish pyrenees and its temporal and spatial context on the evening of the 7 august 1996 an intense storm occurred over the aras catchment near biescas in the central pyrenees eighty seven people were killed as a result of the subsequent flood which hit a campsite located on the alluvial fan at the outlet of the 18 8 km2 catchment this paper presents the main results of a hydromorphological study of the event the betes subcatchment received the most intense rainfall estimated at somewhat in excess of 250 mm which resulted in a peak flow from this tributary of 300 m3 s 1 just downstream from the betes river junction flow in the main channel reached 400 m3 s 1 increasing to around 500 m3 s 1 further downstream rainfall in the larger aso tributary was less intense and in the head reaches flow remained within bank representing a one in two year return period event flow from this tributary did not exceed 100 m3 s 1 indicating that the betes subcatchment supplied some 75 of the flow from just 28 7 of the catchment area the extreme flows caused the collapse of a series of sediment trap dams in the aras channel downstream of the betes junction this resulted in the addition of 68 000 m3 of sediment to an already disastrous event data from other rain gauges in the area showed both the extremely local nature of the event and the problems of return period analysis for such storms whose peaks are rarely observed at gauges together with the high geomorphological risks of the zone this leads to the conclusion that a new method of spatial and temporal risk analysis is required for infrastructure planning 1997 john wiley sons ltd

human influences on the present denudation rates of the paulista peripheral depression brazil abstract chemical weathering and soil erosion in large or small watersheds are used to understand the effect of evolution processes on the earth s surface and climate currently human driven land use changes have substantial effects on landscape changes over a range of temporal and spatial scales in this context the sorocaba river basin sao paulo state brazil is an ideal study area to assess human influence on the present denudation rates of the paulista peripheral depression ppd twelve fluvial water sample collections were carried out at the sorocaba river mouth covering one complete hydrological cycle jun 2009 to jun 2010 in the same period 46 rainfall events were sampled all samples were analyzed for dissolved cations anions and silica and total dissolved solids tds total suspended solids tss were measured only in fluvial samples the export of tds and tss occurs mostly during the wet season accounting for ca 60 and 87 of the total dissolved solids and total suspended sediment transported in the hydrological cycle studied 2009 2010 respectively the total annual specific flux of tss was 74 27 t km2 year including soil erosion by agricultural activities with a small portion being derived from the anthropogenic contributions ca 2 the total annual specific flux of tds 74 43 t km2 year was similar to the tss but after the correction of the atmospheric inputs and anthropogenic contributions ca 18 and 29 respectively this value decreased to 39 35 t km2 year the chemical weathering rate was 7 1 m myear and this process tended towards monosialitization re 2 6 with an atmospheric soil co2 consumption rate of 3 3 105 mol km2 year the difference between the chemical weathering and soil removal rates 7 1 and 49 6 m myear respectively indicated that the soil thickness reduction occured in the sorocaba river basin the climatic control on chemical weathering and soil removal rates was clearly evidenced with the highest values of denudation occurring in the wet and hot climatic conditions however the chemical weathering processes re index was not sensitive to climatic controls in order to assess human influence on chemical weathering and soil removal rates in the ppd the results were compared with other works undertaken in this vast geomorphological province even considering the uncertainties associated with a number of data points the chemical weathering and soil removal rates in the ppd observed in this study were approximately 4 and 7 5 fold higher than these natural denudation rates respectively evidencing the effect of recent land use changes on the present denudation rates in the ppd thus this study reinforces the complexity of the human landscape systems in sao paulo state and increases the values of long term landscape evolution rates

a meta analysis of soil erosion rates across the world abstract over the last century extraordinary efforts have been devoted to determining soil erosion rates in units of mass per area and time under a large range of climatic conditions and land uses and involving various measurement methods we undertook a meta analysis of published data from more than 4000 sites worldwide the results show that there is extraordinarily high variability in erosion rates with almost any rate apparently possible irrespective of slope climate scale land use land cover and other environmental characteristics however detailed analysis revealed a number of general features including positive relationships of erosion rate with slope and annual precipitation and a significant effect of land use with agricultural lands yielding the highest erosion rates and forest and shrublands yielding the lowest despite these general trends there is much variability that is not explained by this combination of factors but is related at least partially to the experimental conditions our analysis revealed a negative relationship between erosion rate and the size of the study area involved significant differences associated with differing measurement methods with direct sediment measurement yielding the lowest erosion rates and bathymetric radioisotope and modeling methods yielding the highest rates and a very important effect of the duration of the experiment our results highlight that when interpreting erosion rates the experimental conditions involved must be taken into account even so the data suggest that only order of magnitude approximations of erosion rates are possible and these retain a very large degree of uncertainty consequently for practical purposes such as calculation of global sediment budgets empirical equations are not a substitute for direct measurements our results also show that a large proportion of the experiments have been short term less than 3 years which reduces dramatically the reliability of the estimated erosion rates given the highly non normal behavior of soil erosion time dependency despite the efforts already made more long term measurement experiments need to be performed especially in regions of the world that are under represented in global datasets in addition protocols need to be established for standardizing the measurement methods and reporting the results to enable data to be compared among diverse sites

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

soil erosion by piping in irrigated fields abstract this paper reports on soil losses from pipe networks in irrigated fields in the ebro basin spain the factors encouraging the evolution of pipes are the number of irrigations the type of crop the existence of more impervious layers in the c soil horizon and the hydraulic gradient the water used for irrigation is a low salinity water frequently unsaturated in calcite and dolomite it therefore dissolves some of the soil carbonate and takes calcium from the exchange complex thus contributing to soil dispersion and erosion from monitoring the hydromorphological behaviour of two pipe networks soil loss from the affected plots is estimated at 3 t ha 1 yr 1 the evolution of piping causes important losses of soil and water and can lead to the abandonment of farm land

lower mediterranean plain accelerated evolution during the little ice age geoarchaeological insight in the tech basin roussillon gulf of lion western mediterranean abstract this paper discusses the evolution of the tech river lower plain western mediterranean from the late middle ages using geomorphological archaeological and historical data geoarchaeological data was obtained from coring and trenching near a buried village and chapel radiocarbon and archaeological dating are used to reconstitute sedimentation rates and major flood event chronology additional data about channel avulsion are provided by historical data increases in sedimentation rate flooding plain enlargement and repeated avulsion are identified between the last 13th to 15th century ad this attests to a shift from low water level regime lwr to flood dominated regime fdr climatic or anthropogenic causes of this change are discussed on the basis of regional synthesis on the western mediterranean scale 1250 1350 ad seems to be a wetter phase associated with the progressive onset of the early little ice age phase from 1330 to 1450 ad

the history of human induced soil erosion geomorphic legacies early descriptions and research and the development of soil conservation a global synopsis abstract this paper presents a global synopsis about the geomorphic evidence of soil erosion in humid and semihumid areas since the beginning of agriculture historical documents starting from ancient records to data from the mid twentieth century and numerous literature reviews form an extensive assortment of examples that show how soil erosion has been perceived previously by scholars land surveyors farmers land owners researchers and policy makers examples have been selected from ancient greek and roman times and from central europe southern africa north america the chinese loess plateau australia new zealand and easter island furthermore a comprehensive collection on the development of soil erosion research and soil conservation has been provided with a particular focus on germany and the usa geomorphic evidence shows that most of the agriculturally used slopes in the old and new worlds had already been affected by soil erosion in earlier prehistoric times early descriptions of soil erosion are often very vague with regard to the roman times geomorphic evidence shows seemingly opposing results ranging from massive devastation to landscapes remaining stable for centuries unfortunately historical documentation is lacking in the following centuries historical records become more frequent and more precise and observations on extreme soil erosion events are prominent sometimes they can be clearly linked to geomorphic evidence in the field the advent of professional soil conservation took place in the late eighteenth century the first extensive essay on soil conservation known to the western world was published in germany in 1815 the rise of professional soil conservation occurred in the late nineteenth and early twentieth centuries soil remediation and flood prevention programs were initiated but the long term success of these actions remains controversial in recent years increasing interest is to recover any traditional knowledge of soil management in order to incorporate it into modern soil conservation strategies the study shows that local and regional variations in natural settings cultural traditions and socioeconomic conditions played a major role for the dynamics and the rates of soil erosion on a long term perspective geomorphic evidence and historical sources can often complement each other but there should be also an awareness of new pitfalls when using them together

geochemical fractionation and risk assessment of trace elements in sediments from tide dominated hooghly ganges river estuary india abstract the geochemical fractionation and potential mobilization of cadmium chromium copper nickel and lead were studied in surficial sediments top 0 10 cm 46 reflecting their adverse impact on benthic organisms as they are weakly bound to the sediment and can migrate to water iii a minor fraction of cu

holocene alluvial morphopedosedimentary record and environmental changes in the bardenas reales natural park ne spain abstract a holocene alluvial morphostratigraphy based on geomorphological mapping sedimentological analysis soil development and radiocarbon chronology is presented for the semiarid blanca basin in the bardenas reales natural park ne spain four morphopedosedimentary alluvial units mu1 mu2 mu3 and mu4 were differentiated which may correspond to two palaeogeographical stages the first one includes the morphopedosedimentary unit mu1 and is the most extensive in the area it is made up of a complex aggradation fill up sequence comprising a braided channel system a sand mud flat 9200 7900 cal bp and a playa lake environment related to a nearly closed depression an intensive fluvial entrenchment period is recognized leading the opening of the blanca basin before the second stage that includes the units mu2 mu3 and mu4 this set of units forms a sequence of cut and fill and nested fill terraces recording the alluvial activity in the blanca basin during the last 6 ka the mu2 unit 5900 3300 cal bp in age represents a period of high geomorphic instability with rapid alluvial sedimentation channel incision oscillating changes on the other hand the mu3 unit has an age of 1050 500 cal bp and appears as a thin extensive alluvial cover overlying previous units finally the mu4 unit comprises superposition of numerous flood depositional sequences centimetric in scale dated from 450 10 cal bp the established soil chronosequence supports the numerical chronology of the four units these accumulation periods mu1 mu2 mu3 mu4 are associated with dry phases and or high hydrological variability floods and droughts at a regional scale changes on the north atlantic atmospheric circulation mode over southern europe may provide the key to explain the nature of alluvial activity during holocene in bardenas reales

mediterranean valleys revisited linking soil erosion land use and climate variability in the northern levant abstract this paper presents results of geomorphological and archaeological investigations undertaken in several small drainage basins in the jebel al aqra region of southern turkey by focusing intensive archaeological settlement survey in basins where securely dated sequences of sedimentary valley fills have been recorded spatially and temporally linked high resolution records of land use and soil erosion have been generated sedimentary data show that throughout most of the holocene floodplains remained rather stable allowing deep soils to form but in the past two millennia probably from ad 150 700 a phase of severe soil erosion was initiated and resulted in the deposition of 3 5 5 0 m of alluvial sediments on valley floors archaeological and historical evidence suggest that while these areas were occupied by agrarian communities since at least 2800 bc nearly three millennia of cultivation during the bronze and iron ages had relatively little effect on soil erosion the intensification of settlement throughout the region and the conversion of upland areas to intensive agricultural production during the hellenistic roman and late roman periods 300 bc ad 650 however created the necessary preconditions for severe soil erosion to occur these data are compared against modern and paleoclimate studies of the eastern mediterranean which show an extremely variable precipitation regime and the effects that it can have on erosion a 400 year lag between the initial settlement of upland areas and the first evidence of soil erosion suggest that it may have been the intersection of extreme precipitation events with particular land use conditions of the roman and late roman periods which worked together to drive soil erosion

flood events in mediterranean ephemeral streams ramblas in valencia region spain abstract this article deals with flood events in mediterranean ephemeral streams typical of the valencia region the combination of the basin physical characteristics steep slopes sparse vegetation thin soils and permeable rock and intense heavy and irregularly distributed rain generates flash floods runoff generation is sudden giving rise to flash floods with sharp narrow hydrographs with short time lags the high amount of runoff is nevertheless only a small fraction of the total rainfall since the characteristics of the river basins are such that infiltration of large amounts of water occurs using daily hydrological data from the rambla de la viuda basin and 5 min data from both the barranc del carraixet and the rambla de poyo basins the rainfall runoff processes have been analysed during flood events in these ephemeral streams