von karman s constant in atmospheric boundary layer flow reevaluated abstract a field experiment has been carried out with the specific objective in mind to determine the value of von karman s constant in atmospheric boundary layer flow and also to investigate its possible dependence on the surface rossby number ro0 data from three field measurement campaigns at marsta sweden were used in the analysis depending on the ground cover deep snow 40 cm plowed field or 15 20 cm high wheat crop the surface roughness in the three campaigns was respectively 1 mm 7 5 mm and 24 mm the corresponding range in ro0 is roughly 2 5 106 6 5 107 in the experiment a turbulence instrument was used the miuu instrument that has been carefully examined for aerodynamic error effects and duly corrected measurements of turbulent fluxes made with this instrument at ca 2 and 6 m above the surface were used together with wind profile measurements data from the measurements with the turbulence instruments were also used to correct the cup anemometers for overspeeding found to be 5

direct and indirect evaluation of denudation rates in central italy abstract this paper presents the main results of a series of geomorphological studies aimed to the quantitative direct and indirect evaluation of denudation processes in central italy these studies which started in some sample areas since long ago were further deepened and extended to a wider number of drainage basins representative of a variety of morphostructural conditions the complex cause effect relationships among factors influencing both the morphogenesis and the plano altimetric configurations of drainage basins resulted in a large variability in the values of the denudation index tu which ranged from 200 to 2500 t km2 year very high values tu 10 000 t km2 year were obtained for small catchments belonging to the wider basins of ombrone river and tevere river where fast morphological modifications occur due to the action of surface running waters and gravity in the drainage basins affected by the most powerful denudation processes direct measurements of denudation were performed several monitoring stations were equipped with iron stakes and disks to record the local modifications of the topographic surface with time whereas some of these stations have been working continuously since 1993 some others have been running only periodically direct measurements pertinent to periods longer than a decade indicated that mean annual values of denudation range between 1 and 2 5 cm year for slopes affected by sharp edged and or rounded edged badlands higher denudation rates 3 4 cm year were obtained for shorter observation periods still higher rates were recorded for short periods at the gully bottom or in coincidence with mass movements before bench marks were turned up or damaged denudation processes are likely to occur discontinuously they show a step like trend with time and are triggered by rainfall events distributed over a number of consecutive days though not greatly intense particularly their amount should overcome the threshold of 60 mm per 5 consecutive days below this threshold the surface runoff does not seem to reach the power necessary to induce significant modifications of the topographic surface in the study area

structure of a cold front over the ocean the kinematic and thermodynamic structure of a strong cold front over the gulf of alaska has been determined using aircraft dropsonde and radiosonde data obtained during the storm transfer and response experiment synoptic scale analysis using the sawyer eliassen secondary circulation equation shows that friction and diabatic heating as well as the geostrophic forcing are important in accounting for the secondary circulation at the front a fine scale analysis with horizontal resolution of 700m and vertical resolution of 100 m shows strong relative inflow of warm boundary layer air toward the front from the east and a weaker inflow of cold air from the west updraught velocities of greater than 6 m s 1 over a 2 km width were measured at 875 mb near the leading edge of the front the frontogenetical effects of confluence turbulent mixing and tilting of isentropic surfaces are evaluated in the region of the front and compared with the results of previous studies the high resolution of the thermodynamic fields provides new data for comparison with high resolution numerical models

interaction of low level flow with the western ghat mountains and offshore convection in the summer monsoon abstract seven year averaged values of percent frequency of occurrence of highly reflective cloud for the months june july and august indicate that offshore convection is a major component of the cloudiness of the southwest monsoon principal areas of convection occur off of the western coats of india burma thailand and the philippines this study concentrates on the area upstream of the western ghats mountains of india analysis of a special boundary layer mission flown during the wmo icsu summer monsoon experiment leads us to believe that partial deceleration of the monsoon flow by upstream blocking effects of the mountains initiates and maintains a vertical and horizontal motion field that could support the observed convection data obtained on this mission allow a large scale momentum budget computation for the subcloud layer which shows pressure deceleration to be significant the budget dominated by advection predicts an increase of average wind speed which is observed the pressure decelera

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

morphological analysis and erosion rate evaluation in badlands of radicofani area southern tuscany italy abstract since 1988 geomorphologic research based on field surveys and photo geological analysis has been conducted in southern tuscany italy in areas characterised by very rapid morphological evolution in the area outcrop pliocene marine claystones uplifted during the quaternary up to 750 m above sea level now undergoing intense erosion processes leading to considerable badlands formation morphodynamic analysis conduced by direct and indirect measurements in a sample area were taken in order to quantify the erosion rate in badland areas the torrente piantrafolla sample area was chosen as representative of the study area it was most recently monitored during the period nov 2000 feb 2004 at this time morphographic and morphometric analyses carried out in selected measurement stations located on slopes identified gravity as the main morphogenetic process responsible for slope shaping the calanchi badland areas are characterised by constant and rapid shrinking of their edges resulting from landslides which occur in autumn and winter as a consequence of intense rainstorms selected measurement stations indicate an erosion rate value range from 5 to 7 5 cm y the comparison between 1976 and 1994 digital elevation models dem obtained from photogrammetric restitution indicated a mean erosion rate of about 5 cm y in a nineteen year period this value considerably higher than the values measured in other italian basins indicate a very rapid evolution of the slopes due mainly to small earth flows inside calanchi badlands

sediment delivery to the three gorges 2 local response abstract information on soil erosion and sediment yields is very limited in the immediate vicinity of the three gorges project tgp although the inceptisols developed on triassic shales and sandstones in this area are known to be highly susceptible to erosion estimated sediment yields for a small reservoir catchment yiwanshui in changshou county downstream of chongqing are high around 3500 t km 2 a 1 and similar to the data from 38 reservoir investigations in sichuan basin but exceeding the yields estimated in the feasibility studies for the tgp the high sediment yield reflects severe soil erosion due to cultivation aligned with slope on steep slopes which is very common throughout sichuan basin and particularly in the tgp area the total sediment delivered to the yangtze from the tgp area has been estimated using small reservoir data and sediment load measured at hydrological stations these are comparable with previous estimates but there is much temporal variability in sediment supply from different parts of the three gorges region suggesting the importance of local impact on sediment flux resettlement of agricultural activity around the three gorges reservoir is likely to further enhance soil erosion temporal changes in sediment yields are reconstructed by using caesium 137 137cs dating techniques they indicate significant changes resulting from human activity and rainfall variability during the past four decades comparing reservoir sedimentation against erosion estimates on catchment soils derived from measurements indicates that 84 of eroded soil is delivered to the reservoir and the remainder is deposited in valley floor paddy fields it is estimated that over 60 of sediment is contributed from arable land the trap efficiency of small catchment reservoirs such as yiwanshui may be an important control on sediment delivery to the main channel of the upper yangtze

sediment yield and erosion rate estimation in the mountain catchments of the camastra artificial reservoir southern italy a comparison between different empirical methods abstract the sedimentary budget assessment is an important topic for the scientific and social community because it is crucial to understand the dynamics of orogenic belts and cope with a number of practical problems such as soil conservation and sediment accumulation in reservoir sediment yield or denudation rate estimates in southern central italy are generally obtained either by applying simple empirical relationships based on the statistical regression between the geomorphic parameters of the drainage network and the suspended sediment yield measured at the drainage basins outlets or by using qualitative quantitative sediment delivery ratio or erosion models in this work we carry out a study of catchment dynamics and a sedimentary yield computation of several mountain catchments of the central western sector of the basilicata region southern italy which are located upstream of an artificial reservoir the sediment yield and erosion rate have been computed through both an indirect assessment of the suspended sediment yield based on the tu index mean annual suspension sediment yield and the application of the rusle and usped empirical methods the results obtained have been compared with the historical data of sediment accumulation measured in the artificial reservoir of the camastra dam where a detailed evaluation of the volumes of historical i e about 40 years sediment storage was collected the collected dataset represents a basic tool both for the investigation of the morpho dynamics of a typical mountain catchment of the mediterranean area and the evaluation of sediment budget related to fluvial and hillslope processes the 38 year long record of the sediment storage in the camastra artificial reservoir located at the outlet of the studied mountain catchments permits the validation of empirical relationships based on the geomorphic and climatic parameters of the drainage basin among the three different methods of sediment yield evaluation tu index rusle and usped the tu index showed the best prediction ability although usped erosion model also furnished a good estimation as also confirmed by other works the indirect estimation of sediment yield based on ciccacci s empirical relationships can represent a good proxy of short term denudation rates in the mediterranean areas with geological and geomorphological features similar to the study area but the use of empirical models with increasing complexity such as the usped erosion model can help to explore the spatial distribution of the sediment yield sectors of the drainage basin the erosion hot spots and the role of landslides in sediment mobilization and hillslope channel connectivity processes

fabric anisotropy induced by primary depositional variations in the silt clay ratio in two fine grained slope fan complexes texas gulf coast and northern north sea article i nfo high resolution x ray texture goniometry hrxtg has been used to quantify the alignment anisotropy of phyllosilicate minerals in a series of diagenetically altered mudstone samples from the deep subsurface of the texas gulf coast and the northern north sea the sampled formations have undergone a simple burial history with no overprint of tectonic deformation that may have influenced the phyllosilicate orientation observations have been made in two constrained temperature windows 148 150 c north sea data and 169 210 c texas gulf coast wherein less than 20 smectite remains in the mixed layer phase illite smectite quantitative x ray powder diffraction xrpd shows quartz which is dominantly detrital and phyllosilicate content having an inverse relationship quantified illite smectite fabric intensity phyllosi licate alignments ranges from low alignment values of 2 42 m r d multiples of a random distribution to high alignment values 6 75 m r d and chlorite kaolinite ranges from 1 80 to 6 46 m r d we propose that the broad range of phyllosilicate fabric intensity observed reflects the range of quartz phyllosilicate ratios that are the imprint of depositional setting bedform truncation and initial grain size detrital quartz acts to disrupt fabric intensity by being non platy producing areas sheltered from effective stress pressure shadows and acting as a matrix support there is no evidence that bioturbation is a significant control on phyllosilicate alignment in these quartz phyllosilicate mixtures these findings have important implications for the role of grain scale alignment on seismic anisotropy in mudstone systems fabric intensity in post diagenetic samples can be predicted from 1 quartz content and 2 total clay content where

space time variability of denudation rates at the catchment and hillslope scales on the tyrrhenian side of central italy studies on denudation rates can provide insight into the influence of climate change tectonics and human activities on landscape evolution research performed in central italy has shown considerable spatial variability of denudation rates in the major river basins these studies have focused mainly on the tyrrhenian side of the italian peninsula where plio pleistocene marine deposits filling nw se elongated sedimentary basins have been uplifted during the quaternary up to several hundreds of meters above present sea level small sub catchments developed on clays are affected by sharp and or rounded edged badlands i e calanchi and biancane representing denudation hot spots in the present day morphoclimatic framework in this paper we analyze the relationships between indirectly estimated denudation rates at the catchment scale and field monitoring data at the hillslope scale we attempt to better understand and quantify all hillslope processes that contribute to seasonal variability of denudation to help with predicting the net input from hot spots to the overall estimated sediment yield at the basin outlets at the hillslope scale we discuss in particular the variability of denudation rates at calanchi and biancane badlands as a function of their different morphoevolution

modeling soil erosion and river sediment yield for an intermountain drainage basin of the central apennines italy abstract the overall aim of this research was to investigate the spatial patterns of the soil erosion risk we focused on accelerated soil erosion processes in an italian central apennine intermountain watershed using modeling techniques implemented in a gis environment our thorough literature review revealed a gap in research on soil erosion processes in such forested intermountain watersheds to gain a better understanding of the soil erosion processes in such landscapes we proposed an integrated modeling approach applying a rusle model and a turbidity unit index the model outcomes were validated through measurements of lake sediment deposition our findings indicate a potential high soil erosion risk with 1 33 m t 1 yr 1 of annual sediment yield corresponding to an area specific sediment yield of 32 35 t ha 1 yr 1 the turano drainage basin belongs to the italian basins with the highest sediment discharge the outcomes of the rusle model showed that despite the diverse forms of forests that cover about 62 of the drainage basin area sizable plots of the investigated area are prone to soil erosion the validation of the model outcomes revealed that the tu index model performed significantly better than the rusle model with regard to sediment yield prediction accordingly we found that even though rill and interrill processes reach very alarming values rusle they are not the dominant sediment source within the turano watershed other geomorphological processes contributing to the watershed sediment yield for instance megarill gully bank and channel erosion and re entrainment of landslide sediments were very active in the study area if both models are used in a combined approach the amount of river load tu index as well as the relative spatial distribution of rill and interrill erosion processes rusle can be described with sufficient precision

vertical structure of the southwest monsoon low level jet over the central and eastern arabian sea abstract the vertical structure of the low level wind jet over the arabian sea during the southwest monsoon is modeled by using the geostrophic wind shear thermal wind and a two layer boundary layer model we show that geostrophic wind shear is dominant above the low level wind maximum while turbulent momentum exchange is dominant below both effects combine to produce a low level wind jet model results compare well with observations obtained from a research aircraft during the 1979 summer monsoon experiment

extensional basins in the tectonically bimodal central apennines fold thrust belt italy response to corner flow above a subducting slab in retrograde motion the apennines fold thrust belt has developed over the past 20 m y in response to southeastward retrograde migration of the adriatic trench in a region of ongoing subduction but little plate convergence the orogenic belt is characterized by a gently sloping southwestern flank in a state of regional extensional collapse and a steeply sloping northeastern flank in regional contraction in any given area in the central apennines the chronologies of thrusting and subsequent extension provide an estimate of the time required for attainment of high elevation 2 5 3 0 km the time between initial extension and eruption of local ultramafic lavas provides an estimate of the time required to collapse by regional crustal thinning these estimates suggest that the northeastern contractional flank of the range is rising at least twice as fast as the southwestern flank is collapsing we propose that the bimodal state of stress in the apennines is maintained by corner flow in the mantle wedge beneath the crest of the range

high resolution x ray texture goniometry high resolution x ray texture goniometry hrxtg significantly improves peak background ratios and allows for the determination of crystallographic preferred fabrics of small regions 1 mm2 in heterogeneously deformed rocks the basic instrument is a commercially available automated single crystal x ray diffractometer equipped with a mo source a stage for transmission mode was constructed that is driven by the original motors so the unit is fully computer controlled absorption corrections are calculated which removes the need for generally difficult to obtain empirical corrections this combined with equipment optimization enables us to use small irradiated volumes of rocks with variable compositions the advantage of hrxtg in heterogeneously deformed rocks is demonstrated in a cleaved mudstone analysis of 1 mm2 areas in a 2 cm bed showing a gradation from micaceous sandstone to slate reveals that fabric intensity of both mica and chlorite increases significantly dm from 0 64 to 1 03 and from 0 45 to 0 78 respectively without appreciable change in the oblate shape km of the fabric thus hrxtg can record a strain state at the mm scale of heterogeneously deformed rocks

review of atmospheric boundary layer research 1983 1986 the atmospheric boundary layer comprises the lower portion of the atmosphere that is dynamically or thermodynamically affected by the presence of and interactions with the underlying surface the momentum heat water vapor and species exchanges at the surface have important effects on the boundary layer and a large portion of man s activities the height of the boundary layer can range from only several tens of meters in extreme inversion situations to many kilometers boundary layer sub specialties are often divided along the lines of the nature of the underlying surface ocean air sea interaction ice smooth terrain urban vegetation of significant height canopies and large scale features such as hills and valleys

a new procedure for gridding elevation and stream line data with automatic removal of spurious pits abstract a morphological approach to the interpolation of regular grid digital elevation models dems from surface specific elevation data points and selected stream lines is described the approach has given rise to a computationally efficient interpolation procedure which couples the minimization of a terrain specific roughness penalty with an automatic drainage enforcement algorithm the drainage enforcement algorithm removes spurious sinks or pits yielding dems which may be used to advantage in hydrological process studies the drainage enforcement algorithm has also been found to significantly increase the accuracy of dems interpolated from sparse but well chosen surface specific elevation data moreover it facilitates the detection of errors in elevation data that would not be detected by more conventional statistical means and forms a sound physical basis for cartographic generalization

assessment of land degradation susceptibility by scenario analysis a case study in southern tuscany italy abstract in the mediterranean area land degradation phenomena are becoming more and more important due to future climate change and increasing climate variability as highlighted in recent global assessment projects such as the millennium ecosystem assessment or the dialogue on water and climate thus there is consistent evidence that extreme events such as droughts and floods are more frequent than before on the other hand the mediterranean area is strongly influenced by human activities such as cultivation over hundreds of years however in the last decades the cultivation methods and techniques are subject to profound changes such as mechanization use of fertilizers and pesticides remodellation of entire hillslopes etc this particular situation leads to and aggravates the existing stress on land resources as a result land degradation and soil erosion phenomena are leading to decreasing soil productivity or the loss of fertile top soil and related water quality and quantity issues the centre for soil erosion studies cres in grosseto tuscany recently started a study to identify and monitor changes of land use in southern tuscany italy the aim of this study is to assess land degradation sensitivity by scenario analysis as a proxi for land degradation surface wash erosion processes such as rill and interill erosion processes are chosen these present day processes are identified by aerial photo interpretation and subsequently modelled with a simple rusle approach on a monthly basis in this study boundary conditions such as future precipitation were taken from the a2 future climate scenario published by the international panel on climate change ipcc special report on emission scenarios sres moreover current land use was identified from aerial photographs and future land use scenarios were developed considering ecological and socio economical issues for present day conditions of the test area subsequently the different climate and land use scenarios were analysed to study soil erosion susceptibility on the landscape scale the study shows that even with a decline in precipitation volume until 2070 in some months higher erosion rates occur due to higher rainfall erosivity furthermore land use changes play an important role for soil erosion susceptibility as shown the various scenarios can effectively reduce or enhance soil erosion

assessment of soil erosion sensitivity and post timber harvesting erosion response in a mountain environment of central italy article i nfo this study aimed to assess the effects of forest management on the occurrence of accelerated soil erosion by water the study site is located in a mountainous area of the italian central apennines here forest harvesting is a widespread forestry activity and is mainly performed on the moderate to steep slopes of the highlands through modeling operations based on data on soil properties and direct monitoring of changes in the post forest harvestingsoilsurfacelevelatthehillslope scale we show thattheobserved site became pronetosoilero sion after human intervention indeed the measured mean soil erosion rate of 49 t ha 1 yr 1 for the harvested watershed is about 21 times higher than the rate measured in its neighboring undisturbed forested watershed 2 3 t ha 1 yr 1 the erosive response is greatly aggravated by exposing the just harvested forest with very limited herbaceous plant cover to the aggressive attack of the heaviest annual rainfall without adopting any conservation practices the erosivity of the storms during the first four months of field measurements was 1571 mj mm h 1 ha 1

preliminary study of the erosion mechanisms in a biancana badland tuscany italy abstract italian badlands are present along the appennini mountains with an annual precipitation which ranges from 400 to 1200 mm the genesis of these badlands has often been studied whereas current processes and erosion rates have only rarely been examined and measured this paper describes a preliminary study on a badland developed in temperate mediterranean climate and located in sw tuscany italy the selected site is characterized by biancane dome shaped features a few meters in height generally having a vegetated nne aspect and severely eroded ssw slope with a sub horizontal basal pediment field rainfall and runoff experiments were carried out field results were substantiated by data collected in specially devised laboratory tests it was concluded that near surface pipes which develop at the point of contact between a surficial layer of weathered and severely fractured regolith and the less fractured and weathered regolith underneath are the main drainage channels while rills play a secondary role soil detachment is largely due to mechanical and chemical slaking of the regolith during infiltration the role of runoff is almost solely transport in particular it was found that the runoff detachment rate is limited by the rate at which the water front penetrates into the regolith

climate scale modelling of suspended sediment load in an alpine catchment debris flow rio cordon northeastern italy abstract pulsing storms and prolonged rainfall can drive hydrological damaging events in mountain regions with soil erosion and debris flow in river catchments the paper presents a parsimonious model for estimating climate forcing on sediment loads in an alpine catchment rio cordon northeastern italian alps hydroclimatic forcing was interpreted by the novel clismssl climate scale modelling of suspended sediment load model to estimate annual sediment loads we used annual data on suspended solid loads monitored at an experimental station from 1987 to 2001 and on monthly precipitation data the quality of sediment load data was critically examined and one outlying year was identified and removed from further analyses this outlier revealed that our model underestimates exceptionally high sediment loads in years characterized by a severe flood event for all other years the clismssl performed well with a determination coefficient r2 equal to 0 67 and a mean absolute error mae of 129 mg y 1 the calibrated model for the period 1986 2010 was used to reconstruct sediment loads in the river catchment for historical times when detailed precipitation records are not available for the period 1810 2010 the model results indicate that the past centuries have been characterized by large interannual to interdecadal fluctuations in the conditions affecting sediment loads this paper argues that climate induced erosion processes in alpine areas and their impact on environment should be given more attention in discussions about climate driven strategies future work should focus on delineating the extents of these findings e g at other catchments of the european alpine belt as well as investigating the dynamics for the formation of sediment loads

atmospheric boundary layer structure and drag coefficients over sea ice this paper estimates the air sea drag coefficient for first year ice from recent aircraft measurements and reconciles the range of observed drag coefficients 103cd 1 2 3 7 referenced to 10 m for all sea ice types based on ice roughness and seasonal meteorology for the purpose of sea ice modeling it is necessary to define an effective drag coefficient which relates regional stress to regional wind because sea ice is heterogeneous on scales less than 20 km regional stress is influenced by the distribution of surface roughness the buoyancy flux from quasi periodic leads and external atmospheric conditions principally the inversion height 103cd is 1 3 1 5 for smooth ice but is much greater for nonflat surfaces for wind speeds greater than 5 m s and air temperatures below freezing the effective 103cd is 2 5 3 0 for nearly continuous pack ice such as first year ice in seasonal ice zones and central arctic basin the range of values of 103cd is 3 0 3 7 for unstable boundary layers typical of off ice winds in the marginal ice zone miz or even greater if the ice has been broken by a recent storm cd values at the lower end of these ranges are associated with low inversion heights these coefficients are confirmed by 103cd of 2 9 2 5 and 3 1 for first year sea ice calculated from gust probe data collected by the noaa p 3 aircraft interior to the inner miz in the bering sea during the marginal ice zone experiment mizex west in february 1983 and 103cd of 2 6 for the arctic calculated from arctic ice dynamics joint experiment aidjex aircraft data for february 1976 the effective drag coefficient with the presence of even a small concentration of sea ice is greater than the oceanic value as shown by a 103cd of 2 2 calculated from noaa p 3 gust probe data over a 40 km track of 0 4 ice concentration in the outer miz of the greenland sea in june 1984 during mizex 84 the relation of surface wind and stress to the geostrophic wind for shallow inversion heights typical of high latitudes is reviewed with a turbulent closure atmospheric boundary layer model the winter arctic is typified by low inversions 100 m low geostrophic drag coefficients and large geostrophic surface wind turning angles with low functional dependence on surface roughness seasonal ice zones are typified by a more modest influence of the inversion on boundary layer characteristics

modeling sediment yields in italian catchments abstract sediment yield observations derived from 40 long term sedimentation records in italian reservoirs were used to calibrate and validate the spatially distributed sediment delivery model watem sedem using the best data available at national scale the sediment yield data set includes records from semi natural catchments in northern italy as well as agricultural and semi natural basins in central and southern italy the average size of the catchments is 150 km2 with mean annual sediment yields ranging from 0 20 to 20 t ha 1 year 1 watem sedem estimates mean annual sediment fluxes to permanent river channels depending on the local transport capacity the sediment flux is detachment limited or transport limited the optimal transport capacity parameters for italian conditions were derived via automatic calibration procedures a global model calibration procedure taking into account all catchments in the dataset led to an overestimation of the sediment yield for the mountain catchments and an underestimation for the non mountain catchments sediment yield estimates are more reliable when calibration procedures are applied separately for mountain and non mountain catchments the model performance of watem sedem is rather poor in the mountain catchments r 0 25 which suggests that the model structure is too simplified to come to an adequate description of the sediment fluxes the model performance for the non mountain catchments which are more important from a management point of view is significantly better r 0 51 considering the fact that data layers with a 75 75 m resolution were used the results are encouraging the further development and application of spatially distributed sediment yield models at regional and national scale levels

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

soil erosion risk scenarios in the mediterranean environment using rusle and gis an application model for calabria southern italy abstract soil erosion by water wse has become a relevant issue at the mediterranean level in particular natural conditions and human impact have made the calabria southern italy particularly prone to intense wse the purpose of this investigation is to identify areas highly affected by wse in calabria by comparing the scenarios obtained by assuming control and preventive measures and actions as well as actual conditions generated by forest fires also in the presence of conditions of maximum rainfall erosion geographic information system techniques have been adopted to treat data of reasonable spatial resolution obtained at a regional scale for application to the rusle model this work is based on the comparison of such data with a basic scenario that has been defined by the present situation present scenario in this scenario i r has been assessed by means of an experimental relation adjusted to calabria on the basis of 5 min observations ii k has been drawn from the soil map of calabria including 160 soilscapes iii ls has been estimated according to the rusle2 model by using among other subfactors a 40 m square cell dtm iv c has been derived by processing the data inferred from the project corine land cover whose legend includes 35 different land uses on three levels and v p has been hypothesized as equal to 1 for the remaining three hypothesized scenarios the rusle factors have been adjusted according to experimental data and to data in the literature in particular forest areas subject to fire have been randomly generated as far as fire location extension structure and intensity are concerned the values obtained by the application of the rusle model have emphasized that land management by means of measures and actions for reducing wse causes a notable reduction of the erosive rate decreasing from 30 to 12 3 mg ha 1 y 1 on the other hand variations induced by hypothetical wildfires in forests on 10 of the regional territory bring wse over the whole region to values varying from 30 to 116 mg ha 1 y 1 this study can be offered to territorial planning authorities as an evaluation instrument as it highlights the merits and limitations of some territorial management actions in fact in calabria no observations exist concerning the implications of these actions

atmospheric boundary layer modification drag coefficient and surface heat flux in the antarctic marginal ice zone during a traverse of the antarctic marginal ice zone miz near the greenwich meridian in october 1981 we launched a series of radiosondes along a 150 km track starting at the ice edge since the wind was from the north off the ocean these radiosonde profiles showed profound modification of the atmospheric boundary layer abl as the increasing surface roughness decelerated the flow the primary manifestation of this modification was a lifting of the inversion layer with increasing distance from the ice edge by the induced vertical velocity but there was also a cooling of the stably stratified mixed layer below the inversion and a consequent flux of sensible heat to the surface that averaged over 200 w m2 the magnitude of this flux suggests that atmospheric heat transport plays a significant role in the destruction of ice in the antarctic miz using the rising of the inversion and abl similarity theory we estimated the change in the neutral stability drag coefficient cd across the miz cd increased from its open ocean value 1 2 10 3 at the ice edge to 4 0 10 3 at 80 90 ice concentration we present an equation for this dependence of drag on ice concentration that should be useful for modeling the surface stress in marginal ice zones