snow grain size profiles deduced from microwave snow emissivities in antarctica spaceborne microwave radiometers are an attractive tool for observing antarctic climate because their measurements are related to the snow temperature however the conversion from microwave emission to snow temperature is not simple and strongly depends on the emissivity through snow properties this difficulty in predicting the snow property profile for antarctic conditions is the main bottleneck in the retrieval of accurate climate information from microwave radiometers we attempt to explain the vertically polarized emissivity at 19 3 and 37 ghz derived from brightness temperatures acquired by the special sensor microwave imager ssm i and physical temperature from the era 40 re analysis in antarctica the snow emissivities at 19 3 and 37 ghz are nearly equal although a decrease with frequency is expected to explain this we consider various profiles of snow grain size and density and predict their emissivity using a dense medium radiative transfer dmrt model the results show that the emissivities cannot be explained by constant profiles of grain size and density heterogeneous snowpacks need to be considered we first test random variations of snow density and grain radius with depth and then monotonic and continuous variations in the snow grain radius in both cases we show that an overall increase of the snow grain radius with depth is required to match the observed emissivity in antarctica in addition two parameters characterizing the snow grain profiles are retrieved and compared with 1 in situ measurements of grain size at various locations in east antarctica 2 grain size estimated using visible spaceborne radiometers and 3 a semi empirical relationship for grain growth

seasonal cycles of antarctic surface energy balance from automatic weather stations we present the seasonal cycle of the antarctic surface energy balance seb using 4 years 1998 2001 of automatic weather station aws data the four awss are situated on an ice shelf in the coastal and inland katabatic wind zone and the interior plateau of dronning maud land to calculate surface temperature we use a seb closure assumption for a surface skin layer modelled and observed surface have a root mean square difference of 1 8 k at the plateau aws corresponding to an uncertainty in the seb of 5 w m 2 and 1 k 3 w m 2 at the other sites the effect of wind speed sensor freezing on the calculated seb is discussed at all sites the annual mean net radiation is negative and the near surface air is on average stably stratified differences in the seasonal cycle of the seb are mainly caused by the different wind climates at the aws sites in the katabatic wind zone a combination of clear skies and strong winds forces a large wintertime turbulent transport of sensible heat towards the surface which in turn enhances the longwave radiative heat loss on the coastal ice shelf and on the plateau strong winds are associated with overcast conditions limiting the radiative heat loss and sensible heat exchange during the short antarctic summer the net radiation becomes slightly positive at all sites away from the cold interior the main compensating heat loss at the surface is sublimation in the interior summer temperatures are too low to allow significant sublimation to occur here surface heat loss is mainly due to convection

sediment budget analysis of slope channel coupling and in channel sediment storage in an upland catchment southeastern australia abstract slope channel coupling and in channel sediment storage can be important factors that influence sediment delivery through catchments sediment budgets offer an appropriate means to assess the role of these factors by quantifying the various components in the catchment sediment transfer system in this study a fine

degradation of the mitchell river fluvial megafan by alluvial gully erosion increased by post european land use change queensland australia along low gradient rivers in northern australia there is widespread gully erosion into unconfined alluvial deposits of active and inactive floodplains on the mitchell river fluvial megafan in northern queensland river incision and fan head trenching into pleistocene and holocene megafan units with sodic soils created the potential energy for a secondary cycle of erosion in this study rates of alluvial gully erosion into incipiently unstable channel banks and or pre existing floodplain features were quantified to assess the influence of land use change following european settlement alluvial gully scarp retreat rates were quantified at 18 sites across the megafan using recent gps surveys and historic air photos demonstrating rapid increases in gully area of 1 2 to 10 times their 1949 values extrapolation of gully area growth trends backward in time suggested that the current widespread phase of gullying initiated between 1880 and 1950 which is post european settlement this is supported by young optically stimulated luminescence osl dates of gully inset floodplain deposits lidar terrain analysis historic explorer accounts of earlier gully types and archival records of cattle numbers and land management it is deduced that intense cattle grazing and associated disturbance concentrated in the riparian zones during the dry season promoted gully erosion in the wet season along steep banks adjacent floodplain hollows and precursor gullies this is a result of reduced native grass cover increased physical disturbance of soils and the concentration of water runoff along cattle tracks in addition to fire regime modifications episodic drought and the establishment of exotic weed and grass species geomorphic processes operating over geologic time across the fluvial megafan predisposed the landscape to being pushed by land used change across an intrinsically close geomorphic threshold towards instability the evolution of these alluvial gullies is discussed in terms of their initiation development future growth and stabilisation and the numerous natural and anthropogenic factors influencing their erosion

a sediment budget for a grazed semi arid catchment in the burdekin basin australia abstract in catchments adjacent to the great barrier reef world heritage area in queensland australia there is a growing concern that sediments and nutrients being exported from the land are having a detrimental effect on coral reef communities there is a need to determine the processes and rates of erosion from the major land use types so that management intervention can be initiated to reduce sediment yields where required this paper presents a sediment budget for weany creek a 13 5 km 2 grazed semi arid sub catchment of the burdekin river catchment australia a range of field methods was used to measure erosion from hillslopes gullies and stream banks as well as identify the amount of sediment being deposited and remobilised on the bed of gullies and the stream network the data suggests that at least during drought conditions the primary erosion source in this catchment is gully erosion however the largest source of sediment in the budget is actually associated with the remobilisation of in channel sediment stores overall the sediment budget is comprised of 81 coarse material and 19 fine sediment and an agreement between the fine sediment yield estimated in the sediment budget and the yield measured at the catchment outlet is within 10 the total sediment yield estimated for this catchment is 4205 t yr 1 and is much lower than expected for a catchment of this size this may reflect the drought conditions during the measurement period however there is also the possibility that the primary erosion sources have been exhausted and the rates of sediment loss may be much lower now than they may have been in the past nonetheless the results show that stored sediment which may have been deposited in the channel many decades ago is an important contributor to end of catchment sediment yields and warrants further investigation

how porosity and permeability vary spatially with grain size sorting cement volume and mineral dissolution in fluvial triassic sandstones the value of geostatistics and local regression although it is well known that sandstone porosity and permeability are controlled by a range of parameters such as grain size and sorting amount type and location of diagenetic cements extent and type of compaction and the generation of intergranular and intragranular secondary porosity it is less constrained how these controlling parameters link up in rock volumes within and between beds and how they spatially interact to determine porosity and permeability to address these unknowns this study examined triassic fluvial sandstone outcrops from the uk using field logging probe permeametry of 200 points and sampling at 100 points on a gridded rock surface these field observations were supplemented by laser particle size analysis thin section point count analysis of primary and diagenetic mineralogy quantitative xrd mineral analysis and sem edax analysis of all 100 samples these data were analyzed using global regression variography kriging conditional simulation and geographically weighted regression to examine the spatial relationships between porosity and permeability and their potential controls the results of bivariate analysis global regression of the entire outcrop dataset indicate only a weak correlation between both permeability porosity and their diagenetic and depositional controls and provide very limited information on the role of primary textural structures such as grain size and sorting subdividing the dataset further by bedding unit revealed details of more local controls on porosity and permeability an alternative geostatistical approach combined with a local modeling technique geographically weighted regression gwr subsequently was used to examine the spatial variability of porosity and permeability and their controls the use of gwr does not require prior knowledge of divisions between bedding units but the results from gwr broadly concur with results of regression analysis by bedding unit and provide much greater clarity of how porosity and permeability and their controls vary laterally and vertically the close relationship between depositional lithofacies in each bed diagenesis permeability and porosity demonstrates that each influences the other and in turn how understanding of reservoir properties is enhanced by integration of paleoenvironmental reconstruction stratigraphy mineralogy and geostatistics

evaluation of prediction capability of the artificial neural networks for mapping landslide susceptibility in the turbolo river catchment northern calabria italy abstract landslides are one of the most widespread natural hazards that cause damage to both property and life every year and therefore the spatial distribution of the landslide susceptibility is necessary for planning future developmental activities in this paper the artificial neural network ann technique is tested for developing a landslide susceptibility map in turbolo river catchment north calabria south italy landslides were mapped through air photo interpretation and field surveys by identifying both the landslide depletion zones dzs and accumulation zones azs and relevant geo environmental thematic layers pertaining to landslide predisposing factors were generated using air photo interpretation field surveys and geographic information system gis tools ten predisposing factors were related to the occurrence of landslide lithology faults land use drainage network and a series of topographic factors elevation slope aspect plan curvature topographic wetness index twi and stream power index spi in order to evaluate and validate landslide susceptibility the dzs were divided in two groups using a random partition strategy the first group training set was used to prepare the susceptibility map employing a back propagation learning algorithm in the idrisi taiga software the second group testing set was used to validate the landslide susceptibility model using the confusion matrix and the receiver operating characteristic roc curve the susceptibility map was classified into five susceptibility classes very low low moderate high and very high about 46 of the study area falls in high to very high susceptible classes and most of the dzs mapped 87 3 occur in the same classes the validation results showed satisfactory agreement between the susceptibility map and the dzs locations over 85 of the dzs of the validation set are correctly classified falling in high and very high susceptibility areas also the roc curve had shown an area under curve auc value of 0 90 which demonstrates the robustness and good reliability of the landslide susceptibility model according to these results we conclude that the map produced by the artificial neural network is reliable and the methodology applied in the study produced high performance and satisfactory results which may be useful for land planning policy

characteristics of spatial distribution of debris flow and the effect of their sediment yield in main downstream of jinsha river china debris flow hazard posts a big threat to the main downstream of jinsha river where a number of huge power stations are under construction the characteristics of spatial distribution of debris flows and the effect of their sediment yield on the reservoir areas have been studied an automatic recognition module was developed to extract the geometry of debris flow channels from remote sensing data spatial distribution pattern of debris flows is obtained through combining the inventory database and multi source remote sensing investigation the distribution of debris flows has high dependency on the various factors including geology geomorphology climate hydrology and human economic activities the debris flows distributed in the study area are characterized by group and pair distribution uncompleted deposition fans highly controlled by faults and tectonic activities spatial variation between left bank and right bank and different subdivisions the sediment yield caused by debris flow activates is evaluated using multi year observation data from numerous observation stations quantitative studies have been performed on the relationship between the sediment yield and the debris flow area a relatively fix ratio of 2 6 104 t km2 has been found in different subdivisions of main downstream area which shows that the source of sediment discharged into jinsha river primarily come from debris flow activities another ratio is evaluated to represent the transforming possibility of debris flow materials to bed sediment load and suspended sediment load in the river based on these findings the potential effect of sediment yield caused by debris flows on reservoir areas is discussed the zonation map shows the different effect of debris flow sediment on different dam site area which shows a good agreement with variation of debris flow spatial distribution

insights into river bank erosion processes derived from analysis of negative erosion pin recordings observations from three recent uk studies recent studies of river bank erosion in three catchments in the uk have been characterized by the persistent occurrence of negative erosion pin results the cause of these negative recordings is considered with reference to field data from the afon trannon nant tanllwyth and river arrow and to a laboratory study of freeze thaw and desiccation processes it seems that there is potential for and in some cases evidence of a number of different circumstances that generate negative results but none of these alone is sufficient to explain all incidents factors considered include deposition of sediment during high flows soil fall from the upper parts of the bank on to lower erosion pins loosening of the soil surface and expansion contraction of the soil mass with fluctuations in temperature and moisture content movement of the erosion pin within the bank and human interference each has its own implications for the use of erosion pins further issues arise when including negative data in subsequent data analysis and it is demonstrated that attempts to correlate erosion rates with hydro meteorological data in order to ascertain causes of erosion will be influenced by the way in which negative data are handled it is thus suggested that any study of river bank erosion using erosion pins should state whether or not negative data were obtained and if so how they were included in data analysis failure to include this information could lead to comparison of mean erosion rates that reflect bank processes very differently the studies presented here offer a clear example of the value of anomalous field data results which do not appear to fit expected patterns can reveal as much about the processes in operation as those that do

badland susceptibility assessment in volterra municipality tuscany italy by means of gis and statistical analysis badlands can be defined as complex and peculiar types of erosional formations that develop in clayey environments and are mainly favoured by lithological and topographic features as well as by markedly seasonal climate this work aims at assessing badland susceptibility in volterra municipality located in tuscany region italy by means of bivariate statistical analysis implemented in a geographic information system the volterra municipality is affected by intense soil erosion processes including rill and gully erosion usually turned out as badland forms mostly occurring on pliocene pleistocene clayey sediments firstly an inventory of 234 badland areas was produced on the basis of an available pre existing database integrated with the interpretation of aerial photographs and supported by a field survey badlands were distinguished in type a and type b according to different evolutional stage vegetation presence and consequently different landforms then nine geoenvironmental factors supposed to be predisposing for badland occurrence were chosen and combined with the spatial frequency of badland areas derived from the inventory through information value statistic approach the result was a badland susceptibility map that highlights a strong control of lithology slope gradient and land use in conditioning badland development in the investigated area the effectiveness of the performed model was demonstrated by a validation test computed through a receiver operating characteristics analysis the outcomes of this work provide an updated badland database that is useful for soil erosion management and further land use planning within the volterra municipality

fluvial sediment budgets in the north carolina piedmont phillips j d 1991 fluvial sediment budgets in the north carolina piedmont geomorphology 4 231 241 sediment budgets for four large 1000 km 2 drainage basins in the piedmont physiographic province of north carolina were estimated from data compiled during erosion and sedimentation surveys budgets for the upper tar upper neuse haw and deep river basins showed broadly similar trends in allocation of eroded sediment among yield and storage sediment yield as a percentage of mean annual gross erosion within the basins averaged 10 this was less than the rate of alluvial storage which averaged 14 of annual gross erosion about 76 of the mean annual erosion was stored as colluvium on hillslopes there are relatively small differences in sediment delivery and storage ratios among the study basins this suggests that the relative order of magnitude of the allocation of eroded sediment for southern piedmont rivers is colluvial storage alluvial storage and yield of the sediment that does reach the streams more than half is stored as alluvium on an average annual basis aggrading channels and floodplains siltation of benthic habitats and sediment pollution problems are thus likely to persist unless dramatic reductions in upland erosion or in sediment delivery to streams are realized with respect to longer term basin evolution results point to the need for an improved understanding of the temporal scales of colluvial and alluvial sediment storage

landslide hazard spatial analysis and prediction using gis in the xiaojiang watershed yunnan china abstract the xiaojiang watershed in southwest china has high landslide hazard and has been given the title of the museum of geohazards in china however the available information on landslides in the xiaojiang watershed is still limited we constructed the essential spatial database of landslides using the gis techniques the quantitative relationships between landslides and factors affecting landslides are established by the certainty factor model cf the affecting factors such as lithology structure slope angle slope aspect elevation and off fault distance are recognized by applying cf value integration and landslide zonation the most significant affecting factors are selected the widespread landslide activities in the xiaojiang watershed are caused and triggered by heavy rain a promising approach to modeling the spatial distribution of rainfall triggered landslide is combining the mechanistic infinite slope stability model with a hydrological model a model modified from stability index mapping sinmap is used to prepare the landslide susceptibility maps for different rainfall conditions information on these maps could be useful for explaining the known existing landslide making emergency decisions and relieving the efforts on the avoidance and mitigation of future landslide hazards

comparison of the implementation of rock engineering system and analytic hierarchy process methods upon landslide susceptibility mapping using gis a case study from the eastern achaia county of peloponnesus greece as landslides are very common in greece causing serious problems to the social and economic welfare of many communities the implementation of a proper hazard analysis system will help the creation of a reliable susceptibility map his will help local communities to define a safe land use and urban development the purpose of this study is to compare the implementation of two semi quantitative landslide assessment approaches using landslide susceptibility maps compiled in a gis environment the compared methods are rock engineering system res and the analytic hierarchy process ahp for the landslide susceptibility analysis the northeastern part of the achaia county was examined this area suffers from many landslides because of its neighborhood with the tectonically active corinthian gulf and its geological setting neogene sediments flysch and other bedrock formations with local overthrusts ten parameters were used in both methodologies and each one was separated into five categories ranging from 0 to 4 representing their specific conditions derived from the investigation of the landslides in the western part of the study area ranking area a layer map was generated for each parameter using gis while the weighting coefficients of each methodology were used for the compilation of res and ahp final maps of the eastern part of the study area validating area by examining these two maps it is revealed that even though both correctly show the landslide status of the second site the res map reveals a better behavior in the spatial distribution of the various landslide susceptibility zones

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

geostatistical analysis in weathering studies case study for stanton moor building sandstone geostatistical techniques for spatial prediction and spatial simulation have been used in an innovative application to the study of weathering of natural building stone the study investigates the differences in the spatial variation of permeability characteristics between fine and coarse grained stanton moor building sandstone non destructive permeability measurements using an unsteady state portable probe permeameter were made on three adjacent faces of two cubic blocks representative of fine to medium grained and medium to coarse grained stanton moor sandstone the findings provide greater understanding in the investigation of the durability characteristics of the stanton moor sandstone and show that the spatial distribution and variability of permeability is more important in predicting the overall strength and weathering properties than mean permeability and absolute minimum and maximum values the results suggest that both primary textural characteristics such as grain size and extent of cementation appear to be important factors in determining the overall durability properties of stanton moor sandstone as a building stone geostatistical analysis has been shown to be an important tool in the characterization of spatial variation for the investigation of weathering of building stones copyright 2006 john wiley sons ltd

magnitude frequency characteristics and preparatory factors for spatial debris slide distribution in the northern faroe islands abstract the faroe islands in the north atlantic ocean are highly susceptible to debris avalanches and debris flows originating from debris slide activity in shallow colluvial soils to provide data for hazard and risk assessment of debris avalanches and debris flows this study aims at quantifying the magnitude and frequency of their debris slide origins as well as identifying which preparatory factors are responsible for the spatial debris slide distribution in the landscape for that purpose a debris slide inventory was generated from aerial photo interpretation api fieldwork and anecdotal sources covering a 159 km2 study area in the northern faroe islands a magnitude cumulative frequency mcf curve was derived to predict magnitude dependant debris slide frequencies while preparatory factors responsible for spatial debris slide distribution were quantified through gis supported discriminant function analysis dfa nine factors containing geological lithology dip geomorphological slope angle altitude aspect plan and profile curvature and land use infield outfield sheep density information were included in the multivariate analysis debris slides larger than 100 m2 with magnitude expressed as topographic scar area can be predicted from the power law function y 936 26x 1 277 r2 0 98 while a physical explanation is preferred for the roll over pattern of smaller slope failures the dfa is able to correctly classify app 70 of the modeled terrain units into their pre determined stable unstable groups preparatory factors responsible for the spatial debris slide distribution are aspect slope angle sheep density plan curvature and altitude while influence of the remaining factors is negligible

statistical models for slope instability classification abstract statistical models for reliable hazard assessment of landslides in a given area are presented the models are based on information theory and regression analysis information theory is a branch of probability in which the most significant feature is unpredictability and regression analysis is based on simple statistical theory both methods of statistical prediction have been applied to slope instability to provide cross validation of the results a fortran 77 program for computer aided assessment of the landslide hazard has been developed the program considers the factors affecting the slope instability and history of past landslides of the area as its input the program also calculates the information and regression value in a given area and classifies the area into different grades of instability a case study of landslide hazard assessment of a 66 km2 area in parts of the alkananda valley the gharwal himalaya is presented the factors considered in the analysis are angle and height of the slope rock type and geological structures such as faults and thrusts the results obtained are illustrated in the form of landslide hazard maps the predicted results are compared by the above methods

landslide spatial susceptibility mapping by using gis and remote sensing techniques a case study in zigui county the three georges reservoir china landslides are one of the most destructive phenomena in nature and damage both property and lives every year in this paper a logistic regression model with datasets developed via a geographic information system and remotely sensed data was used to create a landslide spatial susceptibility map for the three gorges project reservoir region on the yangtze river in zigui county the five causative factors used in the logistic regression model were evaluated in different ways topographic slope and topographic aspect were derived from a topographical map at 1 50 000 scale bed rock slope relationship and lithology were obtained from a geological map at 1 50 000 scale and fractional vegetation cover fvc which represents the reduced frequency of landslides due to the vegetation canopy and ground cover and is also one of the most difficult parameters to estimate over broad geographic areas was generated using a back propagation neural network bpnn method based on cbers china brazil earth resources satellite data the results of which were compared with values measured in the field the obtained pearson correlation coefficient r was 0 899 then the fvc factor and the other four factors were used as the input to a logistic regression model by integrating the five factor maps in the geographical information system gis via pixel based computing the landslide spatial susceptibility map was obtained the study area was reclassified into four categories of landslide susceptibility severe moderate low and very low approximately 15 0 of the study area was identified as severe susceptibility and very low low and moderate susceptibility zones covered 21 8 41 7 and 21 5 of the area respectively these results have an accuracy of 78 90 thus by using a logistic regression model in a gis environment a spatial susceptibility map of landslides can be obtained and the regions in zigui county that are susceptible to landslides and need immediate protective and mitigation measures can be identified

a sediment budget for a small semiarid watershed in southeastern arizona usa article i nfo article history a sediment budget was developed for a 43 7 ha and a nested 3 7 ha semiarid shrub dominated watershed based on hydrologic geomorphic erosion and sediment data collected from 1963 through 2006 on the usda ars walnut gulch experimental watershed in the southwestern us sediment budgets based on such extensive and intensive field campaigns over several decades are rare the sediment budget was bal anced with a high degree of confidence because the study watershed is controlled by an earth dam at the out let although the channel network is well developed and incising in the steeper reaches of the watershed hillslopes are the dominant source of sediment contributing 85 of the overall total sediment yield erosion and sediment redistribution were driven by highly variable rainfall and runoff during july august and september sediment transfers are influenced by channel abstractions and the presence of the outlet dam which created conditions for deposition in the pond approach reach although earth dams are ubiquitous throughout the southwestern us and they can provide a measure of outlet sediment yield these outlet mea surements may be insufficient to interpret temporal and spatial variability in watershed sediment dynamics identification of dominant processes and sediment sources is critical for determining management actions that will improve rangeland conditions published by elsevier b v

effects of the morphology of sediment transporting channels on the erosion and deposition of debris flows a series experiments are conducted to investigate the effects of streambed profile on the erosion and deposition of debris flows it is found that straight channel can increase the run out of debris flows by 10 25 compared to that of surfaces without channels and that travel distance was positively correlated with the hydraulic radius of the channel in addition the presence of straight channels caused the volume of debris flow deposition to become normally distributed with respect to travel distance in the case of curved channels increases in the sinuosity index resulted in significant blockage and obstruction in the deposition zone the maximum deposition volume for a channel with a comparatively low sinuosity index 1 05 was 50 of the minimum deposition volume for a straight channel furthermore the channel curvature affected not only the positions of deposition peaks along the travel distance but also the debris flow magnitudes in each unit interval 0 5 m this study demonstrates the effects of differences in channel morphology on the erosional and depositional processes of gully debris flows these findings are of significant importance for guiding debris flow risk assessment and for the restoration and reconstruction of downstream regions

sediment source changes over the last 250 years in a dry tropical catchment central queensland australia abstract rivers draining to the great barrier reef are receiving increased attention with the realisation that european land use changes over the last 150 years may have increased river sediment yields and that these may have adversely affected the reef environment mitigation of the effects associated with such changes is only possible if information on the spatial provenance and dominant types of erosion is known to date very few field based studies have attempted to provide this information this study uses fallout radionuclide 137cs and 210pbex and geochemical tracing of river bed and floodplain sediments to examine sources over the last 250 years for theresa creek a subcatchment of the fitzroy river basin central queensland australia a monte carlo style mixing model is used to predict the relative contribution of both the spatial geological sources and erosion types the results indicate that sheetwash and rill erosion from cultivated basaltic land and channel erosion from non basaltic parts of the catchment are currently contributing most sediment to the river system evidence indicates that the dominant form of channel erosion is gully headcut and sidewall erosion sheetwash and rill erosion from uncultivated land i e grazed pasture woodland is a comparatively minor contributor of sediment to the river network analysis of the spatial provenance of floodplain core sediments in conjunction with optical dating and 137cs depth profile data suggests that a phase of channel erosion was initiated in the late nineteenth century with the development of land underlain by basalt in the mid twentieth century the dominant source of erosion shifted to cultivated land although improvements in land management practices have probably resulted in a decrease in sediment yield from cultivated areas in the later half of the twentieth century on a basin wide scale because of the limited spatial extent of cultivation channel sources are likely to be the largest contributor of sediment to the fitzroy river accordingly catchment management measures focused on reducing sediment delivery to the great barrier reef should focus primarily on decreasing erosion from channel sources

a physically based model for the topographic control on shallow landsliding a model for the topographic influence on shallow landslide initiation is developed by coupling digital terrain data with near surface through flow and slope stability models the hydrologic model topog o loughlin 1986 predicts the degree of soil saturation in response to a steady state rainfall for topographic elements defined by the intersection of contours and flow tube boundaries the slope stability component uses this relative soil saturation to analyze the stability of each topographic element for the case of cohesionless soils of spatially constant thickness and saturated conductivity the steady state rainfall predicted to cause instability in each topographic element provides a measure of the relative potential for shallow landsliding the spatial distribution of critical rainfall values is compared with landslide locations mapped from aerial photographs and in the field for three study basins where high resolution digital elevation data are available tennessee valley in marin county california mettman ridge in the oregon coast range and split creek on the olympic peninsula washington model predictions in each of these areas are consistent with spatial patterns of observed landslide scars although hydrologic complexities not accounted for in the model e g spatial variability of soil properties and bedrock flow control specific sites and timing of debris flow initiation within areas of similar topographic control

the recent history of erosion and sedimentation on the southern tablelands of southeastern australia sediment flux dominated by channel incision abstract as in other regions colonised from europe within the last few centuries australia s vegetation and soils have been dramatically changed by clearing cropping and grazing in southeastern australia particularly on the southern tablelands the impacts of european settlement are clearly manifested by channel incision by using stratigraphic and documentary evidence in conjunction with aerial photographs sediment budgets for the post settlement period have been constructed to define the fluxes and stores of sediment for each of the major geomorphic components of the 136 km2 catchment of jerrabomberra creek near canberra using these budgets and some plausible assumptions it has been possible to approximate the history of both the sediment delivery ratio and sediment yield for this catchment while the quantities estimated in this analysis are approximations the trends through time are credible sediment yield increased rapidly to a peak after european settlement and has returned to a level between the peak and the pre european value the delivery ratio has followed a similar trend the most general conclusion to emerge is that in this landscape both the total sediment flux and the sediment yield of the catchment have been dominated by channel erosion this result is contrary to the findings in many parts of the world where sheet and rill erosion dominates the fluxes the soil conservation implication of these results is clear to control off site effects of erosion the focus must be on the channels

the dominant erosion processes supplying fine sediment to three major rivers in tropical australia the daly nt mitchell qld and flinders qld rivers abstract the tropics of northern australia have received relatively little attention with regard to the impact of soil erosion on the many large river systems that are an important part of australia s water resource especially given the high potential for erosion when long dry seasons are followed by intense wet season rain here we use 137cs concentrations to determine the erosion processes supplying sediment to two major northern australian rivers the daly river northern territory and the mitchell river queensland we also present data from five sediment samples collected from a 100 km reach of the cloncurry river a major tributary of the flinders river queensland concentrations of 137cs in the surface soil and subsurface channel banks and gully samples were used to derive best fit probability density functions describing their distributions these modelled distributions are then used to estimate the relative contribution of these two components to the river sediments our results are consistent with channel and gully erosion being the dominant source of sediment with more than 90 of sediment transported along the main stem of these rivers originating from subsoil we summarize the findings of similar studies on tropical australian rivers and conclude that the primary source of sediment delivered to these systems is gully and channel bank erosion previously as a result of catchment scale modelling sheet wash and rill erosion was considered to be the major sediment source in these rivers identifying the relative importance of sediment sources as shown in this paper will provide valuable information for land management planning in the region this study also reinforces the importance of testing model predictions before they are used to target investment in remedial action

temperatures heating rates and vapour pressures in near surface snow at the south pole a finite volume model is used to simulate 9 years 1995 2003 of snow temperatures at the south pole the upper boundary condition is skin surface temperature derived from routine upwelling longwave radiation measurements while the lower boundary condition is set to the seasonal temperature gradient at 6 5 m depth taken from prior measurements at the south pole we focus on statistics of temperature heat fluxes heating rates and vapour pressures in the top metre of snow but present results from the full depth of the model 6 5 m the monthly mean net heat flux into the snow agrees with results from previous studies performed at the south pole on shorter timescales the heating rates and vapour pressures show large variability the net heat flux into the snow which is between 5wm 2 in the monthly mean can be greater than 20 w m 2 on hourly timescales on sub daily timescales heating rates exceed 40 k d 1 in the top 10 cm of the snow subsurface temperatures and therefore heating rates are more variable during winter april september due to increased synoptic activity and the presence of a strong surface based atmospheric temperature inversion the largest vapour pressures 60 70 pa and vertical gradients of vapour pressure are found in the top metre of snow during the short summer december january in contrast during the long winter the low temperatures result in very small vapour pressures and insignificant vapour pressure gradients the high summertime vapour pressure gradients may be important in altering the isotopic composition of snow and ice on the antarctic plateau

antarctic boundary layer parametrization in a general circulation model 1 d simulations facing summer observations at dome c the parametrization of the atmospheric boundary layer abl is critical over the antarctic plateau for climate modelling since it affects the large scale temperature inversion and the katabatic winds this study challenges state of the art parametrizations used in general circulation models to represent the clear sky summertime diurnal cycle of the abl at dome c antarctic plateau the laboratoire de meteorologie dynamique zoom model is run in a 1d configuration on the fourth gewex atmospheric boundary layers study case simulations are analysed and compared to observations giving insights into the sensitivity of one model that participates to the intercomparison exercise snow albedo and thermal inertia are calibrated leading to better surface temperatures using the so called thermal plume model improves the momentum mixing in the diurnal abl in stable conditions four turbulence schemes are tested best simulations are those in which the turbulence cuts off above 35m in the middle of the night highlighting the contribution of the longwave radiation in the abl heat budget however the nocturnal surface layer is not stable enough to distinguish between surface fluxes computed with different stability functions the absence of subsidence in the forcings and an underestimation of downward longwave radiation are identified to be likely responsible for a cold bias in the nocturnal abl apart from model specific improvements the paper clarifies on which are the critical aspects to improve in general circulation models to correctly represent the summertime abl over the antarctic plateau

variability of sediment removal in a semiarid watershed field and documentary data from walnut gulch watershed an instrumented semiarid drainage basin of approximately 150 km 2 57 mi 2 in southeastern arizona show that 83 of the alluvium removed from the basin during a 15 year erosion episode beginning about 1930 was excavated from the highest order stream the amount of alluvium removed in the erosion episode would have been equal to a covering of about 4 cm 1 6 in over the entire basin the rate of sediment removal during the erosion episode was 18 times greater than the rate of present channel sediment transport production of sediment from slopes and channel throughput at present rates are approximately equal and refilling will not occur under present conditions the channel forms left by the massive evacuation of sediment impose controls on the spatial distribution of tractive force and total stream power that make renewed storage of sediment likely in only a few restricted locations modern instrumented records of a decade or more provide an inadequate perspective on long term sediment movement

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

rapid assessment of gully sidewall erosion rates in data poor catchments a case study in australia knowledge of erosion rates and sediment yields from gullies is critical for the effective prioritisation of management efforts aimed at reducing the impact of gully derived sediments on water quality this paper describes a rapid assessment method for estimating sidewall gully erosion rates for already established gully networks it combines a conceptual empirical model of the cycle of gully initiation and stabilisation with an easy to apply technique for assessing gully extent and dimensions the method is illustrated using a case study of the avon richardson catchment of north central victoria australia it is estimated that a total of 4 6 106tonnes of sediment have been generated in that catchment from gully erosion since the latest major phase of gullying in the mid 1800s this is equivalent to 8 9tha 1y 1 if sediment generation was evenly distributed spatially and temporally across the 3300km2 catchment over 160years prior to 2010 current rates of gully erosion are estimated to be 4700ty 1 equivalent to 1 4tha 1y 1 the results are comparable with observed rates of sidewall erosion in the avon richardson catchment further testing is required to build confidence in its applicability to assess sediment yields and for assisting regional authorities to plan remediation efforts

validation of the energy budget of an alpine snowpack simulated by several snow models snowmip project many snow models have been developed for various applications such as hydrology global atmospheric circulation models and avalanche forecasting the degree of complexity of these models is highly variable ranging from simple index methods to multi layer models that simulate snow cover stratigraphy and texture in the framework of the snow model intercomparison project snowmip 23 models were compared using observed meteorological parameters from two mountainous alpine sites the analysis here focuses on validation of snow energy budget simulations albedo and snow surface tem perature observations allow identification of the more realistic simulations and quantifi cation of errors for two components of the energy budget the net short and longwave radiation in particular the different albedo parameterizations are evaluated for different snowpack states in winter and spring analysis of results during the melting period allows an investigation of the different ways of partitioning the energy fluxes and reveals the complex feedbacks which occur when simulating the snow energy budget particular attention is paid to the impact of model complexity on the energy budget components the model complexity has a major role for the net longwave radiation calculation whereas the albedo parameterization is the most significant factor explaining the accu racy of the net shortwave radiation simulation

establishing sediment budgets for two small lowland agricultural catchments in the uk sediment budgets have been established for two small 4 km2 lowland agricultural catchments by using 137cs measurements sediment source fingerprinting and more traditional monitoring techniques to quantify the individual components of the budget the gross and net erosion rates for the fields on the catchment slopes were estimated using 137cs measurements within selected fields which encompassed a representative range of slope angles slope lengths and land use these estimates were extrapolated over the entire catchment using a simple topographically driven soil erosion model terrain based gis tbgis superimposed on a dem to derive catchment average gross and net erosion rates suspended sediment yields were measured at the catchment outlets and sediment source fingerprinting techniques were used to establish the relative contributions from the catchment surface subsurface tile drains and eroding channel banks to the sediment yields in channel and wetland storage were quantified using both direct measurements and 137cs measurements the sediment budgets established for the catchments highlighted the importance of subsurface tile drains as a pathway for sediment transfer accounting for ca 60 and 30 of the sediment output from the two catchments erosion from channel banks contributed ca 10 and 6 of the sediment output from the two catchments although the suspended sediment yields from these catchments were considered high by uk standards ca 90 t km 2 year 1 the sediment delivery ratios ranged between 14 and 27 indicating that a major proportion of the mobilised sediment was stored within the catchments in field and field to channel storage were shown to be of similar magnitude but storage of sediment in the channel system and associated wetlands was relatively small representing 5 of the annual suspended sediment yield

optical dating of holocene sediments from a variety of geomorphic settings using single grains of quartz this paper presents an improved method for the optical dating of holocene sediments from a variety of geomorphic settings we have measured the equivalent dose de in individual grains of quartz using green laser light for optical stimulation and have simulated the de distributions for multiple grain synthetic aliquots using the single grain data for 12 samples of known independent age we show that application of a minimum age model to the single grain and small 10 grain aliquot de data provides the most accurate estimate of the burial dose for nine of the samples examined 3 aeolian 5 fluvial and 1 marine the weighted mean de as obtained using the central age model gives rise to burial age overestimates of up to a factor of 10 for these nine samples whether single grains small aliquots or large 100 grain aliquots are used for the other three samples two aeolian and one fluvial application of either the minimum age model or the central age model to the single grain small aliquot and large aliquot de data yields burial ages in accord with the independent age control we infer that these three samples were well bleached at the time of deposition these results show that heterogeneous bleaching of the optical dating signal is commonplace in nature and that aeolian transport offers no guarantee that the sample will be well bleached at the time of deposition we also show that grains sensitive to infrared ir stimulation can give rise to low de values which will result in significant underestimation of the burial dose and hence of the age of deposition we demonstrate that use of a modified single aliquot regenerative dose protocol incorporating ir stimulation prior to green light stimulation deals effectively with contamination by ir sensitive grains we conclude that application of the modified protocol to single grains or small aliquots of quartz using the lowest de population to estimate the burial dose is the best means of obtaining reliable ages for holocene sediments from a wide range of depositional environments d 2003 elsevier b v all rights reserved

changes in the rates of floodplain and in channel bench accretion in response to catchment disturbance central queensland australia analysis of the changes in rates of catchment sediment storage can provide material evidence of the impact of landscape disturbance on catchment sediment flux a number of studies have suggested increased sediment yields from the rivers draining to the great barrier reef since european settlement in the mid nineteenth century many of these predictions which indicate increases between four to ten times the pre disturbance estimates are based on large scale catchment modelling that make some critical assumptions about pre disturbance erosion rates and or sediment delivery ratios in addition the majority have not been validated by empirical data this study uses single grain osl dating and 137cs depth profiles to determine pre and post floodplain accretion rates in theresa creek a subcatchment of the dry tropical fitzroy river basin we demonstrate that floodplain accretion rates have increased by three to four times since european settlement ca a d 1850 decreased rates of floodplain accretion since the mid twentieth century at sites contributed to by gullied terrain suggest a decrease in the supply of sediment derived from gully networks in contrast floodplain accretion rates from areas dominated by cultivation remain high widespread in channel benches deposited since european settlement are stable and appear to be important stores of large volumes of sediment low magnitude increases in post disturbance floodplain sedimentation rates 3 to 4 times in comparison to those reported from mainly temperate climates 10 to 100 times are attributed to the naturally high sediment loads typical of dry tropical catchments consequently previous predictions of large post disturbance increases in sediment yields from large dry tropical catchments draining to the great barrier reef are likely to be overestimates

a distributed slope stability model for steep forested basins a distributed physically based slope stability model dslam based on an infinite slope model a kinematic wave groundwater model and a continuous change vegetation root strength model is presented it is integrated with a contour line based topographic analysis and a geographic information system gis for spatial data extraction and display the model can be run with either individual rainfall events or long term sequences of storms these inputs can be either actual storm records or synthesized random events based on monte carlo simulation the model is designed to analyze rapid shallow landslides and the spatial distribution of safety factor fs in steep forested areas it can investigate the slope stability problem in both temporal and spatial dimensions for example the impact of timber harvesting on slope stability either at a given time or through an extended management period the probability of landslide occurrence for a given year and the delivery of landslide sediments to headwater streams the dslam model was applied in a steep forested drainage of cedar creek in the oregon coast ranges using actual spatial patterns of timber harvesting and measured rainfall during a major storm which triggered widespread landslides in that area in 1975 simulated volume and number of failures were 733 m3 and 4 respectively these values agreed closely with field measurements following the 1975 storm however the effect of parameter uncertainty may complicate this comparison for example when soil cohesion values of 2 0 and 3 0 kpa were used the failure volume changed by factors of 2 04 and 0 41 respectively compared with the average condition of 2 5 kpa used in the simulation for soil depths 30 higher and lower than the standard condition the failure volume changed by factors of 2 0 and 0 27 respectively when maximum root cohesion changed from 12 5 kpa average condition to 10 kpa the failure volume increased 1 73 fold for the case of 15 kpa the failure volume changed by a factor of 0 55 the simulated failures caused by the storm were mostly in hollows the simulations show that the spatial distribution of fs is controlled mainly by topography and timber harvesting patterns and is greatly affected by groundwater flow patterns during major rainstorms most areas with fs 3 0 corresponded with the distribution of blocks clear cut in 1968 and all elements with fs 2 0 were in areas clear cut in 1968 areas with low fs 1 0 1 6 expanded dramatically during the rainstorm and decreased at a slow rate after the storm factors of safety in hollows declined sharply during the storm

on the interaction of geology measurement and statistical analysis of small scale permeability measurements sedimentary rocks exhibit small scale mm permeability variations which can be detected with a probe permeameter the structure of the laminations may provide evidence about the characteristics of the measurement device the statistical interpretation of these measurements using averages and variograms is enhanced when the geological character of the rock is taken into consideration the three aspects of rock characterization namely geology measurement and statistical analysis are best assessed in concert this theme is illustrated using probe data taken from sections of the rannoch and etive formations northern north sea

modeling time series of microwave brightness temperature in antarctica this paper aims to interpret the temporal variations of microwave brightness temperature at 19 and 37 ghz and at vertical and horizontal polarizations in antarctica using a physically based snow dynamic and emission model sdem sdem predicts time series of top of atmosphere brightness temperature from widely available surface meteorological data era 40 re analysis to do so it successively computes the heat flux incoming the snowpack the snow temperature profile the microwaves emitted by the snow and finally the propagation of the microwaves through the atmosphere up to the satellite since the model contains several parameters whose value is variable and uncertain across the continent the parameter values are optimized for every 50 km 50 km pixel simulation results show that the model is inadequate in the melt zone where surface melting occurs on at least a few days a year because the snowpack structure and its temporal variations are too complex in contrast the accuracy is reasonably good in the dry zone and varies between 2 and 4 k depending on the frequency and polarization of observations and on the location at the antarctic scale the error is larger where wind is usually stronger suggesting either that meteorological data are less accurate in windy regions or that some neglected processes e g windpumping surface scouring are important at dome c in calm conditions a detailed analysis shows that most of the error is due to inaccuracy of the era 40 air temperature 2 k finally the paper discusses the values of the optimized parameters and their spatial variations across the antarctic

predicting the topographic limits to a gully network using a digital terrain model and process thresholds a digital terrain model is used with process thresholds to predict the extent of a stable gully network in a 5 km2 catchment of the southeastern highlands of australia the model developed by dietnch et al 1992 1993 predicts the topographic controls on channel networks and interprets these in terms of a critical shear stress for channel incision c applied by saturation overland flow we adapt the model slightly to compare the shear stress applied by hortonian overland flow to that applied by saturation overland flow the limits to gully erosion in the catchment are controlled strongly by a topographic threshold that has an inverse relationship between upslope catchment area and local gradient the topographic threshold for channel incision is reproduced using a simple model of hortonian overland flow and a c appropriate for incision into a degraded grass surface c 245 dyn cm2 this is consistent with historical evidence for the timing of gully erosion the study confirms a strong topographic control on the extent of the channel network in a catchment significantly different from the western north america catchments where the topographic threshold was first demonstrated despite its simplicity the model for incision by overland flow appears capable of distinguishing the hydrological processes responsible for channel incision when these are reflected in the relationship between channel network and landscape morphology the model requires relatively simple inputs suggesting it may be useful for mapping gully erosion hazard in actively eroding catchments

10be derived denudation rates from the burdekin catchment the largest contributor of sediment to the great barrier reef abstract terrestrial cosmogenic nuclides tcns such as beryllium 10 10be are now routinely used to reconstruct erosional rates over tens of thousands of years at increasingly large basin scales 100 000 km2 in australia however the approach and its assumptions have not been systematically tested within a single large drainage basin this study measures 10be concentrations in river sediments from the burdekin catchment one of australia s largest coastal catchments to determine long term 10 000 years time integrated rates of sediment generation and denudation a nested sampling design was used to test for effects of increasing catchment scale on nuclide concentrations with upstream catchment areas ranging from 4 to 130 000 km2 beryllium 10 concentrations in sediment samples collected from the upstream headwater tributaries and mid stream locations range from 1 8 to 2 89 105 atoms g 1 and data confirm that nuclide concentrations are well and rapidly mixed downstream sediment from the same tributaries consistently yielded 10be concentrations in the range of their upstream samples overall no decrease in 10be concentrations can be observed at the range of catchment scales measured here the mean denudation rate for all river sediment samples throughout the fanning subcatchment 1100 km2 is 18 47 m ma 1 which compares with the estimate at the end of the burdekin catchment 130 000 km2 of 16 22 m ma 1 nuclide concentrations in the lower gradient western and southern catchments show a higher degree of variability and several complications emerged as a result of the contrasting geomorphic processes and settings this study confirms the ability of tcns to determine long term denudation rates in australia and highlights some important considerations in the model assumptions that may affect the accuracy of limited sampling in large low gradient catchments with long storage times

topographical and rainfall factors determining the formation of gully type debris flows caused by shallow landslides in the dayi area guizhou province china three groups of factors topography geology and hydrology have influence on the formation of gully type debris flows triggered by shallow landslides in this paper a single representative factor t factor for the topography and a single representative factor r factor for the rainfall hydrology are proposed which can be used to define threshold values for debris flow formation this study was carried out in the dayi area guizhou province china during a heavy rainfall event on june 5 and 6 2011 37 gully type debris flows caused by shallow landslides were triggered in some catchments no such debris flows were triggered even though these catchments were in the vicinity of gullies with debris flows the triggering mechanism for gully type debris flows is the transport of sediment provided by shallow landslides into the gully we isolated and analyzed the influence of the topography on the formation of debris flows in gullies under almost identical hydrological and geological conditions and propose a t factor as a topographical indicator which is a combination of the catchment surface area the ratio of the catchment area with a slope sensitive to trigger debris flows and the average gradient of the drainage channel in the catchment additionally an r factor is proposed as a rainfall indicator which is a combination of the rainfall in 1 h before the debris flow was triggered the cumulative rainfall before the debris flow was triggered and the annual rainfall higher t factor values and higher r factor values are generally related to higher probabilities of debris flow formation the primary probability factor p which is the combination of t and r gives an indication of the probability of debris flow formation the t factor was successfully validated in debris flow gullies with the same initiation mechanism in the cida river catchment sichuan china

experimental study on gully shaped mud flow in the loess area vast expanse of land in northwest china is covered by loess because of the characteristics of loess mud flow disasters can be induced in this area easily worse still due to the mud flow gully transformation and the environmental changes in recent decades mud flow disasters are increasing in order to know more about gully shaped mud flow the field investigation of more than 60 gullies and the similarity principle were applied to determine the test parameters and a physical model of gully was made for mud flow during the tests the motion characteristics velocity acceleration and intermittent debris flow and deposition parameters length width area aspect ratio distribution shape and thickness of mud flow in the model were collected and analyzed the instantaneous velocities of the mud flow fluctuated discharge exerts a maximum impact on the velocity second is unit weight and minimum slope angle in the transportation zone the mud flow flows and forms the bed firstly then the intermittent debris flow occurs which is affected by discharge and unit weight the length width and area of deposition have a certain linear rule and distribution pattern greatly relates to the first accumulation the stacking thickness is decreasing from the center to the edge

comparative investigation of the spatial distribution of past weathering impacts on sandstone masonry abstract inspection of the deterioration of both natural outcrops and historical built stone facades reveals that patterns of disruption are not uniform indicating the influence of material and environmental properties sandstones have a spatial variability in weathering response for this reason geostatistical techniques have been applied to studies of sandstone properties mineralogical and structural that influence susceptibility to decay for this study a comparative analysis of permeability data acquired from a quarry fresh stone and a weathered sample is undertaken the depositional processes that resulted in the formation of sandstone also create structures of spatial variation such as laminations or larger bedding planes within the material using geostatistical techniques the permeability variance observed within quarry fresh blocks of sandstone indicates the subsampling of larger geological structures when cut from the quarry face once blocks have been emplaced within a building they will be subjected to the increased stress of the urban environment these conditions result in exacerbated weathering through processes such as salt and chemical weathering weathering can alter material properties such as permeability with the creation of a secondary permeability produced by the opening pores and alteration of pore connectivity through the application of geostatistics in the analysis of permeability data observed from the weathered block variography reveals the presence of smaller scale structures this suggests that alteration of the sandstone s permeability has led to the creation of new weathering structures within the stone overwriting the initial sedimentary structures these weathering related structures will affect both the magnitude and spatial distribution of permeability within the weathered block the interconnected pathways of permeability created by past weathering facilitate the migration of moisture and salts in solution through the substrate this work has demonstrated that through a geostatistical approach with the application of co kriging these potential moisture pathways can be identified and visualised

accuracy of cross channel sampled sediment transport in large sand gravel bed rivers the accuracy of cross channel integrated sediment transport of bed material is determined with an elaborate set of field measurements in the waal river the netherlands the measurements were done during a discharge wave in the upstream part of the river which has a bimodal sand gravel bed the sampling strategy should take both spatial and temporal aspects into account to obtain maximum accuracy presence of moving bedforms differences in bed sediment grain size in the cross section and presence of preferential transport lanes dictate that at least five subsections for sampling in the cross section are necessary the accuracy of cross channel integrated bedload transport depends mainly on the measurement strategy an uncertainty of 20 bedload and 7 suspended load of cross channel integrated sediment transport is shown to be feasible if 30 samples of bedload and two vertical profiles of suspended bed material load are taken in one subsection provided that the cross section of the river is divid

a numerical model to simulate snow cover stratigraphy for operational avalanche forecasting laws of snow metamorphism have been introduced in a numerical model which simulates the evolution of temperature density and liquid water profiles of snow cover as a function of weather conditions to establish these laws the authors have summarized previous studies on temperature gradient and on wet snow metamorphism and they have also conducted metamorphism experiments on dry or wet fresh snow samples an original formalism was developed to allow a description of snow with parameters evolving continuously throughout time the introduction of laws of metamorphism has improved significantly the derivation of the settlement of internal layers and of snow covered albedo which depend on the simulated stratigraphy i e the type and size of snow grains of different layers of the snow cover the model was tested during a whole winter season without any re initialization comparison between the simulated characteristics of the snow cover and the observations made in the field are described in detail the model proved itself to be very efficient in simulating accurately the evolution of the snow cover stratigraphy throughout the whole winter season

landslide susceptibility assessment what are the effects of mapping unit and mapping method landslide susceptibility assessment forms the basis of any hazard mapping which is one of the essential parts of quantitative risk mapping for the same study area different susceptibility maps can be achieved depending on the type of susceptibility mapping methods mapping unit and scale although there are various methods of obtaining susceptibility maps the efficiency and performance of each method should be evaluated in this study the effect of mapping unit and susceptibility mapping method on landslide susceptibility assessment is investigated when analyzing the effect of susceptibility mapping method logistic regression lr which is widely used in landslide susceptibility mapping and spatial regression sr which have not been used for landslide susceptibility mapping are selected the susceptibility maps with logistic and spatial regression models are obtained using two different mapping units namely slope unit based and grid based mapping units the procedure for investigation of effect of mapping unit on different susceptibility mapping methods is applied to kumluca watershed in bartin province of western black sea region turkey 18 factor maps are prepared for landslide susceptibility assessment in the study region geographic information systems and remote sensing techniques are used to create the landslide factor maps to obtain susceptibility maps and to compare the results the relative operating characteristics roc curve is used to compare the predictive abilities of each model and mapping unit and also the accuracy is evaluated depending on the observations made during field surveys by analyzing the area under the roc curve for grid based and slope unit based mapping units it can be concluded that sr model provide better predictive performance 0 774 in grids and 0 898 in slope units as compared to the lr model 0 744 in grids and 0 820 in slope units this result is also supported by the accuracy analysis for both mapping units the sr model provides more accurate result 0 55 for grids and 0 57 for slope units than the lr model 0 50 for grids and 0 48 for slopes the main reason for this better performance is that the spatial correlations between the mapping units are incorporated into the model in sr while this fact is not considered in lr model

rapid cycles of episodic adjustment understanding the holocene fluvial archive of the daintree river of northeastern australia the dramatic decline in the quality of coral reef cover of the great barrier reef gbr over recent decades has resulted in targeted research to better understand the dynamics of sedimentary sources within river systems of northeastern australia european land use practices are thought to have increased sediment yields to the gbr lagoon by 5 10 times yet there is a poor understanding of the pre 1850 sediment dynamics this study presents the first detailed alluvial chronology of the spatial and temporal responses of fluvial systems in the wet tropics of northeastern australia over the late holocene valley fill sequences of the daintree river one of the least disturbed catchments draining to the gbr lagoon are examined to investigate the significance of floodplain dynamics in sedimentary process an optically stimulated luminescence chronology combined with a detailed sedimentary analysis suggests that floodplain stripping is a major and hitherto unrecognised source of sediment furthermore rates of floodplain accretion are far greater than has been previously estimated from sediment modelling for wet tropical catchments spatial analysis of the topographical relationships between floodplain morphological units suggests that a total of 178 516 ton ha of sediment has been stripped from three small confined floodplain reaches between 1038 215 and 99 10 years evidence suggests that these erosion events are followed by phases of rapid accretion with an average depositional rate of 3 87 0 92 cm yr between 572 74 and 51 12 years across the study area the floodplain appears to be in a constant state of disequilibrium experiencing spatially discontinuous phases of erosion and aggradation resulting in much higher volumes of sediment being redistributed within the catchment than previously considered the unpredictable nature of these regimes and the shear volume of sediment mobilised poses significant challenges in managing sediment sources to the gbr lagoon

gully position characteristics and geomorphic thresholds in an undisturbed catchment in northern australia gullying is a significant process in the long term dynamics and evolution of both natural and rehabilitated i e post mining landscapes from a landscape management perspective it is important that we understand gully initiation and development as it is well recognized that catchment disturbance can result in the development of gullies that can be very difficult to rehabilitate this study examines gully position using geomorphic statistics relating to features such as depth width and length in a catchment undisturbed by european activity in the northern territory australia the results demonstrate that gullying occurs throughout the catchment and that a slope area threshold does not exist and that gully position broadly follows the catchment area slope relationship simple relationships relating catchment area and slope to gully depth width and length provide poor results despite these relationships having been found to apply for ephemeral gullies in cropland the results suggest that gully initiation thresholds are low as a result of an enhanced fire regime a threshold model for gully position that uses catchment area and slope to switch between gully and hillslope was evaluated and found broadly to capture gully position copyright 2006 john wiley sons ltd

surface temperatures in the polar regions from nimbus 7 temperature humidity infrared radiometer monthly surface temperatures in the arctic and antarctic regions have been derived from the 11 5 m thermal infrared channel of the nimbus 7 temperature humidity infrared radiometer thir for a whole year in 1979 and for a winter and a summer month from 1980 through 1985 the data set shows interannual variability and provides spatial details that allow identification of temperature patterns over sea ice and ice sheet surfaces for example the coldest spot in the southern hemisphere is observed to be consistently in the antarctic plateau in the southern hemisphere while that in the northern hemisphere is usually located in greenland or one of three other general areas siberia the central arctic or the canadian archipelago also in the southern hemisphere the amplitude of the seasonal fluctuation of ice sheet temperatures is about 3 times that of sea ice while in the northern hemisphere the corresponding fluctuations for the two surfaces are about the same the main sources of error in the retrieval are cloud and other atmospheric effects these were minimized by first choosing the highest radiance value from the set of measurements during the day taken within a 30 km by 30 km grid of each daily map then the difference of daily maps was taken and where the difference is greater than a certain threshold which in this case is 12 c the data element is deleted overall the monthly maps derived from the resulting daily maps are spatially and temporally consistent are coherent with the topography of the antarctic continent and the location of the sea ice edge and are in qualitative agreement with climatological data quantitatively thir data are in good agreement with antarctic ice sheet surface air temperature station data with a correlation coefficient of 0 997 and a standard deviation of 2 0 c the absolute values are not as good over the sea ice edges but a comparison with russian 2 m drift station temperatures shows very high correlation with correlation coefficient at 0 998 and a standard deviation of 1 1 c overall the rms error is estimated to be from 1 to 2 c depending on the surface while the average bias when compared with in situ data is less than 2 c

an energy and mass model of snow cover suitable for operational avalanche forecasting a numerical model has been developed to simulate energy and mass evolution of snow cover at a given location as a function of meteorological conditions precipitation air temperature humidity wind velocity and incoming short wave and long wave radiation this model named crocus was first tested on a well instrumented field during a whole winter showing its ability to simulate the important phenomena affecting the evolution of the snow layers high temperature gradients wetting compaction and melting freezing cycles a second test was conducted at two locations in the french network used for operational avalanche forecasting though the weather observations are made there only twice daily the snow profiles calculated by the model were very close to those obtained once a week by a pit observation crocus proved itself sufficient to be considered now as a useful objective tool for operational avalanche forecasting

a transient flow syringe air permeameter in response to the need to better describe spatial variations in permeability we designed and built a new portable field air permeameter for use on rocks in outcrop and core in this instrument a chamber containing a small volume of air in contact with the rockissuddenly increased involumecreating a vacuum causing air to flow from the rock into the chamber the instantaneous chamber volume and the air pressure within it were monitored we evaluated a theory to allow interpretation of these data for the rock permeability the theory required knowledge of some difficult to determine geometric constants this difficulty was circumvented in practice through a calibration procedure we described the theory for the design and construction of this instrument and reviewed some successful uses in field scale studies of rock permeability heterogeneity

relating small scale sedimentary structures and permeability in a cross bedded aquifer summary the objective of this study is to investigate the relation between small scale sedimentary structures and permeability in the brussels sands formation an early middle eocene shallow marine sand deposit in central belgium that constitutes a major groundwater source in the region a field campaign was carried out consisting of field observations of the sedimentary structures and in situ measurements of air permeability the sedimentary structures were interpreted sketched digitally photographed and measured in a representative outcrop additionally a total of 2750 cm scale air permeability measurements were carried out in situ analysis of the spatial distribution of sedimentary structures and permeability shows that clay rich sedimentary features such as bottomsets and distinct mud drapes exhibit a different statistical and geostatistical permeability distribution compared to the other lithofacies in the cross bedded sands spatial analysis of the air permeability data shows that permeability anisotropy in the cross bedded lithofacies is dominated by the foreset lamination orientation these results show that small scale sedimentary heterogeneity strongly influences the local spatial distribution of the hydraulic properties and results in permeability heterogeneity and stratification that would produce anisotropy in upscaled permeability values

determining sources and transit times of suspended sediment in the murrumbidgee river new south wales australia using fallout 137cs and 210pb sediment budgets typically require an estimate of the proportional yield from erosion sources to sediments in transport and storage this becomes increasingly difficult as catchments become larger and erosion storage and deposition processes become more complex we demonstrate how fallout radionuclides can be used to estimate the proportional contributions to sediment load from a tripartite classification of erosion sources in a large catchment the mid murrumbidgee 13 500 km2 the three major potential sources of sediment within this catchment are cultivated lands 22 of the surface area uncultivated pastoral lands 78 and the numerous channels and gullies found in this region concentrations of the fallout radionuclides 210pbex and 137cs in representative samples from each of these three sources are significantly different employing these values in a simple mixing model shows that the largest contribution of material is currently derived from subsoil channel gully sources alterations to the suspended sediment 210pbex signature by in situ labeling and decay are also considered applying the model with different concentrations of 210pbex decayed as a function of residence time in channels suggests that the mean residence time of fine grained material within this system is 10 5 years however differences in 137cs concentrations observed between flood and low flow sediments and the presence of the short lived cosmogenic 7be suggest that residence time of some of this fine grained material may be of the order of only weeks to months

bedload transport in se asian streams uncertainties and implications for reservoir management article this paper reviews the current state of knowledge regarding bedload transport in se asian streams and presents the results from a case study on bedload transport in a mountain stream in northern thailand together the review and new data help contextualize the paucity of work done in the region in the face of a rapid increase in development and reservoir building throughout se asia data from both the reviewed studies and the case study indicate that bedload transport in many se asian streams e g catchment areas b 100 km 2 i s often much higherthan iscommonly assumed for tropicalstreams i e about 10 of the totalsediment load estimat ed annual bedload proportion was 18 of the total annual sediment load in the 74 km

towards the identification of scaling relations in drainage basin sediment budgets abstract drainage basin sediment budgets concern inputs storages and outputs of sediments and solutes through monitored cross sections at the mouth of basins or at the base of individual slopes the question under consideration is whether and to what extent it is possible to transfer knowledge from one spatial scale to another the answer hinges on the question of scale invariance of a individual processes of sediment and solute transfer and b aggregate sediment budgets scale invariance of a number of hydrologic parameters has been established but in general with a few exceptions geomorphic parameters are subject to scale distortion by inference but not yet established by experimental or field evidence scale invariance of sediment budgets is improbable there is therefore a priority to explore scaling relations in sediment budgets so as to determine the precise extent of scale distortion that is present in this paper five ways of identifying scaling relations in drainage basin sediment budgets are identified 1 a fractal approach 2 a theory hierarchy approach 3 a non linear dynamic systems approach 4 a panarchy approach and 5 a hybrid approach there are no a priori bases for selection of any one of these approaches until further field research and modeling of sediment and solute fluxes has been completed

sliding mechanical properties of fault gouge studied from ring shear test based microscopic morphology characterization abstract fault activity is a factor causing geological disasters and controlling their spatial distribution the information on fault activity can be recorded by the microstructure of the fault gouge sliding surface which provides an approach to study the macroscopic mechanical behavior of faults in this study the ring shear test was used to simulate the shear sliding behavior of a fault gouge under different stress states and water contents and the microstructure of the shear sliding surface was quantitatively analyzed using scanning electron microscopy sem the results revealed an evident relationship between the microstructure and macroscopic mechanical properties of the fault gouge the microstructure represented by sliding scratches was primarily created by the movement of coarse particles such as sand and quartz an index of the sliding scratch ratio was proposed to characterize the microstructure the sliding scratch ratio is negatively correlated with water content and normal stress and a multivariate model of sliding scratch ratio was established with water content normal stress and coarse particle contents allying the model to natural scratches of the fault gouge reveals that the observed sliding scratches were formed during slope sliding which proves the influence of fault on the occurrence of the studied landslide influenced by the gully land consolidation projects in the loess plateau of china the groundwater level may increase and then weaken the shear strength of fault gouge reducing the stability of slopes crossed by fault zone therefore more attention should be paid to potential geological disasters induced by faults in gully filled areas

timing and causes of gully erosion in the riparian zone of the semi arid tropical victoria river australia management implications abstract gully erosion in the seasonally wet tropics of australia is a major source of sediment in rivers stabilization of gullies to reduce impacts on aquatic ecosystems and water storages is a focus for management however the cause of the gully erosion is poorly understood and so a critical context for soil conservation is missing it is uncertain if they are the result of post european cattle grazing or are they much older and related to non human factors the causes of riparian gully erosion along a reach of the victoria river in the semi arid tropics of australia were investigated using several methods gully complexes were described and characterised by two major components a flood drainage channel fdc and upslope of this an outer erosion feature oef characterised by badlands set within an amphitheatre the oef is likely to be a major source of sediment that appears to be of recent origin a review of historical records combined with optically stimulated luminescence osl dating showed that the fdcs were well established prior to the introduction of domestic stock it also showed that the badlands began to develop about 90 years ago that is about 40 years after the arrival of domestic stock in addition an analysis of aerial photos coupled with an on ground survey and analysis of fallout radionuclides revealed that erosion processes are still active within the gully complexes while the fdcs are natural drainage channels cattle grazing probably triggered the badland formation with the expansion aided by increased rainfall in the past 40 years therefore the oefs are of human origin and protection from grazing of the riparian zone should slow badland erosion and reduce sediment input to the river

snow atmosphere coupled simulation at dome c antarctica using a snow atmosphere coupled model the evolution of the surface and near surface snow temperature is modeled at dome c antarctica during the period 20 30 january 2010 firstly the detailed multilayer snow model crocus is run in stand alone mode with meteorological input forcing data provided by local meteorological observations the snow model is able to simulate the evolution of surface temperature with good accuracy it reproduces the observed downward propagation of the diurnal heatwave into the upper 50 cm of the snowpack reasonably well secondly a fully coupled 3 d snow atmosphere simulation is performed with the arome regional meteorological model for which the standard single layer snow parameterization is replaced by crocus in spite of a poor simulation of clouds the surface and near surface snow temperatures are correctly simulated showing neither significant bias nor drifts during the simulation period the model reproduces particularly well the average decrease of the diurnal amplitude of air temperature from the surface to the top of the 45 m instrumented tower this study highlights the potential of snow atmosphere coupled models over the antarctic plateau and the need to improve cloud microphysics and data assimilation over polar regions

dynamical instability in surface permeability characteristics of building sandstones in response to salt accumulation over time abstract this paper explores how the surface permeability of sandstone blocks changes over time in response to repeated salt weathering cycles surface permeability controls the amount of moisture and dissolved salt that can penetrate in and facilitate decay connected pores permit the movement of moisture and hence soluble salts into the stone interior and where areas are more or less permeable soluble salts may migrate along preferred pathways at differential rates previous research has shown that salts can accumulate in the near surface zone and lead to partial pore blocking which influences subsequent moisture ingress and causes rapid salt accumulation in the near surface zone two parallel salt weathering simulations were carried out on blocks of peakmoor sandstone of different volumes blocks were removed from simulations after 2 5 10 20 and 60 cycles permeability measurements were taken for these blocks at a resolution of 20 mm providing a grid of 100 permeability values for each surface the geostatistical technique of ordinary kriging was applied to the data to produce a smoothed interpolation of permeability for these surfaces and hence improve understanding of the evolution of permeability over time in response to repeated salt weathering cycles results illustrate the different responses of the sandstone blocks of different volumes to repeated salt weathering cycles in both cases after an initial subtle decline in the permeability reflecting pore blocking the permeability starts to increase reflected in a rise in mean maximum and minimum values however between 10 and 20 cycles there is a jump in the mean and range permeability of the group a block surfaces coinciding with the onset of meaningful debris release after 60 cycles the range of permeability in the group a block surface had increased markedly suggesting the development of a secondary permeability the concept of dynamic instability and divergent behaviour is applied at the scale of a single block surface with initial small scale differences across a surface having larger scale consequences as weathering progresses after cycle 10 group b blocks show a much smaller increase in mean permeability and the range stays relatively steady this may be explained by the capillary conditions set up by the smaller volume of the stone allowing salts to migrate to the back of the blocks and effectively relieving stress at the front face

probe permeametry an overview and bibliography applications of probe permeameters in both laboratory and outcrop studies of permeability heterogeneity are common we present an overview of the current status of probe permeameter data acquisition analysis and application the multidisciplinary nature of probe permeameter studies has led to their publication in diverse scientific journals we present a bibliography that includes literature covering both the technology and the application of probe permeametry

alluvial gully erosion an example from the mitchell fluvial megafan queensland australia considerable attention has been focused on the role of gullies as a contributor to contemporary sediment loads of rivers in australia in southern australia rapid acceleration of hillslope gully erosion has been widely documented in the post european period last 200 years in the northern australian tropics however gully erosion processes operating along alluvial plains have not been well documented and can differ substantially from those gullies eroding into colluvium on hillslopes aerial reconnaissance surveys in 2004 along 13 500 km of the main stem rivers that drain into the gulf of carpentaria goc identified extensive areas of alluvial lands that have been impacted by a pervasive form of gully erosion more detailed remote sensing based mapping within the 31 000 km2 mitchell river fluvial megafan has identified that active gullying into alluvium occupies 0 4 129 km2 of the lower mitchell catchment these alluvial gullies are concentrated along main drainage channels and their scarp heights are highly correlated to the local relief between the floodplain and river thalweg while river incision into the megafan since the pleistocene has developed the relief potential for erosion other factors such as floodplain hydrology soil dispersibility and vegetation also influence the distribution of gullies in this paper we present a conceptual model of alluvial gullies and contend that they represent a distinct end member in the continuum of gully forms that have been described in the geomorphic literature an understanding of the processes driving this form of alluvial gullying can only be gained when they are differentiated from widely described colluvial hillslope gully models and theories we present evidence of type examples of alluvial gullying in the mitchell and through analysis of their distribution and morphology at different scales highlight some of the key mechanisms that are potentially initiating these features and driving their expansion copyright 2009 john wiley sons ltd

recent geomorphological changes of the middle and lower calore river campania southern italy the geomorphological changes experienced by the middle and lower calore river southern italy between 1957 and 1998 were investigated data derived from field surveys and interpretation of topographic maps and aerial photos were introduced into a geographic information system gis and processed the results showed that the calore river underwent a mean narrowing of 66 with a peak of 86 the channel length increased by approximately 75 m and the sinuosity from 1 311 to 1 314 the extension of fluvial bars reduced by more than 83 while their number increased from 151 to 381 field evidence of riverbed lowering such as river terraces formed in the considered time span and exhumation of foundations of bridges and flood walls were also constantly detected due to these channel adjustments the calore river morphology changed from transitional to single thread these results were coherent with those reported in the pre existing literature about channel adjustments experienced by many rivers during the twentieth century they all were explainable with a reduction of the bedload transport this latter in turn is completely in accordance with the environmental changes that affected the calore river system in the considered period i e damming and or channelization of the main tributaries reduction of liquid discharge due to water withdrawals and sediment mining from the riverbed

paired geochemical tracing and load monitoring analysis for identifying sediment sources in a large catchment draining into the great barrier reef lagoon while sediment tracing has been typically applied to identify sediment sources that are difficult to measure by gauging monitoring it can also be useful in estimating relative sediment yields from gauged river catchments the major and trace element composition of river sediments from eleven locations in the 130000 km2 burdekin river catchment northeastern australia was analysed to examine relative contributions from upstream source areas in the 2011 12water year sediment tracing results are compared against estimates derived fromsediment load monitoring at three locations comparisons show that there is good agreement between tracing results and monitoring data at one of the tributary confluences at the second site notable contrastswere found between the load estimates from the monitoring and tracing data at this site a large impoundment occurs between the upstream sampling gauging sites for source sediments and the downstream sampling gauging sites for target sediments the contrast is likely caused by temporal variations in particle size distributions of suspended sediment fromeach river and differential trapping efficiencies in the impoundment for sediment derived fromthe different tributaries in the absence of the detailed particle size data and trapping efficiency estimates sediment tracing provides the unique opportunity to elucidate source contributions of the finer fractions of suspended sediment at a third site where there were recognised measurement gaps in the monitoring data during large discharge events the relative load estimates fromthe tracing data provided a means of constraining the recognized uncertainty of monitored load estimates we conclude that sediment tracing can be used as a valuable adjunct to monitoring data particularly in remote large and data sparse catchments both tracing results and monitoring data showthat the upper burdekin river and bowen bogie riverswere the dominant source of the b10 m sediments being delivered to the gbr lagoon from the burdekin river catchment in the 2011 12 water year more substantial contribution from the belyando suttor rivers indicated by the tracing results than the monitoring data is attributed to preferential delivery of the 1 10 m sediments through the impoundment and has uncovered a knowledge gap in sediment budgets in the catchment

the usefulness of outcrop analogue air permeameter measurements for analyzing aquifer heterogeneity quantifying outcrop hydraulic conductivity and its spatial variability saturated hydraulic conductivity k is one of the most important parameters determining groundwater flow and contaminant transport in both unsaturated and saturated porous media although several well established laboratory methods exist for determining k in situ measurements of this parameter remain very complex and scale dependent often the limited accessibility of subsurface sediments for sampling means an additional impediment to our ability to quantify subsurface k heterogeneity one potential solution is the use of outcrops as analogues for subsurface sediments this paper investigates the use of air permeameter measurements on outcrops of unconsolidated sediments to quantify k and its spatial heterogeneity on a broad range of sediment types the neogene aquifer in northern belgium is used as a case study for this purpose to characterize the variability in k 511 small scale air permeability measurements were performed on outcrop sediments representative over five of the aquifer s lithostratigraphic units from these measurements outcrop scale equivalent k tensors were calculated using numerical upscaling techniques validation of the air permeameter based k values by comparison with laboratory constant head k measurements reveals a correlation of 0 93 overall the results indicate that hand held air permeameters are very efficient and accurate tools to characterize saturated k as well as its small scale variability and anisotropy on a broad range of unconsolidated sediments the studied outcrops further provided a qualitative understanding of aquifer hydrostratigraphy and quantitative estimates about k variability at the centimetre scale to metre scale copyright 2013 john wiley sons ltd

a process based model for colluvial soil depth and shallow landsliding using digital elevation data a model is proposed for predicting the spatial variation in colluvial soil depth the results of which are used in a separate model to examine the effects of root strength and vertically varying saturated conductivity on slope stability the soil depth model solves for the mass balance between soil production from underlying bedrock and the divergence of diffusive soil transport this model is applied using high resolution digital elevation data of a well studied site in northern california and the evolving soil depth is solved using a finite difference model under varying initial conditions the field data support an exponential decline of soil production with increasing soil depth and a diffusivity of about 50 cm 2 yr the predicted pattern of thick and thin colluvium corresponds well with field observations soil thickness on ridges rapidly obtain an equilibrium depth which suggests that detailed field observations relating soil depth to local topographic curvature could further test this model bedrock emerges where the curvature causes divergent transport to exceed the soil production rate hence the spatial pattern of bedrock outcrops places constraints on the production law the infinite slope stability model uses the predicted soil depth to estimate the effects of root cohesion and vertically varying saturated conductivity low cohesion soils overlying low conductivity bedrock are shown to be least stable the model may be most useful in analyses of slope instability associated with vegetation changes from either land use or climate change although practical applications may be limited by the need to assign values to several spatially varying parameters although both the soil depth and slope stability models offer local mechanistic predictions that can be applied to large areas representation of the finest scale valleys in the digital terrain model significantly influences local model predictions this argues for preserving fine scale topographic detail and using relatively fine grid sizes even in analyses of large catchments