analysis of gully dimensions and sediment texture from southeast australia for catchment sediment budgeting abstract catchment scale sediment budgeting models are increasingly being used to target remediation works aimed at controlling erosion and improving water quality gully erosion is often a major sediment source and needs to be accounted for in such models in a manner consistent with the scale of analysis and available data using 130 measurements of gully cross sectional area and 45 measurements of gully wall sediment texture the variability in gully dimensions and particle size distribution for the lake burragorang catchment in australia is examined the distribution of gully cross sectional area measurements is log normally distributed and modelling indicates a representative value of 23 m 2 be used in catchment sediment budgeting applications the proportion of gully eroded sediment contributing to the bedload budget defined as particles 63 m diameter of a river link is approximately half though may be higher in igneous landscapes a continental scale spatially distributed subsoil texture dataset provided limited capacity to predict the finer scale spatial variation in the proportion of sediment contributing to bedload from gully erosion within the lake burragorang catchment

a geochemical reconnaissance of the duman tumen river and the hot springs of mt baekdu changbai weathering of volcanic rocks in mid latitude setting abstract the duman river and the hot springs and streams of mt baekdu were sampled and analyzed for their major elements 87 sr 86 sr d 18 o and 13 c the duman river drains an extensive volcanic plateau in northeast asia and mt baekdu is a volcanic cone on the plateau and their fluvial geochemistry reflects weathering of volcanic rock two different volcanic end members could be distinguished basalt and trachyte weathering of trachytic rock is characterized by lower ca tz and higher 87 sr 86 sr 0 7082 while that of basaltic rock contributes higher ca tz and lower 87 sr 86 sr 13 c of dissolved inorganic carbon dissolved organic carbon and particulate organic carbon along with chemical variations of major elements in the main channel suggest a transition from volcanic rock weathering in the upper reach to carbonate weathering in the lower reach the 87 sr 86 sr ratio was useful in discerning minor input from granitoid rocks in the lower reach according to the d 18 o data the source of the river water in august is mostly precipitation supplied from the east sea japan sea related to the summer monsoon of east asia the natural co 2 uptake rate is estimated to be 22 2 27 8 10 4 mol km 2 yr 1 this is on the lower end of other basaltic regions of the world and is due to lower temperature and runoff and to lack of glaciation the hot spring samples of mt baekdu have high tds total dissolved solids 381 1431 mg l and are of na hco 3 type geothermometric calculations and d 18 o data indicate that meteoric water infiltrates into the geothermal field but emerges at the surface before attaining equilibrium with the host rock the hot spring samples affect the chemistry of nearby freshwater streams but are chemically distinct from the duman river

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

stages in gully evolution and self organized criticality the process of gully erosion at the active stage is far from equilibrium rather the gully shows the characteristics of a self organizing system that is close to crisis this qualitative description is similar to the understanding of open dynamic systems at a state of selforganized criticality soc we tried to find the quantitative attributes of soc in numerical simulations of gully evolution with a dynamic gully erosion model three scenarios were used 1 gully evolution is controlled by initial topography and texture when the discharge and base level are constant 2 discharge is constant and the base level lowers over time 3 the base level is constant and the discharge changes naturally the results of numerical simulations of gully evolution are consistent with the expectations of the soc theory under the first scenario when the gully was at the initial active stage of evolution the system showed all the soc attributes a fractal long profile a red noise spectrum and the power law frequency magnitude relationship fmr with gully stabilization the system had lost soc behaviour and became non fractal with a blue noise spectrum and exponential fmr for this scenario soc criteria can be used to find the boundary between active and stable states of gully evolution simulations under the second scenario showed that the riverbed incision made the active stage of the gully evolution with all soc attributes much longer than with a stable base level simulation under the third scenario with variable discharge with the elements of soc showed that the soc attributes of the hydrological system could be induced on the landform system while the gully had evidently reached the stable stage the process of gully volume change still indicated active stage soc attributes therefore some landform systems can really be in the soc stage which can diagnose their activity others only show soc attributes induced by climatic or hydrologic systems copyright 2006 john wiley sons ltd

in stream wetlands and their significance for channel filling and the catchment sediment budget jugiong creek new south wales abstract evidence is presented here of recent and extensive infilling of the incised channel network of the jugiong creek catchment se australia the present channel network resulted from widespread stream and gully incision in the period between 1880 and 1920 our survey shows that gully floors have been colonised extensively by emergent macrophyte vegetation since before 1944 forming continuous dense in stream wetlands which now cover 25 of the channel network in the 2175 km 2 catchment and have so far trapped almost 2 000 000 t of nutrient enriched fine sediments this mass of sediments represents the equivalent of 4 7 years of annual sediment production across the catchment and in some tributaries more than 20 years of annual yield is stored within in stream wetlands previous work on the late quaternary stratigraphy of the region has shown that there were repeated phases of channel incision in the past following which the channels quickly stabilised by natural means and then filled with fine grained sediment to the point of channel extinction creating unchannelled swampy valley floors the current formation and spread of in stream wetlands is interpreted to be the onset of the next infill phase but it is not known whether present conditions will allow complete channel filling and reformation of the pre existing swampy valley floors nevertheless further spread of in stream wetlands is likely to increase the sediment trapping capacity and further reduce the discharge of sediments and nutrients into the murrumbidgee river the in stream wetlands may provide a significant capacity to buffer erosion from gullied catchments of considerable size up to 300 km 2 as an adjunct to current riparian management options they may also assist the recovery of sediment impacted channels downstream

major features and forcing of high latitude northern hemisphere atmospheric circulation using a 110 000 year long glaciochemical series the greenland ice sheet project 2 glaciochemical series sodium potassium ammonium calcium magnesium sulfate nitrate and chloride provides a unique view of the chemistry of the atmosphere and the history of atmospheric circulation over both the high latitudes and mid low latitudes of the northern hemisphere interpretation of this record reveals a diverse array of environmental signatures that include the documentation of anthropogenically derived pollutants volcanic and biomass burning events storminess over marine surfaces continental aridity and biogenic source strength plus information related to the controls on both high and low frequency climate events of the last 110 000 years climate forcings investigated include changes in insolation of the order of the major orbital cycles that control the long term behavior of atmospheric circulation patterns through changes in ice volume sea level events such as the heinrich events massive discharges of icebergs first identified in the marine record that are found to operate on a 6100 year cycle due largely to the lagged response of ice sheets to changes in insolation and consequent glacier dynamics and rapid climate change events massive reorganizations of atmospheric circulation that are demonstrated to operate on 1450 year cycles changes in insolation and associated positive feedbacks related to ice sheets may assist in explaining favorable time periods and controls on the amplitude of massive rapid climate change events explanation for the exact timing and global synchroneity of these events is however more complicated preliminary evidence points to possible solar variability climate associations for these events and perhaps others that are embedded in our ice core derived atmospheric circulation records

evaluation of heavy metal contamination and implication of multiple sources from hunchun basin northeastern china present concentrations and distributions of heavy metals through profiles surface soil and stream sediment samples in the hunchun area north eastern china were investigated to determine the elemental background values this study also aims to characterize potentially toxic materials such as pulverized fly ash pfa from power stations or ash and slag from coal used domestically in urban areas agrochemicals applied inappropriately and urban sewage sludges from hunchun city as well as to ascertain the possibility of natural enrichment through site characterization by mineralogical and geochemical investigation the distribution of contaminants in the alluvial soils fluvisol of this area has been influenced by several interacting factors the parent alluvial materials from weathered products of amphiboles have made coatings such as ferrihydrite goethite and hematite this natural inheritance factor is supported by the fact that the concentrations of weak acid extractable plant available heavy metals are very low except for fe and mn however in agricultural soils and adjacent stream sediments an anthropogenic input of cd pb ni and cr by agrochemicals is strongly suggested also f contamination by coal combustion and the dissolution of f bearing minerals could cause some future problems wide distribution and significantly high concentrations of cd fe mn and f in soils throughout the combination of pollutants originating from lithogenic and the anthropogenic sources pose potential problems in utilizing water resources

chronological refinement of an ice core record at upper fremont glacier in south central north america the potential to use ice cores from alpine glaciers in the midlatitudes to reconstruct paleoclimatic records has not been widely recognized although excellent paleoclimatic records exist for the polar regions paleoclimatic ice core records are not common from midlatitude locations an ice core removed from the upper fremont glacier in wyoming provides evidence for abrupt climate change during the mid 1800s volcanic events krakatau and tambora identified from electrical conductivity measurements ecm and isotopic and chemical data from the upper fremont glacier were reexamined to confirm and refine previous chronological estimates of the ice core at a depth of 152 m the refined age depth profile shows good agreement 1736 10 a d with the sup 14 c age date 1729 95 a d the delta sup 18 o profile of the upper fremont glacier ufg ice core indicates a change in climate known as the little ice age lia however the sampling interval for delta sup 18 o is sufficiently large 20 cm such that it is difficult to pinpoint the lia termination on the basis of delta sup 18 o data alone other research has shown that changes in the delta sup 18 o variance are generally coincident with changes in ecm variance the ecm data set contains over 125 000 data points atmore a resolution of 1 data point per millimeter of ice core a 999 point running average of the ecm data set and results from f tests indicates that the variance of the ecm data decreases significantly at about 108 m at this depth the age depth profile predicts an age of 1845 a d results indicate the termination of the lia was abrupt with a major climatic shift to warmer temperatures around 1845 a d and continuing to present day prediction limits error bars calculated for the profile ages are 10 years 90 confidence level thus a conservative estimate for the time taken to complete the lia climatic shift to present day climate is about 10 years suggesting the lia termination in alpine regions of central north america may have occurred on a relatively short decadal timescale c 2000 american geophysical union less

a northern hemisphere volcanic chemistry record 1869 1984 and climatic implications using a south greenland ice core the effect of volcanic emission of acidic aerosols on climate is well documented the presence of acid droplets in the stratosphere can reduce transmissivity and hence decrease surface temperatures since the amount and chemical composition of erupted material has important effects on regional climate knowledge of past volcanic events is of extreme importance detailed glaciochemical records provide the only milieu wherein the geochemistry of paleovolcanic events can be fully documented we present a detailed sulfate and chloride record from an ice core drilled at site 20 d 40 km sw of dye 3 in southern greenland the record spans the time period 1869 1984 with chemical analyses of approximately eight samples per year time series decomposition and locally weighted scatter plot smoothing techniques were used to extract long term trends from the data so that individual volcanic eruptions could be documented a number of events identified here have been unnoticed previously and a high percentage of the major chemical signatures documenting these events is associated with large decreases in temperature in the latitudinal zone 60 90 on many authors have pointed out that the amount of volcanic acids such as hci and h2s04 injected into the atmosphere has a very important influence on global climate yet this volcanic input has been difficult to quantify prior to 1960 our data help to alleviate this problem these individual events can be compared to available frost tree ring data from north america further establishing a volcanism climatic linkage

dendrogeomorphology in badlands methods case studies and prospects soil and vegetation are interacting factors controlling erosion soil degradation processes may affect the normal tree and shrub development and inversely vegetation can modulate the velocity and intensity of soil development or denudation a dendrogeomorphological approach can be used to study these interactions allowing to obtain a date and estimate mean or specific erosion rates this is especially useful in an unrecorded badlands and gullied environments where the scarce vegetation may be the only proxy available to quantify the different geomorphic processes which have occurred this paper provides a fundamental review of the dendrogeomorphological methodology applied to erosion measurement in badlands focusing on the response of the vegetation to the geomorphic processes this paper a describes the methodology developed to estimate erosion rates with exposed roots b shows new advances through case studies and finally c discusses future lines of research to reduce methodological uncertainties and for making dendrogeomorphology more widely applicable

assessment of gully erosion in eastern ethiopia using photogrammetric techniques abstract eastern ethiopia is severely affected by soil erosion as it is revealed by the commonly occurring deep and wide gullies these gullies are dynamically expanding into agricultural lands at an alarming rate they are also the chief sources of sediment causing siltation of lakes that are valuable sources of both drinking and irrigation water in the alemaya and harar areas a quantitative assessment of gully dynamics and the associated soil loss and a prognosis of areas susceptible to further gullying were deemed crucial aerial photographs from two different dates 1966 and 1996 with approximate scales of 1 45 000 were used to study the development and dynamics of gullies as indicated by volume changes between the two dates they were digitized at a pixel size of 20 m digital elevation models dem with grid widths of 20 and 2 m were derived from stereo image pairs separately gully breaklines and borderlines were measured for the identified gully systems gully profiles were positioned at regular intervals of 20 m along the gully length giving rise to gully sections that are portions of a gully between neighbouring profiles gully volume was computed for every gully section soil loss was estimated from the computed gully volumes using soil bulk density it showed that soil loss per unit of gully surface is very high 1 7 tons m 2 of gully surface over the 30 years time period indicating the severity of gully erosion in the subcatchment there was significant agreement between breakline measured and field measured gully depth and width for selected points this is an indication of the potential of the method for reliable gully volume estimation and hence quantification of soil loss due to gully erosion the possibility of predicting hill slope areas susceptible to further gullying based on the topographic attributes such as specific contributing area and local slope from an interpolated detailed dem with 2 m resolution was tested it was found that wetness index alone or a combination of the wetness index and the compound topographic index at the threshold values established in literature would give better results as viewed from better connectivity of flow lines and higher conformity of the predicted susceptible areas to natural gully headcut and expansion in a landscape reality

development and controlling factors of gullies and gully complexes east coast new zealand sequential aerial photographs of a small headwater catchment in the waiapu basin east coast region north island new zealand were interpreted to measure and analyse temporal changes in active area of gullies and gully complexes for a longer time span 1939 2003 and with higher temporal resolution compared to previous studies we focus on the conditions leading to the development of gullies and gully complexes under pasture and forest by using topographic thresholds slope area relationships of catchments for the initiation of gullies and gully complexes in addition the influence of two different lithologies as well as the occurrence of major rainfall events was related to gully activity twenty gullies and four gully complexes occupying 62 5 ha or 12 5 per cent of the catchment area occurred in the study catchment between 1939 and 2003 however the majority of these were not active at all of the dates studied gullies developed in the sandstone dominated tapuwaeroa formation tended to attain their maximum size by 1957 with a mean catchment area of 2 1 ha gullies developed in mudstone of the whangai formation attained their maximum size in 1939 with a mean catchment area of 4 31 ha exceptions are gullies which developed into mass movement deposits or into an earth flow deposit as well as gullies developed under indigenous forest topographic threshold values for gullies under pasture and indigenous forest show that values for gullies under forest plot far above the threshold line of gullies under pasture indicating that the topographical threshold for gully development under forest is higher compared to under pasture a threshold value of 9 4 ha in catchment area is needed for the development of gully complexes under pasture all located in the whangai formation and with the same orientation as the strike of the mudstones gully complex area and dominance of mass movement erosion increased with larger catchment area a decreasing distance to the threshold line for gullies under pasture indicates a later development for gully complexes no gully complexes developed under indigenous forest indicating that the threshold value for gully complex development is higher than for gully complexes under pasture and was not reached in the study area a model of shifting topographical threshold for gully development for a given catchment is developed which depends on land use when a catchment has an indigenous forest cover the topographical threshold is very high after conversion to pasture threshold values decrease drastically with the invasion of scrub the threshold slowly increases and returns to a similar level to that under indigenous forest after reforestation development of gullies and gully complexes is a highly dynamic phenomenon and phases of expansion and inactivity indicate that models describing only unidirectional advancing stages without periods of inactivity are not suitable therefore this study adds more phases to models of gully and gully complex development in the east coast region the threshold line for gully initiation under pasture and a value of 9 4 ha in catchment area for gully complex initiation permits one to predict which catchments under similar environmental settings develop gullies and gully complexes on a physical basis this enables land managers to implement sustainable land use strategies to reduce erosion rates of gullies and gully complexes copyright 2006 john wiley sons ltd

electrical conductivity measurements from the gisp2 and grip greenland ice cores the direct current electrical conductivity of glacial ice depends on its acidity1 3 and can also indicate changes in climate as ice formed in cold dusty periods has a high concentration of alkaline dust1 4 5 which significantly reduces the conductivity6 7 compared to warmer less dusty periods here we present electrical conductivity records for the greenland ice sheet project 2 gisp2 and greenland ice core project grip ice cores drilled 28 km apart to enable direct comparison of the results the upper parts of both records are consistent with previous evidence from other greenland cores4 8 12 for a stable greenland climate during the holocene and a series of warm events punctuating the last glacial period however there is a significant discrepancy between the two records in the bottom 10 of the cores calling into question recent reports of climate variability in the last interglacial4 8 and the penultimate glaciation8 at this stage it is too early to say what exactly is causing the discrepancy although ice flow may have introduced some discontinuities into the records further work will be necessary to establish how much climatic information it will eventually be possible to extract from the lower parts of the two cores

trace metal pollution of soils in northern england data from a regional geochemical survey of topsoils n 818 in rural and peri urban areas over a single parent material coal measures are used to identify two types of trace metal pollution severe local contamination at 20 sites and widespread diffuse pollution in more densely populated areas median concentrations of several trace metals in topsoils were significantly higher in areas of high compared to low population density percentage increases in parenthesis as 31 cu 39 fe 7 mo 26 36 ni 29 pb 20 sn 40 and zn 11 four potential pathways of diffuse trace metal pollution are postulated coal ash dispersal atmospheric aerosols derived from coal combustion the historical spreading of sewage waste and those related to road vehicles the statistical analysis of geochemical data classified by local human population density can be an effective means of identifying the magnitude and extent of diffuse pollution and could help to establish natural background levels

high resolution gully erosion and sedimentation processes and land use changes since the bronze age and future trajectories in the kazimierz dolny area naleczow plateau se poland abstract this paper presents the results of 40 years of research on the gully system in the doly podmularskie catchment 0 35 km in size which is situated in the south western part of the loess covered naleczow plateau in se poland topographic stratigraphic and pedologic investigations and monitoring of a tributary gully gully area 0 7 ha catchment 2 5 ha were combined with historical archaeological and palaeoecological records the results reveal a long and complex history in terms of the temporal and spatial extent and the impact of land use on gully erosion and the long term feed back mechanisms between land use changes and natural processes since the end of the pleistocene phases of gully erosion and subsequent filling occurred in the bronze age and around the 10th to 11th centuries the most severe deepening and expansion of the gully took place in the 17th century the results also show that field structures and land use intensity had a significant influence on the frequency and magnitude of run off soil erosion piping and landslide events the last significant erosion phase started in the mid 19th century with renewed headward retreat and down cutting within older gully fills today most of the catchment is either forested or the land is covered in berry shrubs in the future the area will continue to produce sediments because of the steep slopes and because there are still areas of bare soil with a low resistance to erosion a legacy from past land uses which will remain a factor affecting soil erosion and sedimentation processes in the future this study is an example of how important it is to observe and understand slow geomorphologic processes and rare extreme events in the light of land use changes when investigating long term human environment interactions

the flickering switch of late pleistocene climate change polar ice contains a unique record of past climate variations previous greenland ice cores have documented relatively warm interstadial periods during the last glaciation and short centuryscale returns to colder conditions during the glacial to interglacial warming see for example ref 1 these climate features have also been observed to varying degrees in ocean sediment cores2 4 and terrestrial pollen and insect records5 7 here we report electrical conductivity measurements from a new greenland ice core which confirm these previous observations and also reveal a hitherto unrecognized mode of rapid climate variation fluctuations in ice conductivity on the scales of 5 20 years reflect rapid oscillations in the dust content of the atmosphere this flickering between two preferred states would seem to require extremely rapid reorganizations in atmospheric circulation

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

holocene valley aggradation and gully erosion in headwater catchments south eastern highlands of australia late quaternary stratigraphy of a 50 km2 catchment on the south eastern highlands of australia reveals processes and history of denudation and helps resolve a long standing debate about factors controlling episodic valley aggradation and degradation during holocene times valley sedimentation occurred when swampy vegetation fully colonized valley floors and obliterated all channels promoting aggradation for periods of several thousand years with most incoming sediment being trapped in swampy meadows much of the sediment was reworked from late pleistocene alluvial fan and valley fill deposits and primary hillslope erosion was minor during the holocene differing sedimentation patterns between the late pleistocene holocene and post european settlement periods reflect regional changes in sediment supply and transport capacity as a result of major environmental change within the holocene however valley fill stratigraphy is controlled by massive episodic gully erosion terminating aggradation gully initiation appears to be controlled more by thresholds of incision into vegetated valley floors than by changes to sediment supply whether the thresholds are exceeded because of climatic change autonomous change or extreme events cannot yet be determined overall the holocene history represents continuing complex response to events of the late pleistocene and does not support the k cycle concept which has strongly influenced late quaternary geomorphology in australia

prehistoric and roman gullying in the european oess belt a case study from central belgium in contrast with the understanding of present day soil erosion processes knowledge on past soil erosion phenomena is still rather limited although some studies report on severe gully erosion phases during the fourteenth and eighteenth centuries almost no evidence is available that documents earlier gully erosion phases this study investigates the development and age of two old permanent gullies that are conserved in the ancient meerdaal forest in central belgium the development history of both gullies is very similar in the first gully archaeological evidence was found indicating an erosion phase during roman times followed by a partial infilling of the gully in the second gully radiocarbon dating provided evidence of the same roman activity phase cal yr 46 bc ad 78 but also of an earlier incision phase during the middle bronze age cal yr 1743 1602 1568 1533 bc also here the erosion phase was followed by a partial infilling this limited infilling indicates that the catchment of the gullies was reforested quite rapidly hereby cutting off all runoff and sediment production this has led to a unique situation in the meerdaal forest with the conservation of about 43 similar large gullies in an area of about 17 km 2 this area has a high geovalue as the studied gullies are among the oldest and best conserved gullies in northwestern europe

dynamic and static models of gully erosion abstract the main causes of gully formation are anthropogenic factors the clearing of native forests tilling of fallow lands and associated change of the hydrological conditions in the rainfall runoff system gully channels formation is very rapid during the period of gully initiation when morphological characteristics of a gully length depth width area and volume are far from stable this period is relatively short about 5 of a gully s lifetime for the most part of a gully s lifetime its size is near stable maximum value these two stages of gully development led to two types of gully erosion models 1 dynamic models to predict rapid changes of gully morphology at the first period of gully development 2 static models to calculate final morphometric parameters of stable gullies the dynamic gully model is based on the solution of the equations of mass conservation and gully bed deformation the model of straight slope stability was used for prediction of gully side walls inclination the static gully model is based on the assumption of final morphological equilibrium of a gully when averaged for several years elevations and width of gully bottom do not change this stability is associated with a negligible rate both of erosion and sedimentation at the gully bottom it means that flow velocity is less than the threshold value for erosion initiation but is more than the critical velocity of wash load sedimentation the dynamic and static gully models were verified on the data on gullies morphology and dynamics from yamal peninsula russia and new south wales australia

visual stratigraphic dating of the gisp2 ice core basis reproducibility and application annual layers are visible in the greenland ice sheet project 2 ice core from central greenland allowing rapid dating of the core changes in bubble and grain structure caused by near surface primarily summertime formation of hoar complexes provide the main visible annual marker in the holocene and changes in cloudiness of the ice correlated with dustiness mark wisconsinan annual cycles both markers are evident and have been intercalibrated in early holocene ice layer counts are reproducible between different workers and for one worker at different times with 1 error over century length times in the holocene reproducibility is typically 5 in wisconsinan ice age ice and decreases with increasing age and depth cumulative ages from visible stratigraphy are not significantly different from independent ages of prominent events for ice older than the historical record and younger than approximately 50 000 years visible observations are not greatly degraded by brittle ice or many other core quality problems allowing construction of long consistently sampled time series high accuracy requires careful study of the core by dedicated observers

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

sediment erosion dynamics of a gullied debris slide a medium term record medium term post event sediment flux investigations are rare for headwater catchments and particularly sparse for gullied hillslope failures repeat field observation ground photography and cross section measurements of a debris slide scar at the wet swine gill headwater catchment 0 65 km2 in the english lake district uk provide evidence of erosion and deposition dynamics over the medium term 2002 2014 these data are compared to site topographic and meteorological conditions to evaluate potential process response linkages rill and gully erosion networks establish soon after the slide failure 1 february 2002 thereafter gully enlargement proceeds rapidly first by vertical downcutting prior to lateral expansion and gully wall angle decline changes in cross sectional width depth and area 2002 2013 are characterised by statistically significant p 0 05 negative exponential growth models r2 width 0 88 0 97 depth 0 71 0 86 area 0 87 0 93 gully walls were dominated by erosion but the gully bed was characterised by episodic sediment production storage and transfer often leading to temporary deposition specific erosion rates on the gully wall exceeded those on the adjacent slide scar by up to 764 maximum values wall 0 0084 scar 0 0011 m2 m 1 d 1 upslope contributing runoff area and slope gradient are generally important for erosion although linear regression analysis demonstrates weak or insignificant relationships between meteorological conditions and gully scar sediment flux a general conceptual model of slide scar evolution integrating gully growth and capture summarises activity at this site however transferability to locations with terrain characteristics land management practices and climate conditions different to those existing in the uk uplands remains to be tested this investigation adds to growing appreciation of the complexities of sediment dynamics in headwater catchments and provides clear evidence for the potential of early management intervention to counter detrimental post failure sediment erosion which at this site would have been most effective up to 3 4 years following gully initiation

gully erosion in the siwalik hills nepal estimation of sediment production from active ephemeral gullies a simple field based monitoring programme was established in a small catchment area 4 6 km2 to find the rates of gully erosion in the siwalik hills nepal the rates are used to estimate the amount of sediment produced by gully erosion in the catchment three large and active gullies were selected with areas ranging from 0 44 to 0 78 ha aerial photographs taken in 1964 1978 and 1992 were ortho rectified and used to study the dynamics of gully heads the same gullies were also monitored manually using an orthogonal reference system fixed by erosion pins around the gully heads results from the aerial photos indicated that the gullies expanded remarkably over the period from 1964 to 1992 by 34 to 58 per cent head retreat rates during that period were 0 48 0 55 and 0 73 m a 1 and average annual sediment evacuation was estimated as 2534 171 959 60 and 2783 118 m3 a 1 for the three gullies respectively from the field measurement estimated volumes were found to vary from 731 57 to 2793 201 m3 a 1 over the monitoring period of two years it was also found that the gullies produce sediment which accounts for up to 59 per cent of the sediment produced from surface erosion in the headwater catchment the findings are useful for planning and executing appropriate control measures and constructing a sediment hazard map at the catchment scale copyright 2006 john wiley sons ltd

reconstructing annual and seasonal climatic responses from volcanic events since a d 1270 as recorded in the deuterium signal from the greenland ice sheet project 2 ice core a 200 m ice core at the gisp 2 site summit greenland provides a 720 year record of volcanic eruptions identified by pronounced increases in so42 in relation to the background concentration deuterium hydrogen isotope ratios d measured in the same core provide a proxy climate record temperature used to examine the response of the climate system in greenland to these eruptions a group of 34 known volcanic events and a subgroup of the six largest volcanic events are isolated and examined for both groups significant negative cooler isotopic excursions occur beginning the year the volcanic event is detected in the ice core cooling is significant for 1 to 2 years the maximum isotopic excursion averages 4 0 7 c for all 34 events and 10 1 8 c for the subgroup of largest events for individual events the response in the isotope signal to volcanic events is highly variable but occurs at most 1 year before so42 is detected in the core examination of subannual isotope data suggests that peak winter isotope values are lowered more than peak summer values we hypothesize that this result is flawed by posted positional alteration of the isotopic profile by vapor diffusion to test this hypothesis we use numerical deconvolution to account for the smoothing effects of vapor diffusion in the firn analysis of the deconvolved data shows greater summer than winter cooling a result more consistent with instrumental temperature data

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

historic eruptions of tambora 1815 krakatau 1883 and agung 1963 their stratospheric aerosols and climatic impact abstract decreases in surface temperatures after the eruptions of tambora 1815 krakatau 1883 and agung 1963 were of similar magnitude even though the amount of material dust and volatiles injected into the stratosphere by these three events differed greatly large amounts of fine ash and volatiles were dispersed into the upper atmosphere by krakatau and tambora the agung eruption in 1963 was a much smaller vulcanian type eruption which injected dust and volatiles into the stratospheric aerosol layer more directly analyses of magmatic volatiles indicate that the agung eruption was proportionately richer in so 2 and cl than either tambora or krakatau relative amounts of fine ash produced by the tambora krakatau and agung eruptions are estimated at about 150 20 1 whereas the masses of atmospheric sulfate aerosols produced were on the order of 7 5 3 1 decreases in surface temperature of a few tenths of a degree c for several years following volcanic eruptions are primarily a result of the sulfate aerosols rather than of the silicate dust the similarity in the atmospheric response after these three eruptions supports the idea of limiting mechanisms on volcanic stratospheric aerosol loading which is suggested by microphysical processes of aerosol particles fluctuations in stratospheric aerosol optical depth seem to be controlled to a large degree by high intensity sulfur rich eruptions e g agung 1963 which may however be relatively small in total ejecta volume such eruptions leave little geologic record but appear as acidity peaks in polar ice cores

comparison of conceptual landscape metrics to define hillslope scale sediment delivery ratio abstract the aim of this study was to evaluate four metrics to define the spatially variable regionalised hillslope sediment delivery ratio hsdr a catchment model that accounted for gully and streambank erosion and floodplain deposition was used to isolate the effects of hillslope gross erosion and hillslope delivery from other landscape processes the analysis was carried out at the subcatchment 40 km 2 and the cell scale 400 m 2 in the avon richardson catchment 3300 km 2 south east australia the four landscape metrics selected for the study were based on sediment travel time sediment transport capacity flux connectivity and residence time model configurations with spatially constant or regionalised hsdr were calibrated against sediment yield measured at five gauging stations the impact of using regionalised hsdr was evaluated in terms of improved model performance against measured sediment yields in a nested monitoring network the complexity and data requirements of the metric and the resulting spatial relationship between hillslope erosion and landscape factors in the catchment and along hillslope transects the introduction of a regionalised hsdr generally improved model predictions of specific sediment yields at the subcatchment scale increasing model efficiency from 0 48 to 0 6 in the best cases however the introduction of regionalised hsdr metrics at the cell scale did not improve model performance the flux connectivity was the most promising metric because it showed the largest improvement in predicting specific sediment yields was easy to implement was scale independent and its formulation was consistent with sedimentological connectivity concepts these properties make the flux connectivity metric preferable for applications to catchments where climatic conditions can be considered homogeneous i e in small medium sized basins up to approximately 3000 km 2 for australian conditions with the avon richardson catchment being at the upper boundary the residence time metric improved model assessment of sediment yields and enabled accounting for climatic variability on sediment delivery but at the cost of greater complexity and data requirements this metric might be more suitable for application in catchments with important climatic gradients i e large basins and at the regional scale the application of a regionalised hsdr metric did not increase data or computational requirements substantially and is recommended to improve assessment of hillslope erosion in empirical semi lumped erosion modelling applications however more research is needed to assess the quality of spatial patterns of erosion depicted by the different landscape metrics

the δ18o record along the greenland ice core project deep ice core and the problem of possible eemian climatic instability over 70 000 samples from the 3029 m long greenland ice core project grip ice core drilled on the top of the greenland ice sheet summit have been analyzed for 8o a highly detailed and continuous 8o profile has thus been obtained and is discussed in terms of past temperatures in greenland we also discuss a three core stacked annual 8o profile for the past 917 years the short term 50 years variability of the annual 8o signal is found to be 1 in the holocene and estimates for the coldest parts of the last glacial are 3 or higher these data also provide insights into possible disturbances of the stratigraphic layering in the core which seems to be sound down to the onset of the eemian spectral analysis of highly detailed sequences of the profile helps determine the smoothing of the 8o signal which for the holocene ice is found to be considerably stronger than expected we suggest this is due to a process involving diffusion of water molecules along crystal boundaries in the recrystallizing ice matrix deconvolution techniques were employed for restoring with great confidence the highly attenuated annual 8o signal in the holocene we confirm earlier findings of dramatic temperature changes in greenland during the last glacial cycle abrupt and strong climatic shifts are also found within the eem sangamon interglaciation which is normally recorded as a period of warm and stable climate in lower latitudes the stratigraphic continuity of the eemian layers is consequently discussed in section 3 of this paper in terms of all pertinent data which we are not able to reconcile

volcanic aerosol records and tephrochronology of the summit greenland ice cores the recently collected greenland ice sheet project 2 gisp2 and greenland ice core project ice cores from summit greenland provide lengthy and highly resolved records of the deposition of both the aerosol h2so4 and silicate tephra components of past volcanism both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism climate system the continuous time series of volcanic so42 for the last 110 000 years show a strong relationship between periods of increased volcanism and periods of climatic change the greatest number of volcanic so42 signals many of very high magnitude occur during and after the final stages of deglaciation 6000 17 000 years ago possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins sea level change the increase in the number of volcanic so42 signals at 27 000 36 000 and 79 000 85 000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation respectively a comparison of the electrical conductivity of the gisp2 core with that of the volcanic so42 record for the holocene indicates that only about half of the larger volcanic signals are coincident in the two records other volcanic acids besides h2so4 and other so42 sources can complicate the comparisons although the threshold level picked to make such comparisons is especially critical tephra has been found in both cores with a composition similar to that originating from the vatnaoldur eruption that produced the settlement layer in iceland mid a d 870s from the icelandic eruption that produced the saksunarvatn ash 10 300 years ago and from the icelandic eruption s that produced the z2 ash zone in north atlantic marine cores 52 700 years ago the presence of these layers provides absolute time lines for correlation between the two cores and for correlation with proxy records from marine sediment cores and terrestrial deposits containing these same tephras the presence of both rhyolitic and basaltic shards in the z2 ash in thegisp2 core and the composition of the basaltic grains lend support to multiple icelandic sources torfajokull area and katla for the z2 layer deposition of the z2 layer occurs at the beginning of a stadial event further reflecting the possibility of a volcanic triggering by the effects of changing climatic conditions

monitoring of gully erosion on the loess plateau of china using a global positioning system abstract with the development of a technique global positioning system gps has become progressively less expensive lighter and easier to use the accuracy of gps has been improved and it appears applicable to the continuously monitoring morphology changes on the earth surface with small and slow change the objective of this study is to use gps to measure the morphology of gullies in a small catchment near suide shaanxi province china there are three main gully types in the study area bank gullies floor gullies and hill slope gullies and this study mainly focuses on the hill slope gullies the hill slope gullies in the study area are mainly discontinuous and are developing rapidly the gully density in the study area is very large the retreat rate of hill slope gullies is 0 16 2 02 m year 1 the relationships between the upslope drainage area a and the critical slope gradient s for hill slope gullies is s 0 1839a 0 2385 the values of as2 range from 41 to 814 m2 for the hill slope gully headcuts and most of them fell into the range of 100 300 m2 both of these relationships are suggested as indexes for estimating the location of gully headcuts

erosion and sedimentation on the russian plain ii the history of erosion and sedimentation during the period of intensive agriculture the processes of sheet rill and gully erosion on the slopes of the russian plain are controlled by the same factors as elsewhere cover erodibility erosivity and landform the combination of land use history and variations in these bio physical factors produced a history of erosion that is unique to this area the most eroded soils occur in the non black earth area especially where there are soddy podzolic soils over the entire russian plain 99 109 m3 of soil have been lost from the slopes since ad 1696 on the arable land a layer 40 cm has been eroded about 2 106 gullies more than 300 m in length have formed during the last 300 years mobilizing about 4 109 m3 of sediment about 97 of this vast amount of soil has been redeposited on the plain rather than transported to the oceans the effect of the sediment on stream channels has been greatest in the headwaters where large numbers of low order channels have been completely infilled up to 5 6 m of sediment has accumulated in some of these small valleys copyright 2003 john wiley sons ltd

electrical measurements on the greenland ice sheet project 2 core the greenland ice sheet project 2 gisp2 electrical conductivity measurement ecm record is an indication of the concentration of h in the core the ecm detected seasonal variations in the nitrate concentration of the core which were used to assist in dating the core by annual layer counting volcanic eruptions that produce acidic aerosols are recorded in the ecm record evidence of biomass burning is detected by the ecm because fire related ammonium emissions neutralize the acids in the core rapid climate transitions associated with the younger dryas and dansgaard oeschger interstadial events alter the concentration of alkaline dust and are detected by the ecm the ecm has been used to develop stratigraphic ties between the gisp2 and the greenland ice core project cores users of the data should be aware of some instrument related artifacts in the ecm record

medium term gully headcut retreat rates in southeast spain determined from aerial photographs and ground measurements this paper deals with gully retreat rates at different time scales whereby the short term time scale may span a time interval of 1 5 years the medium term time scale a time interval of 5 50 years and the long term time scale a time interval of more than 50 years an analysis of high altitude aerial photographs in combination with ground measurements allowed us to quantify volumetric gully head retreat rates for 12 permanent gullies in southeast spain guadalentin and guadix study areas over a 40 43 year time interval medium term time scale this resulted in an average retreat rate ve of 17 4 m3 year 1 a power relationship between drainage basin area a and medium term volumetric gully head retreat rate ve 0 069a0 380 r2 0 51 n 21 was found by combining the gully head retreat rates obtained in this study with those obtained by a dendrochronological method the exponent b and the coefficient of determination r2 of the power relationships ve aab increases from the short term to the long term time scale expressing the increasing importance of drainage basin area in gully development with time considerable differences between gully head retreat rates measured at the short and medium term time scales at individual gullies showed the importance of land use changes and unsuccessful management practices on gully head retreat and the episodic nature of gully head retreat when piping and tension cracking are involved higher gully head retreat rates are obtained at the medium term time scale compared to the short term time scale but the differences are not significantly different at 10 the medium term methods tend to measure proportionally more high gully retreat rates but less extreme values compared to the short term method this is explained by a more equal distribution of extreme rainfall events both in space and time at a longer term time scale and hence a higher probability of measuring the average effect of both small and extreme rainfall events at each gully

comparison of gis based gullying susceptibility mapping using bivariate and multivariate statistics northern calabria south italy abstract this paper presents gis aided procedures for the evaluation of gullying susceptibility on a statistical basis field surveys and air photo interpretation allowed us to identify gullies geology and land use while some predisposing factors were derived from a 7 5 m cell size dem in order to investigate the role of each instability factor in controlling the spatial distribution of gullies we implemented four models that differ in the types of method bivariate vs multivariate training set sampling polygon or point based and variables continuous or categorical the models were applied to the turbolo river catchment a tributary of the crati river northern calabria italy the susceptibility values were classified into five categories model performance was evaluated using prediction rate curves and by comparing the proportion of each susceptibility class with gully distribution in the validation set although all models showed relatively good performances the bivariate method overestimated the extent of the high susceptibility classes the multivariate logistic regression model using continuous variables was found to be the best model in predicting gullying susceptibility of the study area the area classified as stable increased with dem cell size meaning that a reasonably fine dem should be used

a spatial information technology approach for the mapping and quantification of gully erosion abstract in contrast to the effort during the last decades to investigate sheet interrill and rill soil erosion processes relatively few studies have been focused on quantifying and or predicting gully erosion the extension of the use of modern spatial information technologies such as geographical information systems gis digital elevation modelling dem and remote sensing have created new possibilities for research in this field a key issue to be addressed as the basis for predicting the effects of global changes such as land use and climate changes is the mapping and quantification of gully erosion rates including rate of retreat of gully walls and rate of sediment production this research work presents a method to compute the rate of retreat of gully walls and the associated rate of sediment production caused by gully erosion the proposed method uses multitemporal aerial photographs and multitemporal digital elevation models both of which have been processed using gis techniques the research was applied to a sample catchment of 25 km2 located in catalonia spain aerial photographs at scale of 1 30 000 from 1957 and orthophotos from 1993 were used to map gully erosion and determine erosion rates between 1957 and 1993 the rates of channel incision and sediment production were computed from the subtraction of multitemporal digital elevation models the rate of gully walls retreat was 0 2 m year 1 representing a rate of 0 9 m2 year 1 the maximum rate of channel incision 0 7 0 8 m year 1 occurred at the head of the gully and at meandering zones the rate of sediment production caused by gully erosion was 1322 142 ton ha 1 year 1 in comparison with other methods to compute sediment production caused by gully erosion processes the proposed method integrates the losses due to overland flow mass movements and gully deepening and supposes an improvement to locate the areas within the gullies with higher erosional activity

contribution of glacier meltwater to streamflow in the wind river range wyoming inferred via a bayesian mixing model applied to isotopic measurements the wind river range wrr of wyoming has the largest concentration of alpine glaciers in the american rockies and contributes to several major river systems in the western united states declines in the areal extent and volume of these glaciers are well documented and eventual loss of alpine glaciers will reduce the amount of water available for agricultural and domestic use the contribution of glacial melt to streamflow remains largely unquantified in wyoming we used isotope measurements and bayesian modeling to estimate the fractional contribution of glacier meltwater to dinwoody creek dc in the wrr on bi weekly and seasonal spring summer and fall time scales over 2 years in 2007 and 2008 we made temporally intensive measurements of the stable isotope composition of water from the dc watershed samples of the primary sources of streamflow snowmelt glacier melt rain and baseflow were collected during field campaigns and automated collection of stream samples occurred over the melt season isotope data d and 18o were analyzed within a hierarchical bayesian framework that incorporated temporal and spatial correlations glacial melt contributed a significant proportion 53 59 to streamflow in a low flow year 2007 or when streamflow was low during a high flow year 2008 in 2008 a large and persistent snowpack contributed significantly 0 42 51 to streamflow in mid summer the large contribution of glacial melt to streamflow suggests that the loss of glaciers may impact riparian ecosystems and human water supplies in the late summer and in years with low snowpack copyright 2011 john wiley sons ltd

biomass burning recorded in the gisp2 ice core a record from eastern canada combustion byproducts from biomass burning are preserved in annually stratified layers in the greenland ice sheet electrical conductivity ecm and ammonium records from the gisp2 ice core in central greenland have been used to develop a 6000 year record of biomass burning although there is some uncer tainty regarding the source area for the combustion byproducts it is likely that the majority of the material originates in eastern canada time periods of high biomass burning activity occurred in 0 150 bp 350 750 bp and 5000 to 6000 bp the period 1150 3250 bp is characterized by moderately elevated levels of biomass burning activity these periods are associated with drier conditions the 5000 to 6000 bp period of high biomass burning activity may also be related to forest successional sequences following the removal of the laurentide ice sheet this paper explains how ice cores can be used to develop records of biomass burning and offers suggestions for future studies

a new technique for the automatic monitoring of erosion and deposition rates the rates and processes of erosion and deposition of soils and sediments are subjects of widespread and increasing concern in the earth and environmental sciences process inference from field studies however has been hampered by a lack of information on the precise magnitude frequency and timing of erosional and depositional activity because no automatic monitoring technique has hitherto been available i describe here an automatic photo electronic erosion pin peep system which apparently for the first time allows quasi continuous time series of erosion and deposition data to be collected example results from a river bank site show how the peep system helps to define the true temporal distribution of geomorphological change quantify the erosional impact of individual forcing events and discriminate between competing hypotheses of process control in erosional and depositional contexts the system should thus allow more effective testing of erosion models of high temporal resolution and facilitate a more rigorous linking of catchment sediment output to supply dynamics

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

gully erosion impacts factors and control gully erosion attracts increasing attention from scientists as reflected by two recent international meetings poesen and valentin eds catena 50 2 4 87 564 li et al 2004 gully erosion under global change sichuan science technology press chengu china 354 pp this growing interest is associated with the increasing concern over off site impacts caused by soil erosion at larger spatial scales than the cultivated plots the objective of this paper is to review recent studies on impacts factors and control of gully erosion and update the review on dgully erosion and environmental change importance and research needst poesen et al 2003 catena 50 2 4 91 134 for the farmers the development of gullies leads to a loss of crop yields and available land as well as an increase of workload i e labour necessary to cultivate the land gullies can also change the mosaic patterns between fallow and cultivated fields enhancing hillslope erosion in a feedback loop in addition gullies tend to enhance drainage and accelerate aridification processes in the semi arid zones fingerprinting the origin of sediments within catchments to determine the relative contributions of potential sediment sources has become essential to identify sources of potential pollution and to develop management strategies to combat soil erosion in this respect tracers such as carbon nitrogen the nuclear bomb derived radionuclide 137 cs magnetics and the strontium isotopic ratio are increasingly used to fingerprint sediment recent studies conducted in australia china ethiopia and usa showed that the major part of the sediment in reservoirs might have come from gully erosion gullies not only occur in marly badlands and mountainous or hilly regions but also more globally in soils subjected to soil crusting such as loess european belt chinese loess plateau north america and sandy soils sahelian zone north east thailand or in soils prone to piping and tunnelling such as dispersive soils most of the time the gullying processes are triggered by

factors controlling the erosion rates in a semi arid zone bardenas reales ne spain abstract bardenas reales is an erosive depression 415 km 2 in area located in the central western part of the ebro depression tertiary sediments crop out in the margin of the basin whereas quaternary sediments holocene in age occur only in its centre these holocene sediments clays and silts are the result of the erosion and weathering of the tertiary clays and are made up of 3 different stratigraphic units erosion is clearly the dominant process in the centre of the depression generating gullies up to 10 km in long and 8 m deep in order to analyse and quantify the erosion rates of the studied area erosion was measured on two soil erosion plots with volumetric and instrumental techniques that have been supplied for the last 12 years the results show that the estimated erosion rates depend extrinsically on the used method and intrinsically on the time of the year in which they are measured the most accurate values are those obtained by means of collector devices the values obtained by the microtopographic profile gauge are overestimated while the results of the measurement with erosion pins are clearly lower the study area is located in a semi arid environment with two pluviometric maximums in spring and autumn associated with convective storms in summer and winter rainfall is related to atlantic cyclonal fronts soil loss is significant during the pluviometric maximums when rainfall quantity and intensity are higher during cyclonal periods in contrast water erosion is null or scarce and soil loss is related to mudflows in addition the erosion rates of each holocene unit are different the c2 holocene unit has undergone greater erosion because of its physico chemical properties all the stratigraphic units have similar characteristics regarding tertiary materials since 1993 the average erosion rate measured by the collector device on the tertiary materials is 32 mg ha 1 year 1 and 77 mg ha 1 year 1 in the holocene

the measurement of river bank erosion and lateral channel change a review a detailed review and chronological survey is presented of the various techniques which have been used for the measurement of river bank erosion and channel change the techniques are classified according to the time scales involved long intermediate and short and each is discussed with respect to accuracy and repeatability the methods covered include sedimentological evidence botanical evidence historical sources planimetric resurvey repeated cross profiling erosion pins and terrestrial photogrammetry prospects for future developments are also discussed

alluvial sedimentation rates from southeastern australia indicate post european settlement landscape recovery increased catchment sediment yields are common following the introduction of european style agriculture to relatively undisturbed landscapes catchment erosion rates generally increase immediately after disturbance and then decline over time consequently where a catchment currently sits along this disturbance recovery sequence will strongly influence future catchment sediment yields and river morphology in this study field stratigraphy optical dating and hydraulic modelling are used to investigate changes in catchment sediment yield and storage in the lake burragorang catchment in australia with emphasis placed upon changes occurring since european settlement in a d 1820 on the southern tablelands and the upper cox s river subcatchment a large volume of sediment was liberated by gully erosion early in the post settlement period much of which was deposited at break of slope positions below the catchment s headwaters or stored in alluvial benches adjacent to the channel but within the confines of older holocene alluvium a lack of substantial sediment deposition over the last 20 to 40 years is evidence that catchment sediment yields have strongly declined this is consistent with both reduced erosion rates and re aggradation of the incised gullies that in their erosive phase dominated the catchment s post settlement sediment flux collectively these characteristics indicate the catchment is undergoing a phase of landscape recovery

nitrate and heavy metal pollution resulting from agricultural activity a case study from eskipazar karabuk turkey in most countries of the world groundwater and surface water are at a serious risk of pollution due to chemicals used in agricultural activities the present study examined whether such a risk exists in eskipazar turkey and the surrounding area which covers a surface area of 696 km2 nitrate pollution no3 was observed in waters discharging from the orencik formation consisting of loose conglomerate sandstone mudstone siltstone and claystone levels from the yoruk member of the orencik formation consisting of limestone from areas where the orencik formation and yoruk member are located together and from alluvium agricultural is practiced in these areas and the waters discharging from these formations are used as drinking water and for domestic purposes in particular periodically varying levels of pollutants such as b pb hg se were detected in wells drilled in orencik formation featuring a high no3 concentration the concentrations of s cr mn fe cu zn ga br sr y i ba and u in these waters are also slightly higher than other cold waters in the study area in addition to the no3 pollution high levels of ca and so4 pollution was observed at a well drilled in alluvium in addition some trace element concentrations identified in the wells drilled in the orencik formation were higher than the average values at geothermal and or mineral springs in the study area the study area has an adequate sewage system and has no sources of pollution such as mineralization industrial center waste disposal area etc therefore it is believed that the main causes of no3 and trace element pollution are fertilizers and pesticides used in agricultural activities water rock interaction usage period of fertilizers and pesticides amount of precipitation groundwater level usage of elements by plants mobility of elements ph value of the environment redox potential adsorption desorption biochemical processes etc are thought to be the causes of the periodical variation of some trace element concentrations observed in these waters

recent gully erosion in the el cautivo badlands tabernas se spain abstract detailed geomorphic observations in el cautivo badland area in the semiarid se of spain show a recent renewal of linear channel erosion following a period of aggradation prior to this renewal the landscape was characterized by smooth colluvial pediments on the north east facing aspects and relatively steep crusted microhillslopes on south west facing aspects first order valleys within the badland landscape were smooth floored and filled with silty deposits connected with pediment colluvial deposits the conditions under which valley bottom deposition was replaced by channel incision were analyzed by a study of flow hydraulics magnitude frequency of eroding events vs resistance of valley floor to water flow and the pollen sequence in the recently cut deposits changes in the vegetation carpeting the valley bottom seem to be responsible for the deposition erosion alternation rather than changes in the magnitude frequency of major runoff events given the high sensitivity of flow hydraulics to changes in roughness present rainfall rates would not on their own be able to erode a well vegetated valley bottom yet the pollen sequence in the valley fills demonstrates a progressive deterioration in climatic conditions with the eventual disappearance of groups that require a constant level of soil moisture alnus corylus cyperaceae an increase in yearly rainfall or a change in temporal patterns would increase infiltration leading to permanent denser vegetation on footslopes and valley floors helped by the natural water harvesting system this vegetation cover would reduce the flow velocity and induce the deposition of the colluvium and valley fills whereas erosion on headslopes would have been active enough to supply the sediments that were deposited downslope or on the valley bottoms the reactivation of linear erosion would seem therefore to be a consequence of the decay of this permanent vegetation induced by an increase in the duration or severity of drought periods which meant that the water storage capacity of the valley fillings was insufficient to support it