seismic stratigraphy and morphology of the holocene progradational system beneath bohai bay bohai sea lobate evolution of a multi sourced subaqueous fluviodeltaic complex abstract since 6 kyr bp the subaerial deltas of the yellow the yanshan and the taihang river systems evolved along the bohai bay coast forming several lobate progradational systems associated with frequent avulsions of these river systems their subaqueous parts consist of a multi sourced subaqueous deltaic complex in bohai bay but little is known about the complex s subsurface structure morphology and evolutionary history here we investigate these characteristics using a dense high resolution seismic survey using stratigraphic superposition seismic geometry and the results of previous studies we identified nine seismic units sus in the post last glacial maximum stratigraphy which are interpreted from bottom to top as 1 fluvial lacustrine sediments su0 2 marine sands combined with estuarine coastal deposits su1 and 3 a subaqueous fluviodeltaic complex sus2 8 these units correspond to the lowstand system tract the transgressive and or highstand system tracts and the normal regressive system tract respectively and evolved as a function of eustatic fluctuations the subaqueous fluviodeltaic complex is characterized by a discrete and spatially confined lobate architecture which is indicative of step wise switching of subaqueous lobes two sets of progradational systems ps a northern one sus2 3 and a southern one sus4 8 were observed within the complex tapering in opposite directions and bounded by an erosional unconformity r3 these characteristics indicate that the two ps were sourced from different river systems and prograded at different times r3 forms the base of the southern ps but cross cuts the northern ps indicating that it is a diachronous surface marks the preexisting seafloor which was further reworked eroded by the progradation of the southern ps in each ps the internal subaqueous lobes correlated well with the onshore lobes superlobes of the subaerial deltas suggesting the lobate evolution of the complex is driven predominantly by alternating erosion and deposition caused by the variation in fluvial supply which appears to be linked to the frequent avulsions of the major river systems in addition to the multi sourced supply based on the dipping geometries and the locations of the depocenters we hypothesize that 1 the northern ps is the seaward extension of the ancient haihe river s northern branch 2 the bulk of southern ps in the middle and southern bohai bay is correlated with the principal body of the yellow river subaqueous delta 3 the majority of the volume of the northern ps in northern bohai bay consists of the modern haihe river subaqueous delta

flow and solute transport through the soil matrix and macropores of a hillslope segment subsurface flow from various portions of a soil profile on a steep forested hillslope was evaluated by two sets of step change miscible displacement tests at different application rates and antecedent hydrologic conditions solutions of nacl 1000 mg l 1 cl were applied at steady state rates equivalent to 20 and 30 mm h 1 of standing water over the entire plot area using a line irrigation source located 1 5 m upslope lateral distance from an excavated soil pit subsurface flow and tracer breakthrough from five portions the organic rich soil layer including macropores the mineral soil matrix and three groups of macropores in the mineral soil layer of the soil profile were individually measured and analyzed using a convective dispersive model matrix flow dominated discharge from the soil pit during tracer tests 70 93 of total discharge however during wet periods with upslope drainage macropores including organic rich soil contributed proportionally more flow than during periods when upslope drainage was minimal outflow from macropores during the test with wet antecedent conditions had lower cl concentrations than drainage from the soil matrix suggesting dilution in macropores from upslope drainage effective pore volumes calculated for the flow averaged breakthrough data from the entire profile were much less 40 than the estimates measured by tensiometers of total volume of pore water suggesting that preferential flow significantly contributed to subsurface transport of tracer the pore volume for the entire profile increased only slightly with increasing application rate however the relative proportions of pore volumes calculated for individual portions varied proportionally to antecedent hydrologic conditions these changes are attributed to the expansion of individual macropores with surrounding soil and the lateral extension of macropore networks during wetter conditions

effect of catchment scale subsurface mixing on stream isotopic response a 3 8 ha watershed on the west coast of new zealand was instrumented with suction lysimeters and automatic water samplers to determine the relationship between subsurface isotopic and chemical concentrations to those of rainfall and resulting streamflow a t test showed that 2 represented a significant difference between successive sample deuterium values eleven rainfall episodes were subdivided into two categories 1 two events where stream isotopic composition did not deflect 2 from prestorm values and 2 four events which demonstrated new water flushing detailed analysis of one 47 mm rainfall 9 8 mm runoff event showed that old water dominated stream water exiting the watershed by 90 using a standard two component hydrograph separation for deuterium corroborated by cl and electrical conductivity three component hydrograph separation indicated that 12 16 was in the form of soil water with 5 as on channel precipitation and 80 groundwater analysis of over 1000 water samples revealed systematic trends in soil water and groundwater isotopic composition both in a downslope and downprofile direction between storm suction lysimeter deuterium data showed a systematic dampened response to temporally variable rainfall deuterium concentrations multivariate cluster analysis revealed three distinct soil water groundwater groupings with respect to soil depth and geographic position within the watershed within storm suction lysimeter sampling preserved similar groupings indicating that the subsurface reservoir is poorly mixed on short time scales understanding subsurface mixing response to rainfall should greatly improve models of episodic stream response and partitioning of storm flow into waters of different age

kinematic wave approximation to infiltration into soils with sorbing macropores infiltration into soils with macropores is treated as two domain flow the first domain is the soil matrix in which water is subjected to capillarity and infiltration is approached by philip s sorptivity concept the second domain is the soil macropore system in which water moves only under gravity and flow is approached by kinematic wave theory a sink function with respect to flow in the macropore system accounts for water sorption by the soil matrix the two domain flow model is then applied to infiltration into a block of undisturbed soil containing macropores

the capillary fringe and its effect on water table response abstract shallow water tables are often observed to respond in a highly disproportionate manner to precipitation events that is the magnitude of the response is often much greater than would be predicted on the basis of the specific yield of the geologic material and the amount of rainfall physical arguments are presented to show that if the capillary fringe the zone of tension saturation extends to ground surface then the addition of a very small amount of water can result in an immediate and large rise in the water table the arguments are supported by a field experiment in which the addition of 0 3 cm of water caused the water table to rise 30 cm in 0 25 min thus demonstrating the large and highly transient influence of the capillary fringe on the position of the water table the evidence in this study as well as recent work of others suggests that the capillary fringe effect could have a major influence on the process of stream flow generation contaminant transport to surface waters and contaminant transport in hydrogeologic regimes having shallow water tables it is further shown that calculations of groundwater recharge and consumptive use based on water table response and an assumed specific yield could be substantially in error

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

distribution and transport of suspended sediments off the yellow river huanghe mouth and the nearby bohai sea abstract hydrological and sedimentological investigations were carried out off the yellow river huanghe mouth and the nearby bohai sea during august september 2007 to examine the distribution and transport of suspended sediments our data witnessed that suspended sediments from the yellow river mouth primarily extend southerly and southeasterly during the flood season high suspended sediment concentration ssc occurs as turbid plume on both sides of the river mouth where it can reach 20 mg l 1 in the surface water and 40 mg l 1 in the bottom water accordingly salinity varies from 25 to 29 psu mean grain size dmz is 200 m and volume concentration vc is 100 l l 1 high ssc was concentrated in the river mouth area as two muddy patches i e the north mud and south mud consisting mostly of fine grained silt and clayey silt sediments our results have verified the larger extent of the south mud than that of the north one implicating south and southeastward sediment dispersal paths that prevail near the river mouth area the existing anti clockwise and clockwise flows in the river mouth area were synthesized as the major hydrodynamics responsible for forming the two muddy patches tidal and residual currents are considered as the key hydrodynamic factors controlling the sediment distribution and transport in the region

runoff generation processes estimated from hydrological observations on a steep forested hillslope with a thin soil layer abstract in order to understand runoff generation processes on a forested hillslope involving large heterogeneities this study monitored runoff from a steep hillslope with a thin soil layer as well as matric potential within it and analyzed their responses to storm rainfall a comparison of storm runoff responses from the study slope with those from two adjacent catchments one of which includes it showed that physical properties of the slope reflected the runoff characteristics although no responses occurred in very dry conditions because of the absence of wet zones near the stream the area contributing to storm runoff more rapidly extended to the whole slope due to its topographic properties they also caused its steep hydrographs produced in the wettest condition where almost all the rainfall contributed to storm runoff in this wettest condition tensiometric responses near bedrock showed the vertical quick propagation of the rainfall pulse and a good agreement of storm hydrograph simulated through a kinematic wave runoff model suggested that runoff from the slope was produced by a lateral flow on the bedrock receiving the quick propagation in a transition process from dry to the wettest conditions the development of the lateral flow producing smaller responses at the downslope end was estimated from decreasing of matric potential near bedrock from high negative to low values with increasing cumulative rainfall

travel times in the vadose zone variability in space and time water travel times reflect hydrological processes yet we know little about how travel times in the unsaturated zone vary with time using the soil physical model hydrus 1d we derived time variable travel time distributions for 35 study sites within the attert catchment in luxembourg while all sites experience similar climatic forcing they differ with regard to soil types 16 cambisols 12 arenosols and 7 stagnosols and the vegetation cover 29 forest and 6 grassland we estimated site specific water flow and transport parameters by fitting the model simulations to observed soil moisture time series and depth profiles of pore water stable isotopes with the calibrated model we tracked the water parcels introduced with each rainfall event over a period of several years our results show that the median travel time of water from the soil surface to depths down to 200 cm is mainly driven by the subsequent rainfall amounts the median time until precipitation is taken up by roots is governed by the seasonality of evapotranspiration rates the ratio between the amount of water that leaves the soil profile by on the one hand and evaporation and transpiration on the other hand also shows an annual cycle this time variable response due to climatic forcing is furthermore visible in the multimodal nature of the site specific master transit time distribution representing the flow averaged probability density for rainwater to become recharge the spatial variability of travel times is mainly driven by soil texture and structure with significant longer travel times for the clayey stagnosols than for the loamy to sandy cambisols and arenosols

subsurface flow velocities through selected forest soils south island new zealand subsurface flow through soils in tawhai big bush and craigieburn state forests has been studied by applying water at a line source 1 m upslope from a pit in the base of which an intercepting trough is located by measuring lag times between the centres of mass of input and outflow and between the start of input and start of outflow minimum estimates of mean and maximum flow velocity v and vmax at 51 locations were obtained mean values for the tawhai sites were for v 0 3 cm s and for vmax 0 42 cm s but a considerable degree of variability was present with coefficients of variation up to 90 a number of different pathways through the soil are followed by flowing water macropore networks root channels etc are effective transmitters of water and at some sites conveyed up to 40 of the input rapidly to the interception trough variability in flow velocity and the proportion of the input appearing as rapid outflow is a function of antecedent moisture conditions and of the relative importance of the various pathways at a given site which is in turn a function of the characteristics of the soil the macropore network and the parent material at the base of the soil at sites where the soil had an open structure and the parent material was shattered or permeable the macropore network was a less important control upon soil hydrological behavior than where the subsoil had a less open structure and was underlain by impermeable bedrock measurements of flow velocities on undisturbed logged and logged burned planted sites were made at tawhai sf but the spatial and temporal variability was such that no statistically significant differences could be discerned the time lapse since logging may be insufficient for changes in the root systems to be having a hydrological impact but the high variability would require a sample size of over 1000 to show a significant difference in velocity of even 10 for rapid flow through macropores to have a significant influence on streamflow saturation of the soil is necessary before water can enter the macropores soil topographic geologic and climatic conditions in tawhai sf are such that saturation of the lower layers of the soil regularly occurs so that rapid flow through macropores can contribute to storm period streamflow water may reach the channel system from a proportion of the catchment which varies with antecedent moisture conditions and storm duration and intensity but which may attain 100 in moderate to large rain events because of the drier climate and deeper soils subsurface flow contributions to stormperiod streamflow should be less important in the big bush area and particularly in the craigieburn area where the parent materials shattered sandstone or ancient scree deposits do not provide an impermeable layer which diverts flow laterally

hillslope threshold response to rainfall 1 a field based forensic approach summary hillslope threshold response to storm rainfall is poorly understood basic questions regarding the type location and flow dynamics of lateral subsurface flow remain unanswered even at our most intensively studied field sites here we apply a forensic approach where we combined irrigation and excavation experiments at the well studied maimai hillslope to determine the typology and morphology of the primary lateral subsurface flowpaths and the control of bedrock permeability and topography on these flowpaths the experiments showed that downslope flow is concentrated at the soil bedrock interface with flowpath locations controlled by small features in the bedrock topography lateral subsurface flow is characterized by high velocities several orders of magnitude greater than predicted by darcy s law using measured hydraulic conductivities at the site we found the bedrock to be moderately permeable and showed that vertical percolation of water into the bedrock is a potentially large component of the hillslope water balance our results suggest that it is the properties of the bedrock topography and permeability that control subsurface flow at maimai and the soil profile plays a less significant role than previously thought a companion paper incorporates these findings into a conceptual model of hydrological processes at the site to explore the generalities of whole hillslope threshold response to storm rainfall

conceptualizing lateral preferential flow and flow networks and simulating the effects on gauged and ungauged hillslopes 1 one of the greatest challenges in the field of hillslope hydrology is conceptualizing and parameterizing the effects of lateral preferential flow our current physically based and conceptual models often ignore such behavior however for addressing issues of land use change water quality and other predictions where flow amount and components of flow are imperative dominant runoff processes like preferential subsurface flow need to be accounted for in the model structure this paper provides a new approach to formalize the qualitative yet complex explanation of preferential flow into a numerical model structure we base our examples on field studies of the well studied maimai watershed new zealand we then use the model as a learning tool for improved clarity into the old water paradox and reasons for the seemingly contradictory findings of lateral preferential flow of old water where applied line sources of tracer appear very quickly in the stream following application we evaluate the model with multiple criteria including ability to capture flow hydrograph composition and tracer breakthrough we generate output ensembles with different pipe network geometries for model calibration and validation analysis surprisingly the range of runoff response among the ensembles is narrow indicating insensitivity to specific pipe placement our new model structure shows that high transport velocities for artificial line source tracers can be reconciled with the dominance of preevent water during runoff events even when lateral pipe flow dominates response the work suggests overall that preferential flow can be parameterized within a process based model structure via the structured dialog between experimentalist and modeler

geomorphology sedimentology and recent evolution of the anthropogenically modified simeto river delta system eastern sicily italy abstract the purpose of this paper is to present a complete stratigraphic framework for the modern simeto river delta eastern sicily italy by the description of its geomorphology and sedimentology which allow an analysis of its recent evolution the simeto river delta represents an asymmetric wave influenced delta which developed during the holocene by prograding into the catania gulf this delta represents a good example of a mediterranean type system characterized by a micro tidal regime and moderate wave energy the peculiar distribution of sedimentary facies both in the subaerial and in the subaqueous sectors is interpreted as the response of the system to the intimate interaction of geological and in recent times anthropogenic coastal activity the integration of a large amount of historical data allows the definition of prograding and retrograding pattern within the delta and the cyclical shifting of the river mouth over the last two centuries a hypothetical model is proposed to explain this phenomenon and it is suggested that this may be a characteristic of several mediterranean type deltas progradation of the delta ended during the early middle xix century after which it began to retreat the retreat of the coastline accelerated after the 1950s when owing to the construction of embankments on the delta plain and since 1970s increasing diversion of water resources in the upper part of the simeto river drainage basin the sediment input of the river to the ionian sea sharply decreased this caused a dramatic change of the deltaic morphology and significant coastal land loss the morphological and sedimentary features of the simeto river fully reflect the processes of its adaptation to the persistence of coastal human activity within an active geological setting

river mouth bar formation riverbed aggradation and channel migration in the modern huanghe yellow river delta china this paper addresses the recent 1970s 1990s processes of river mouth bar formation riverbed aggradation and distributary migration in the huanghe river mouth area in the light of station based monitoring field measurements and remote sensing interpretation the results show that the morphological changes of the river mouth bar have been closely associated with the largely reduced fluvial discharge and sediment load landforrn development such as bar progradation occurred in two phases i e before and after 1989 which correspond to faster and lower bar growth rates respectively fast riverbed aggradation in the mouth channel was strongly related to river mouth bar progradation during 1976 1996 about 2 8 of the total sediment loads were deposited in the river channel on the upper to middle delta therefore the river water level rose by a few meters from 1984 to 1996 the frequent distributary channel migration which switched the radial channel pattern into the se directed pattern in the mid 1980s was linked with mouth bar formation marine conditions also constrain seaward bar progradation furthermore the history of river mouth bar formation reflects human impacts such as dredging and dyking in order to stabilize the coastal area c 2005 elsevier b v all rights reserved

the role of lateral pipe flow in hillslope runoff response an intercomparison of non linear hillslope response the importance of lateral pipe flow on runoff generation in wet steep hillslopes has been described in many case studies from around the world however most hillslope studies are done in isolation and usually focus on the idiosyncrasies of individual hillslope characteristics and pipe flow response at a single site consequently the first order controls on pipe flow responses remain poorly understood we present a new intercomparison of pipe flow response to storm rainfall at four well instrumented sites panola georgia usa toinotani kyoto japan jozankei hokkaido japan and hakyuchi tokyo japan our objective was to minimize the complexities of lateral pipe flow on hillslopes by looking for commonality across different hillslope types despite the large differences between the study sites in topography climate soil type and soil matrix hydraulic conductivity we found several common pipe flow responses to storm rainfall 1 the relationship between total rainfall amount and total pipe flow volume was highly non linear at each site 2 initiation of measurable pipe flow was threshold dependent controlled by the total rainfall amount and the pre storm wetness 3 once significant pipe flow response occurred the maximum pipe flow rate was sensitive to the measured rainfall intensity and 4 the ratio of total pipe flow to total hillslope discharge for each site was constant regardless of total rainfall amount once the precipitation threshold for significant pipe flow response was reached we used these results to develop a decision tree to determine the general conditions necessary for significant pipe flow to occur the controls derived from our comparisons agree largely with the controls reported by the previous individual hillslope pipe flow studies in the literature the commonality of response between our four very different forested hillslope settings indicates that site intercomparison may be effective for extracting common first order controls on complex hillslope processes we argue that a decision tree may be a useful organizational framework to summarize and organize comparative analyses and may provide a structure for defining the hierarchy of process controls necessary for model development

tracking lead origin in the yellow river estuary and nearby bohai sea based on its isotopic composition the pb concentration and pb isotopes pb 204 pb 206 pb 207 and pb 208 in surface sediments from the yellow river estuary and nearby bohai sea have been determined to investigate the pb sources in this area results showed that pb in the yellow river estuary and northern laizhou bay yre nl sediments was mainly from the yellow river catchment as a consequence of lithogenic sediments from rock weathering accumulation however pb in the coastal area of southern laizhou bay cslb sediments was from both natural and anthropogenic sources sewage discharged near the mihe mouth of the cslb did not extend further to the middle and outer shelves because of the current in laizhou bay the total pb concentration varied from 14 5 to 30 4 mu g g with an average concentration of 20 1 4 2 mu g g thus significant pb pollution was not observed in the yellow river estuary and nearby bohai sea however pb contamination in some sites was indicated by pb isotope ratios c 2015 elsevier ltd all rights reserved

experimental studies on the effects of pipeflow on throughflow partitioning abstract recent research has revealed that natural soil pipes provide important pathways for sub surface movement of water and solutes as well as contributing to landslide initiation a benchscale experiment in a sloping box 1 m in length was conducted with a uniform sand to evaluate the effect of pipeflow on the overall hydrologic regime a single drainage pipe 13 mm inside diameter id composed of five 20 cm segments each with a different roughness coefficient manning s n was placed 5 cm above the base of the 12 8 sloping box roughness elements were arranged in four different spatial combinations during hydraulic experiments piezometric levels were highest and pipeflow was lowest when the high roughness n 0 325 portion of the pipe was located at the downslope end of the box measured values of pipeflow for different hydraulic gradients in each experiment were related to piezometric head above the pipe raised to the 0 32 0 42 power pipeflow was proportional to matrix flow in the soil above the pipe raised to the power of 0 4 0 6 these findings may be useful in estimating pipeflow in uniform soils and in validating two domain models involving preferential flow in soils

how do disconnected macropores in sloping soils facilitate preferential flow runoff from hillslopes is generated by processes such as infiltration excess and saturation overland flow subsurface stormflow and subsurface return flow preferential flow through macropores can affect any one of these runoff generation processes field studies at the hitachi ohta experimental watershed in japan have noted that self organization processes may manifest the connectivity of such subsurface flow paths particularly via macropores from hillslopes to stream channels it is well established from soil physics principles that the connectivity of macropore networks depends on soil wetness and this has been shown experimentally at hitachi ohta where subsurface flow and streamflow respond to thresholds of wetness numerical solutions to the three dimensional richards equation are derived for a sloping soil block containing a population of disconnected macropores of various sizes shapes and orientations solutions for the case of steady water flux applied to the surface of the soil block are evaluated to determine the conditions where the disconnected macropores become active in the flow process results show that subsurface flow is directed through the preferential flow network in the saturated portion of the soil but bypasses the macropores in the drier regions the preferential flow network expands as the degree of saturation increases the expanding network of active macropores leads to less resistance to overall flow in the domain and access to increased volumes of the flow domain although the individual macropores are disconnected it is argued that large localized hydraulic gradients can potentially lead to preferred zones of subsurface erosion in addition to the importance of these findings related to stormflow generation in catchments they add support to the concept of self organization of subsurface flow systems in soils copyright 2010 john wiley sons ltd

seismic framework and the holocene morphological evolution of the changjiang river mouth china abstract acoustic profiling in combination with coring has been used to examine the recent evolution of river mouth of the changjiang two acoustic facies are present petrologic radiometric and seismic analyses show that the upper facies i of 10 20 m thick fine sand and silt represents the sandy shoals of late holocene age in the distributary and the 5 20 m thick lower facies ii of fine grained silty clay with abundant marine microfossils represents the mid holocene prodelta facies deposited as fillings in the former large estuarine valley of late pleistocene to early holocene origin rapid accumulation during the holocene has led to some instability of unconsolidated sedimentary strata in the distributary such as strata collapse and mud diaper formation the existence of large cross beddings such as tabular and trough stratification in facies i identifies the sediment transport as predominantly bed load driven by runoff and tidal currents two sets of discrete flood ebb flow troughs oriented nw and se reflect controls by tidal waves generated from the sea and the superimposition of runoff and ebb flows symmetrical sand waves that appear at the northern trough of one of the distributaries also indicate the balancing sediment dynamics between runoff ebb and flood currents whereas the asymmetrical ones in the southern trough indicate superimposed sedimentation by runoff and ebb flows a large quantity of sediment has been deposited in the slack water region between the discrete flood and ebb flows to form sandy shoals the principal mechanism of the evolution of estuarine islands in the holocene changjiang mouth the morphology of the extended river mouth to the southeast possibly indicates an external driving force such as the coriolis effect nw prevailing wind and longshore currents

changing pattern of accretion erosion of the modern yellow river huanghe subaerial delta china based on remote sensing images abstract the yellow river shifted from the diaokou course to the qingshuigou course in 1976 and shifted again at the north bank of the qingshuigou course in 1996 as a result the entire modern yellow river delta has experienced complicated patterns of erosion and accretion multitemporal remote sensing data of landsat mss and tm from 1976 to 2000 totaling twenty scenes were used to examine the changing pattern of accretion and erosion of the modern yellow river subaerial delta with gis tools during the period 1976 to 2000 the maximum erosion occurred at the head of the last two abandoned promontories diaokou and shenxiangou promontories where the coastline retreated landward over 7 and 4 5 km respectively with mean net erosion rates of 0 29 and 0 19 km a respectively in contrast the maximum accretion occurred at the head of the qingshuigou promontory where the coastline advanced seaward over 20 km with a mean net accretion rate of 0 83 km a the coastline at the head of the q 8 promontory also advanced seaward 7 km with a mean net accretion rate of 0 29 km a during the period 1996 to 2000 total area of the diaokou and shenxiangou promontories was reduced by 141 3 km 2 with a mean net erosion rate of 6 03 km 2 a total area of the qingshuigou and q 8 promontories increased by 384 16 and 11 88 km 2 respectively with mean net accretion rates of 16 4 and 3 03 km 2 a respectively relative to the diaokou shenxiangou and qingshuigou promontories the west area of the diaokou promontory and south area of the qingshuigou promontory were relatively stable although minor erosion occurred the general pattern of accretion and erosion of the modern yellow river subaerial delta was divided into three stages rapid accretion stage 1976 1984 accretion erosion adjustment stage 1985 1995 and slow erosion stage 1996 present the factors affecting the pattern of erosion and accretion over the yellow river delta such as structural geology the yellow river sediment discharge coastal processes meteorological conditions human activity sea level rise and land subsidence were summarized the cumulative area of increase over the entire subaerial delta is closely correlated with the cumulative yellow river sediment discharge wave induced longshore current is the major driving force to transport sediment from eroded areas along the last two abandoned promontories diaokou and shenxiangou promontories mostly westerly and partially easterly together with these coastal processes is the geographical shift of the yellow river course associated with its discharge regime after 1976 leading to the accretion along the present qingshuigou promontory and then the q 8 promontory

structures and hydrologic function of soil landscapes with kettle holes using an integrated hydropedological approach the hummocky post glacial soil landscapes with kettle holes as internal drainage systems are characterized by ponds that trap lateral fluxes in topographic depressions a quantitative description is mostly limited by the unknown complexity of hydraulically relevant soil and sediment structures this paper is focussing on a structure based approach to identify relevant field scale flow and transport processes illustrative examples demonstrate extreme variations in water table fluctuation for adjoining kettle holes explanations require a pedohydrologic concept of the arable soil landscape identification of structures is based on geophysical methods and soil hydraulic measurements electrical resistivity imaging yields 0 5 m scale spatial structures that correspond with soil texture distributions electromagnetic induction provides larger scale field maps that reflect major soil and sediment features results of both methods correspond within the limits of the different spatial resolutions with geophysical exploration methods colluvial areas with textural differences between upper and deeper soil layers coarse textured sediment lenses and stony colluvial regions around kettle holes are identified as potentially relevant flow structures the colluvial fringe around the pond seems to be a sensitive area with important lateral exchange fluxes tensiometer measurements perpendicular to this boundary indicate hydraulic gradients directed from the pond towards the partially saturated soil the localized infiltration of trapped water in kettle holes can control large fractions of ground water recharge and may have implications for the fate of agricultural chemicals in post glacial landscapes while surface and subsurface hydraulic structures may be inferred using minimal invasive techniques better understanding of processes and properties governing lateral exchange fluxes between pond and surrounding soil are required

the tidal intrusion front an estuarine convergence zone freshwater discharge in a small estuary flows seaward as a density current which is forced back into the estuary during the flood phase of the tidal streams the development of the two layer flow and the associated frontal structure is described the front exhibits a v configuration with an isolated point convergence at its apex and an associated gyre system

sediment transport off the huanghe yellow river delta and in the adjacent bohai sea in winter and seasonal comparison abstract based on the data on the current velocity water temperature salinity turbidity and concentration of suspended sediment collected in november 2006 along three survey transects at three time series ship based stations off the huanghe yellow river delta and at twenty four grid survey stations in the adjacent bohai sea sediment transport off the huanghe delta and in the adjacent bohai sea under winter regime were studied and compared with those from the summer season the homogeneous distribution of salinity temperature and sediment in the water column indicated a well mixed body of water a zone of high suspended sediment concentrations ssc 100 mg l 1 with a width of 35 km was identified along the delta coast two highest ssc centers were found in the surface and middle water layers around the abandoned diaokou huanghe river mouth and the present huanghe river mouth and the third one in the bottom layer around the abandoned qingshuigou huanghe river mouth these three highest ssc centers become major sediment source areas in winter based on the location of the high bottom shear stress zone the prevailing wave directions and the protuberant topography of the river mouths we identified the resuspension origin of the three highest ssc centers caused mostly by the winter storm waves partially by tidal currents suspended sediment flux ssf along the three coastal transects indicated that the sediment in the northwest part of the delta was transported northeastward and southeastward along the coast of the recent delta lobe the ssc and ssf were higher in winter than summer by 1 7 27 1 and 2 122 5 times respectively except around the present river mouth this indicates that the intensity of sediment transport in winter is much stronger than in summer due to the powerful effect of winter storms although the river water and sediment discharges to the sea were much greater in summer the massive huanghe sediment to the sea was accumulated in a narrow coastal area due to weak hydrodynamics in summer and then strongly resuspended mostly by storm waves in winter and transported to the offshore area the coastal area off the huanghe delta acts as a sediment sink in summer and converted to be a sediment source in winter in response to the seasonal variation of the east asian monsoon in this region the erosion accumulation pattern of the huanghe subaqueous delta from 1976 to 2003 illustrates that river laden sediment is deposited mainly in the southern part off the coastal area and it is also the result of intensive southward sediment transport in winter

sedimentation in the yellow river delta part ii suspended sediment dispersal and deposition on the subaqueous delta abstract rapid deposition and suspended sediment dispersal off the modern yellow river mouth has been examined from the data of topographic maps 1 25 000 suspension and bed sediments current and salinity which were measured in the field the results show that the sedimentation rate of the mouth bar is the highest of all the environments of deposition in the modern yellow river delta about 30 40 of the sediment that the river transports into the sea has been deposited within the mouth bar area rapid deposition of the mouth bar results mainly from kinetic energy dissipation of the river under the influence of three ambient mechanisms these three mechanisms occur simultaneously as shear front movement which obstructs the river s jet like flow small scale circulations where large velocity gradients occur and the bulldozer effect of the tide sensitive zone in the estuary at ebb based on the analysis of morphologic changes the mouth bar can be divided into two morphologic types one is the double lobe and single channel type and the other double channel and single lobe type weak hyperpycnal plumes with small density differences between the river flow and ambient water dissipate rapidly and deposit about 20 of the river sediments on the delta front slope while hyperpycnal underflows from the river mouth can go through the steep delta front slope to form a rise apron along the upper part of the prodelta grain size analysis of suspended sediment shows that the flow can be divided into three layers a tide layer in the upper part and a hyperpycnal layer in the lower part these two layers are normally graded and a transition layer with inverse grading in the mid part the fine suspended sediments have been transported in the hypopycnal plume layer into the prodelta and deep sea such as the north huanghai sea north yellow sea this study indicates that the tidal current field has dominated the distribution of deposition of sediment on the subaqueous delta and the movements of the river effluent and hyperpycnal underflows

a comparison of simplified methods for routing topographically driven subsurface flow a series of numerical experiments are used to evaluate the accuracy of two approaches for modeling topographically driven subsurface flow suitable for inclusion in spatially distributed hydrologic models the first is an explicit grid cell by grid cell approach and the second is a statistical dynamic method widely used in topmodel both approaches were compared with analytical solutions to the kinematic wave equation for flow down an inclined plane of constant slope using a power law transmissivity function the hillslope discharge and water table profiles simulated by the explicit method were in good agreement with the analytic solution in all test cases the statistical dynamic method converged on the correct steady state solution but failed to reproduce accurately transient conditions the two algorithms were then compared using a 30 m dem representation of the mahantango pa basin and hourly precipitation measured at the site the agreement in discharge between the two methods improved with increasing soil thickness surface conductivity and power law exponent however the percent root mean squared difference rmsd in hourly discharge was above 20 percent in all cases the statistical dynamic model was then calibrated to discharge simulated by the explicit method calibration was most effective for soils with low power law exponents generally producing discharge hydrographs in closemore agreement for soils with linear transmissivity profiles however even under these conditions there are large discrepancies between local water table depths simulated by the two models the level of agreement is best during dry conditions and decreases during wetter conditions as the number of cells with surface soil saturation increases less

sedimentation in the yellow river delta part i flow and suspended sediment structure in the upper distributary and the estuary abstract a 44 year data record measured by lijin hydraulic station on the yellow river shows that sediment concentration has been increasing while river discharge has been decreasing into the delta since the 1970s these changes are important because flood waters of the yellow river which are heavily laden with sediment must be used to supply dongying city and shengli oil company which are located on the delta based on the analyses of data of velocity sediment concentration salinity and sediment grain size from four cross section measurements at lijin station and one 8 vessel simultaneous measurement cruise in the estuary structural characteristics of the river flow and suspended sediments throughout the upper distributary and the estuary have been studied and discussed results show that when sediment concentrations of the yellow river exceed 100 kg m 3 in the lower layer of the river flow during the flood period the river flow structure does not coincide with the logarithmic law of wall and becomes vertically layered and the vertical distributions of suspended sediment do not coincide with the diffusion law the channel length influenced by the tide wave is less than 15 km and there is no tidal intrusion flow only weak osmosis of salinity occurs inside the river mouth during the flood period of the yellow river simultaneous 8 vessel measurements and simulation using the method of preissman show that there is a tidal sensitive zone inside the river mouth bar with a length of 6 7 km when the discharge is as large as 1100 m 3 s and an area of very active sedimentation the tidal sensitive region near the river mouth becomes a low velocity zone that traps a large amount of river sediment which rapidly forms a plastic bed at flood tide and a high velocity zone with a strong hydrodynamic action to erode the new bed and transport the sediments into the sea at ebb tide

sedimentation in the yellow river delta part iii seabed erosion and diapirism in the abandoned subaqueous delta lobe abstract historical bathymetry satellite remote sensing and river discharge data have been used to examine the evolution of an abandoned delta lobe in the northern area of the modern yellow river delta results show three stages of evolution in the subaqueous delta slope after lobe abandonment 1 rapid erosion stage 2 slow erosion stage and 3 erosion accumulation adjustment stage according to 1 10 000 bathymetry data and high resolution seismic profiles diapirism in the subaqueous abandoned delta lobe is closely related to seabed erosion which mainly occurs in the middle part of subaqueous delta slope diapirism results from the deformation of soft fine grained prodeltaic sedimentary stratum when the accumulation body on the soft stratum is removed in rapid erosion stage the maximum accumulation centre in the delta lobe during growth coincides with the maximum erosion centre in the delta lobe abandonment phase the diapir body occurs there distinguishing from diapirism in the mississippi delta three stages of the soft stratum deformation and diapirism are established in the yellow river delta the mobile strata and its diapirism are destructive to the offshore engineering facilities

historical changes in the yellow river delta china abstract the lower yellow river delta has experienced numerous avulsions during the last 2000 years and the floodplain can be divided into four provinces alluvial fan western plain middle plain and eastern plain coastal deltas the yellow river delta complex is composed of several delta superlobes resulting from shifts in the lower river channel and each delta superlobe consists of several smaller lobes formed by shifts in the distributary channels these two kinds of channel shifts have resulted in a complicated imbrication pattern in the delta complex two imbricated delta superlobes are divided by a reworked bed and buried shelf deposits shelly ridges form the surface boundaries between the various delta superlobes the delta superlobes passed through an active stage a reworking stage and were then finally overlain by later superlobes

on the variation of infiltration into a homogeneous soil matrix containing a population of macropores a population of channels penetrates a soil matrix that is otherwise homogeneous the channels are assumed to be vertical and of circular cross section with constant diameter but channel depths and radii are allowed to vary over the population this paper uses a model based on the green ampt assumptions to predict infiltration rates through the walls and bases of channels resulting in a mathematical description of the way in which infiltration develops in the soil and in which channels fill with water until eventually overland flow is initiated this model takes account of the fact that there may be a random distribution of channels in space expressions for the expected mean and variance of infiltration volumes are derived some example results are given and show that below the matrix wetting front the variance of the change in water content with 30 and 50 channels per square meter may be of the same order as the mean change in water content the presence of channels can lead to significant increases in predicted channel volumes

recent changes in sediment delivery by the huanghe yellow river to the sea causes and environmental implications in its estuary summary over the past 60 years climate change and human activities in the huanghe yellow river basin have changed the river system in particular construction of large reservoirs and soil conservation practices within the river basin have reduced sediment flux to the sea by 90 and increased the grain size of suspended sediment delivered to the sea 30 m now versus 18 m before in median grain size scouring of the channel in the lower reaches has added a new sediment source to those derived from the loess region of the middle reaches before construction of the xiaolangdi reservoir at the downstream end of the middle reaches suspended sediment concentrations at station lijin the last hydrographic station before the river enters the sea were high enough 35 kg m 3 in the flood season to offset the density contrast between freshwater and ambient seawater thus hyperpycnal flows developed along the subaqueous slope at the river mouth during the flood season observations from two cruises near the huanghe river mouth one before and one after the operations of the xiaolangdi reservoir suggest that buoyant hypopycnal plumes rather than hyperpycnal plumes have occurred at the river mouth since the dramatic changes in concentration and grain size of suspended sediment discharged to the sea the rapid decrease of sediment discharge to the sea and the increase of grain size of suspended sediments not only changed the sediment dispersal pattern at the river mouth but also modified the shoreline and subaqueous slope the effects of climate change and human activities in the river basin have been transferred along the hydrological pathway to the estuary and delta and have changed estuarine sediment dynamics and delta morphology the huanghe presents an illustrative example of river basin coastal zone interactions in the context of climate change and human activities

rare earth element composition of paleo maar sediments latest pleistocene early holocene jeju island korea implications for asian dust record and monsoon climate abstract the rare earth element ree composition of a 4 96 m long sediment core retrieved from the hanon paleo maar in jeju island korea was studied to investigate the east asian monsoon variations during the latest pleistocene to early holocene 22 300 9000 cal bp the studied paleo maar core sediment has two restricted source materials with distinctively different geochemical signatures asian dust blown from central asia especially northern china and mongolia and basement rock composed of trachybasalt the ree characteristics of sediments depend on the relative contribution of these two sources and thus can be used to delineate the monsoon climate in jeju island the proportion of asian dust generally decreased gradually from 67 at 22 300 cal bp indicative of progressive weakening of the winter monsoon strength in central asia integration of the ree data with toc and ms records reveals that the summer monsoon strength in jeju island decreased from 22 300 cal bp until the last glacial maximum at 18 000 cal bp and then increased to 14 000 cal bp the abrupt intensification of the summer monsoon occurred from 14 000 to 13 300 cal bp followed by the weakened summer monsoon from 13 300 to 11 000 cal bp in anti phase with the strengthened winter monsoon in central asia in the early holocene jeju island experienced further intensified summer monsoon strength