climate change and the episodicity of sediment flux of small california rivers abstract we studied the streamflow and sediment flux characteristics of the 20 largest streams entering the pacific ocean along the central and southern california coast extending for 750 km from monterey bay to just south of the u s mexico border drainage basins ranged in area from 120 to 10 800 km2 with headwater elevations ranging from 460 to 3770 m annual streamflow ranged from 0 to a maximum of documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont declaretextfontcommand textcyr cyr pagestyle empty declaremathsizes 10 9 7 6 begin document landscape 1 times 10 9 end document m3 yr for the santa clara river in 1969 with a

catchment clearing accelerates the infilling of a shallow subtropical bay in east coast australia abstract understanding processes that govern the transport and distribution of terrestrial sediments to and within bays is critical for interpreting the drivers of long term changes in these ecosystems on the east coast of australia increased soil erosion and sediment delivery following extensive land clearing in the contributing catchments associated with european settlement is highlighted as a key driver of the decline of numerous nearshore habitats including seagrass meadows and in shore coral reefs here we use optical radiocarbon and radionuclide dating to estimate mass accumulation rates and type of terrestrial sedimentation in central moreton bay during the holocene we compare the long term rates of infilling within the central basin with the recent past and show a 3 9 fold increase in sediment accretion over the last 100 years compared to the long term last 1500 to 3000 yrs average infilling during the holocene is not spatially uniform with preferential deposition occurring within the now submerged palaeochannels of the brisbane and pine rivers we suggest that modern turbidity regimes in moreton bay are the result of the compounded effect of both a historical increase in fine sediment supply and a rapid decline in the effective storage capacity of the basin

downstream effects of flaming gorge reservoir on the green river colorado and utah the green river is one of the principal tributaries in the colorado river basin and drains 44 700 m 2 in wyoming colorado and utah since october 1962 flows of the green river have been regulated by flaming gorge reservoir which is located 412 river miles upstream from its confluence with the colorado river mean annual runoff has not been affected by the reservoir the duration of the relatively large discharges that transport most of the annual sediment load however has decreased significantly as a result the mean annual sediment discharge has decreased by 54 to 3 21 10 6 tons from 6 92 10 6 tons at the jensen gage located 105 river miles downstream from the reservoir and by 48 to 8 83 10 6 tons from 17 0 10 6 tons at the green river utah gage located 290 river miles downstream from the reservoir sediment supply to i he channel equals the annual transport within a relatively short distance 68 river miles downstream from the reservoir downstream from river mile 166 the supply of sediment from upstream plus tributary inflow exceeds the transport of sediment by 5 4 10 6 tons per year on an average the quasi equilibrium that appears to have existed prior to the reservoir no longer occurs along a majority of the green river in response to the reduced peak discharges the bankfull channel width of the green river has decreased by 10 adjustment of the channel to decreased peak flows and altered sediment loads is nowhere complete at present it appears that a century or more will be required for the green river to adjust to the effects of flaming gorge reservoir

sediment fluxes from california coastal rivers the influences of climate geology and topography abstractthe influences of geologic and climatic factors on erosion and sedimentation processes in rivers draining the western flank of the california coast range are assessed annual suspended bedload and total sediment fluxes were determined for 16 river basins that have hydrologic records covering all or most of the period from 1950 to 2006 and have been relatively unaffected by flow storage regulation and depletion which alter the downstream movement of water and sediment the occurrence of relatively large annual sediment fluxes are strongly influenced by the el nino southern oscillation enso and the pacific decadal oscillation pdo the frequency of relatively large annual sediment fluxes decreases from north to south during la nina phases and increases from north to south during el nino phases the influence of enso is modulated over a period of decades by the pdo such that relatively large annual sediment fluxes are more frequent during a la nina phase in conjunction with a cool pdo and du

the sediment delivery problem abstract the linking of on site rates of erosion and soil loss within a drainage basin to the sediment yield at the basin outlet and improved knowledge and representation of the associated processes of sediment delivery represent a major research need within the field of erosion and sedimentation and also an important scale problem in drainage basin studies this paper reviews the limitations of the sediment delivery ratio concept by considering the problems of temporal and spatial lumping and its blackbox nature some recent advances in our understanding of the sediment delivery system and its modelling are described and the lack of detailed empirical investigations is highlighted the significance of recent concern for the role of sediments in the transport of nutrients and contaminants to sediment delivery studies is introduced and the need for further work in this field is emphasised

continental erosion and large scale relief a worldwide investigation of continental erosion is carried out by the study of large drainage basins on the basis of hydrological data environmental factors and basin relief distribution inside each basin mean geochemical and mechanical denudation rates are defined a multicorrelation analysis shows that the mechanical denudation rates ds are uncorrelated with environmental factors and correlated with mean basin elevation h while chemical denudation rates dd are insensitive to relief but correlated with mean annual precipitation furthermore two linear relationships between h and ds are detected 1 ds m 10 yr 419 10 6 h m 0 245 with v explained variance 95 1 this law concerns basins related to orogenies younger than 250 ma the negative intercept is interpreted as a continental sedimentation rate of 245 m m y an alternative model in which one invokes a critical elevation separating erosion from sedimentation is equally successful and leads to lower sedimentation rates 60 110 m m y for both models one derives from the slope of the adjustments erosion time constants on the order of 2 5 m y 2 ds m 10 yr 61 10 6 h m with v 86 5 this law concerns basins related to older orogenies the null intercept suggests the lack of continental storage because of the more important dispersion of the data the erosion time constant is calculated separately for each basin it ranges from 15 to 360 m y the tectonic implications of these results are discussed in particular the short time constant 2 5 m y agrees with orogenic uplift rates on the order of 1 mm yr observed in active mountain chains

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

tectonics fracturing of rock and erosion 1 we argue that by fracturing rock not by raising it relative to base level tectonics plays its most important role in causing rapid incision of valleys and rapid erosion of hillslopes tectonic deformation riddles the upper crust with fractures which not only provide avenues for water flow and thus promote weathering and further disintegration of rock but also fragment bedrock into debris that is readily extracted and transported by surface processes bends in active faults require straining of adjacent rock masses aftershocks that occur subsequent to slip on primary faults reflect penetrative brittle deformation of the upper crust at least some aftershocks must nucleate or lengthen cracks which contribute to the comminution of these rock masses scaling rules suggest that dimensions of ruptures for very small m 2 earthquakes can be meters or less the gutenberg richter recurrence relationship implies that such earthquakes are common as high magnification seismographs in low noise environments confirm moreover large differences among fault plane solutions for aftershocks show that the small faults on which they occur are not parallel to one another some faults must intersect thus the upper crust in tectonically active regions should be fragmented into blocks down to the scale of boulders or smaller dismembered rock arrives at the earth s surface already prepared to be transported away as a corollary both deeply exhumed lower crust and posttectonic igneous rock never deformed under brittle conditions and not deformed recently should be less susceptible to detachment and subsequent transport than fractured rock

sediment yield from the tectonically active semiarid western transverse ranges of california sediment yields from the world s rivers are generally highest from steep drainage basins with weak lithology active tectonics or severe land use impacts here we evaluate sediment yields from the western transverse ranges of california in an attempt to explain why they are two to tenfold greater than the surrounding areas of california we found that suspended sediment yields across the gauged basins of the western transverse range during 1969 1999 varied by approximately an order of magnitude 740 5300 t km2 yr similarly fine sediment concentrations for normalized discharge rates varied by almost two orders of magnitude e g 1 3 110 g l for the mean annual flood for 11 previously unmonitored drainages of the santa ynez mountains areas with high sediment yields consistently have weakly consolidated bedrock quaternary pliocene marine formations and are associated with the highest rates of tectonic uplift of the region 5 mm yr these regions are important to the sediment discharge budgets because 50 of the total suspended sediment discharge from the western transverse range is estimated to be generated within these regions even though they represent only 10 of the total watershed area previous estimates of suspended sediment discharge from the ventura river have likely been underestimated by 50 because the gauging station is located immediately upstream of a high sediment yield region we also found a significant and positive correlation between sediment yield and the percentage of a watershed with grassland and agricultural land use these results suggest that there is adequate variation within the lithology tectonics and land use of the broader western transverse range geologic province to induce large variations in sediment yield at the local scale

controls on sediment distribution in the coastal zone of the central california transform continental margin usa abstract we use 10 000 km of high resolution seismic reflection data together with multibeam bathymetry to document complex and highly variable post last glacial maximum lgm sediment distribution and thickness in the coastal zone 10 m isobath to 5 6 km offshore along a 800 km section of central california s transform continental margin sediment thickness ranges from 0 seafloor bedrock to 64 m with a mean of 8 7 m we delineate 25 coastal zone sediment domains and group them based on common geomorphology and sediment occurrence thickest sediment occurs in mountain front and large river domains which comprise 14 5 and 7 9 of the coastal zone and contain 30 1 and 18 2 of coastal zone sediment respectively in contrast small river domains and sediment poor shelf domains comprise 50 7 and 15 7 of the coastal zone and contain 18 4 and 12 7 of its sediment the distribution and thickness of post lgm sediment in the coastal zone is controlled by a combination of tectonics sediment supply and eustasy sediment is derived from a tectonically controlled coastal landscape of rapidly uplifting mountain fronts more slowly uplifting marine terraces and fault bounded headlands and alluvial estuarine troughs sediment supply is maximized along steep landslide prone mountain fronts and at the mouths of large watersheds and minimized along lower relief terraced coastal landscape drained by smaller rivers and creeks in the offshore coastal zone tectonics generates local uplifts and basins and influences shelf width and gradient as well as the locations of some shelf incised submarine canyons sea level rise raises base level drowns estuaries creates accommodation space on the shelf amount based on gradient and isolates the heads of many submarine canyons at or near the shelfbreak comparison of shelf sediment volumes with estimates of unaltered watershed sediment supply reveals that a relatively small proportion of post lgm sediment supply is preserved on the shelf offshore of some of the largest rivers sediments deposited in shoreline and shelf environments have limited preservation potential and the most complete long term geologic record of the post lgm transgression and highstand is likely represented in slope and submarine fan deposits

model investigation of the influence of the crustal magnetic field on the oxygen ion distribution in the near martian tail 1 to investigate the influence of the martian crustal magnetic field on the acceleration and escape of the planetary ions in the near tail region the distributions of planetary oxygen ions are studied by means of test particle simulation in an electromagnetic environment created by a recent multispecies magnetohydrodynamics mhd simulation of the solar wind interaction with mars with crustal field included or excluded results under different crustal field conditions are compared to determine the effects of crustal field it is found that when crustal field is present draped magnetic field lines are replaced by closed field lines in the near tail region and the electric field is also intensified because of the hall effect as a result the oxygen ion distribution reveals distinct stream structures in the tail region when crustal field is included with one hot stream at the central tail and two cold streams at the flank of the tail some energetic ions inside the hot stream are accelerated toward the planet instead of escaping downstream

a 50 degree spherical harmonic model of the magnetic field of mars this paper presents a 50 degree and order spherical harmonic model of the magnetic field of mars derived at 120 km altitude using the three orthogonal components of the vector magnetic field data acquired by the mars global surveyor within the 80 to 200 km altitude range the downward continued vector magnetic field components to the surface of mars delineate details of the martian magnetic field the strong magnetic anomalies in the southern hemisphere do not show compelling evidence for magnetic lineations similar to those associated with the seafloor spreading on earth the anomalies are more or less equidimensional the magnetic signatures surrounding the impact basins hellas argyre and isidis show that the prominent magnetic anomalies are older than the impact events an average magnetization of 2 a m is estimated for the upper crust surrounding hellas basin four isolated magnetic anomalies are modeled by vertical prisms with circular cross sections of 170 to 190 km radius and 20 to 30 km thickness the magnetization of the model prisms is 5 a m more than that of the surroundings

river loads and modern denudation of the alps a review this paper presents the first comprehensive analysis of sediment and dissolved load across an entire mountain range we investigate patterns and rates of modern denudation of the european alps based on a compilation of data about river loads and reservoir sedimentation from 202 drainage basins that are between ca 1 to 10 000 km2 large the study basins cover about 50 of the total area of the alps modern glaciated basins have the highest sediment yields of up to 7000 t km 2 a 1 which are on average 5 to 10 times higher than in non glaciated basins likewise sediment yield and glacial cover are positively correlated instead relief is a relatively weak predictor of sediment yield the strong glacial impact in the correlations is due to glacier recession since the 19th century as well as due to glacial conditioning during repeated quaternary glaciations which have produced the strong transient state of the alpine landscape we suggest that this is the major cause for ca 3 fold enhanced denudation of the western compared to the eastern alps chemical denudation rates are highest in the external alps dominated by carbonate sedimentary rocks where they make up about one third of total denudation the high rates cannot be explained without anhydrite dissolution we estimated that only 45 of the sediments mobilized in headwaters are exported out off the alps most sediments being trapped in artificial reservoirs the total amount of sediment annually trapped within the alps equates to 43 mt when corrected for sediment storage we obtain an area weighted mean total denudation rate for the alps of about 0 32 mm a 1 the pre dam rate might be as high as 0 42 mm a 1 in total ca 35 plus 23 mt of mass are exported each year out of the alps as solids and solutes respectively these rates are not enough to out pace modern rock uplift nevertheless pattern of sediment yield across the alps coincides roughly with the intensity of glacial conditioning and modern rock uplift supporting the hypothesis of an erosion driven uplift of the alps

geology geography and humans battle for dominance over the delivery of fluvial sediment to the coastal ocean abstract sediment flux to the coastal zone is conditioned by geomorphic and tectonic influences basin area and relief geography temperature runoff geology lithology ice cover and human activities reservoir trapping soil erosion a new model termed bqart in recognition of those factors accounts for these varied influences when applied to a database of 488 rivers the bqart model showed no ensemble over or underprediction had a bias of just 3 across six orders of magnitude in observational values and accounted for 96 of the between river variation in the long term 30 years sediment load or yield of these rivers the geographical range of the 488 rivers covers 63 of the global land surface and is highly representative of global geology climate and socioeconomic conditions based strictly on geological parameters basin area relief lithology ice erosion 65 of the between river sediment load is explained climatic factors precipitation and temperature account for an additi

anisotropic seismic scattering in old atlantic crust an oblique seismic experiment ose was carried out at ocean drilling program odp hole 418a in the western north atlantic to investigate vertical lateral and azimuthal structural variations in the upper portions of relatively old ocean crust original analysis of the data for travel time anisotropy did not show systematic azimuthal trends in seismic structure except at shallow depths immediately adjacent to the borehole subsequent analysis of the ose data presented here reveals a correlation between scattering strengths versus azimuth and spreading direction of the crust analyses are performed on body and coda waves and include coda energy and normalized coda energy calculations spectral analysis coda dropoff rates and cross correlation analysis all of the analyses show trends indicating an increase in seismic scattering along directions parallel to the paleospreading direction these results suggest that evidence of crustal formation processes is still present and seismically detectable after 108 m y of crustal evolution scattering is likely caused by crustal cracks and or aligned heterogeneities indicating that either large crustal cracks are still present in the crust or that homogenization of the crust through hydrothermal deposition of secondary minerals is not complete at this site

first measurements of the ionospheric plasma escape from mars before the phobos mission the magnetosphere of mars was relatively unexplored basically all data on the charged particle environment of mars had come from the soviet mars missions mars 2 3 4 and 5 here we report the results of an ion composition experiment on board the soviet phobos 2 spacecraft which allowed us to determine the loss of plasma from the ionosphere of mars because mars has a very small intrinsic magnetic field the ion outflow had been expected to be similar to that of venus surprisingly there were many similarities between the ionospheric outflow from mars and the earth the ion loss from mars results from both ion pick up that results from mass loading of the solar wind in the martian boundary layer and ionospheric o beams of energies up to several kev possibly from upward acceleration processes similar to those observed above the earth s auroral oval a preliminary estimate of the ionospheric outflow from mars indicates that the planet is losing oxygen at a rate of 3 x 1025 ions s 1 this corresponds to an evacuation of its present total atmospheric oxygen content contained in co2 and o2 in less than 100 million years

plasma intrusion above mars crustal fields mars express aspera 3 observations abstract using data of the aspera 3 instrument on board the european mars express spacecraft we investigate the effect of the martian crustal fields on electrons intruding from the magnetosheath for the crustal field strength we use published data obtained by the mars global surveyor mag er instrument for a fixed altitude of 400 km we use statistics on 13 months of 80 100 ev electron observations to show that the electron intrusion altitude determined by a probability measure is approximately linearly dependent on the total field strength at 400 km altitude we show that on the dayside the mean electron intrusion altitude describes the location of the magnetic pile up boundary mpb such that we can quantify the effect of the crustal fields on the mpb on the nightside we quantify the shielding of precipitating electrons by the crustal fields

interpreting quaternary uplift rates at the mendocino triple junction northern california from uplifted marine terraces analysis of the altitudinal spacing of 14 flights of marine terraces indicates a spatial pattern of varying uplift rates that agrees with that determined from previously dated terraces for the past 3 81 ka and temporal changes in uplift rates from 1 m ka to 3 5 m ka that may reflect response to changes in tectonic regime during passage of the mendocino triple junction mtj a possible mechanism for regional uplift is growth of a slab window south of the mtj the region of most rapid uplift is 25 43 km south of the mtj immediately south of the northern boundary of the slab window the coastline is tilted upward to the south in the region directly above the southern edge of the subducted gorda plate at point delgada 55 km south of the present mtj where the northern edge of the slab window passes approximately 300 ka uplift rates have been 1 2 m ka for at least 330 ka more than 1 4 m y after passage of the southern edge of the subducted slab at the mendocino coast uplift rates have been less than 0 4 m ka for at least 330 ka

denudation processes and rates in the transverse ranges southern california erosional response of a transitional landscape to external and anthropogenic forcing 1 quantification of denudation in the transverse ranges of california permits reconstruction of spatial and temporal variations in erosion that represent both the response and evolution of interacting hillslopes and channels on the southern front of the san gabriel mountains observational records of the infilling of debris basins and dams define twentieth century landscape erosion rates averaging 1 6 and 0 9 mm yr 1 respectively although all major sediment transport occurs during intense winter storms debris production on hillslopes is greatly enhanced by recurrent fires consequently in this populated region anthropogenic fires have augmented the natural erosion rates we perform a global inversion to estimate the role of precipitation intensity burned areas and local slope on catchment denudation rates after subtracting the effects of anthropogenic fires we estimate landscape denudation rates given natural fire ignition rates increased fire during the past century has augmented sediment production in debris basins by an average of 60 and individual basins show increases up to 400 to identify the dominant hillslope erosion processes the volumetric contribution of landslides was estimated using repeat aerial photographs for the same time interval over which the debris basins have been operative between 1928 and 1973 landsliding produced only 10 of the sediment in debris basins even in the long term when infrequent but volumetrically important landslides occur bedrock landslides appear to contribute a maximum of 50 to the long term landscape denudation previous mapping of soil slippage in the san dimas experimental forest within the san gabriel mountains rice et al 1969 rice and foggin 1971 indicates that shallow landsliding is likely to be the dominant modern hillslope erosion process when compared to incision rates derived from a fluvial shear stress model and to exhumation rates based on low temperature thermochronological data blythe et al 2000 modern natural erosion rates are comparable to denudation rates since the pliocene comparisons of modern erosion rates suggest that debris production on hillslopes and first order channels is directly dependent on vegetation cover and precipitation intensity for higher order channels drainage areas 2 km2 only major storms convey the sediments down valley during the past century some temporal decorrelation occurs between small scale and large scale catchments because hillslope produced sediment is stored in second order and higher channels until major storms mobilize it thus the larger fluvial network damps the episodic fire induced hillslope sediment pulses that occur within small watersheds at a longer temporal scale however uplift and denudation may have been sustained sufficiently long in much of the san gabriel mountains for the topography to reach a macroscale steady state in contrast to rapidly eroding 2 mm yr 1 ranges for which quantification of bedrock landsliding will approximate the sediment flux the san gabriel mountains occupy a niche of intermediate rates 0 1 1 0 mm yr 1 in which a broad suite of hillslope processes including shallow seated and deep seated landslides debris flows and wet and dry ravel contribute to the sediment flux

reductions in fluvial sediment discharge by coastal dams in california and implications for beach sustainability abstract the long term sustainability of california s beaches depends on periodic deliveries of sand and gravel from coastal rivers and streams to assess the long term health of california s beaches this study characterized the current state of fluvial sediment delivery and quantified on a littoral cell basis the cumulative impacts of dams in decreasing annual discharge presently more than 500 dams impound more than 42 000 km2 or 38 of california s coastal watershed area flow modeling suggests that by diminishing flood hydrographs these dams have reduced the average annual sand and gravel flux to 20 major littoral cells by 2 8 million m3 yr or 25 in 70 of the streams considered in this study suspended sediment loads during equivalent discharge events have declined over the past three decades which indicates that dams have also significantly reduced downstream sediment supplies approximately 23 or 274 km of the 1193 km of beaches in california are downcoast from rivers that have had s

oxygen ion precipitation in the martian atmosphere and its relation with the crustal magnetic fields without a global intrinsic magnetic field oxygen ions in the martian atmospheric corona can be picked up by the solar wind directly the majority of the pickup ions escape while some can precipitate into the atmosphere producing sputtering of atmospheric constituents which may play a significant role in the loss of neutral atmosphere with its widely distributed crustal magnetic fields mars is unique while it has been shown that mars s crustal fields can alter the global distribution of escaping ions little is known about the influence of the crustal fields on the spatial distribution and energy deposition of precipitating pickup ions in this paper the global distribution and energy spectrum of the precipitating pickup oxygen ions are calculated using the test particle method in the electric and magnetic fields set up by mhd simulation cases of different crustal field conditions are compared to show the influence of the crustal fields on the oxygen ion precipitation we find using a test particle code that the crustal fields likely change the spatial distribution of the precipitation resulting in irregularly distributed low energy ion precipitation parches and wide high energy ion precipitation belts on both the dayside and nightside the crustal fields increase o ion precipitation substantially enhancing energy deposition especially on the nightside our results imply that atmospheric sputtering and accompanying neutral escape might happen globally and may be enhanced by a factor of almost 2 with the presence of the crustal magnetic fields

eel river margin source to sink sediment budgets revisited abstract the eel river coastal margin has been used as a representative source to sink sediment dispersal system owing to its steep high sediment yield river and the formation of sedimentary strata on its continental shelf one finding of previous studies is that the adjacent continental shelf retains only 25 of the eel river fine grained sediment less than 63 m discharged over time scales of both individual floods and the 20th century thus suggesting that the eel shelf trapping efficiency is uniquely lower than other similar systems here i provide data and analyses showing that sediment discharge relationships in the eel river have varied strongly with time and include substantial decreases in suspended sediment concentrations during the latter 20th century including these trends in margin wide sediment budgets i show that previous eel river sediment discharge rates were overestimated by a factor of two thus revised sediment budgets shown here reveal that the eel shelf retained 50 of the discharged river fine grained suspended sediment during intensively sampled events of 1995 97 and over the 20th century in light of this hypotheses about high rates of sediment export away from the primary shelf depocenter should be reevaluated

estimating river sediment discharge to the ocean application to the eel margin northern california abstract hydrotrend a synthetic river discharge numerical model can simulate the natural variability daily annually and longer in the flux of water and sediment delivered to the coastal ocean the numerical model is designed to make discharge predictions based on climate even though field measurements of river flow are not available provided that appropriate assumptions are made regarding past climate the model can predict how a river may have behaved in the geological past sediment load is determined from a river s rating coefficients when applied to the flood dominated eel river northern california hydrotrend captures the intermonthly and interannual variability of discharge and loads over a century or more hydrotrend is applied to the ice age paleo eel river when sea level was lower and climate much cooler and wetter the paleo eel river at 18 000 year bp would see its hinterland runoff increase but not the magnitude of the peak discharges the post dicted sediment load of the paleo eel river was 25 greater than today s although basin precipitation was 45 greater and the hinterland area 4 greater through sea level lowering a method is provided to obtain sediment discharge rating coefficients for unmonitored modern rivers and paleo rivers the relationship q s g 1 2 h 3 2 a 1 2 provides for an estimate of a river s sediment load q s to within a factor of 3 over 7 orders of magnitude from knowledge of basin relief h and basin area a rating coefficients are determined from this estimate of q s and the power law rating curve q s aq b 1 where q is discharge

a 560 year record of santa ana fires reconstructed from charcoal deposited in the santa barbara basin california microscopic charcoal from varved santa barbara basin sediments was used to reconstruct a 560 yr record a d 1425 to 1985 of santa ana fires comparison of large 3750 m2 charcoal with documented fire records in the santa barbara ranger district shows that high accumulations correspond to large fires 20 000 ha that occurred during santa ana conditions the charcoal record reconstructed a minimum of 20 large fires in the santa barbara region during the study period the average time between fires shows no distinct change across three different land use periods the chumash period apparently characterized by frequent burning the spanish early american period with nominal fire control and the 20th century with active fire suppression pollen data support the conclusion that the fire regime has not dramatically changed during the last 500 yr comparison of large charcoal particle accumulation rates and precipitation reconstructed from tree rings show a strong relationship between climate and fire history with large fires consistently occurring at the end of wet periods and the beginning of droughts