large scale erosion rates from in situ produced cosmogenic nuclides in european river sediments abstract we have calculated long term erosion rates of 20 100 mm kyr from quartz contained 10be in the bedload of middle european rivers for catchments ranging from 102 to 105 km2 these rates average over 10 40 kyr and agree broadly with rock uplift incision and exhumation rates historic soil erosion rates and erosion rates calculated from the measured sediment loads of the same rivers moreover our new erosion rate estimates correlate well with lithology and relief however in the regen neckar loire and meuse catchments cosmogenic nuclide derived erosion rates are consistently 1 5 4 times greater than the equivalent rates derived from measured river loads this may be due to the systematic under representation of high magnitude low frequency transport events in the gauging records which cover less than a century alternatively the discrepancy may derive from spatially non uniform erosion and preferential tapping of deeper sections of the irradiation profile a third explanation relates the high cosmogenic nuclide derived erosion rates to inheritance of an elevated pleistocene erosion signal uncertainties associated with the cosmogenic nuclide derived erosion rate estimates are not greater than the potential errors in conventional estimates therefore the cosmogenic nuclide approach is an effective tool for rapid catchment wide assessment of time integrated rates of bedrock weathering and erosion and we anticipate its fruitful application to the quaternary sedimentary record

quantification of soil production and downslope creep rates from cosmogenic 10be accumulations on a hillslope profile average soil transport rates over a period of 3500 yr on a convex soil mantled hillslope have been quantified using a mass balance model that incorporates the soil concentration of the cosmogenic isotope 10 be the 10 be model results support the assumption used in most geomorphic models that the soil creep rate is proportional to surface gradient the predicted diffusion coefficient is 360 55 cm 3 yr 1 cm 1 contour length and the average rate of soil production is 0 026 0 007 cm yr within the uncertainty of this technique the data do not reject g k gilbert9s hypothesis that some hillslopes may exist in a condition of dynamic equilibrium with a uniform soil production rate however the model does not require an assumption of dynamic equilibrium and may be an approach that uniquely allows the quantification of a local soil production rate law

basin and river profile morphometry a new index with a high potential for relative dating of tectonic uplift abstract geomorphometry may be a powerful tool to describe the characteristics of the landscape s response to tectonic signals but the meaning of morphometric indices is often obscured by the interplay between the many variables controlling the geomorphological evolution moreover although the so called hypsometric integral refers to the basin scale most indices are generally derived from the river long profiles and thus focus mainly on the short term response of a drainage network to base level change providing limited information in regions of older and or moderate uplift here using the rhenish shield western europe an area of moderate quaternary uplift as a test case i attempt to build an index yielding a comprehensive view of the stage attained by the landscape s response and indirectly an evaluation of the timing of the triggering base level change this index called r 1 is a ratio of differences between the three integrals linked respectively to the classical basin s hypsometric curve to the main river s long profile and at the intermediate level to a drainage network s hypsometric curve while its ratio form minimizes the lithological effect on r 1 this index is strongly correlated with basin size regional correlation coefficients are in the range 0 88 0 93 reflecting the way an erosion wave propagates from the outlet of a basin toward its headwaters therefore it is not directly usable as a proxy for relative uplift age however one can show that the relation between r 1 and basin size is theoretically expected to change with time following uplift the slope s r of the linear relation r 1 f ln a first increases rapidly but briefly then it gradually diminishes over several million years this is fully confirmed by the analysis of r 1 and s r in the study area once its initial increase is completed assumedly in a few ten thousand years s r appears to be a reliable indicator of relative uplift or any other cause of base level lowering age

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

the humped soil production function eroding arnhem land australia we report erosion rates and processes determined from in situ produced beryllium 10 10be and aluminum 26 26al across a soil mantled landscape of arnhem land northern australia soil production rates peak under a soil thickness of about 35 cm and we observe no soil thicknesses between exposed bedrock and this thickness these results thus quantify a well defined humped soil production function in contrast to functions reported for other landscapes we compare this function to a previously reported exponential decline of soil production rates with increasing soil thickness across the passive margin exposed in the bega valley south eastern australia and found remarkable similarities in rates the critical difference in this work was that the arnhem land landscapes were either bedrock or mantled with soils greater than about 35 cm deep with peak soil production rates of about 20 m ma under 35 40 cm of soil thus supporting previous theory and modeling results for a humped soil production function we also show how coupling point specific with catchment averaged erosion rate measurements lead to a better understanding of landscape denudation specifically we report a nested sampling scheme where we quantify average erosion rates from the first order upland catchments to the main sixth order channel of tin camp creek the low 5 m ma rates from the main channel sediments reflect contributions from the slowly eroding stony highlands while the channels draining our study area reflect local soil production rates 10 m ma off the rocky ridge 20 m ma from the soil mantled regions quantifying such rates and processes help determine spatial variations of soil thickness as well as helping to predict the sustainability of the earth s soil resource under different erosional regimes copyright 2009 john wiley sons ltd

an automated method to extract fluvial terraces from digital elevation models the vesdre valley a case study in eastern belgium abstract fluvial terraces are a powerful tool for unraveling the combined tectonic and climatic conditions that controlled directly or indirectly the quaternary incision of rivers terrace long profiles are usually retrieved from sparse traces of ancient floodplains preserved in the present topography however when these traces classically collected from topographic maps aerial photographs and field analyses are too few the inferred profiles may be questionable yet the now available high quality and high resolution digital elevation models dems offer an opportunity to increase greatly the quantity of information usable to reconstruct terrace profiles therefore the purpose of this study was to develop a new dem based method of terrace recognition in order to create a larger database and better constrain the profile reconstruction moreover particular procedures of image and numerical processing were defined to fully automate the analysis basically our method relies on the production of bivariate scatter plots depicting the relation between slope and relative altitude i e the altitude above the current alluvial plain for all pixels of successive sections of the valley for each scatter plot the curve of the lowest slope values observed at every relative altitude is smoothed and its minima are assumed to locate the altitudes of the terrace elements preserved in the section we successfully tested this method in the vesdre valley incised in the ne ardenne massif e belgium notably identifying fault deformation of the profiles the main advantages of our approach are its objectivity exhaustiveness and rapidity allowing fast and coherent analysis of many rivers over extended regions

statistical description of slope dependent soil transport and the diffusion like coefficient 1 for hillslopes undergoing diffusive soil transport it is often assumed that the soil flux is proportional to the local land surface gradient where the coefficient of proportionality is like a diffusion coefficient inasmuch as transport involves quasi random soil particle motions related to biomechanical mixing and similar dilational processes a slope dependent relation arises from a balance between particle fluxes that tend to loft a soil and gravitational settling of particles into available pore space a specialized form of the fokker planck equation adapted to such particle motions clarifies how the particle flux involves advective and diffusive parts this in turn contributes to a kinematic description of the diffusion like coefficient ingredients of this coefficient include an active soil thickness a characteristic particle size the porosity in excess of a consolidated porosity and the rate of particle activation as a function of depth these last two ingredients vertical porosity structure and activation rate in effect characterize the magnitude and frequency of settling particle motions related to biological activity and thereby set the rate constant of the transport process the significance of land surface slope is that it is a measure of the downslope component of slope normal lofting that is balanced by settling because the diffusion like coefficient contains the soil thickness the analysis suggests that the soil flux is proportional to the depth slope product the analysis is consistent with published profiles of soil creep displacement and with published estimates of soil flux obtained by downslope integration of soil production rates for hillslopes in california and australia

hydrochemistry and nutrient cycling in yalgorup national park western australia lakes clifton hayward and preston western australia are part of an east west chain of 11 ground water fed lakes that make up the clifton preston lakeland system their hydrochemistries exhibit a large range in salinities 14 207 kg m 3 total dissolved solids tds both seasonally within each lake and among lakes the chemistry of all the lake waters in the system is an nacl so4 brine similar to seawater composition however all three lakes have less so4 br sr mn and probably fe than seawater the concentrations of ca and hco3 vary seasonally the variation of ca and hco3 in all three lakes suggests that calcium carbonate is precipitated during the late summer and early autumn when evaporation is most intense in the upper and lower water layers of lake hayward the concentrations of conservative ions such as na cl and k decrease in winter and increase in summer indicating dilution by winter rain and concentration via evaporation in the summer concentrations of total fe and mn in the lower layer increase in winter suggesting release from the sediments and or decay of the benthic microbial mat on the lake floor tin total inorganic nitrogen po4 p ratios and tn total nitrogen po4 p ratios are high in all lakes suggesting that p is the limiting nutrient in the system observed increases of the macroalgae cladophora in lake clifton suggest that any potential increase in the po4 load to the lake will be taken up by the invigorated growth of these algae and may not be detected by measuring lake water po4 concentrations the increased growth of cladophora is detrimental to the health of the well established microbialite community on the eastern shore of lake clifton

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

natural experiments in landscape evolution a natural experiment in landscape evolution is a case study of landform development in which only one element varies significantly and for which the driving forces initial conditions and or boundary conditions are well constrained natural experiments provide a means of testing landscape evolution theory on the large space and time scales to which that theory applies natural experiments can involve either steady or transient conditions cases with steady conditions allow one to test predictions about the relationships among topography erosion rates and various attributes related to climate and material properties transient cases are valuable for distinguishing between models whose predictions might be similar and therefore indistinguishable under steady conditions essential ingredients of a natural experiment include minimal variation in all but one factor good constraints on timing and or rates well characterized processes and high quality topographic data other useful ingredients include information about intermediate topographic states such as a former valley profile revealed by strath terraces and knowledge of the time history of erosion rates in order to deepen our understanding of the physics and chemistry of long term landscape evolution there is a pressing need to identify natural experiments and develop the necessary databases to take advantage of them copyright 2009 john wiley sons ltd

soil production and hillslope transport in mid latitudes during the last glacial interglacial cycle a combined data and modelling approach in northern ardennes

cosmogenic nuclides topography and the spatial variation of soil depth abstract if the rate of bedrock conversion to a mobile layer of soil depends on the local thickness of soil then hillslopes on uniform bedrock in a landscape approaching dynamic equilibrium should be mantled by a uniform thickness of soil conversely if the depth of soil varies across an actively eroding landscape then rates of soil production will also vary and consequently the landscape will not be in morphologic equilibrium the slow evolution of hillslopes relative to the tempo of climatic variations and tectonic adjustments would suggest that local morphologic disequilibrium may be expected in many landscapes here we explore this issue of equilibrium landscapes through a previously developed model that predicts the spatial variation in thickness of soil as a consequence of the local balance between soil production and erosion first we confirm the assumption in the model that soil production varies inversely with the thickness of soil using two independent methods one method uses the theoretical prediction that at local steady state soil production equals removal the depth of soil should vary inversely with hillslope curvature the second method relies on direct measurements of in situ produced concentrations of cosmogenic 10 be and 26 al in bedrock at the base of the soil column for our study site in northern california the two methods agree and yield the expression that the rate of soil production declines exponentially with the thickness of soil from 0 077 mm year with no soil mantle to 0 0077 mm year under 1 m of soil we then use this function of soil production in a coupled production and diffusive model of sediment transport to explore the controls on the spatial variation of the depth of soil on four separate spur ridges noses where we measured the data for the function of soil production model predictions are sensitive to boundary conditions grid scale and run time nonetheless we found good agreement between predicted and observed depths of soil as long as we used the observed function of soil production the four noses each have spatially varying curvature and consequently have varying depths of soil implying morphologic disequilibrium we suggest that our study site has been subjected to a wave of incision and varying intensities of erosion because of tectonic and climatic oscillations that have a frequency shorter than the morphologic response time of the landscape

holocene and eemian sea surface temperature trends as revealed by alkenone and mg ca paleothermometry in this study we review a global set of alkenone and foraminiferal mg ca derived sea surface temperatures sst records from the holocene and compare them with a suite of published eemian sst records based on the same approach for the holocene the alkenone sst records belong to the actualized ghost database kim j h schneider r r 2004 ghost global database for alkenone derived holocene sea surface temperature records available from http www pangaea de projects ghost while the mg ca derived sst database represents a new compilation the actualized ghost database not only confirms the sst changes previously described but also documents the holocene temperature evolution in new oceanic regions such as the northwestern atlantic the eastern equatorial pacific and the southern ocean a comparison of holocene sst records stemming front the two commonly applied paleothermometry methods reveals contrasting sometimes divergent sst evolution particularly at low latitudes where sst records are abundant enough to infer systematic discrepancies at a regional scale opposite sst trends at particular locations could be explained by out of phase trends in seasonal insolation during the holocene this hypothesis assumes that a strong contrast in the ecological responses of coccolithophores and planktonic foraminifera to winter and summer oceanographic conditions is the ultimate reason for seasonal differences in the origin of the temperature signal provided by these organisms as a simple test for this hypothesis eemian sst records are considered because the holocene and eemian time periods experienced comparable changes in orbital configurations but had a higher magnitude in insolation variance during the eemian for several regions sst changes during both interglacials were of a similar sign but with higher magnitudes during the eemian as compared to the holocene this observation suggests that the ecological mechanism shaping sst trends during the holocene was comparable during the penultimate interglacial period although this ecology hypothesis fails to explain all of the available results we argue that any other mechanism would fail to satisfactorily explain the observed sst discrepancies among proxies c 2010 elsevier ltd all rights reserved

soil landscape response to mid and late quaternary climate fluctuations based on numerical simulations abstract we use a numerical dynamic soil landscape model to study one aspect of the spatio temporal soil landscape evolution process the effect of climatic fluctuations on soil grading distribution in space and time in response to the interplay between physical weathering and surface erosion soil mineralogical fluxes we simulate a synthetic soil landscape system over the middle and late quaternary last 400 ka the results show that 1 soil landscape response to climate change is non linear and highly spatially variable even at hillslope scale and 2 soil landscape adjustment to climate change can lag tens of thousands of years and is both spatially and temporally variable we propose that the legacy of past climatic condition i e last glacial maximum in modern soil landscape systems vary considerably in space this implies that the spatiotemporal uniformity in which soil is typically described in earth system modeling and analysis e g carbon cycle grossly underestimates their actual complexity

stochastic processes of soil production and transport erosion rates topographic variation and cosmogenic nuclides in the oregon coast range landscapes in areas of active uplift and erosion can only remain soil mantled if the local production of soil equals or exceeds the local erosion rate the soil production rate varies with soil depth hence local variation in soil depth may provide clues about spatial variation in erosion rates if uplift and the consequent erosion rates are sufficiently uniform in space and time then there will be tendency toward equilibrium landforms shaped by the erosional processes soil mantle thickness would adjust such that soil production matched the erosion previous work in the oregon coast range suggested that there may be a tendency locally toward equilibrium between hillslope erosion and sediment yield here results from a new methodology based on cosmogenic radionuclide accumulation in bedrock minerals at the base of the soil column are reported we quantify how soil production varies with soil thickness in the southern oregon coast range and explore further the issue of landscape equilibrium apparent soil production is determined to be an inverse exponential function of soil depth with a maximum inferred production rate of 268 m ma 1 occurring under zero soil depth this rate depends however on the degree of weathering of the underlying bedrock the stochastic and large scale nature of soil production by biogenic processes leads to large temporal and spatial variations in soil depth the spatial variation of soil depth neither supports nor rejects equilibrium morphology our observed catchment averaged erosion rate of 117 m ma 1 is however similar to that estimated for the region by others and to soil production rates under thin and intermediate soils typical for the steep ridges we suggest that portions of the oregon coast range may be eroding at roughly the same rate but that local competition between drainage networks and episodic erosional events leads to landforms that are out of equilibrium locally and have a spatially varying soil mantle copyright 2001 john wiley sons ltd

modeling the response of the rhine meuse fluvial system to late pleistocene climate change abstract we use a landscape evolution model to infer the effect of late pleistocene climate change on the incision aggradation behaviour of the rhine meuse fluvial system we model the routing of runoff and sediment in the catchment in order to predict grainsize trends and the incision and aggradation behaviour in the downstream reach where we compare it to the sequence of events and grainsize characteristics inferred from borehole corings this sequence starts with an important incision taking place around the mis 3 to mis 2 climatic transition during the coldest part of mis 2 a coarse grained sedimentary unit is deposited that shows an upward increase in the sand gravel ratio the model experiments do not predict an incision at the mis 3 to mis 2 transition therefore the incision should be attributed to other causes most likely effects of glacio isostatic uplift however a relative upward increase in sand content of the sediments is predicted by the model this increase is the result of the difference in transport rates between sand and gravel starting from a homogeneous pre existing mis 3 deposit the gravel content in the active layer increases because the sand is removed quickly and transported further downstream whereas the gravel travels slowly and piles up with gravel originating from immediately upstream resulting in a net accumulation at a later stage sand originating from much further upstream progrades fan like over the gravelly deposits according to the record during the early late glacial warming part of mis 2 bolling allerod interstadial neither incision nor aggradation has taken place this is in accordance with modelling results which show that despite the reduction of sediment input due to re vegetation of hillslopes sufficient sediment remains available for fluvial transport in the channel network itself it takes several thousands of years before effects of sediment depletion in the catchment are noted downstream that is why we argue that the inferred incision at the late late glacial the start of the younger dryas in our downstream study area might reflect depletion effects related to the preceding early late glacial conditions in general our modelling results show that terraces along one large fluvial system are diachronic features in particular terrace surfaces are older upstream compared to downstream in addition complex responses to climate change are likely to occur in a large fluvial system like the rhine meuse and correlation of morphological features in the fluvial record to specific short term palaeo climatic events for example dansgaard oeschger events could be risky without consideration of catchment size characteristics and associated response times

uplift driven valley incision and climate controlled river terrace development in the thames valley uk abstract the sequence of terraces of the river thames in southeast england has previously been shown to span the period from the earliest pleistocene to the present this terrace sequence contains biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary large scale fluvial incision resulting in basin wide terrace formation appears to have been concentrated at the warming limbs of the major climatic glacial interglacial cycles when sediment supply was greatly reduced this incision and subsequent valley floor widening created the accommodation space for the later aggradation of the terrace sediments during the following warm cold transitions and during the cold stages when high sediment supply conditions prevailed although the timing of terrace aggradation may be controlled by climate change the progressive valley incision recorded by terrace staircases cannot easily be explained in terms of quaternary climatic change alone and recently developed models suggest that long term incision by the thames has been driven by uplift this paper presents an overview of the available terrace data and tabulates incision amounts and rates between key stratigraphic horizons superimposed upon these broad changes revealed by the complex internal sedimentary architecture of many terrace sediments are the geomorphological system responses to both higher frequency climate driven changes and more localized intrinsic fluvial system adjustments

timescales climate and river development abstract in the long term glacial interglacial sequences river development follows general climatic evolution however at the scale of one cold warm cycle it appears that the geomorphological effect of river activity is best expressed at times of climatic change such periods of pronounced fluvial action last only a short time in more detail the internal evolution in a drainage basin after a climatic event results in a delayed response of the morphology and sedimentation pattern finally on the shortest timescale local thresholds may play a decisive role in the reactions of river systems it is concluded that the relation between fluvial development and climate is not a simple one but is fundamentally dependant on the timescale

upper cretaceous paleocene conifer woods from big bend national park texas abstract conifer wood types from the upper cretaceous aguja and javelina formations and the paleocene black peaks formation of big bend national park texas are briefly described the big bend conifer woods represent the largest assemblage of late cretaceous conifer wood thus far described from the western interior of north america and include samples with characteristics of the araucariaceae and cheirolepidiaceae and cupressaceae and podocarpaceae cupressaceae podocarpaceae types of the maastrichtian javelina formation have on average narrower rings than those of the campanian aguja formation consistent with the drier climate already proposed for the javelina formation angiosperm wood assemblages differ between the lower shale and upper shale members of the aguja formation the javelina formation and the black peaks so do the conifer assemblages the big bend conifer woods differ from those described from other western interior localities and document more variation in growth ring types than previously recognized for the whole of the northern hemisphere late cretaceous the sizes of some logs and width of their growth rings suggest that some trees might have reached diameters of 1 m in approximately 80 years woods of the cupressaceae podocarpaceae type show that the strategy of having juvenile wood with narrower tracheids and less distinct growth rings than in mature wood occurred in the late cretaceous the incidence of compression wood in mature trunk wood is relatively high and may reflect either unstable substrates or frequent storms with high winds

reconciling geodetic and geological rates of vertical crustal motion in intraplate regions abstract tectonic motion rates of individual faults and regional deformation in an intraplate setting are estimated based on the analysis of ten yearly surveys of a regional levelling network in ne ardenne w europe owing to the frequency and number of measurement epochs much greater than in classical comparisons of general surveys the tectonic and near surface components of ground motion are clearly separated the marked temporal variability in ground motion strongly depends on the amount of precipitation fallen during the six months preceding each survey and the subsequent drying off of the subsoil at the time of the surveys moreover the ground response to this influence varies from place to place leading to high differential movements at the local scale taking into account the percentage of surveyed faults which moved tectonically during the time of the study i calculate fault motion rates of 0 06 0 09 mm yr similar to geological rates moreover the data indicate that one way for intraplate normal faults to accommodate tectonic strain aseismically is intermittent fault creep with short episodes of a few mm displacement separated by many year long time intervals of fault quiescence a flexural deformation shows the superposition of a tilt event on a trend corresponding to a tilt rate of 0 16 rad yr for a 2 8 km long segment

toward quantifying uncertainty in travel time tomography using the null space shuttle 1 the solution of large linear tomographic inverse problems is fundamentally non unique we suggest to explore the non uniqueness explicitly by examining the null space of the forward operator we show that with the null space shuttle it is possible to assess robustness in tomographic models and we illustrate the concept for the global p wave model mit p08 we found a broad range of acceptable solutions compatible with the travel time data the root mean square rms velocity perturbations vary from 0 2 to 0 6 in the lowermost mantle and from 0 3 to 1 3 in the upper mantle such large variations in average amplitudes prohibit meaningful inferences on temperature or chemical variations in the earth from tomographic models alone on a global scale much short wavelength structure resides in the null space of the forward operator suggesting that the data do not everywhere resolve structure on the smallest length scale 200 km allowed by the block parameterization used in mit p08 and similar models this indicates that great care should be taken when interpreting such structure as a practical measure we suggest that only those structures for which the wave speed perturbations do not change sign within the range of models permitted by the data should be considered robust with this criterion the model null space analysis shows that the high velocity anomalies in the lower mantle which are often interpreted as remnants of slabs of subducted lithosphere are required by the seismic data low velocity anomalies underneath for instance hawaii iceland and africa show varying degrees of robustness

climatic control of bedrock river incision bedrock river incision drives the development of much of earth s surface topography and thereby shapes the structure of mountain belts and modulates earth s habitability through its effects on soil erosion nutrient fluxes and global climate although it has long been expected that river incision rates should depend strongly on precipitation rates quantifying the effects of precipitation rates on bedrock river incision rates has proved difficult partly because river incision rates are difficult to measure and partly because non climatic factors can obscure climatic effects at sites where river incision rates have been measured here we present measurements of river incision rates across one of earth s steepest rainfall gradients which show that precipitation rates do indeed influence long term bedrock river incision rates we apply a widely used empirical law for bedrock river incision to a series of rivers on the hawaiian island of kaua i where mean annual precipitation ranges from 0 5 metres to 9 5 metres ref 12 over 70 per cent of the global range and river incision rates averaged over millions of years can be inferred from the depth of river canyons and the age of the volcanic bedrock both a time averaged analysis and numerical modelling of transient river incision reveal that the long term efficiency of bedrock river incision across kaua i is positively correlated with upstream averaged mean annual precipitation rates we provide theoretical context for this result by demonstrating that our measurements are consistent with a linear dependence of river incision rates on stream power the rate of energy expenditure by the flow on the riverbed these observations provide rare empirical evidence for the long proposed coupling between climate and river incision suggesting that previously proposed feedbacks among topography climate and tectonics may occur