Papers by Maarten Kleinhans
Fluvial meander belt sediments form some of the most architecturally complex reservoirs in hydroc... more Fluvial meander belt sediments form some of the most architecturally complex reservoirs in hydrocarbon fields due to multiple scales of heterogeneity inherent in their deposition. Currently, characterization of meander belt bodies largely relies on idealized vertical profiles and a limited number of analogue models that naively infer architecture from active river dimensions. Three-dimensional architectural data are needed to quantify scales of grain-size heterogeneity, spatial patterns of sedimentation and bar preservation in a direct relationship with the relevant length scales of active river channels. In this study, three large flume experiments and a numerical model were used to characterize and construct the architecture (referred to as 'archimetrics') and sedimentology of meander belt deposits, while taking reworking and partial preservation into account. Meander belt sandbody width-to-thickness ratios between 100 and 200 were observed, which are consistent with reported values of natural meander belts. For the first time, the relief of the base of a meander belt is quantified, enabling improved estimates of connectedness of amalgamated meander belts. A key observation is that the slope and number of lateral-accretion packages within natural point bar deposits can be well predicted from fairly basic observ-ables, a finding subsequently tested on several natural systems. Probability curves of preserved architectural characteristics for three dimensions were quantified allowing estimates of bar dimensions, baffle and barrier spacing distributions and container dimensions. Based on this, a set of rules were identified for combining reservoir parameters with the identified probability curves on sand-body dimensions and character, to help create more realistic geomodels for estimating exploration success on the basis of seismic and core data.
Geometry of Wave-Formed Orbital Ripples in Coarse Sand
Journal of Marine Science and Engineering, 2015
Kennis over publiceren. Publicatietradities in de wetenschap
A Modelling Framework to Assess the Effect of Pressures on River Abiotic Habitat Conditions and Biota
PLOS ONE, 2015
River biota are affected by global reach-scale pressures, but most approaches for predicting biot... more River biota are affected by global reach-scale pressures, but most approaches for predicting biota of rivers focus on river reach or segment scale processes and habitats. Moreover, these approaches do not consider long-term morphological changes that affect habitat conditions. In this study, a modelling framework was further developed and tested to assess the effect of pressures at different spatial scales on reach-scale habitat conditions and biota. Ecohydrological and 1D hydrodynamic models were used to predict discharge and water quality at the catchment scale and the resulting water level at the downstream end of a study reach. Long-term reach morphology was modelled using empirical regime equations, meander migration and 2D morphodynamic models. The respective flow and substrate conditions in the study reach were predicted using a 2D hydrodynamic model, and the suitability of these habitats was assessed with novel habitat models. In addition, dispersal models for fish and macroinvertebrates were developed to assess the re-colonization potential and to finally compare habitat suitability and the availability/ability of species to colonize these habitats. Applicability was tested and model performance was assessed by comparing observed and predicted conditions in the lowland Treene River in northern Germany. Technically, it was possible to link the different models, but future applications would benefit from the development of open source software for all modelling steps to enable fully automated model runs. Future research needs concern the physical modelling of long-term morphodynamics, feedback of biota (e.g., macrophytes) on abiotic habitat conditions, species interactions, and empirical data on the hydraulic habitat suitability and dispersal abilities of macroinvertebrates. The modelling framework is flexible and allows for including additional models and investigating different research and management questions, e.g., in climate impact research as well as river restoration and management.
NEW HIGH-RESOLUTION MEASUREMENTS OF WAVE BOUNDARY LAYER FLOW UNDER FULL-SCALE SURFACE WAVES
Coastal Engineering 2008 - Proceedings of the 31st International Conference, 2009
Existing sand transport models are primarily based on data from oscillatory flow tunnel (OFT) exp... more Existing sand transport models are primarily based on data from oscillatory flow tunnel (OFT) experiments. However, theory and former experiments indicate that flow differences between full scale surface waves and OFT's may have a substantial effect on the net sand ...
Measured and predicted suspended sand transport on a sandy shoreface
Coastal Dynamics 2005 - Proceedings of the Fifth Coastal Dynamics International Conference, 2006
ABSTRACT
Proceedings of the 5th IAHR Symposium on River, Coastal and Estuarine Morphodynamics, Enschede, NL, 17-21 September 2007, 2007
The prediction of suspended sediment concentration and transport by combined currents and waves i... more The prediction of suspended sediment concentration and transport by combined currents and waves is hampered by a lack of data in energetic conditions and in sediment mixtures. Our aim is to improve predictors for the entire range of no motion to high wave and current energy. We measured hydrodynamics, sediment transport and bedform dimensions and shapes on an ebb-tidal delta with current velocities up to 1 m/s and orbital velocities up to 1.2 m/s over a very poorly sorted sandy gravel sediment with a mean grain size of 0.3-0.6 mm. In varying conditions symmetrical vortex ripples or asymmetrical current dunes occurred. Our proposed model consists of shear stress predictors, diffusivity profiles for currents and waves, and a reference concentration predictor. In wave-only conditions the concentration decays exponentially as expected, but in current-only conditions the diffusivity is much larger than expected. This could not be explained by finer sediment suspended higher above the bed. We hypothesise that the effective mixing is enhanced by the short disequilibrium bedforms. A correction for this effect considerably improved concentration predictions. In combined currents and waves the concentrations were best predicted for a linear addition of wave-and current-related diffusivities in contradistinction to the common squared addition verified for lower-energy conditions. The reference concentrations were best reproduced by the method of Van Rijn 1984 which has a more conservative estimate of orbital bed shear stress than alternative formulations.
Proceedings of the 5th IAHR Symposium on River, Coastal and Estuarine Morphodynamics, Enschede, NL, 17-21 September 2007, 2007
We present a proof of principle for using a recent model for grain size-sorting over a bed form l... more We present a proof of principle for using a recent model for grain size-sorting over a bed form lee face to reconstruct the bed form height from a partially preserved dune or delta deposit. The lee face sorting model was developed to describe the grain size-selective deposition of particles over a bed form lee face for use in a new type of stochastic sediment continuity model for conditions with nonuniform sediment and river dunes. The lee face sorting model is applied to variable elevation ranges of the measured sorting in dunes and deltas of which the height is known but not used in the model predictions. We find that reliable estimates of the bed form height and the composition of the lee face deposit can be derived, under the conditions that more than 50% of the original bed form height has been preserved and sufficient samples of the bed composition over this range are taken. The estimate of the bed form height is a lower limit, as the method shows a systematic underestimation of the original bed form height due to the sorting being stronger over the lower part of a bed form than over its upper part. The sorting model can thus be applied to estimate bed form height and bed load sediment composition from vertical sorting profiles collected from individual cross-sets of partially preserved bed form deposits. Bed form height and sediment composition are robust indicators for palaeoflow conditions.
Proceedings of the International Conference on Fluvial Hydraulics, Lisbon, Portugal, 6-8 September 2006, 2006
River dunes, alternate bars, and subaqueous deltas are often characterised by a lee face at about... more River dunes, alternate bars, and subaqueous deltas are often characterised by a lee face at about the angle of repose. Transport of mixed-size sediment over the crest of such a bed form results in grain sizeselective deposition of particles over the lee face. The complex interaction between two different deposition mechanisms, i.e. grain fall from suspension and grain flows at nearly the angle of repose, results in coarse particles preferentially depositing at the lower elevations of the lee face, and fine particles at the upper ones. In this study we develop a simple empirical model describing the sorting of particles over the lee face of a bed form. This lee face sorting model is calibrated and verified on data from flume experiments with deltas and dunes. Field data of lee face sorting over dunes in an ebb-tide dominated mouth bar of the river Teign, UK, are used to validate the model. The lee face sorting model describes the grain size-selective deposition over a lee face well, although the model does not reproduce the deposition of fines from suspended load which slightly modifies the sorting by producing a fine deposit at the base of the bed forms.
Chaos suggest large scale collapse and subsidence (1500 m) of the entire area, which is consisten... more Chaos suggest large scale collapse and subsidence (1500 m) of the entire area, which is consistent with a massive expulsion of liquid water from the subsurface in one single event. Morphological analysis of Aram Valley suggests a complex process starting with the outflow of water from two small channels, continuous groundwater sapping and headward erosion ending with catastrophic lake rim collapse and carving of the Aram Valley, synchronous with the 2.5 Ga stage of Ares Vallis formation. The water volume and the formative time scale needed to carve the Aram channels indicate that a single, rapid (maximum tens of days) and catastrophic (flood volume of 9.3·10 4 km 3 ) event carved the outflow channel. We conclude that the subice lake collapse scenario can explain the features of Aram Chaos -Valley system as well as the time scale needed for its formation.
Stability of River Bifurcations from Bedload to Suspended Load Dominated Conditions
Bifurcations (also called diffluences) are as common as confluences in braided and anabranched ri... more Bifurcations (also called diffluences) are as common as confluences in braided and anabranched rivers, and more common than confluences on alluvial fans and deltas where the network is essentially distributary. River bifurcations control the partitioning of both water and sediment through these systems with consequences for immediate river and coastal management and long-term evolution. Their stability is poorly understood and seems to differ between braided rivers, meandering river plains and deltas. In particular, it is the question to what extent the division of flow is asymmetrical in stable condition, where highly asymmetrical refers to channel closure and avulsion. Recent work showed that bifurcations in gravel bed braided rivers become more symmetrical with increasing sediment mobility, whereas bifurcations in a lowland sand delta become more asymmetrical with increasing sediment mobility. This difference is not understood and our objective is to resolve this issue. We use a one-dimensional network model with Y-shaped bifurcations to explore the parameter space from low to high sediment mobility. The model solves gradually varied flow, bedload transport and morphological change in a straightforward manner. Sediment is divided at the bifurcation including the transverse slope effect and the spiral flow effect caused by bends at the bifurcation. Width is evolved whilst conserving mass of eroded or built banks with the bed balance. The bifurcations are perturbed from perfect symmetry either by a subtle gradient advantage for one branch or a gentle bend at the bifurcation. Sediment transport was calculated with and without a critical threshold for sediment motion. Sediment mobility, determined in the upstream channel, was varied in three different ways to isolate the causal factor: by increasing discharge, increasing channel gradient and decreasing particle size. In reality the sediment mobility is mostly determined by particle size: gravel bed rivers are near the threshold for sediment motion whereas sand bed rivers have highly mobile sediment at channel-forming conditions. For sediment transport without a critical threshold for motion, bifurcations become more asymmetrical with increasing sediment mobility. In contrast, sediment transport prediction including the threshold for motion leads to highly asymmetrical bifurcations for low sediment mobility, more symmetrical bifurcations for higher mobility and again decreasing symmetry for higher mobility where results of transport with and without the threshold converge. Thus, the general trend is more asymmetrical bifurcations for higher sediment mobility, but the presence of the threshold for motion leads to an optimum in symmetry. Results were similar for the different options used to vary mobility, excluding first-order effects of backwater adaptation length and hydraulic roughness. We conclude that the seemingly conflicting results between gravel-bed and sand-bed rivers in literature are well explained by the difference in sediment mobility.
The sedimentary dynamics of a lowland river system can be defined as the whole of processes that ... more The sedimentary dynamics of a lowland river system can be defined as the whole of processes that involve erosion, transport or deposition of sediment in the systemincluding the floodplains -on every possible spatial and temporal scale. The sedimentary dynamics of the river Rhine in the Netherlands have been influenced by many human activities in the past. A major human intervention has been the embankment around 1300 AD, by which the so far free meandering river was confined between dikes. Previous studies analyzed the impact of human interventions in the period after the embankment. The present study focuses on the sedimentary dynamics of the natural river Rhine. We reconstructed the amount of sedimentation and erosion that is involved with lateral migration of the river, and estimated the residence time of the sediment on the floodplain. Lateral migration was reconstructed with a one-dimensional bank erosion model. Lateral migration rates of meander bends were modeled based on channel parameters (e.g. bend radius, discharge) and bank material, all derived from detailed borehole reconstructions of sub-recent channel belts from previous studies. Model results will be used to compare the sedimentary dynamics of the natural river Rhine, with dynamics in human-influenced periods, and hence to predict present and future sedimentation and erosion processes. Moreover, results of reworked sediment volumes can be included in existing large-scale sediment budgets of the river Rhine to evaluate the dynamics within these slices.
Bedform development and distribution on the lower shoreface (14-18 m LLWS) of the central Dutch c... more Bedform development and distribution on the lower shoreface (14-18 m LLWS) of the central Dutch coast differ markedly between fair-weather and storm conditions. Modern observations of bedforms on multibeam sonar images confirm that unidirectional tide-dominated currents rework the lower shoreface during fair-weather conditions with significant waveheights below 2.5 m. Several Spring-Neap cycles produced straight-crested 2D-megaripples as the dominant bedform in two research areas. The megaripples are very similar to those generally observed below wave base on the inner shelf. Even minor seasonal storms (significant waveheights 3-4 m) produce an entirely different type of bedform distribution with round-crested 3D 'hummocky' bedforms (wavelength 20-40 m) and 3D-megaripples (spacing 5-8 m and 12-14 m). The bedforms observed here in a seabed of medium sands differ from those characteristic of fine sand(stone)s. Spatial differences in bedform development are partly attributed to feedback mechanisms between hydrodynamics and wave damping by the tube worm Lanice conchilega.
Quantifying flow retention due to vegetation in an earthen experimental channel using the Aggregated Dead Zone (ADZ) dilution approach
Geophysical Research Abstracts, 2014
For the prediction of river bed destabilisation and fractional sediment transport of mixtures, we... more For the prediction of river bed destabilisation and fractional sediment transport of mixtures, we aim to solve two problems that are poorly understood. First, the flow and pressure fluctuations surrounding both the embedded and exposed particles must be parameterised for hydraulically smooth to rough flow. Second, an adequate relation between particle size and particle exposure should be based on the particle size distribution and the (water-worked) bed structure. We use a recently developed force balance model for the threshold of motion of uniform sediments incorporating the effects of particle exposure, pressure fluctuations into the bed, very shallow flow and bed slope. The flow module is extended to non-uniform roughness of sediment mixtures. Our extended model predicts the critical Shields values of arbitrary mixtures directly as function of exposure and no longer needs empirical hiding-exposure relations. Several empirical and geometrical relations between particle size and exposure were tested. The results are compared to extensive datasets from the literature of incipient fractional transport rates. The modelled hiding-exposure relations are very sensitive to the relation between particle size and exposure, which differ for unimodal, skewed and bimodal mixtures. This is explained by the pore structure of these sediments. The existing relations fail particularly for the smaller particles in bimodal and skewed distributions. These small particles percolate through the pores so their exposure or embedding strongly depends on the fractional content and pore structure, in agreement with empirical data. We are working on a universal relation for exposure containing particle size distribution, pore structure and water-working. The model reproduces data of uniform sediments well for the entire physically possible range of particle exposures and for hydraulically rough to nearly smooth conditions. Trends in existing data for mixtures are also reproduced but depend strongly on exposures that were not measured.
Aram Chaos outflow channel: water volume and time scale
ABSTRACT The evaluation of the water volume and the formative time scale needed to carve the outf... more ABSTRACT The evaluation of the water volume and the formative time scale needed to carve the outflow channels repre- sents a fundamental process for the validation of their evolutive models. We calculate these attributes for the Aram channels and we compared the results with the volume of liquid water that was produced in a single chaotization event of the Aram Chaos. The analysis suggests that a single rapid and catastrophic event is sufficient to carve the channel and the volume of flood is compatible with the volume of liquid water release in a single chaotization event of the Aram Chaos.
Icarus, 2016
The quasi-circular collapsed landforms occurring in the Chryse region of Mars share similar morph... more The quasi-circular collapsed landforms occurring in the Chryse region of Mars share similar morpholog- ical characteristics, such as depth of collapse and polygonally fractured floors. Here, we present a statis- tical analysis of diameter, maximum and minimum depth, and amount of collapse of these features. Based on their morphometric characteristics, we find that these landforms have a common origin. In par- ticular, the investigated landforms show diameter-depth correlations similar to those that impact craters of equivalent diameters exhibit. We also find that the observed amount of collapse of the collected fea- tures is strongly correlated to their diameter. Furthermore, the linear relation between minimum filling and pristine depth of craters, the constant ratio between collapse and the amount of filling and the frac- tured and chaotic aspect of the filling agree with melting and subsequent collapse of an ice layer below a sediment layer. This interpretation is consistent with a buried sub-ice lake scenario, which is a non-climatic mechanism for producing and storing abundant liquid water under martian conditions.
Proceedings of the 5th IAHR Symposium on River, Coastal and Estuarine Morphodynamics, Enschede, NL, 17-21 September 2007, 2007
For the prediction of river bed destabilisation and fractional sediment transport of mixtures, we... more For the prediction of river bed destabilisation and fractional sediment transport of mixtures, we aim to solve two problems that are poorly understood. First, the flow and pressure fluctuations surrounding both the embedded and exposed particles must be parameterised for hydraulically smooth to rough flow. Second, an adequate relation between particle size and particle exposure should be based on the particle size distribution and the (water-worked) bed structure. We use a recently developed force balance model for the threshold of motion of uniform sediments incorporating the effects of particle exposure, pressure fluctuations into the bed, very shallow flow and bed slope. The flow module is extended to non-uniform roughness of sediment mixtures. Our extended model predicts the critical Shields values of arbitrary mixtures directly as function of exposure and no longer needs empirical hiding-exposure relations. Several empirical and geometrical relations between particle size and exposure were tested. The results are compared to extensive datasets from the literature of incipient fractional transport rates. The modelled hiding-exposure relations are very sensitive to the relation between particle size and exposure, which differ for unimodal, skewed and bimodal mixtures. This is explained by the pore structure of these sediments. The existing relations fail particularly for the smaller particles in bimodal and skewed distributions. These small particles percolate through the pores so their exposure or embedding strongly depends on the fractional content and pore structure, in agreement with empirical data. We are working on a universal relation for exposure containing particle size distribution, pore structure and water-working. The model reproduces data of uniform sediments well for the entire physically possible range of particle exposures and for hydraulically rough to nearly smooth conditions. Trends in existing data for mixtures are also reproduced but depend strongly on exposures that were not measured.
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Papers by Maarten Kleinhans