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    Offshore migration of coastal sand-bars at Wanganui, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Geography at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Shand, Roger Duncan
    Net offshore bar migration (NOM) refers to the systematic seaward migration of coastal sand-bars across the surf zone. These bars form near the shore-line and disappear in the outer surf zone. NOM behaviour is repetitive and has been described as cyclic. Over the past decade NOM has been recognised on the North Carolina coast, the Dutch coast and by the author on the west coast of the New Zealand North Island. The aim of this project is to elaborate on the behaviour and causative processes of NOM. The New Zealand data used in this study comprise a 6.3 year bar-crest record from an approximately six kilometre long field site at Wanganui. These data were collected using aerial and terrestrial photography and supplemented with ground surveys. Image processing techniques were developed for photographic data abstraction and analysis. Published data from the other 'global' NOM sites were analysed and compared after data compatibility procedures had been developed and applied. The NOM cycles were quantified using parameters for NOM width (cross-shore migration distance), duration and rate, together with return period. The global NOM sites are characterised by multiple sand-bars, the predominance of sea waves and a narrow band of storm strength wind and wave conditions. The longer-term (average cyclic) parameter values for the global data-set were as follows: NOM width ranged between 195 and 930 m; duration ranged between 1.2 and 13 years; NOM rate ranged between 35 and 196 m/yr, and NOM return period varied between 1.2 and 14.4 years. NOM characteristics for the global sites were found to be correlated with cross-shore slope, coastal orientation and extreme wave height. The Wanganui bar-crest data were also analysed for shorter-term (within-cycle) bar behaviour. Cross-shore bar migrations had a bimodal frequency distribution. The group of larger migrations, termed 'episodic seaward jumps', significantly influenced the characteristics of individual NOM cycles. Episodic seaward jumps appear to be preceded by the degeneration of the adjacent seaward bar. Longshore non-synchronous variation in NOM characteristics were found to be mainly related to 'bar switching' (longshore bar realignment). Based on the above results, a conceptual morphodynamic model for NOM was formulated. The model incorporates three main components: a drive mechanism; a morphodynamic modification mechanism; and a timing mechanism. Net offshore bar migration is a significant mode of morphological behaviour within the surf zone. Its influence upon other aspects of coastal geomorphology such as shoreline change, and its relationship with existing 'beach-state' based models, require further investigation.
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    GCM-derived climate change scenarios and their impacts on New Zealand water resources : this thesis is presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Mpelasoka, Freddie Simon
    The derivation of local scale climate information from experiments of coarse- resolution general climate models (GCM) can be addressed with variety of 'downscaling techniques. 'Downscaling' refers to attempts to address the scale mismatch between information from the GCMs and that at which impacts occur. Methods for downscaling range from simple interpolation of climate model outputs to the use of regional climate models nested within larger-scale simulations. Some methods use statistical representations and interpolations; some use dynamic approaches. All of these methods depend on the quality of the initial simulation. Downscaling models fitted to present climatological records are generally referred to as empirical approaches. In a semi-dynamical approach, regional free atmospheric circulation indices simulated by a GCM were employed in this study to derive local climate variables from cross-scale relationships. The relationships were captured from historical records of simultaneously observed local variables and regional-scale circulation indices. Subsequent climate change scenarios were used in impact case studies of two New Zealand catchments' response and water resources. The assessment of climate change impacts requires data at the spatial and temporal resolution at which impacts occur. The outputs of the current GCMs cannot be used directly in the development of specific climate change scenarios due to their coarse resolution although semi-empirical downscaling of GCM outputs to desired scales may offer an immediate solution by relating GCM outputs to single-site climate elements. Artificial neural network (ANN) and multivariate statistics (MST) models were adapted to derive the changes to a number of New Zealand site precipitation and temperature characteristics from free atmosphere circulation indices in a comparative study of their potential in downscaling outputs of GCM transient experiments. Both downscaling models capture similar general patterns from free atmosphere circulation indices. Subsequently the ANN model was used to derive changes of mean monthly precipitation and temperature characteristics from circulation variables projected in a transient climate change experiment performed by the Hadley Centre coupled ocean-atmosphere global climate model (HadCM2). HadCM2 validated well with respect to the National Centers for Environment Prediction reanalysis for its 'present climate' simulation. The predicted changes in seasonal mean sea level pressure fields over the 'New Zealand' region include an intensified anticyclonic belt coupled with negative pressure tendencies to the southwest, which is expected to squeeze stronger westerly winds over southern and central New Zealand. Monthly mean precipitation and temperature time series for 18 points on a 0.25°latitude x 0.25°longitude grid over New Zealand were derived from the circulation indices. The indices were defined by anomalies (with respect to 1961-1990) of mean sea level pressure, zonal and meridional mean sea-level pressure gradients, atmospheric geopotential thickness between 850-700 hPa pressure surfaces, and wind speeds at 10 m above the surface over New Zealand for the period 1980- 2099. Temperature and precipitation characteristics were examined for four decades (1980-2009, 2010-2039, 2040-2069 and 2070-2099), and changes projected with respect to the pseudo-present tri-decade (1980-2009). An average temperature increase of 0.3-0.4°C per tri-decade is projected. Precipitation distribution was modelled using the Gamma probability function and the precipitation characteristics determined by the 'scale' and 'shape' parameters of the Gamma function. Precipitation is predicted to decrease over the north of North Island while marked precipitation increases are projected over the western, central and southwestern areas of the country. Changes in coefficients of variation of monthly precipitation exhibited both increases and decreases in interannual variability of precipitation over the region. Interannual variability in monthly precipitation increases to 1.2-2.2 and decreases to 0.5-0.9 times the pseudo-present coefficients of variations of monthly precipitation by 2070-2099 are projected. The tri-decade to tri-decade changes however, show no trend and this may be attributed to high frequency variations in monthly precipitation. A water balance model was adapted to assess the impacts of changes in precipitation and temperature in two case studies of catchment response. Time series of monthly flows were simulated for each tri-decade. Data for each tri-decade were modelled using a lognormal distribution to generate a 3000-year data set, which was used in a risk analysis to determine the reliability, resiliency and vulnerability of the two water resource systems (hydro power and irrigation schemes). For both of these water resource systems, the changes in operational risk-descriptors with respect to the pseudo-present tri-decade, are within limits in which adjustments can be made, taking into account that traditional design criteria incorporate considerable buffering capacity for extreme events.
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    Practical aspects of phytoextraction : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science, Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Anderson, Christopher William Noel
    Phytoextraction for heavy metals is an emerging technology that has potential application for the remediation of many contaminated sites around the world. The technology has similar application to the mining of low-grade ore bodies. Several practical aspects of the technology are addressed in this thesis. Natural and induced-uptake phytoextraction trials have been conducted on two contaminated substrates: an area of industrial pollution in northern France, where base metals are present in an oxide and carbonate mineral phase, and an area of mine tailings in New Zealand, where base metals are present in a sulphide or sulphate mineral phase. The uptake response of several hyperaccumulator and non-accumulator plant species is described. Geochemical models are then presented that explain the observed metal uptake as a function of the predominant chemical form of metal present in the soil. Natural uptake is dependent upon the form of metal. It appears that the relative efficacy of various hyperaccumulator species to accumulate metals is also dependent upon site-specific geochemistry. The efficacy of chelating agents, in particular EDTA, to induce uptake is similarly dependent upon the chemical form of metals in the soil. A field trial for cadmium phytoextraction was conducted on an area of pastoral land contaminated with this metal due to the application of cadmium to soil through superphosphate fertilisation. Natural uptake at this site by the hyperaccumulator species Thlaspi caerulescens could remove the equivalent of 17 years of annual cadmium application in one harvest. The chelating agent EDTA (ethylenediaminetetraacetic acid) did not induce significant uptake by the non-accumulator Brassica species. Instead, the action of this chemical was to redistribute 14% of the cadmium initially present in the 0-5 cm soil depth to the 5-10 cm depth, and to leach approximately 4% of the cadmium initially present at the site to below 10 cm in the soil profile, as shown by mass balance calculations. Phytoextraction effected by T.caerulescens is proposed as a management tool for cadmium in the pastoral environment. Phytoextraction for nickel has been investigated at a field site in the central North Island of New Zealand. Hyperaccumulation was effected by two Alyssum species and by Berkheya coddii. However, the biomass of the harvested plant material was below that reported in the literature. The conclusion from this trial is that substrate modification of ultramafic soil may be necessary before phytoextraction for nickel could be implemented. A significant obstacle hindering the practical application of phytoextraction in some environments, is the paucity of hyperaccumulator species that are native to some parts of the world. Western Australia has many sites that may benefit from phytoextraction for nickel. However, only one hyperaccumulator species is native to this region, Hybanthus floribundus, a species that has in the past been difficult to germinate from seed. This thesis describes a successful approach to germination, involving the use of one-year-old seeds, treated with 'Regen 2000 smoke water' and germinated under dark conditions, that may overcome this practical aspect (a limitation) of phytoextraction technology. The most recent advance of induced phytoextraction technology has been the thioligand-induced uptake of gold by plants. The initial discovery and the geochemical rationale behind the induced uptake of gold is described. The maximum gold uptake presented is accumulation of 57 mg/kg dry weight gold by Brassica juncea and it is proposed that this level of uptake could make the phytomining of gold from tailings areas an economic proposition. The conclusion of this thesis is that potential for the implementation of phytoextraction is large. Globally, the technology could offer an environmentally and economically friendly alternative to the traditional decontamination of metals from some sites. There is also potential for the phytomining of metals from low-grade ores. The social implications of phytoextraction technology in third-world countries could also be large. Phytoextraction for gold, for example, from auriferous tailings in Africa and South America, has the potential to improve both the environment and the standard of living of the local communities who live off contaminated land.
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    Quantifying slope-channel coupling in an active gully and fan complex at Tarndale, Waipaoa catchment, New Zealand
    (2010-11-18T20:34:46Z) Fuller, Ian C; Dean, Josh F; Phillips, Emma; Massey, Chris; Marden, Mike
    Two RIEGL LMS‐Z420i scanner surveys (November 2007 and November 2008) of the Tarndale Gully complex and its associated fan were used to generate a digital elevation model (DEM) of difference in order to quantify gully‐fan‐channel connectivity. The Te Weraroa Stream, into which the first order Tarndale system feeds, is buffered from sediment generated by the gully complex by a fan. Sediment yields and the role of the fan in buffering Te Weraroa Stream are inferred from the TLS of the entire complex. DEM analysis suggests that c.25% of material derived from the gully is buffered from the stream by being stored in the fan. This figure was applied to fan behaviour since December 2004, mapped on nine successive occasions using detailed GPS surveys to get a longer‐term picture of sediment supply within the system and appraise a qualitative assessment of connectivity constructed on the basis of fan behaviour alone.
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    Quantification of channel planform change on the lower Rangitikei River, New Zealand, 1949-2007: response to management?
    (2010-09-06T21:16:59Z) Richardson, Jane M.; Fuller, Ian C
    The Rangitikei River, a large gravel‐bed wandering river located in the North Island of New Zealand, has outstanding scenic characteristics, recreational, fisheries and wildlife habitat features. Recently concerns have been raised over the potential negative impact that perceived channel changes in the latter part of the 20th century may be having on the Rangitikei River recreational fishery. This study describes and quantifies the large‐scale morphological changes that have occurred in selected reaches of the lower Rangitikei River between 1949 and 2007. This research utilised historical aerial photography and analysis in ArcGIS® to quantify channel planform change in three reaches, encompassing ~18 km of the lower Rangitikei River. This showed that the lower Rangitikei was transformed from a multi‐channelled planform to a predominantly single‐thread wandering planform, with an associated reduction in morphological complexity and active channel width of up to 74%, between 1949 and 2007. Bank protection measures instigated under the Rangitikei River Scheme have primarily driven these changes. Gravel extraction has also contributed by enhancing channel‐floodplain disconnection and exacerbating sediment deficits. The findings of this study have implications for future management of the Rangitikei. Previous lower Rangitikei River management schemes have taken a reach‐based engineering approach with a focus on bank erosion protection and flood mitigation. This study has confirmed the lower river has responded geomorphologically to these goals of river control. However questions as to the economic and ecological sustainability of this management style may encourage river managers to consider the benefits of promoting a self‐adjusting fluvial system within a catchment‐framed management approach.
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    Late quaternary lahars from Mount Ruapehu in the Whangaehu River, North Island, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosoophy in Soil Science at Massey University
    (Massey University, 1993) Hodgson, Katherine Anne
    The stratigraphic record of lahars in the Whangaehu River reveals that in the past 180,000 years this route has been one of the main conduits for lahars from Mount Ruapehu, the highest active andesitic stratovolcano in the Central North Island of New Zealand. Both debris flows and hyperconcentrated flows have engulfed surfaces up to 160 km distance from the Volcano. Eight episodes of laharic activity are recognized by the distinctive lithology and similar age of their deposits. The newly defined upper Pleistocene Whangaehu Formation provides evidence for the earliest lahar event in the Valley, c. 180,000- 140,000 years ago. There is only meagre evidence for laharic activity following this event until the Ohakean and Holocene, although two new informally named deposits - the Mangatipona pumice sand (c. 37,000 years B.P.) and Apitian lahars (c. 32,000-25,500 years B.P) - are recognized, of minor extent. The formerly defined late Quaternary Te Heuheu (c. 25,500- 14,700 years B.P.), Tangatu (c. 14,700-5,370 years B.P.), Manutahi (c. 5 ,370-3,4600 years B.P.), Mangaio (c. 4,600 years B.P.) and Onetapu (< c. 1,850 years B.P.) Formations are here described and interpreted. Triggering mechanisms for lahar deposits are distinguished based on lithological criteria. (a) Bouldery deposits in the Whangaehu Formation are interpreted to have been emplaced by a single highly competent debris flow triggered by a southerly-directed flank collapse at Mount Ruapehu. This debris flow was competent enough to transport boulders up to 2 m in diameter over 140 km from the Volcano. Bouldery deposits are also recognized in the Onetapu Formation, but are restricted to higher gradient surfaces on the Mount Ruapehu ring plain. The Onetapu Formation deposits are interpreted to have been emplaced by lahars resulting from catastrophic drainage of Crater Lake, which occupies the active crater on Mount Ruapehu. (b) Pebbly and sandy deposits are interpreted to have been emplaced by low competence debris flows and hyperconcentrated flows. These lahar deposits are recognized in all formations described. The lithology in these deposits is commonly pumice and they are interpreted to have been triggered by eruptions and/or high rainfall events at the Volcano. Formations, and individual members within Formations, were dated by radiocarbon dating of organic material found below, within or above lahar deposits, or by coverbed stratigraphy. Both rhyolitic and andesitic tephras provided recognizable time planes in the late Quaternary coverbeds overlying lahar deposits. In this study quantitative analysis of quartz abundance, which is shown to vary between loesses and palaeosols, is used as an indirect means of establishing a surrogate for past climate changes which have been correlated to the deep sea oxygen isotope curve. A minimum age for the newly defined Whangaehu Formation is established by this method. The accumulation rate for lahars in the Whangaehu River has accelerated from 1 km3 every c. 23,000 years in the past c. 160,000 years to 1 km3 in 589 years in the past c. 2,000 years. This acceleration probably results from the increased frequency of lahars in the River following the development of Crater Lake c. 2,000 years B.P. According to this pattern an estimated 0.17 km3 volume of lahars could be anticipated over the next 100 years. If the 2,000 year accumulation rate were to be met over the next 100 years there would be 170 lahars of l0[superscript]6 m3 in this time interval , or 17 lahars of 10[superscript]7 m3 (or 1.7 lahars of 10[superscript]8 m3). The largest reported volume for an historic lahar is 10[superscript]6 m3 and these have occurred on average once every 30 years. The accumulation rate for historic lahars is 0.0054 km3 in 100 years. Therefore, although the accumulation rate appears to have slowed down, further large lahars with magnitudes 10 or 100 times greater than those witnessed could be expected.
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    A preliminary Scanning Electron Microscope (SEM) study of magnetite surface microtextures from the Wahianoa moraines, Mt Ruapehu, New Zealand.
    (2010-05-11T21:08:23Z) Mandolla, Stephanie; Brook, Martin S
    Scanning electron microscope (SEM) of quartz micro‐textures has routinely been used to identify the depositional environment of sediments in areas of former ice‐sheet glaciation. On volcanic mountains, where the geomorphic origin of ridge deposits is often poorly understood, quartz is much less abundant, so SEM analysis has not been used as a depositional discriminator. Preliminary research on surface micro‐textures of abundant magnetite grains from the Wahianoa moraines, south‐eastern Mt Ruapehu, suggests that SEM of magnetite may be useful in determining the process‐origin of deposits. We describe micro‐textures and surface characteristics of samples of magnetite, and our study shows that many of the micro‐textures visible on quartz, thought to be diagnostic of glacial transport, are present on magnetite too. However, evaluating whether SEM analysis of magnetite is an applicable technique will require a better understanding of the microtextures occurring on known glacial, fluvioglacial and aeolian deposits on volcanic mountains.
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    Hyperspectral proximal sensing of the botanical composition and nutrient content of New Zealand pastures : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science
    (Massey University, 2009) Sanches, Ieda Del'Arco
    The potential of hyperspectral proximal sensing to quantify sward characteristics important in making critical decisions on the management of sheep and dairy pastures in New Zealand has been investigated. Hyperspectral data were acquired using an ASD FieldSpec® Pro FR spectroradiometer attached to the Canopy Pasture Probe (CAPP). The CAPP was developed to enable the collection of in situ reflectance data from New Zealand pasture canopies independent of ambient light conditions. A matt white ceramic tile was selected as a reflectance standard to be used with the CAPP, after testing a variety of materials. Pasture reflectance factor spectra between 350-2500 nm (with spectral resolutions of 3 nm between 350-1000 nm and 10 nm between 1000-2500 nm) and pasture samples were collected from six hill country and lowland areas, across all seasons (August 2006 to September 2007) in a number of regions in the North Island of New Zealand. After pre-processing (e.g. spectral averaging, de-stepping, elimination of noisy wavelengths, smoothing) the spectral data collected from sites were correlated against pasture botanical composition (expressed as proportions of grass, legume and weed) and pasture nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, sodium and sulphur) expressed in percentage of dry matter (%) and amount (kg ha-1) using partial least squares regressions (PLSR). The accuracy and precision of the calibrations were tested using either the full cross-validation leave-one-out method or testing datasets. Regressions were carried out using the reflectance factor data per se and after mathematical transformation, including first derivative, absorbance and continuum-removed spectra. Overall best results were obtained using the first derivative data. The quality of predictions varied greatly with the pasture attribute, site and season. Some reasonable results were achieved for the prediction of pasture grass and legume proportions when analysing samples collected during autumn (grass: R2 > 0.81 and SD/RMSEP 2.3 and legume: R2 > 0.80 and SD/RMSEP 2.2), but predicting pasture weed content was poor for all sites and seasons (R2 = 0.44 and SD/RMSEP = 1.2). The inaccurate predictions might be explained by the fact that the diversity found in the field and observed in the pasture spectral data was not taken into account in the pasture botanical separation. The potential for using proximal sensing techniques to predict pasture nutrients in situ was confirmed, with the sensing of pasture N, P and K increased by the procedure of separating the data according to the season of the year. The full potential of the technology will only be realised if a substantial dataset representing all the variability found in the field is gathered. The importance of obtaining representative datasets that embrace all the biophysical factors (e.g. pasture type, canopy structure) likely to affect the relat ionship, when building prediction calibrations, was highlighted in this research by the variance in the predictions for the same nutrient using different datasets, and by the inconsistency in the number of common wavelengths when examining the wavelengths contributing to the relationship. The ability to use a single model to predict multiple nutrients, or indeed individual nutrients, will only come through a good understanding of the factors likely to influence any calibration function. It has been demonstrated in this research that reasonably accurate and precise pasture nutrient predictions (R2 > 0.74 and SD/RMSEP 2.0) can be made from fresh in situ canopy measurements. This still falls short of the quality of the predictions reported for near infrared reflectance spectroscopy (NIRS) for dried, ground samples analysed under controlled laboratory conditions
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    Towards improving volcanic mass flow hazard assessment at New Zealand stratovolcanoes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2009) Procter, Jonathan
    The most common hazards for communities surrounding mountain‐forming stratovolcanoes are mass flows of a range of types. Determining their frequency, characteristics and distribution is a major focus of hazard mapping efforts. Recent improvements in computer power and numerical models have meant that simulation of mass flow scenarios is a new tool available for hazard analysis. Its application to hazard mapping, land use planning and emergency management awaits robust evaluation of the conditions under which simulation tools are effective. This study focuses on this question in attempting to improve mass‐flow hazard assessments at the typical stratovolcanoes of Mts. Taranaki and Ruapehu in New Zealand. On Mt. Ruapehu, Titan2D modelling was applied to forecast behaviour of non‐cohesive lahars in the Whangaehu River, primarily produced by Crater Lake break‐outs, such as on 18 March 2007. The simulations were accurate in predicting inundation area, bifurcation, super‐elevation, hydraulic ponding, velocity and travel times of the lahar to 9‐10 km. A 6 x 10[exponent 6] m³ simulated granular flow had a minimum discharge of 1800‐2100 m³/s at the apex of the Whangaehu Fan, 9‐10 km from source, comparable to all historic information. The modelling implied that it was highly unlikely for a flow of this nature to overtop a lahar training dyke (bund) at the fan‐apex location and avulse northward into a more vulnerable catchment. Beyond this point, the model could not cope with the rapid and complex changes in rheology of these non‐cohesive lahars. At Mt. Taranaki chronostratigraphic grouping of mapped past lahar deposits often clouds the actual series of landscape forming processes and hence variations in hazard that occurred over time. Here, patterns of mass flows following emplacement of a 7 km³ debris avalanche deposit were examined from field geology and Titan2D modelling to define a three‐stage recovery process, where lahars of different types and sources were focused initially beside and later on top of the debris avalanche deposit for up to 10 000 years. Results from Titan2D were used to identify source areas of mass flows at different stages and their probable rheologies. Debris avalanche emplacement at Mt. Taranaki was investigated on the c. 7 ka B.P. Opua Formation with the help of Titan2D simulations to identify initial collapse parameters and major flow paths. Once again, the simulations were reliable in proximal reaches, but could not reproduce the rheological transformations from an initial collapsing/sliding pile through to a cohesive clay‐rich flow with long runout. In a further example, past block‐and‐ash flows (BAFs) and dense pyroclastic flow deposits northwest of the current crater were analysed to define the range of realistic model parameters for Titan2D simulations. These could be incorporated inside aGeographic Information System to produce a gradational map of relative probabilities of inundation by future BAF events that took both modelling and geological variability into account. This study highlights that computational models are now reaching the stage where a holistic approach can be taken to hazard analysis that combines both geological mapping and simulation of mass flow scenarios in a probabilistic framework to provide better tools for decision makers and land‐use planners.
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    Morphological budgeting in the Motueka River: an analysis of technique
    (2009-12-17T20:44:49Z) Fuller, Ian C.; Vale, Simon S.
    Morphological budgeting is a key method for monitoring and studying sediment transfers within gravelly rivers. We assess the utility of traditional cross‐section approaches to budgeting using Digital Elevation Model (DEM) analysis. DEMs give a more accurate volume calculation within the constraint of sampling frequency compared with cross sections, since a greater area of river bed is sampled. DEM volume calculation within the 1.7 km ‘Three Beaches’ reach in the upper Motueka revealed a net loss of 3219 m3 in this reach between 2008‐2009. Comparisons of this value with cross section‐based volume calculations at a range of section spacing using (i) Mean Bed Level (MBL) analysis and (ii) DEMs generated from cross section data, suggest accuracy of the budget is maximised at a critical cross section spacing not exceeding 90 m. Careful positioning of cross sections could lengthen this distance further and is essential to accurately represent river channel morphology. MBL analysis using cross‐sections in the reach monumented by Tasman District Council (TDC) for river monitoring underestimates the magnitude of net sediment transfers by c. 30%.