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Item Incorporating hydrology into climate suitability models changes projections of malaria transmission in Africa.(Springer Nature Limited, 2020-08-28) Smith MW; Willis T; Alfieri L; James WHM; Trigg MA; Yamazaki D; Hardy AJ; Bisselink B; De Roo A; Macklin MG; Thomas CJContinental-scale models of malaria climate suitability typically couple well-established temperature-response models with basic estimates of vector habitat availability using rainfall as a proxy. Here we show that across continental Africa, the estimated geographic range of climatic suitability for malaria transmission is more sensitive to the precipitation threshold than the thermal response curve applied. To address this problem we use downscaled daily climate predictions from seven GCMs to run a continental-scale hydrological model for a process-based representation of mosquito breeding habitat availability. A more complex pattern of malaria suitability emerges as water is routed through drainage networks and river corridors serve as year-round transmission foci. The estimated hydro-climatically suitable area for stable malaria transmission is smaller than previous models suggest and shows only a very small increase in state-of-the-art future climate scenarios. However, bigger geographical shifts are observed than with most rainfall threshold models and the pattern of that shift is very different when using a hydrological model to estimate surface water availability for vector breeding.Item Geothermal exploration using hyperspectral and thermal remote sensing : inferring shallow hydrology of the Waiotapu Geothermal Field, New Zealand : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Earth Sciences at Massey University, (Manawatū Campus), Palmerston North, New Zealand(Massey University, 2023) Rodriguez-Gomez, CeciliaGeothermal areas can exhibit a series of surface manifestations (e.g. mineral alteration and deposition, thermal anomalies, hot springs, and characteristic plant species) which can be directly detected with remote sensing techniques within the visible, near-infrared, and thermal ranges. These surface manifestations are, to some extent, a reflection of the subsurface activity. There is a wealth of techniques, including geological, geophysical, and geochemical methods, which can be used to explore and monitor geothermal areas; however, remote sensing techniques from airborne and spaceborne platforms can provide a cost-effective alternative. In many cases, geothermal areas are densely covered by vegetation which can further increase the time and cost of exploration. However, vegetation has the capability to reflect the environment it lives in. Here, we propose vegetation can be utilised as a proxy for subsurface geothermal activity using a combination of hyperspectral (VNIR/SWIR), thermal infrared, and LiDAR imagery with rock/soil and plant elemental concentration values. These techniques are used in geothermal areas but have rarely been employed to analyse plants growing in the area. At Waiotapu Geothermal Field, less than 10% of the surface is directly exposed, areas where the hyperspectral airborne successfully identified three main lithologies and alteration minerals; acid-sulphate alteration, “mixed” alteration, and silica-sinter deposition. While plants cover the remaining 90% of the surface, with kanuka shrub (kunzea ericoides var. microflora) as the dominant species in soils >40 °C. As such, kanuka was selected for our investigation and four geothermally relevant elements were chosen (Ag, As, Ba, and Sb). In areas with near-neutral high-chloride springs with a significant upflow (e.g. Champagne Pool), Ag, As, and Sb are enriched in rock/soil samples and are uptaken by kanuka plants. Whereas high Ba concentrations were found in plants living in peripheral areas where water mixing is taking place. The foliar element concentration zonation maps were successfully developed through classification using Random Forest and regression with Kernel Partial Least Squares. Employing ICPMS data and laboratory, airborne, and satellite hyperspectral (VNIR/SWIR) remote sensing data to create models to predict the foliar element concentrations. The results correspond well with the geology and thermal profile of Waiotapu Geothermal Field. Additionally, thermal anomalies selected from airborne TIR broadband imagery were studied using point pattern analysis such as randomness test-statistics, to map their preferred patterns and orientation, which appear to be controlled by subsurface permeability and water flow. This research opens new opportunities for geothermal exploration and monitoring through plants using hyperspectral imaging, which can overcome the limitations of geothermal exploration methods in densely vegetated areas.Item Quantifying bed stability : the missing tool for establishing mechanistic hydrological limits : 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, 2018) Neverman, Andrew J.Sediment transport processes are a key mechanism of ecological change in riverine systems, and certain levels of sediment flux are necessary for healthy ecosystem functioning. Altered flow regimes and sediment mobility are contributing to a global problem of higher substrate embeddedness reducing the frequency of substrate scour events and leading to increases in periphyton accrual. Excess periphyton accrual leads to fish and invertebrate kills from oxygen depletion, degraded ecological health, altered sediment dynamics, deterioration in water taste, and odour nuisance. In recent decades, reports of toxic periphyton proliferations have increased and are linked with health problems in humans including asthma, skin rashes, liver damage, and the death of domestic dogs. Excess periphyton accrual is prominent in impounded catchments where dams have a considerable impact on flow and sediment regimes. With at least 3,700 large dams currently under construction or in the planning phase the problem is set to increase in the foreseeable future. Hydrological limits are widely implemented by authorities in an attempt to manage periphyton accrual. Hydrological limits are frequently based on flow-ecology relationships but are often ineffective. Sediment transport thresholds have been found to have a better relationship with periphyton accrual than hydrological metrics. Flow-ecology relationships do not account for the mechanisms of periphyton removal (scour, abrasion, and molar action) which are likely to vary between sites at equivalent flows, and the species-specific resistance to each mechanism also likely varies. Abrasion and molar action result from transport of sediment. Improving the effectiveness of hydrological limits as a tool for river management therefore relies on setting flows with the aim of inducing sediment transport to initiate mechanisms of periphyton scour. This will require models which can accurately predict the flow required to induce different phases of sediment transport. The research presented in this thesis focuses on improving the estimation of gravel entrainment to advance entrainment models as a means of setting hydrological limits to induce molar action and improve the effectiveness of periphyton removal. A literature review of methods for estimating gravel particle entrainment thresholds in natural channels revealed a considerable gap in methods being available to quantify substrate characteristics to calculate resistance thresholds. The review also found significant challenges in identifying the onset of gravel transport in natural channels, and difficulty obtaining corresponding hydrodynamic data to identify entrainment thresholds. Further, the review found seepage was an important component of hydrodynamic forces for inducing particle entrainment in flumes, but seepage is not considered in conventional entrainment formulae, and is not measured alongside bedload transport data in the field. A suite of tools is identified and developed to improve the quantification of substrate structure and resistance, identification of incipient motion, and quantification of entrainment thresholds in natural gravel beds to advance the assessment of bed mobility. Optical and ranging techniques are compared to identify an optimal approach to remotely quantify substrate structure. Both approaches were found to produce a comparable quantification of surface roughness using point cloud elevations, but identified different trends in surface layer development. Quantification of surface layer development was found to be sensitive to the cell size used to grid the data, and this sensitivity increased with higher-order statistical moments which were used to describe armouring. Airborne optical sensors were found to be the most versatile method for remote characterisation of gravel-bed surface structure, with a larger range of metrics being derivable from the same dataset to quantify a wider range of substrate structural and textural characteristics. Whilst quantifying bed structure is critical for developing bed mobility models, measuring the resistive force of the bed created by the structural arrangement of particles is required for model calibration and empirical data collection. A protocol was developed to use a modified penetrometer to quantify the resistive force of the armour (active) layer in gravel-bed channels. The modifications made to the penetrometer made it sensitive to variations in armour layer compactness, and allowed for adaptive penetration depths enabling variations in armour layer thickness to be accounted for. The protocol and modified penetrometer provide a significant advancement in the ability to empirically quantify bed resistance and relate bed structure to potential bed mobility, and build on the remote sensing methods to provide a suite of bed resistance parameters for entrainment models. Measurement of bed mobility is also critical for calibrating entrainment models and relating ecological metrics to bed mobility thresholds. Both direct and indirect measurement of bed mobility have benefits for research and river management. Tick-box indices are frequently used in ecological studies to provide an indirect assessment of substrate (in)stability (i.e. bed mobility). These indices often provide a poor approximation of bed mobility, and do not relate well with biotic communities, but their low-cost and rapidity make them a valuable tool for research and management. An improved index is developed to provide rapid, low-cost assessment of bed mobility. This index improves on previous methods by focusing on objective measurements of parameters where low-cost approaches are available, or providing a framework for scoring parameters where visual assessment is required. The index scores correlated well with tracer particle data, and were found to relate to accrual of Phormidium biomass. This index therefore provides a means to rapidly and cost-effectively estimate bed mobility and predict periphyton accrual. Direct measurement of bed mobility is also required to provide an empirical dataset for the calibration of particle entrainment and transport models, and for the empirical derivation of hydrological limits. A multi-sensor system was developed to measure the onset of particle movement, and record corresponding hydrodynamic data, including bed seepage, to identify hydraulic entrainment thresholds in natural channels, and therefore address the challenges of identifying bedload entrainment thresholds identified in the literature review. A pilot study testing the system identified bed seepage and turbulence intensity as key predictors of particle entrainment, and discharge and mean velocity as the worst predictors. These findings challenge the use of discharge and mean velocity as the metrics used to set hydrological limits if mechanistic limits based on bed mobility-ecology relationships are to be established effectively. These tools provide a means for scientists to study bedload entrainment and transport, identify their thresholds, and relate the frequency and magnitude of these processes to benthic community dynamics. This research will form the basis for establishing the mechanisms required to achieve removal of excess periphyton and establish hydrological limits to ensure these mechanisms function and effective removal of periphyton is achieved to maintain ecosystem health.Item Characterisation and numerical simulation of the Lower Manawatu Catchment hydrogeological system : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Sciences at Massey University, Manawatu, New Zealand(Massey University, 2018) Zarour, Hisham Ibrahim SabriThe Lower Manawatu Catchment (LMC) hydrogeological system presents an example of extensive stratified heterogeneous aquifers. A conceptual model was developed for the system through systematic characterisation of its geology, soil, climate, hydrology, hydrogeology and hydrochemistry. Numerical groundwater flow modelling provided an effective integrated framework for the analysis. The developed knowledge and models are useful for the identification and comparison of land and water resources management options in the catchment. The research involved the development of a soil moisture balance modelling code to evaluate recharge. Stratigraphical modelling has been possible through incorporating imaginary lithological well logs and stratigraphical cross-sections in data-sparse areas. Geological material heterogeneity was represented in the groundwater flow model through hybridising zonal and pilot point calibration techniques. The developed soil moisture, geology and heterogeneity modelling techniques have universal applications. The study indicates that the LMC hydrogeological system is more suitably represented as a continuous groundwater flow system rather than a sequence of discrete aquifers and aquitards. Average groundwater recharge is estimated at about 25% of average rainfall. Average baseflow is estimated at about 10% of the average runoff, the equivalent to more than half the estimated average recharge. The LMC groundwater resource is mainly tapped at shallow depths, the locus where most of the interaction with surface water occurs. Catchment-scale steady-state numerical groundwater flow modelling suggests that in average groundwater abstraction may have been depleting overall surface water flow by about 5%. Groundwater levels in the LMC were found to be generally stable, implying sustainable resource development. Rising groundwater levels noted in the eastern and southern outskirts of Palmerston North may be related to prolonged practice of irrigation. No evidence of land use impacts on groundwater quality was found in the catchment. Nitrate concentrations are believed to have been kept at acceptable levels in groundwater due to denitrification stimulated by extensive organic content in some geological units. This thesis represents a one stop shop for information on groundwater in the LMC. The knowledge and tools developed through this research have immediate use in the LMC and elsewhere, and they provide solid basis for further work.Item A study of the hydrological and sedimentological characteristics of two catchments of contrasting land use : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Soil Science at Massey University(Massey University, 1976) Bargh, Brian JamesThe hydrological and sedimentological characteristics of two catchments of contrasting land use were studied for a period of one year. Both catchments were situated in the Northern Tararua Ranges, near the Manawatu Gorge, some 27 km from Palmerston North, New Zealand. The 10 ha Ballance Catchment has native forest vegetation, whereas the 180 ha Tuapaka Catchment is part of a mixed sheep and cattle farm. The water balance estimated for the catchments indicated that a small amount of deep percolation occurred in both. Streamflow and rainfall were recorded at both catchments. During the study year approximately 26% and 14% of total rainfall was discharged as streamflow from the Tuapaka and Ballance Catchments, respectively. Throughfall and stemflow were also recorded at Ballance. The average monthly throughfall was 54% of total rainfall; the equivalent stemflow, was 16% of total rainfall. An attempt was made to identify and quantify the inputs of phosphorus (P) and nitrogen (N) forms to the two catchments. Phosphate fertilizer application, N - fixation by clovers, and rainfall, were considered as the inputs of P and N forms in the Tuapaka Catchment. In the Ballance Catchment, rainfall was assumed to be the only input of P and N forms. The output of suspended sediment, dissolved material, and P and N forms, was measured during the study year. The output of sediment was 1.4 x 10³kg/ha and 1.6 x 10² kg/ha from the Tuapaka and Ballance Catchments, respectively. The output of dissolved material from the Tuapaka Catchment was only 13% of the sediment output. Significant quantities of P and N output were associated with suspended sediment. Of the annual loss of total P (1.6 kg/ha) from the Tuapaka Catchment, 76% was in the particulate form. At Ballance, 52% of the annual loss of total P (0.2 kg/ha) was in particulate form. Within the bounds of error, the Ballance Catchment appeared to be slightly conservative of P and strongly conservative of N. At the Tuapuka Catchment, however, inputs of P and N balanced outputs, within the bounds of error. It is difficult, if not impossible, to determine whether a particular catchment is conservative for P and N unless adequate attention is paid to the errors involved. The differences obtained for the output of sediment and P and N forms, from the two catchments, are interpreted in terms of the effects of agricultural activities, particularly vegetation differences, on the inputs of particulate and dissolved phases to the streams.Item The role of substrate hydrogeology and surface hydrology in the construction of phreatomagmatic volcanoes on an active monogenetic field (Auckland, New Zealand) : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Earth Science at Massey University, Palmerston North, New Zealand(Massey University, 2015) Agustín Flores, JavierPhreatomagmatic activity is pervasive in the Auckland Volcanic Field (AVF) with more than two thirds of the erupted volcanoes showing this type of activity at different degrees, dominantly at the onset of their eruptive histories. In general, the volcanoes built in the northern AVF rest on Late Miocene Waitemata Group rocks (turbiditic siltstone and sandstone succession), whereas in the southern AVF the Waitemata rocks are overlain by tens of metres of Plio-Pleistocene, water-saturated sediments (Tauranga Group and Kaawa Formation). Identifying the control exerted by the type of substrate in the eruption dynamics of the phreatomagmatic phases of three volcanoes in the AVF is the objective of this study. The stratigraphic, sedimentary, and pyroclast characteristics of the phreatomagmatic sequences of Maungataketake, Motukorea, and North Head volcanoes, together with supplementary information on the geology and hydrogeology of the area, were investigated to solve the problem. Three phreatomagmatic eruptive scenarios were outlined. Scenario 1 (Maungataketake eruption) and Scenario 2 (Motukorea eruption) depict the formation of maar-diatreme volcanoes in the southern and northern AVF, respectively. The dominant presence of lithics from the upper part of the substrate in their tephra rings suggests the construction of their tephra rings from shallow-seated explosions. Due to the water-saturated sediments filling the diatreme in Scenario 1, the eruption appears to have remained relatively wet throughout. Conversely, the drier Waitemata rocks involved in Scenario 2 promoted a progressive drying of the eruption. Scenario 3 (North Head eruption) represents a Surtseyan eruption scenario in which the rising magma erupted to the shallow sea floor (a few metres-water depth), promoting rapid chilling and explosive fragmentation. This study shows that the characterization of lithics within the tephra ring and the geological and hydrogeological information provide valuable clues to envisage the degree of influence of the substrate in the phreatomagmatic eruption dynamics. Other studies in the AVF appear to confirm this view. It is proposed that any future phreatomagmatic eruption in the AVF will be strongly influenced by the substrate hydrogeology and geology, as well as the surface hydrological conditions.