A5006707161- Hydrology and Watershed Management Studies
- Advanced Control Systems Optimization
- Control Systems and Identification
- Soil erosion and sediment transport
- Flood Risk Assessment and Management
- Fault Detection and Control Systems
- Hydrology and Sediment Transport Processes
- Hydrology and Drought Analysis
- Groundwater flow and contamination studies
- Soil and Water Nutrient Dynamics
- Atmospheric and Environmental Gas Dynamics
- Toxic Organic Pollutants Impact
- Heavy metals in environment
- Hydrological Forecasting Using AI
- Plant Water Relations and Carbon Dynamics
- Climate variability and models
- Atmospheric chemistry and aerosols
- Greenhouse Technology and Climate Control
- Water resources management and optimization
- Mine drainage and remediation techniques
- Soil and Unsaturated Flow
- Aquatic Ecosystems and Biodiversity
- Stability and Control of Uncertain Systems
- Forecasting Techniques and Applications
- Energy Efficient Wireless Sensor Networks
Lancaster University
2013-2023
Australian National University
2006-2009
Fisheries and Oceans Canada
2006
Lancaster University Ghana
1993
This paper describes in detail a flexible approach to nonstationary time series analysis based on Dynamic Harmonic Regression (DHR) model of the Unobserved Components (UC) type, formulated within stochastic state space setting. The is particularly useful for adaptive seasonal adjustment, signal extraction and interpolation over gaps, as well forecasting or backcasting. Kalman Filter Fixed Interval Smoothing algorithms are exploited estimating various components, with Noise Variance Ratio...
Phosphorus losses from land to water will be impacted by climate change and management for food production, with detrimental impacts on aquatic ecosystems. Here we use a unique combination of methods evaluate the impact projected future phosphorus transfers, assess what scale agricultural would needed mitigate these transfers. We combine novel high-frequency flux data three representative catchments across UK, new high-spatial resolution model, uncertainty estimates an ensemble simulations,...
Two decades of atmospheric measurements polycyclic aromatic hydrocarbons (PAHs) were conducted at three Arctic sites, i.e., Alert, Canada; Zeppelin, Svalbard; and Pallas, Finland. PAH concentrations decrease with increasing latitude in the order Pallas > Zeppelin Alert. Forest fire was identified as an important contributing source. Three representative PAHs, phenanthrene (PHE), pyrene (PYR), benzo[ a]pyrene (BaP) selected for assessment their long-term trends. Significant decline these PAHs...
Century-to-millennial scale fluctuations in precipitation and temperature are an established feature of European Holocene climates. Changes moisture delivery driven by complex interactions between ocean sources atmospheric circulation modes, making it difficult to resolve the drivers behind millennial variability precipitation. Here, we present two overlapping decadal resolution speleothem oxygen isotope (δ(18)O) records from a cave on Atlantic coastline northern Iberia, covering period...
Regional effects of farming on hydrology are associated mostly with irrigation. In this work, we show how rainfed agriculture can also leave large-scale imprints. The extent and speed expansion across the South American plains over past four decades provide an unprecedented case hydrology. Remote sensing analysis shows that as annual crops replaced native vegetation pastures, floods gradually doubled their coverage, increasing sensitivity to precipitation. Groundwater shifted from deep (12 6...
Abstract. An extensive database of organochlorine (OC) pesticide concentrations measured at the Norwegian Arctic monitoring station Ny-Ålesund, Svalbard, was analysed to assess longer-term trends in atmosphere. Dynamic Harmonic Regression (DHR) is employed investigate seasonal and cyclical behaviour chlordanes, DDTs hexachlorobenzene (HCB), isolate underlying inter-annual trends. Although a simple comparison annual mean (1994–2005) suggest decline for all OCs investigated, identified by DHR...
The techniques of dialysis and diffusional equilibration in thin films (DET) are used to measure solute concentrations sediment porewaters. Their performance was assessed using two-dimensional modeling with a view establishing their limitations providing guidelines for application the field subsequent interpretation results. Three alternative types supply samplers were considered: (i) where porewater well buffered by desorption from or dissolution solid phase; (ii) there is no resupply apart...
Abstract Quantification of the source suspended sediments generated by selective forestry activities is central to development sustainable guidelines. This assessment hampered a dearth available studies, particularly from tropics. study involved monitoring (at 10 s intervals) surface discharge and turbidity 15 contributory areas 44 ha catchment. The catchment located within lowland dipterocarp rain forest on Borneo Island, in region recovering first episode timber removal that took place...
Long-term (21-30 years) erosional responses of rainforest terrain in the Upper Segama catchment, Sabah, to selective logging are assessed at slope, small and large catchment scales. In 0.44 km(2) Baru slope erosion measurements over 1990-2010 sediment fingerprinting indicate that sources 21 years after 1989 mainly road-linked, including fresh landslips gullying scars toe deposits 1994-1996 landslides. Analysis modelling 5-15 min stream-suspended discharge data demonstrate a reduction...
We analyzed the vapor phase atmospheric concentrations of representative persistent chemicals (i.e., α- and γ-hexachlorocyclohexane, phenanthrene, PCB-18 PCB-52) in samples collected at a remote site near Eagle Harbor, Michigan, an urban Chicago, Illinois, using four time series models: modified Clausius–Clapeyron equation, multiple linear regression that includes both harmonic dependence on time, digital filtration (DF), dynamic (DHR). The results these different models were evaluated terms...
Insufficient temporal monitoring of water quality in streams or engineered drains alters the apparent shape storm chemographs, resulting shifted model parameterisations and changed interpretations solute sources that have produced episodes poor quality. This so-called 'aliasing' phenomenon is poorly recognised research. Using advances in-situ sensor technology it now possible to monitor sufficiently frequently avoid onset aliasing. A systems modelling procedure presented allowing objective...
Polycyclic aromatic hydrocarbon (PAH) air concentrations measured over the period 1992−2000 at Canadian High Arctic station of Alert were subject to time-series analysis using dynamic harmonic regression (DHR). For most PAHs, DHR model fit observed data was good, with capable interpolating missing points during periods when below detection limits. As expected, identified seasonal increases in PAH concentrations. However, it has also additional, subtler "seasonal" patterns as a series...
The first dynamic model of dissolved organic carbon (DOC) export in streams derived directly from high frequency (subhourly) observations sampled at a regular interval through contiguous storms is presented. optimal model, identified using the recently developed RIVC algorithm, captured rapid dynamics DOC load 15 min monitored rainfall with simulation efficiencies and constrained uncertainty second-order (two-pathway) structure. Most four headwater basins studied was associated faster...
A numerical model of the transport and dynamics metal complexes in resin gel layers a DGT (diffusive gradients thin films) device was developed used to investigate how chelating metal−ligand solution affect uptake. Decreasing stability constant or concentration binding increases competition for free ions by ligands solution, lowering rate mass Such effects would be rarely observed moderately strongly resins (K > 1012), including Chelex, which out-compete labile solution. With weakly resins,...
ABSTRACT The theoretical basis for using measurements of metal uptake by the technique diffusive gradients in thinfilms (DGT) to mimic processes soils that affect metals plants is examined. and DGT were compared conceptually quantitatively classic Barber model plant DIFS (DGT‐induced fluxes soils) DGT. For most considered, similar those induced common gel layer thicknesses 0.2 2mm. Consequently perturbs chemical equilibrium soil solution between solid phase, a extent plants, therefore...