Abstract Fluid–sediment interactions control river channel forms and processes. Analysis of spatial hydraulic patterns the resulting boundary shear stress are required to aid understanding system behaviour. In this paper, processes active in a natural pool–riffle sequence simulated using three‐dimensional computational fluid dynamics (CFD) model. Methods employed for prescription model conditions outlined. Model calculations assessed comparisons with field observations acquired over range...

Abstract. This paper investigates the impacts on floods of hypothetical changes to river channel geometry by construction or removal embankments prevent water spreading onto floodplain at high flows. A numerical model is applied River Cherwell between Oxford and Banbury simulate flood hydrographs. Embanking increases peak flows downstream 50-150%. Restoring through pre-engineered dimensions reduces flow around 10-15% levels within 0.5-1.6 m. These results suggest that rehabilitation, in...

Abstract It is widely accepted that the Earth's climate changing more rapidly than it has in past and over next 100 years temperatures will rise patterns of precipitation be altered. These predictions for future have important implications all ecosystems, particularly those, such as wetlands, whose ecological character very dependent on its hydrological regime. The potential impacts change wetland hydrology are interest to a wide range stakeholders from managers international policy makers....

The management of streams and rivers can be aided by knowledge reference conditions. Data from >1000 sites across New Zealand was used to develop a technique estimate median ammoniacal-N, clarity, Escherichia coli, filterable reactive phosphorus, nitrate-N, suspended solids, total nitrogen phosphorus values under conditions for as classified the River Environment Classification (REC). REC enabled us account natural variation in climate, topography geology when estimating Values minimally...

Summary Flood‐related disturbances are predicted to be seriously altered by climate change effects, and this will have strong implications for stream communities. Predicting how why community structure responds changes in disturbance regimes require measures of that closely linked variability. A range been tested their ability explain patterns periphyton invertebrate assemblages, but assessments fish largely focussed on flow as predictors. Consequently, the mechanisms driving assemblage...

Abstract Robust relationships between biological characteristics and hydrological indices are required to provide a quantitative basis for environmental flows. Data from 1075 river sites distributed across New Zealand were used investigate invertebrate communities flow regimes, whilst also including the influence of additional factors. Variance decomposition analysis was proportion variance explained by hydrological, geomorphological, land cover, catchment community matrix each three biotic...

Abstract Prediction of changes to in‐stream ecology are highly desirable if decisions on river management, such as those relating water abstractions, effluent discharges or modifications the channel, be justified stakeholders. The physical habitat simulation (PHABSIM) system is a well‐established hydro‐ecological model that provides suite tools for numerical modelling hydraulic suitability fish and invertebrate species. In UK, most high‐profile PHABSIM studies have focused rural,...

Snelder, Ton, Doug Booker, and Nicolas Lamouroux, 2011. A Method to Assess Define Environmental Flow Rules for Large Jurisdictional Regions. Journal of the American Water Resources Association (JAWRA) 47(4):828-840. DOI: 10.1111/j.1752-1688.2011.00556.x Abstract: Hydrological rules thumb are used across jurisdictional regions set minimum flows allocation limits that apply by default (i.e., when more detailed site-scale studies have not been carried out). Uniform do account spatial variation...

Abstract. Hydrological classification has emerged as a suitable procedure to disentangle the inherent hydrological complexity of river networks. This practice contributed determining key biophysical relations in fluvial ecosystems and effects flow modification. Thus, plethora approaches, which agreed general concepts methods but differed largely specific procedures, have last decades. However, few studies compared implication applying contrasting approaches specifications over same data. In...

Characterizing biologically relevant stream disturbance regimes is challenging, but necessary to answer questions about effects on ecological processes. No universally accepted approach exists for characterizing regimes. Our goal was evaluate approaches that can be applied test of benthic organisms. We defined as events or environmental conditions caused by changes in discharge affect the stability habitability bed. used several metrics describe mountain streams were not permanently gauged 1...

Abstract In urban rivers, flow regime and channel morphology are the drivers of physical habitat quality for aquatic species. Peak discharges increased at high flows as a result impermeable catchments engineering flood protection schemes. Hazardous conditions flashy hydrographs mean that measurement velocities is difficult task. This research uses three‐dimensional computational fluid dynamics (3D‐CFD) model to simulate hydraulic patterns in two river channels. A 3D‐CFD code, called SSIIM,...

Summary 1. Numerous interacting abiotic and biotic factors influence niche use assemblage structure of freshwater fishes, but the strength each factor changes with spatial scale. Few studies have examined role interspecific competition in structuring stream fish assemblages across scales. We used field laboratory approaches to examine microhabitat partitioning effect on two sympatric fishes ( Galaxias ‘southern’ gollumoides ) at large (among streams among sites within streams) small (within...

ABSTRACT The correspondence and performance of six classifications flow regimes New Zealand rivers that were all mapped onto the same digital river network assessed. Classification 1 was defined deductively, based on expert‐defined rules. Classifications 2 to 6 inductively using hydrological indices calculated from 321 natural daily records. 4 by first clustering gauges then predicting class each segment a Random Forest classifier. 5 for regression models. Cluster analysis used group...

This paper describes a model for simulating the trajectories of migrating Atlantic salmon (Salmo salar) in ocean. Surface current and temperature representations were used as boundary conditions simulation migration trajectories. Representations surface currents derived from general circulation forced by realistic winds then tested through comparisons with observed drifting buoys. Observed climatology data to represent sea patterns. The was simulate 15 individual that tagged their home...

Abstract Anthropogenic alterations to flow regimes have been identified as a serious threat river ecology. Such can affect the magnitude and timing of high low flows. It is therefore important understand how antecedent conditions aquatic communities. However, few studies investigated whether cause common, generalizable perhaps predictable changes in invertebrate communities across range rivers. Using 22 years data from 66 sites New Zealand, we (1) there were common relationships between time...

This study aimed to develop quantitative relationships for Maori cultural values supported by streamflow. We examined the results of a Cultural Flow Preference Study (CFPS) five streams in Canterbury, New Zealand, and used mixed effects models quantify how observed streamflow scores Overall Health (OH). Relationships between OH differed sites assessors within each site. Ignoring differences assessors, there was positive relationship that explained 5% variation OH. After accounting 53% 62%...