CANOPEX: A Canadian hydrometeorological watershed database

Over the past few years, many international initiatives and collaborations were launched to improve and share knowledge in hydrology research. Large databases allowed finding patterns and relationships across regions and scales. This paper introduces the Canadian model parameter experiment (CANOPEX) database, which is adapted from the US MOPEX project data and methods. The CANOPEX database includes meteorological and hydrometric data as well as watershed boundaries for 698 basins. Two sets of basin‐averaged meteorological data (Maximum and minimum temperature and precipitation) are provided. The first dataset is directly taken from Environment Canada's weather stations whereas the second is extracted from the Natural Resources Canada gridded climate data product. Data are provided in MOPEX and Matlab formats. CANOPEX watersheds are well distributed over Canada, which allows investigating a variety of physiological and climatological conditions. The CANOPEX database can be used in a variety of hydrologic research projects such as climate change impact studies, model comparisons, multi‐modelling, ensemble streamflow prediction and model parameter estimation. CANOPEX could be used to generalize findings to other cold climate catchments as well as assess the robustness of research methodologies and procedures. Copyright © 2016 John Wiley & Sons, Ltd.     

A combined geological, hydrochemical, and geophysical approach to understanding a disease contamination hazard in groundwaters at a state fish hatchery

At the Midway, Utah, USA fish hatchery, a groundwater development program was conducted to help transition the facility from surface to groundwater in response to contamination by whirling disease, which is caused by a trout parasite. The unconfined aquifer system that provided the hatchery water became infected through the recharge of infected irrigation water obtained from the Provo River. Whirling disease was first discovered in Utah in 1991 at a private fish farm. Infected fish from the farm quickly infected many of Utah’s waterways and infected the hatchery in 2000. Because the parasite completes its life cycle in multiple organisms and can survive for decades in a variety of harsh environments, a comprehensive study of the hydrostratigraphy and hydrodynamics at the hatchery was critical in order to understand the hazard and avoid further contamination. Drilling revealed the presence of a shallow unconfined (surface to 10 m) and two deeper confined aquifer systems (~20–35 m and >40 m bgs). Confinement is related to tufa layers, detected both by drilling and reflection seismology. The tufa layers are associated with past discharge of the thermal system. Vertical leakage is apparent from upward hydraulic head gradients and incrementally increasing unconfined aquifer discharge into downstream on-site drainage canals. High-resolution seismic profiles reveal small-offset faults that provide pathways for upward flow. Analysis of water quality data demonstrates an inverted geochemical gradient in that apparent ¹⁴C ages, solute concentrations, and temperatures decrease with depth. The origin of the inverted geochemical gradient is related to mixing of upwelling thermal, high-TDS waters with cold, low-TDS systems several kilometers up-gradient from the hatchery. Thermal upwelling appears to be fault controlled. Up-gradient of the hatchery, near-surface groundwater mixes with a larger proportion of thermal groundwater than does deeper groundwater. As these mixed systems flow toward the hatchery, a major locus of groundwater discharge, they are segregated into confined and unconfined compartments. Our study requires integration of hydrological, geochemical, and geophysical strategies in order to understand a complex natural hazard and thus may serve as a model for other similarly complex hydrological environments.     

Questioning emissions-based approaches for the definition of REDD+ deforestation baselines in high forest cover/low deforestation countries

Background

REDD+?is being questioned by the particular status of High Forest/Low Deforestation countries. Indeed, the formulation of reference levels is made difficult by the confrontation of low historical deforestation records with the forest transition theory on the one hand. On the other hand, those countries might formulate incredibly high deforestation scenarios to ensure large payments even in case of inaction.

Results

Using a wide range of scenarios within the Guiana Shield, from methods involving basic assumptions made from past deforestation, to explicit modelling of deforestation using relevant socio-economic variables at the regional scale, we show that the most common methodologies predict huge increases in deforestation, unlikely to happen given the existing socio-economic situation. More importantly, it is unlikely that funds provided under most of these scenarios could compensate for the total cost of avoided deforestation in the region, including social and economic costs.

Conclusion

This study suggests that a useful and efficient international mechanism should really focus on removing the underlying political and socio-economic forces of deforestation rather than on hypothetical result-based payments estimated from very questionable reference levels.

     

Morphodynamics of alternate bars in the presence of riparian vegetation

Alpine gravel-bed rivers are dynamic systems that have been subjected to many anthropic alterations in the past centuries. Riparian vegetation development on previously bare sediment bedforms has been a common adjustment, raising important management issues in terms of flood risks and biodiversity. Many of these rivers are also channelized, and as a result present a pattern of alternate bars. Considering recent advances in numerical biomorphodynamic modeling, this study aims at exploring numerically the morphodynamics of alternate bars in the presence of riparian vegetation. To this end, a dynamic vegetation module has been implemented on top of an existing morphodynamic model, accounting for ecological processes of seed dispersal, seedling recruitment, growth, and mortality. Numerical simulations have been performed on a simplified reach of a gravel-bed river with free migrating alternate bars at initial state. In this work 96 scenarios have been simulated, each representing 50 years of channel evolution, with different flood regimes characterized by various peak discharges and flood durations. Yearly peak discharge variability is explicitly modeled in 48 scenarios. Model outcomes present two possible equilibrium biomorphodynamic behaviors: stationary vegetated bars, or free migrating bars in the case of frequent vegetation removal during floods. This binary behavior holds true when the stochasticity of annual peak discharges is represented, and for a wide range of parameter values included in vegetation dynamic modeling. Transient mobility of vegetated bars is observed in specific configurations where large sediment deposits deflect the flow field, eroding bar heads. Modeled bar wavelengths are in the range of values predicted for free bars by linear bar theory, and remain far from the theoretical values of hybrid, steady bars. The shift from unvegetated migrating bars to steady vegetated bars seems to show that in these simulations vegetation constitutes a hydraulic forcing, leading to a shift from free bars to forced bars, with a final configuration largely inherited from the initial state. © 2019 John Wiley & Sons, Ltd.     

Ocean change around Greenland under a warming climate

Climate Dynamics - The impact of climate warming on the ocean near Greenland is investigated with a high resolution coupled global climate model. The ocean around Greenland exhibits a strong...     

Impact of interactive vegetation phenology on the Canadian RCM simulated climate over North America

Climate Dynamics - Biosphere–atmosphere interactions play a very important role in modulating regional climate. To capture these bi-directional interactions, a dynamic vegetation model, the...     

Why do people not learn from flood disasters? Evidence from Vietnam’s northwestern mountains

This article explores how the causes and impacts of a flood event as perceived by local people shape immediate responses and future mitigation efforts in mountainous northwest Vietnam. Local flood perception is contrasted with scientific perspectives to determine whether a singular flood event will trigger adjustments in mitigation strategies in an otherwise rarely flood-affected area. We present findings from interdisciplinary research drawing on both socioeconomic and biophysical data. Evidence suggests that individual farmers?? willingness to engage in flood mitigation is curbed by the common perception that flooding is caused by the interplay of a bundle of external factors, with climatic factors and water management failures being the most prominent ones. Most farmers did not link the severity of flooding to existing land use systems, thus underlining the lack of a sense of personal responsibility among farmers for flood mitigation measures. We conclude that local governments cannot depend on there being a sufficient degree of intrinsic motivation among farmers to make them implement soil conservation techniques to mitigate future flooding. Policy makers will need to design measures to raise farmers?? awareness of the complex interplay between land use and hydrology and to enhance collective action in soil conservation by providing appropriate incentives and implementing coherent long-term strategies.     

Ophicalcites from the northern Pyrenean belt: a field,petrographic and stable isotope study

Brecciated and fractured peridotites with a carbonate matrix, referred to as ophicalcites, are common features of mantle rocks exhumed in passive margins and mid-oceanic ridges. Ophicalcites have been found in close association with massive peridotites, which form the numerous ultramafic bodies scattered along the North Pyrenean Zone (NPZ), on the northern flank of the Pyrenean belt. We present the first field, textural and stable isotopic characterization of these rocks. Our observations show that Pyrenean ophicalcites belong to three main types: (1) a wide variety of breccias composed of sorted or unsorted millimeter- to meter-sized clasts of fresh or oxidized ultramafic material, in a fine-grained calcitic matrix; (2) calcitic veins penetrating into fractured serpentine and fresh peridotite; and (3) pervasive substitution of serpentine minerals by calcite. Stable isotopic analyses (O, C) have been conducted on the carbonate matrix, veins and clasts of samples from 12 Pyrenean ultramafic bodies. We show that the Pyrenean ophicalcites are the product of three distinct genetic processes: (1) pervasive ophicalcite resulting from relatively deep and hot hydrothermal activity; (2) ophicalcites in veins resulting from tectonic fracturing and cooler hydrothermal activity; and (3) polymictic breccias resulting from sedimentary processes occurring after the exposure of subcontinental mantle as portions of the floor of basins which opened during the mid-Cretaceous. We highlight a major difference between the eastern and western Pyrenean ophicalcites belonging, respectively, to the sedimentary and to the hydrothermal types. Our data set points to a possible origin of the sedimentary ophicalcites in continental endorheic basins, but a post-depositional evolution by circulation of metamorphic fluids or an origin from relatively warm marine waters cannot be ruled out. Finally, we discuss the significance of such discrepancy in the characteristics of the NPZ ophicalcites in the frame of the variable exhumation history of the peridotites all along the Pyrenean realm.     

Combination of multi-scale and multi-edge X-ray spectroscopy for investigating the products obtained from the interaction between kaolinite and metallic iron in anoxic conditions at 90 °C

In the context of radioactive waste repository in geological formation, kaolinite-metallic iron interaction in chlorine solution was conducted in batch experiments, under anoxic conditions at 90 °C during 9 months. After a mineralogical characterization at a global scale, products were analyzed at the micrometer and nanometer scales by X-ray absorption spectroscopic techniques (XAS and STXM). Absorption at Al, Si and Fe edges was investigated to have a complete overview of the distribution and status of constituting elements. Whereas Si K-edge results do not evidence significant evolution of silicon status, investigations at Al K-edge and Fe L-edges demonstrate variations at aggregate and particle scales of ^IVAl:^VIAl and Fe²⁺:Fe³⁺ ratios. Spectroscopic data evidence the systematic crystallization of Fe-serpentines onto the remaining particles of kaolinite and the absence of pure species (kaolinite or Fe-serpentines). Combination of spatially resolved spectroscopic analyses and TEM-EDXS elemental distribution aims to calculate unit cell formulae of Fe-serpentines layers and abundance of each species in mixed particles. For most of the investigated particles, results reveal that the variations of particles composition are directly linked to the relative contributions of kaolinite and Fe-berthierine in mixed particles. However, for some particles, microscale investigations evidence crystallization of two other Fe-serpentines species, devoid of aluminum, cronstedtite and greenalite.     

An attempt to deconstruct the Atlantic Multidecadal Oscillation

The link between the Atlantic Multidecadal Oscillation (AMO) and low-frequency changes of the Atlantic Meridional Overturning Circulation (AMOC) is investigated in three historical and five control simulations with different climate models. An AMOC intensification is followed by a positive AMO phase in each case, but the time lag and the strength of the AMO–AMOC link depend on the model and the type of simulation. In historical simulations, the link is sensitive to the method used to remove the influence of external and anthropogenic forcing from the sea surface temperature (SST) before defining the AMO. Subtracting the regression onto the global mean SST leads to better correlations between the AMO and the AMOC than linear or quadratic detrending, or removing the global mean SST, but a dynamical filter based on linear inverse modeling (LIM) yields even slightly higher correlations. The LIM filter, which decomposes the SST field into non-orthogonal normal modes that may have a physical interpretation, allows investigating whether removing Pacific links from SST improves the AMOC–AMO correlation. In several cases, there is a small improvement when removing the links to the El Niño Southern Oscillation, but the correlation becomes weaker in one historical simulation, so no firm conclusion can be drawn. Additionally removing the modes associated with the Pacific decadal variability strongly degrades the representation of AMOC changes by the AMO in one model, and it tends to reduce the AMOC–AMO correlation in most others, reflecting the strong relation between the Pacific and the Atlantic at decadal scales. The LIM-based filter is finally applied to observed SSTs, confirming that the AMO amplitude is smaller and its recent positive phase weaker than when the global effects are represented by a linear trend. When the global signal is removed, the observed AMO leads the Pacific Decadal Oscillation, but does not significantly lag it, as suggested earlier, stressing the need to carefully remove global changes when investigating low-frequency interbasin connections.