On the need for bias correction in regional climate scenarios to assess climate change impacts on river runoff

In climate change impact research, the assessment of future river runoff as well as the catchment scale water balance is impeded by different sources of modeling uncertainty. Some research has already been done in order to quantify the uncertainty of climate 5 projections originating from the climate models and the downscaling techniques as well as from the internal variability evaluated from climate model member ensembles. Yet, the use of hydrological models adds another layer of incertitude. Within the QBic3 project (Qu´ebec-Bavaria International Collaboration on Climate Change) the relative contributions to the overall uncertainty from the whole model chain (from global climate 10 models to water management models) are investigated using an ensemble of multiple climate and hydrological models. Although there are many options to downscale global climate projections to the regional scale, recent impact studies tend to use Regional Climate Models (RCMs). One reason for that is that the physical coherence between atmospheric and land-surface 15 variables is preserved. The coherence between temperature and precipitation is of particular interest in hydrology. However, the regional climate model outputs often are biased compared to the observed climatology of a given region. Therefore, biases in those outputs are often corrected to reproduce historic runoff conditions from hydrological models using them, even if those corrections alter the relationship between temperature and precipitation. So, as bias correction may affect the consistency between RCM output variables, the use of correction techniques and even the use of (biased) climate model data itself is sometimes disputed among scientists. For those reasons, the effect of bias correction on simulated runoff regimes and the relative change in selected runoff indicators is explored. If it affects the conclusion of climate change analysis in 25 hydrology, we should consider it as a source of uncertainty. If not, the application of bias correction methods is either unnecessary in hydro-climatic projections, or safe to use as it does not alter the change signal of river runoff. The results of the present paper highlight the analysis of daily runoff simulated with four different hydrological models in two natural-flow catchments, driven by different regional climate models for a reference and a future period. As expected, bias correction of climate model outputs is important for the reproduction of the runoff regime of the 5 past regardless of the hydrological model used. Then again, its impact on the relative change of flow indicators between reference and future period is weak for most indicators with the exception of the timing of the spring flood peak. Still, our results indicate that the impact of bias correction on runoff indicators increases with bias in the climate simulations

An ensemble approach to assess hydrological models’ contribution to uncertainties in the analysis of climate change impact on water resources

Over the recent years, several research efforts investigated the impact of climate change on water resources for different regions of the world. The projection of future river flows is affected by different sources of uncertainty in the hydro-climatic modelling chain. One of the aims of the QBic3 5 project (Que´bec-Bavarian International Collaboration on Climate Change) is to assess the contribution to uncertainty of hydrological models by using an ensemble of hydrological models presenting a diversity of structural complexity (i.e. lumped, semi distributed and distributed models). The study investigates two humid, mid-latitude catchments with natural flow conditions; one located in 10 Southern Que´bec (Canada) and one in Southern Bavaria (Germany). Daily flow is simulated with four different hydrological models, forced by outputs from regional climate models driven by a given number of GCMs’ members over a reference (1971–2000) and a future (2041–2070) periods. The results show that the choice of the hydrological model does strongly affect the climate change response of selected hydrological indicators, especially those related to low flows. Indicators related to high flows seem less sensitive on the choice of the hydrological model. Therefore, the computationally less demanding models (usually simple, lumped and conceptual) give a significant level of trust for high and overall mean flows

Potentiel d'adaptation aux changements climatiques de la gestion d'un système hydrique exploité pour la production hydroélectrique : étude de la rivière Péribonka (Québec, Canada)

Des tendances significatives dans les regimes hydrologiques ont ete observees au cours des dernieres decennies et elles pourraient s'accentuer au cours du prochain siecle. Les exploitants de systemes hydriques devront envisager d'ajuster la gestion afm d'attenuer les effets des fluctuations du climat. Cependant, I'incertitude des changements climatiques, l'inertie des organisations et les habitudes des exploitants freinent I'adaptation. Les rares publications parues a present sur le sujet se sont consacrees aux impacts sur la gestion, sans consideration explicite de I'adaptation et de I'incertitude. La presente recherche vise a evaluer le potentiel d'adaptation aux changements climatiques d'un systeme hydrique d'apres plusieurs projections climatiques. L'etude est realisee pour la riviere Péribonka (Quebec, Canada), exploitee pour la production hydroelectrique par Rio Tinto Alcan. Les impacts des changements climatiques sur la gestion du systeme hydrique ont d'abord été quantifies en ne modifiant pas la gestion actuelle. Les principaux resultats demontrent que les reservoirs seraient moins fiables, que la production hydroelectrique diminuerait et que les deversements non productibles augmenteraient sous la plupart des projections climatiques. Par la suite, le potentiel d'adaptation sur la periode 2010-2099 a ete investigue en modifiant les regies de gestion avec un modele d'optimisation dynamique et stochastique. Les regimes hydrologiques qui ont servi d'intrants ont ete simules scion deux approches : (i) modelisation hydrologique conceptuelle globale et projections climatiques scion la methode des deltas, et (ii) modelisation hydrologique distribute a base physique et projection climatique d'un modele regional de climat. L'adaptation de la gestion se manifesterait par des modifications saisonnieres des niveaux d'eau moyens des reservoirs. De plus, la production hydroelectrique annuelle change de -2 a +22 % par rapport a la periode de reference, dependamment de la projection climatique, du modele hydrologique et de I'horizon. Les deversements non productibles moyens annuels augmenteraient pour toutes les projections climatiques, malgre des baisses d'hydraulicite. Cette situation serait consequente aux changements de variabilite des apports hydrologiques. La principale conclusion de la recherche est que l'adaptation de la gestion du système hydrique de la riviere Peribonka pourrait attenuer les effets des fluctuations du climat dans le futur. L'adaptation pourrait aussi ameliorer sa performance par rapport a la periode de reference 1961-1990

Comparaison de cultures intercalaires pour la répression des adventices et la stabilité des agrégats du sol dans la vigne semi-rustique en implantation au Québec

Au Québec, la température hivernale atteint -35 °C et les cépages non-rustiques (Vitis vinifera L.) doivent être protégés du gel par l'installation de géotextiles ou par buttage qui consiste en un travail du sol intensif et bisannuel pour recouvrir et découvrir les vignes. Ces conditions restreignent l'implantation de cultures intercalaires : (1) leur établissement et leur croissance sont limités à la saison de production, (2) le buttage détruit la végétation intercalaire à l'automne et (3) l'installation de géotextiles permet la culture d'espèces pérennes, mais elle est plus coûteuse. Au Québec, l'adoption de cultures intercalaires demeure donc marginale, malgré les bienfaits reconnus de ces cultures, dont le contrôle des adventices et l'atténuation de l'érosion hydrique. Leur impact sur la croissance et la production de la vigne sont également méconnus sous le climat continental du Québec. Une expérience en blocs aléatoires complets a été établie (2018-2020) dont l'objectif était de comparer l'effet du désherbage mécanique à deux mélanges de graminées intercalaires (annuelles vs pérennes) sur le contrôle des adventices et leur diversité, la stabilité des agrégats du sol ainsi que la croissance et la productivité de la vigne durant la période d'implantation. L'expérience incluait aussi un témoin enherbé (adventices). Le désherbage mécanique a mieux contrôlé les adventices, et a diminué la richesse et la diversité de la flore comparativement aux couverts végétaux. La densité des adventices annuelles et vivaces n'a pas diminué sous cultures intercalaires et le recouvrement des adventices au sol surpassait les 50 % en fin de saison. Néanmoins, la biomasse aérienne des adventices est demeurée en-dessous de celle du traitement enherbé durant les deux premières années. En fin de saison, la stabilité des agrégats du sol était plus élevée sous couvert végétal comparativement au désherbage mécanique. Ni le rendement, ni la qualité des raisins n'ont été affectés par la régie de culture dans l'entre-rang.Non-hardy grapevine varieties require winter protection in southern Quebec because temperature can drop to –35 °C and cause irreversible frost damage. Winter protection is provided either by geotextiles or hilling, the latter generating intensive soil disturbance twice a year. These constraints limit the adoption of intercrops because 1) their establishment and growth are concurrent with the crop, 2) hilling destroys intercrops every fall, and 3) the use of geotextiles allows the adoption of perennial intercrops but is more expensive. Although it can control weeds and mitigate soil erosion, intercropping in Quebec vineyards is limited. Moreover, grapevine response to intercropping is poorly documented under Quebec's continental climate. A randomized complete block design experiment was conducted (2018-2020) to compare mechanical weeding to two grass mixture intercrops (annual vs perennial), during vineyard establishment. Variables tested included weed control and diversity, soil aggregate stability, vine growth, and grape yield. A weedy control was also included. Cultivation was more efficient at controlling weeds than both intercrops but decreased plant species richness and diversity in comparison to other treatments. Weed density did not decrease over time and weed cover was relatively high (> 50% at the end of the growing season) under intercrops. Nevertheless, weed shoot biomass was lower under intercrops than in the weedy control during the first two years. Cultivation was also detrimental to soil structure, it showed lower aggregate stability compared to vegetated treatments by the end of the season. None of the interrow management methods had an impact on vine yield fruit quality

Postoperative delirium is a risk factor of institutionalization after hip fracture: an observational cohort study

IntroductionHip fracture is a common clinical problem in geriatric patients often associated with poor postoperative outcomes. Postoperative delirium (POD) and postoperative neurocognitive disorders (NCDs) are particularly frequent. The consequences of these disorders on postoperative recovery and autonomy are not fully described. The aim of this study was to determine the role of POD and NCDs on the need for institutionalization at 3 months after hip fracture surgery.MethodA population-based prospective cohort study was conducted on hip fracture patients between March 2016 and March 2018. The baseline interview, which included a Mini-Mental State Examination (MMSE), was conducted in the hospital after admission for hip fracture. NCDs were appreciated by MMSE scoring evolution (difference between preoperative MMSE and MMSE at day 5 >2 points). POD was evaluated using the Confusion Assessment Method. The primary endpoint was the rate of new institutionalization at 3 months. We used a multivariate analysis to assess the risk of new institutionalization.ResultsA total of 63 patients were included. Thirteen patients (20.6%) were newly institutionalized at 3 months. Two factors were significantly associated with the risk of postoperative institutionalization at 3 months: POD (OR = 5.23; 95% CI 1.1–27.04; p = 0.04) and IADL evolution (OR = 1.8; 95% CI 1.23–2.74; p = 0.003).ConclusionOnly POD but not NCDs was associated with the risk of dependency and institutionalization after hip fracture surgery. The prevention of POD appears to be essential for improving patient outcomes and optimizing the potential for returning home

Increased creatinine clearance in polytrauma patients with normal serum creatinine: a retrospective observational study

International audienceINTRODUCTION: The aim of this study, performed in an intensive care unit (ICU) population with a normal serum creatinine, was to estimate urinary creatinine clearance (CLCR) in a population of polytrauma patients (PT) through a comparison with a population of non trauma patients (NPT). METHODS: This was a retrospective, observational study in a medical and surgical ICU in a university hospital. A total of 284 patients were consecutively included. Two different groups were studied: PT (n = 144) and NPT (n = 140). Within the second week after admission to the ICU, renal function was assessed using serum creatinine, 24 h urinary CLCR . RESULTS: Among the 106 patients with a CLCR above 120 mL minute(-1) 1.73 m(-2), 79 were PT and 27 NPT (P < 0.0001). Only 63 patients had a CLCR below 60 mL minute(-1) 1.73 m(-2) with 15 PT and 48 NPT (P < 0.0001). Patients with CLCR greater than 120 mL minute(-1). 1.73 m(-2) were younger, had a lower SAPS II score and a higher male ratio as compared to those having CLCR lower than 120 mL minute(-1). 1.73 m(-2). Through a logistic regression analysis, age and trauma were the only factors independently correlated to CLCR. CONCLUSIONS: In ICU patients with normal serum creatinine, CLCR, is higher in PT than in NPT. The measure of CLCR should be proposed as routine for PT patients in order to adjust dose regimen, especially for drugs with renal elimination

Multicentre, prospective, double-blind, randomised controlled clinical trial comparing different non-opioid analgesic combinations with morphine for postoperative analgesia: the OCTOPUS study

BACKGROUND: Head-to-head comparisons of combinations of more than one non-opioid analgesic (NOA) with morphine alone, for postoperative analgesia, are lacking. The objective of this multicentre, randomised, double-blind controlled trial was to compare the morphine-sparing effects of different combinations of three NOAs-paracetamol (P), nefopam (N), and ketoprofen (K)-for postoperative analgesia. METHODS: Patients from 10 hospitals were randomised to one of eight groups: control (C) received saline as placebo, P, N, K, PN, PK, NK, and PNK. Treatments were given intravenously four times a day during the first 48 h after surgery, and morphine patient-controlled analgesia was used as rescue analgesia. The outcome measures were morphine consumption, pain scores, and morphine-related side-effects evaluated 24 and 48 h after surgery. RESULTS: Two hundred and thirty-seven patients undergoing a major surgical procedure were included between July 2013 and November 2016. Despite a failure to reach a calculated sample size, 24 h morphine consumption [median (inter-quartile range)] was significantly reduced in the PNK group [5 (1-11) mg] compared with either the C group [27 (11-42) mg; P&lt;0.05] or the N group [21 (12-29) mg; P&lt;0.05]. Results were similar 48 h after surgery. Patients experienced less pain in the PNK group compared with the C, N, and P groups. No difference was observed in the incidence of morphine-related side-effects. CONCLUSIONS: Combining three NOAs with morphine allows a significant morphine sparing for 48 h after surgery associated with superior analgesia the first 24 h when compared with morphine alone. CLINICAL TRIAL REGISTRATION: EudraCT: 2012-004219-30; NCT01882530

Regional anesthesia with noninvasive ventilation for shoulder surgery in a patient with severe chronic obstructive pulmonary disease: a case report

Interscalene block (ISB) impairs ipsilateral lung function and generally is not used for patients with respiratory insufficiency. We present a 49-year-old man with chronic obstructive pulmonary disease scheduled for shoulder surgery. He was given a regional technique with an ISB (short-acting local anesthetic to minimize duration of diaphragmatic dysfunction) and suprascapular and axillary nerves blocks (long-acting local anesthetic). He was supported with noninvasive ventilation during the time of hemidiaphragmatic paralysis as documented by serial ultrasound examination. A discussion about ISB and its alternatives (general anesthesia versus brachial plexus block versus selective peripheral nerve blocks) always should occur for patients at risk for pulmonary complications

Adaptation strategy to mitigate the impact of climate change on water resources in arid and semi-arid regions : a case study

Climate change and drought phenomena impacts have become a growing concern for water resources engineers and policy makers, mainly in arid and semi-arid areas. This study aims to contribute to the development of a decision support tool to prepare water resources managers and planners for climate change adaptation. The Hydrologiska Byråns Vattenbalansavdelning (The Water Balance Department of the Hydrological Bureau) hydrologic model was used to define the boundary conditions for the reservoir capacity yield model comprising daily reservoir inflow from a representative example watershed with the size of 14,924 km2 into a reservoir with the capacity of 6.80 Gm3. The reservoir capacity yield model was used to simulate variability in climate change-induced differences in reservoir capacity needs and performance (operational probability of failure, resilience, and vulnerability). Owing to the future precipitation reduction and potential evapotranspiration increase during the worst case scenario (−40% precipitation and +30% potential evapotranspiration), substantial reductions in streamflow of between −56% and −58% are anticipated for the dry and wet seasons, respectively. Furthermore, model simulations recommend that as a result of future climatic conditions, the reservoir operational probability of failure would generally increase due to declined reservoir inflow. The study developed preparedness plans to combat the consequences of climate change and drought