Impacts of Climate Change on Water Resources / Effets des changements climatiques sur les ressources en eau
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Item Faire face aux changements ensemble (FACE) : mieux s’adapter aux changements climatiques au Canada et en Afrique de l’Ouest dans le domaine des ressources en eau(2016-04) Proulx-McInnis, Sandra; St-Hilaire, André; Gachon, Philippe; Seidou, Ousmane; Alahsanne, AgaliItem Study of seasonal-scale atmospheric water cycle with ground-based GPS receivers, radiosondes and NWP models over Morocco(Elsevier, 2011) Koulali, Achraf; Ouazar, Driss; Bock, Olivier; Fadil, AbdelaliThis study investigates the seasonal variation of precipitable water vapor, moisture transport and precipitation over Morocco and the Canary Islands using data from ground-based GPS receivers, radiosondes, GPCP and NCEP reanalysis II. In a first part, the datasets are inter-compared. Humidity biases are evidenced in both radiosonde observations (dry) and NCEP reanalysis (dry and wet) compared to GPS. Moisture transport and precipitation from the reanalysis and observations show a good agreement. Precipitable water shows a maximum in late summer whereas precipitation is peaking in winter and spring over Morocco. Moisture transport occurs preferentially in two layers, below and above 850 hPa. The monthly mean precipitable water variation over Morocco is controlled by the upper layer zonal and meridional moisture flux. Precipitation is rather controlled by the lower layer moisture flux and the upper layer meridional flux. The GPS tropospheric gradients show also a consistent seasonal evolution, which is explained by gradients both in the thickness of the troposphere and in the precipitable water vapor. Tropospheric gradients are correlated with moisture fluxes, mostly in the upper layer, and may therefore provide valuable information for meteorology and climatology.Item Assessment of Canadian prairie drought : past, present, and future(Springer, 2012-06) Bonsal, Barrie R.; Aider, Rabah; Philippe Gachon; Suzan LappWithin Canada, the Canadian Prairies are particularly drought-prone mainly due to their location in the lee of the western cordillera and distance from large moisture sources. Although previous studies examined the occurrence of Canadian Prairie droughts during instrumental, pre-instrumental and to a lesser extent, future periods, none have specifically focused on all time three scales. Using two different drought indicators, namely the Palmer Drought Severity Index (PDSI) and Standardized Precipitation Index (SPI), this investigation assesses the variability of summer drought duration and intensity over a core region of the Prairies during (a) the pre-instrumental record extending back several centuries (inferred from tree rings), (b) the instrumental record (1901–2005), and (c) the twenty-first century using statistically downscaled climate variables from several Atmosphere–Ocean Global climate models with multiple emission scenarios. Results reveal that observed twentieth century droughts were relatively mild when compared to pre-settlement on the Prairies, but these periods are likely to return (and even worsen) in the future due to the anticipated warming during the course of the twenty-first century. However, future drought projections are distinctly different between the two indices. All PDSI-related model runs show greater drought frequency and severity mainly due to increasing temperatures. Conversely, the precipitation-based SPI indicates no significant changes to future summer drought frequency although there tends to be a higher persistence of multi-year droughts in central and southern portions of Canadian Prairies. These findings therefore stress the importance of considering anticipated warming trends when assessing future regional-scale drought, especially given the uncertainties and lack of consistency in future precipitation signals among climate models. This study can be considered an initial step toward quantifying and understanding Canadian Prairie drought occurrence and severity over several centuries as determined from paleo, instrumental, and climate model data sources.Item General and flexible methodology to define thresholds for heat health watch and warning systems, applied to the province of Québec (Canada)(Springer, 2012-10) Chebana, Fateh; Martel, Barbara; Gosselin, Pierre; Giroux, Jean-Xavier; Ouarda, Taha B.M.J.Several watch and warning systems have been established in the world in recent years to prevent the effects of heat waves. However, many of these approaches can be applied only in regions with perfect conditions (e.g., enough data, stationary series or homogeneous regions). Furthermore, a number of these approaches do not account for possible trend in mortality and/or temperature series, whereas others are generally not adapted to regions with low population densities or low daily mortality levels. In addition, prediction based on multiple days preceding the event can be less accurate if it attributes the same importance to each of these days, since the forecasting accuracy actually decreases with the period. The aim of the present study was to identify appropriate indicators as well as flexible and general thresholds that can be applied to a variety of regions and conditions. From a practical point of view, the province of Québec constitutes a typical case where a number of the above-mentioned constraints are present. On the other hand, until recently, the province's watch and warning system was based on a study conducted in 2005, covering only the city of Montreal and applied to the whole province. The proposed approach is applied to each one of the other health regions of the province often experiencing low daily counts of mortality and presenting trends. The first constraint led to grouping meteorologically homogeneous regions across the province in which the number of deaths is sufficient to carry out the appropriate data analyses. In each region, mortality trends are taken into account. In addition, the proposed indicators are defined by a 3-day weighted mean of maximal and minimal temperatures. The sensitivity of the results to the inclusion of traumatic deaths is also checked. The application shows that the proposed method improved the results in terms of sensitivity, specificity and number of yearly false alarms, compared to those of the existing and other classical approaches. An additional criterion based on the Humidex is applied in a second step and a local validation is applied to historical observations at reference forecasting stations. An integrated heat health watch and warning system with thresholds that are adapted to the regional climate has thus been established for each sub-region of the province of Quebec and became operational in June 2010.Item Evaluation of regional climate model simulations versus gridded observed and regional reanalysis products using a combined weighting scheme(Springer, 2011) Eum, Hyung-Il; Gachon, Philippe; Laprise, René; Ouarda, TahaThis study presents a combined weighting scheme which contains five attributes that reflect accuracy of climate data, i.e. short-term (daily), mid-term (annual), and long-term (decadal) timescales, as well as spatial pattern, and extreme values, as simulated from Regional Climate Models (RCMs) with respect to observed and regional reanalysis products. Southern areas of Quebec and Ontario provinces in Canada are used for the study area. Three series of simulation from two different versions of the Canadian RCM (CRCM4.1.1, and CRCM4.2.3) are employed over 23 years from 1979 to 2001, driven by both NCEP and ERA40 global reanalysis products. One series of regional reanalysis dataset (i.e. NARR) over North America is also used as reference for comparison and validation purpose, as well as gridded historical observed daily data of precipitation and temperatures, both series have been beforehand interpolated on the CRCM 45-km grid resolution. Monthly weighting factors are calculated and then combined into four seasons to reflect seasonal variability of climate data accuracy. In addition, this study generates weight averaged references (WARs) with different weighting factors and ensemble size as new reference climate data set. The simulation results indicate that the NARR is in general superior to the CRCM simulated precipitation values, but the CRCM4.1.1 provides the highest weighting factors during the winter season. For minimum and maximum temperature, both the CRCM4.1.1 and the NARR products provide the highest weighting factors, respectively. The NARR provides more accurate short- and mid-term climate data, but the two versions of the CRCM provide more precise long-term data, spatial pattern and extreme events. Or study confirms also that the global reanalysis data (i.e. NCEP vs. ERA40) used as boundary conditions in the CRCM runs has non-negligible effects on the accuracy of CRCM simulated precipitation and temperature values. In addition, this study demonstrates that the proposed weighting factors reflect well all five attributes and the performances of weighted averaged references are better than that of the best single model. This study also found that the improvement of WARs’ performance is due to the reliability (accuracy) of RCMs rather than the ensemble size.Item Effets de la coupe des feuilles et de la transplantation des jeunes plants sur la consommation hydrique et la croissance du mil (Pennisetum glaucum [L.] R.Br.) au Niger : mémoire de fin de cycle(Faculté des Sciences et Techniques (FST), Université de Maradi, 2013) Abdoul-Aziz Ben, Seybou Omar; Université de Maradi, Faculté des Sciences et Techniques (FST)Le mil (Pennisetum glaucum [L.] R. Br.) est la plante alimentaire la plus cultivée dans la zone sahélienne du Niger. L’agriculture Nigérienne reste tributaire des conditions agro-climatiques et phytosanitaires très aléatoires donnant lieu à une récurrence de chocs liés à la fréquence des sécheresses, inondations et attaques des ennemis des cultures. En effet, l’installation de la culture de mil (et celle des autres céréales pluviales) ne dévient effective qu’après un ou plusieurs échecs de semis. Ceci engendre aux paysans, déjà meurtris par la pauvreté et la rareté des sources de revenu, des pertes énormes en semences et en capitaux. C’est face à tout ce qui précède et pour minimiser l’impact de la variabilité du climat sur l’installation de la principale culture vivrière du sahel (comme le mil) que le Centre Régionale AGRHYMET (CRA) a initié, en collaboration avec le CRDI, le projet dénommé « Optimisation et valorisation de l’utilisation de l’eau et des prévisions climatiques en agriculture» en vue de tester les comportements de deux variétés de mil HKP (90-95 jours) et SOMNO (120 à 130 jours) sur les effets de la coupe des feuilles et de la transplantation des jeunes plants sur la consommation hydrique et leur croissance. Ainsi un essai de mil composés de blocs randomisés (2 variétés x 4 traitements) a été mis en place au sein du Centre Régional Agrhymet (CRA) de Niamey pendant la saison pluvieuse 2012. Les mesures effectuées dans l’essai ont porté sur la phénologie, accumulation de matière sèche, l’indice de surface foliaire (LAI), la variation de l’humidité du sol et les composantes du rendement à la récolte. Les résultats ont montré que la coupe des feuilles des jeunes plants du mil n’a pas d’effets significatifs sur la phénologie, mais tend à réduire l’indice de surface foliaire (LAI) et la hauteur des plants des variétés de mil HKP et SOMNO. Par contre, lorsqu’elle est répétée pendant le bas âge des plants (avant début montaison), elle a tendance à favoriser le développement des talles, de la biomasse sèche des tiges et l’augmentation des composantes du rendement à la récolte, particulièrement chez la variété précoce HKP. Quant à la transplantation des jeunes plants au 21ème Jours Après Semis (JAS), elle a eu tendance à retarder le tallage et la montaison, sans pour autant affecter significativement la durée globale du cycle de mil. L’aspect le plus positif montré par ces techniques (transplantation et coupe des feuilles des jeunes plants) concerne notamment la gestion du stock d’eau dans le sol, Ceci permet de dire que ces techniques culturales pourraient jouer un rôle important comme stratégies prometteuses d’adaptation de la culture du mil aux variations et changement climatique.Item Assessment of summer extremes and climate variability over the North-East of North America as simulated by the Canadian Regional Climate Model(John Wiley & Sons, 2011-08) Roy, Philippe; Gachon, Philippe; Laprise, RenéThe present study focuses on the evaluation and comparison of the ability of two versions of the Canadian Regional Climate Model (CRCM) driven by re-analyses (NCEP–NCAR) to reproduce the observed extremes and climate variability in summer (1961–1990). The analysed variables are daily precipitation, minimum and maximum temperatures over three regions located in north-eastern North America that are characterized by different topography and observation density. The validation has been performed with multiple climate extreme indices characterizing the frequency, intensity and duration of precipitation and temperature events. The assessment of the ability of the CRCM is done through an in-depth analysis of the statistical distribution, performance scores and interannual variability of extreme indices. The reference database has been constructed by kriging the daily observed data from local meteorological stations onto the CRCM 45-km grid. The vast majority of results over the three regions show that, with respect to the previous (i.e. 3.7.1) CRCM version, the latest version (4.1.1) improves in general the simulated extreme events. In particular, the intensity of extreme hot summer temperature, diurnal temperature range, wet days occurrence, seasonal dry spell, and to a lesser extent extreme cold summer temperature and heavy rainfall. The study suggests that improvements in the simulated extremes in the latest version are due mainly to the introduction of the new land surface scheme (CLASS 2.7), with a more sophisticated representation of the soil moisture content. This suggests the importance of surface processes parameterization as a potential cause of errors in simulated extremes.Item Statistical methods to expect extreme values : application of POT approach to CAC40 return index(CESER Publications, 2013) Zoglat, A.; El Adlouni, S.; Ezzahid, E.; Amar, A.; Okou, C.G.; Badaoui, F.The main objective of the present study is to compare the performances of methods of prediction in the case of financial risk estimations related to market turmoil, and to assess the performance of the Peaks Over Threshold (POT) approach, combined with the maximum likelihood and moment methods for parameter estimations.