The variability of the atmospheric precipitation in the region of Wielka Laka dam reservoir

Climate change has impacts on both natural and human systems. Accurate information regarding variations in precipitation and temperature is essential for identifying and understanding these potential impacts. This research applied Mann-Kendall, rescaled range analysis and wave transform methods to analyze the trends and periodic properties of global and regional surface air temperature (SAT) and precipitation (PR) over the period of 1948 to 2010. The results show that 65.34% of the area studied exhibits significant warming trends (p < 0.05) while only 3.18% of the area exhibits significant cooling trends. The greatest warming trends are observed in Antarctica (0.32 °C per decade) and Middle Africa (0.21 °C per decade). Notably, 62.26% of the area became wetter, while 22.01% of the area shows drying trends. Northern Europe shows the largest precipitation increase, 12.49 mm per decade. Western Africa shows the fastest drying, -21.05 mm per decade. The rescaled range analysis reveals large areas that show persistent warming trends; this behavior in SAT is more obvious than that in PR. Wave transform results show that a 1-year period of SAT variation dominates in all regions, while inconsistent 0.5-year bands are observed in East Asia, Middle Africa, and Southeast Asia. In PR, significant power in the wavelet power spectrum at a 1-year period was observed in 17 regions, i.e., in all regions studied except Western Europe, where precipitation is instead characterized by 0.5-year and 0.25-year periods. Overall, the variations in SAT and PR can be consistent with the combined impacts of natural and anthropogenic factors, such as atmospheric concentrations of greenhouse gases, the internal variability of climate system, and volcanic eruptions.

Interannual and multidecadal time-scale anomalies in sea surface temperatures (SST) of the North Atlantic and North Pacific Oceans could result in persistent atmospheric circulation and regional precipitation anomalies for years to decades. Understanding the processes that connect such SST forcings with circulation and precipitation anomalies is thus important for understanding climate variations and for improving predictions at interannual–decadal time scales. This study focuses on the interrelationship between the Atlantic multidecadal oscillation (AMO) and El Niño–Southern Oscillation (ENSO) and their resulting interannual to multidecadal time-scale variations in summertime precipitation in North America. Major results show that the ENSO forcing can strongly modify the atmospheric circulation variations driven by the AMO. Moreover, these modifications differ considerably between the subtropics and the mid- and high-latitude regions. In the subtropics, ENSO-driven variations in precipitation are fairly uniform across longitudes so ENSO effects only add interannual variations to the amplitude of the precipitation anomaly pattern driven by the AMO. In the mid- and high latitudes, ENSO-forced waves in the atmosphere strongly modify the circulation anomalies driven by the AMO, resulting in distinctive interannual variations following the ENSO cycle. The role of the AMO is shown by an asymmetry in precipitation during ENSO between the warm and cold phases of the AMO. These results extend the outcomes of the studies of the recent Climate Variability and Predictability (CLIVAR) Drought Working Group from the AMO and ENSO effects on droughts to understanding of the mechanisms and causal processes connecting the individual and combined SST forcing of the AMO and ENSO with the interannual and multidecadal variations in summertime precipitation and droughts in North America.

In this study, the sensitivities of net primary production (NPP), soil carbon, and vegetation carbon to precipitation and temperature variability over China are discussed using the state-of-the-art Lund-Potsdam-Jena dynamic global vegetation model (LPJ DGVM). The impacts of the sensitivities to precipitation variability and temperature variability on NPP, soil carbon, and vegetation carbon are discussed. It is shown that increasing precipitation variability, representing the frequency of extreme precipitation events, leads to losses in NPP, soil carbon, and vegetation carbon over most of China, especially in North and Northeast China where the dominant plant functional types (i.e., those with the largest simulated areal cover) are grass and boreal needle-leaved forest. The responses of NPP, soil carbon, and vegetation carbon to decreasing precipitation variability are opposite to the responses to increasing precipitation variability. The variations in NPP, soil carbon, and vegetation carbon in res...

Reservoir storage plays an important role in water supply during the dry season when precipitation is insufficient. In a watershed where the streams are controlled by reservoirs, drought occurrences depend on not only precipitation variations but also reservoir regulation. In this study, the joint dependence structure of the reservoir storage and its relevant variables of precipitation and/or upstream outflow were analyzed for two cascade reservoirs in a headwater basin of the Huaihe River, China. Correlation analysis indicates that the reservoir storage in October (the end of the wet season) depends highly on the regional precipitation at time scales of several months, e.g., 7 months for the upstream and 9 months for the downstream. Additionally, the downstream storage is correlated with outflow from the upstream reservoir at the 5-month timescale significantly. For estimation of the joint probability of pairs of the storage and its relevant variables, univariate marginal distributions and bivariate copula were appropriately selected in terms of statistical tests. The bivariate return period of \(T(X < x,Y < y)\) and \(T(X \le x,Y \ge y)\) and the conditional probability of \(P(Y \ge y|X \le x)\) were estimated by using the selected Clayton copula. The results from contour lines of the bivariate return period demonstrate that the probability of drought occurrences affected by both reservoir storage and precipitation/outflow is smaller than that by either of the variables. Meanwhile, the concurrent drought probability between precipitation and reservoir storage in the upstream is higher than that in the downstream. The estimated conditional probability offers useful information on how much the regular storage could be remained under some specified drought levels of precipitation/upstream outflow. Therefore, the results are helpful for improving the operation strategies of the cascade reservoirs for the adaptive management of drought under different climate variations.

Iran's precipitation analysis using synoptic modeling of major teleconnection forces (MTF)

Climate is one of the main components that define the development and behaviour of the plant, conditioning the health status and the final quality of the grapes. The objective was to describe the precipitation (PP) variability during the last 32 years and how Tannat and Albariño responded in three growing seasons (GS). We analyzed PP data from two agro-meteorological stations and calculated descriptive indexes. In addition, we measured vine water potential, plant physiological parameters, grapes’ final composition and health status at harvest in 2019, 2020 and 2021. In the last 32 years, PP during GS ranged from 133-1154 mm and 10-599 mm during the grape ripening period. An average of 51 days had PP, which means one event every four days. However, when analyzing the dry periods (moving average of 15 days with PP&lt;6 mm), 24 events per GS were recorded with a variability from 0-101, which shows the alternation between excess and deficit of water in the terroir. Regarding plant response, both cultivars showed differences in soluble solids, pH and berry weight between GS. In particular, Albariño showed differences in bunch weight. In contrast, Tannat showed differences in total acidity, anthocyanins, leaf area, yield with the incidence of Botrytis cinerea sp., pruning weight and bunch weight between GS. Therefore, the inter-annual variability had an impact on Tannat performance. Still, Albariño was more stable than Tannat between rainy and dry GS, an interesting option for winegrowers searching for durable and sustainable products.

Spatiotemporal deformation characteristics and triggering factors of Baijiabao landslide in Three Gorges Reservoir region, China

Multifractal analysis of streamflow records of the East River basin (Pearl River), China

در این مطالعه، به بررسی تغییر پذیری و تحلیل نوسان های بارش های حدی غرب و شمال غرب کشور با استفاده از آزمون های آماری تحلیل طیفی و من کندال در نیم سده گذشته پرداخته شده است. فراسنج‌های مورد مطالعه عبارتند از نمایه‌های دور پیوندی NAO، AO، ENSO و MEI، کلف‌های خورشیدی و مراکز فشار شامل کم‌فشار مدیترانه، کم‌فشار دریای سیاه، کم‌فشار سودان و پرفشار سیبری است. بدین منظور از 8 ایستگاه همدید، که دارای آمار 50 سال اخیر (1961-2010) هستند، و همچنین از 10 نمایه حدی بارش استفاده شده است. نتایج نشان می‌دهد که تنها در ایستگاه سنندج روند نمایه های حدی بارش افزایشی بوده است. گرچه برخی از نمایه‌ها در ایستگاه‌هایی محدود دارای روندی افزایشی بوده اند، اما بطور کلی نتایج نشان می‌دهد که بارش‌های حدی این منطقه در طی 50 سال گذشته دارای روندی کاهشی است که این روند کاهشی در ارتباط با رفتار نمایه‌های دورپیوندی AO، NAO و ENSO و همچنین مراکز فشار تأثیرگذار بر بارش منطقه اعم از پرفشار سیبری، کم فشار سودانی و کم فشار مدیترانه است و سبب کاهش در بارش ها در غرب و شمال غرب کشور می شوند. نتایج تحلیل طیفی نشان می دهد که چرخه فرین های بارش در درجه اول در ارتباط با چرخه شدت و ضعف مرکز کم فشار مدیترانه و چرخه های 2 تا 3 ساله آن است. همچنین در بین نمایه های دور پیوندی، بیش از همه چرخه بارش های حدی در ارتباط با چرخه 3 تا 5 ساله نمایه انسو می باشد، بگونه ای که در تمام ایستگاه ها نمایه انسو با بارش های حدی منطقه مورد مطالعه دارای ارتباط است. لازم به توضیح است که تأثیر کلف های خورشیدی بر بارش های منطقه مورد مطالعه بسیار محدود بوده و تنها در ایستگاه ارومیه، چرخه نمایه مقدار سالانه بارش روزهای تر متناظر با چرخه 11 ساله لکه های خورشیدی می باشد.

The intrinsic atmospheric and ocean-induced tropical precipitation variability is studied using millennial control simulations with various degrees of ocean coupling. A comparison between the coupled simulation and the atmosphere-only simulation with climatological sea surface temperatures (SSTs) shows that a substantial amount of tropical precipitation variability is generated without oceanic influence. This intrinsic atmospheric variability features a red noise spectrum from daily to monthly time scales and a white noise spectrum beyond the monthly time scale. The oceanic impact is inappreciable for submonthly time scales but important at interannual and longer time scales. For time scales longer than a year, it enhances precipitation variability throughout much of the tropical oceans and suppresses it in some subtropical areas, preferentially in the summer hemisphere. The sign of the ocean-induced precipitation variability can be inferred from the local precipitation–SST relationship, which largely reflects the local feedbacks between the two, although nonlocal forcing associated with El Niño–Southern Oscillation also plays a role. The thermodynamic and dynamic nature of the ocean-induced precipitation variability is studied by comparing the fully coupled and slab ocean simulations. For time scales longer than a year, equatorial precipitation variability is almost entirely driven by ocean circulation, except in the Atlantic Ocean. In the rest of the tropics, ocean-induced precipitation variability is dominated by mixed layer thermodynamics. Additional analyses indicate that both dynamic and thermodynamic oceanic processes are important for establishing the leading modes of large-scale tropical precipitation variability. On the other hand, ocean dynamics likely dampens tropical Pacific variability at multidecadal time scales and beyond.

Dam construction alters planktonic microbial predator‒prey communities in the urban reaches of the Yangtze River

Abstract. Hydropower is the leading renewable energy source, but its vulnerability to environmental pressures remains a critical concern, particularly under climate change. While climate impacts on hydropower are well studied, the interplay between precipitation variability, sediment dynamics, and dam operation strategies has received comparatively less attention. This study investigates these interactions in the French Mediterranean region, focusing on the Mont d'Orb dam reservoir. An integrated approach was adopted, combining (1) sediment core analysis using fallout radionuclide dating to assess the impact of extreme rainfall on sediment yield; (2) statistical analysis of meteorological records to detect long-term trends and seasonal shifts; and (3) hydrological and operational data analysis to evaluate how sedimentation, precipitation variability, and reservoir management influence hydropower generation. Results show that extreme rainfall events (top 1 %) contribute disproportionately – 20 %–50 % – to the annual sediment delivery. Although annual precipitation has not significantly changed since 1950, a clear seasonal shift from winter- to fall-dominant precipitation emerged. This change is driven by a significant increase in fall event frequency (+87 % to +400 % for 100 to 150 mm d−1 thresholds) and intensity (+31 %), alongside a −19 % decrease in winter precipitation, which is key to reservoir recharge. During the first two management periods, hydropower generation was more impacted by multipurpose dam objectives (e.g., flood control, water supply) than by direct climatic forcing. A high sedimentation rate of 19.3 mm yr−1 was observed. While sedimentation did not directly affect electricity production yet, it poses long-term risks to storage capacity and turbine functioning. Hydropower output declined by 25 % between 1976–1997 and 2006–2022, underlining the growing sensitivity of hydropower to hydroclimatic constraints. These findings highlight the need to better anticipate future environmental impacts in the context of rising electricity demand and climate uncertainty.

Preface to the English Edition. Acknowledgements. Acknowledgements to the English Edition. Translator's Note. Symbols. 1. Introduction. 2. A Review of the Literature. 3. Data and Methods. 4. Variability in Atmospheric Circulation in the Arctic between 1939 and 1990. 5. Variability of Air Temperature. 6. Variability of Atmospheric Precipitation. 7. Scenarios of Thermal-Precipitation Conditions in a Warmer World. 8. Conclusions. 9. Variability of Air Temperature and Atmospheric Precipitation over a Period of Instrumental Observations in the Arctic: An Update to 2000. References. Index.

Hydropower is the leading renewable energy technology, yet its vulnerability to combined environmental factors, particularly in the context of climate change, remains understudied. While the effects of climate change on hydropower are well-documented, research addressing the interplay between precipitation variability, sediment dynamics, and their effects on hydropower operations is lacking. This study investigates these interactions in the French Mediterranean region, with a focus on the Mont d&amp;#8217;Orb dam reservoir.An integrated approach was adopted and consisted of three main steps: (1) a sediment core analysis, relying on the establishment of an age model based on fallout radionuclide measurements, was conducted to reconstruct the influence of extreme rainfall events on sediment yield; (2) precipitation data from weather stations were statistically analyzed to identify temporal trends and shifts; and (3) dam water level and hydropower data, supplied by the operator, were analyzed to assess the combined effects of sediment accumulation, precipitation variability, and water level changes on hydropower generation.The results show that extreme rainfall events contributed 20&amp;#8211;60% of the annual sediment yield. While annual precipitation trends since 1950 showed no statistically significant changes, a seasonal shift in precipitation patterns was detected. Although sediment accumulation is currently not a primary constraint to hydropower generation due to reservoir management strategies, it may pose a long-term risk to storage capacity and turbine operation as it approaches critical levels. These findings highlight a critical gap in sediment management practices and emphasize the need for developing strategies to adapt to the currently changing climatic and hydrological conditions. This study highlights the necessity of integrating sediment and precipitation variability into hydropower planning to ensure its long-term sustainability in a context with an increasing frequency of droughts and extreme rainfall events exacerbated by climate change, particularly in the Mediterranean region.

ABSTRACTThe Streamflow Synthesis and Reservoir Regulation (SSARR) model was calibrated and verified on the Madison and Gallatin watersheds in the upper Missouri River drainage. The study was performed to determine if the SSARR model could simulate snowmelt‐runoff volumes to effect better operation of six multipurpose reservoirs on the Missouri River. Physical watershed characteristics and parameter sensitivity are incorporated into a procedure which expedites model calibration. Criteria are established to facilitate parameter development and to objectively evaluate calibration and verification results. A ratio of simulated to observed snowmelt‐runoff volumes of the Madison River averaged 1.00 and 1.02 for calibration (N = 8 years) and verification (N = 6 years) with corresponding standard deviations of 0.08 and 0.13. Gallatin volume ratios averaged 0.99 and 0.95 for calibration (N = 7 years) and verification (N = 5 years) with respective standard deviations of 0.08 and 0.28.