Winter Months Research Articles

Solar Influences on Winter Atmospheric Circulation Over the Ural, North Atlantic and North Pacific Regions: Pitchfork‐Like Relationships

AbstractLi's previous study found a one‐to‐two correspondence relationship between the total solar irradiance (TSI) and monthly anomalies of the Ural atmospheric circulation during winter months. This relationship roughly meets the so‐called supercritical pitchfork bifurcation model, hence termed a pitchfork‐like (PL) relationship. Here, we extend this study and provide more evidence to support previous findings. By analyzing data from 192 winter months and estimating the joint probability density function, we find that over the Ural, North Atlantic, and North Pacific regions, there are all PL relationships between the TSI and geopotential height anomalies at pressure levels no higher than 700 hPa. When the TSI gradually decreases and passes a critical threshold of 1360.9 W m−2, the preferred circulation patterns undergo a regime transition from one regime to two others. When TSI < 1360.9 W m−2, positive and negative geopotential height anomalies occur at nearly equal frequencies within the same TSI range. This quantitative relation is met in almost the whole troposphere in each region. We suggest that the occurrence of PL relationships may be associated with the interaction between the westerly flow and topographic barriers; The decrease in TSI can regulate this interaction by reducing the stability of background westerly flow over all three regions, via increasing the land‐ocean thermal contrast and altering the planetary wavenumber‐2 wave at the mid‐high latitudes. Our work highlights the same quantitative relation between the TSI and the monthly mean geopotential height anomalies of three regions in winter, which has important implications for seasonal climate prediction.

Quantifying the influence of climate change on streamflow of Rietspruit sub-basin, South Africa

Abstract This study integrated climate projections from five global climate models (GCMs) into the soil and water assessment tool to evaluate the potential impact of climate alterations on the Rietspruit River sub-basin under two representative concentration pathways (RCP4.5 and 8.5). The model's performance was evaluated based on the coefficient of determination (R2), percent bias (PBIAS), Nash–Sutcliffe efficiency (NSE), probability (P)-factor and correlation coefficient (R)-factor. Calibration results showed an R2 of 0.62, NSE of 0.60, PBIAS of 20, P-factor of 0.86 and R-factor of 0.91, while validation produced an R2 of 0.64, NSE of 0.61, PBIAS of 40 and P-factor of 0.85 and R-factor of 1.22. Precipitation is predicted to increase under both RCPs. Maximum temperature is projected to increase under both RCPs, with a major increase in the winter months. Minimum temperatures are projected to decrease under RCP4.5 in the near (−0.99 °C) and mid (−0.23 °C) futures, while the far future is projected to experience an increase of 0.14 °C. Precipitation and temperature changes correspond to increases in streamflow by an average of 53% (RCP4.5) and 47% (RCP8.5). These results indicate a need for an integrated approach in catchment water resource management amid potential climate and land use variations.

Economic and Environmental Benefits of Heating of Poultry Houses with Geothermal Energy: A Case Study for Nevşehir Province of Turkey

In this study, as an example of the use of geothermal energy resources for the air-conditioning of animal shelters, the technical, economic and environmental gains that will be achieved in the case of heating a chicken coop with a total floor area of 480 m2 in Nevşehir province of Turkey in the winter months have been evaluated. For this purpose, a standard chicken coop with a length of 40 m, a width of 12 m and a height of 2.5 m and a capacity of 4320 chickens has been considered. The optimum indoor temperature for adult chickens is considered to be 22 °C. The total heat losses related to the different structural components of the considered standard house were determined. The annual total highest heat load for the poultry house was calculated as Qt = 197.32 kW. For geothermal resources suitable for house heating in the region, the amount of heat to be gained from the geothermal fluid to the house environment was calculated, taking into account the lowest physical properties (the lowest temperature Tgeo = 30 °C and the lowest flow rate mgeo = 30 m3/h). Since the amount of heat energy gained to the poultry environment with geothermal fluid (Qgeo=278.96 kW) is higher than the total heat losses (Qt = 197.32 kW) of the poultry house (Qgeo>Qt), it can be used for poultry heating with geothermal fluid. In case the considered poultry house is heated with geothermal energy, a total of 45073 kg of fuel will be saved annually from LPG consumption and 42186.4 kg of diesel fuel consumption will be saved. If Diesel or LGP fuel is used instead of geothermal fluid for poultry heating, the annual total fuel cost will be 266 211.6 TL for LPG usage and 274 585.2 TL for Diesel usage. In case the considered house is heated with geothermal energy, 136 571.2 kgCO2-eq or 133 798.3 kgCO2-eq from the annual total greenhouse gas emissions will save compared to the use of LPG and Diesel, respectively.

Estimated reproductive parameters for a vulnerable Australian humpback dolphin population

AbstractUnderstanding reproductive output and success is integral to the conservation and management of threatened species and populations. Little is known about the reproductive parameters of Australian humpback dolphins (Sousa sahulensis), a species subject to cumulative pressures from anthropogenic threats due to their coastal distribution and strong site fidelity. This study assesses several reproductive parameters, including crude birth, recruitment, fecundity, and calf survival rates, in addition to interbirth intervals of Australian humpback dolphins inhabiting the near‐urban embayment of Moreton Bay, Queensland. Between 2014 and 2020, 106 adult females were photographically identified during 222 boat surveys. Of these, 75.5% (n = 80) were observed with calves. Birth seasonality was apparent and coincided with austral autumn and winter months. Interbirth intervals ranged between 1 and >6 years, with an average of 3.1 (SD = 1.1) years if offspring survived. Findings indicate declining fecundity rates (p < .05, M = 0.12, SD = 0.02), relatively low recruitment rates (M = 0.04, SD = 0.01) and calf survival rates to 1 year of age (M = 0.63, SD = 0.15). This study provides a useful baseline that can inform viability assessments and conservation measures, for both this population and others throughout the species range.

ICESat-2 shows sea ice leads have little overall effects on the Arctic cloudiness in cold months

Abstract The effect of leads in Arctic sea ice on clouds is a potentially important climate feedback. We use observations of clouds and leads from the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) to study the effects of leads on clouds. Both leads and clouds are strongly forced by synoptic weather conditions, with more clouds over both leads and sea ice at lower sea level pressure. Contrary to previous studies, we find the overall lead effect on low-level cloud cover is −0.02, a weak cloud dissipating effect in cold months, after the synoptic forcing influence is removed. This is due to compensating contributions from the cloud dissipating effect by newly frozen leads under high pressure systems and the cloud enhancing effect by newly open leads under low pressure system. The lack of proper representation of lead effect on clouds in current climate models and reanalyses may impact their performance in winter months, such as in sea ice growth and Arctic cyclone development.

Career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand

Context Racing structure and focus for racehorses differs across jurisdictions and is poorly described. In New Zealand and Australia, jumps racing accounts for a small proportion of total Thoroughbred races each year, as opposed to the larger jumps-racing (National Hunt) industry with purpose-bred horses found in the UK and Ireland. Aims This study aimed to describe the career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand. Methods Metrics from every horse with a full jumps-racing career (n = 1276, 89% geldings) between the 2005/06 and 2021/22 racing seasons (n = 40,302 starts) were examined. Descriptive statistics, box plots and heat maps were used to describe the data, by using horse age as a proxy for career progression. Key results Jumps-racing horses had a median of 17 flat starts (IQR 9–30) before their first jumps-racing start. The median career of a jumps-racing horse was 3.7 years (IQR 2.3–5.2) and 29 starts (IQR 16–44). Older horses had a decreasing number of flat-racing starts and an increasing proportion of steeplechase-racing starts. However, the majority of horses still had at least one flat-race start per calendar year, often prior to the first jumps race. Most horses had one spell each season (length 194 days, IQR 124–259), and a condensed preparation length over the winter months, with a median of 14 days (IQR 10–21) between starts. Conclusion The career pattern for jumps-racing horses in New Zealand reflects the industry retention of horses with a prior career in flat racing into a secondary jumps-racing career. Successful horses have increased focus on preparation for the winter jumps-racing season. Implications Jumps racing provides a secondary racing career for some flat-racing horses, particularly geldings. This strategy reduces wastage of horses from the industry.

Improving the efficiency of solar photovoltaics by means of geothermal cooling: A year-long test campaign

Heating up of photovoltaic modules during operation results in a significant power output reduction. This effect is especially relevant in regions with the highest photovoltaic potential, where irradiance and ambient temperature are particularly high. In this paper, a novel low enthalpy geothermal cooling system that improves the efficiency of a commercial solar module is described and experimentally validated. Two heat exchangers, one attached to the backside of the module, and another introduced inside a 15 m deep borehole, are connected in a closed circuit. A water-based coolant is pumped through the system, evacuating the excess heat from the module, and dissipating it underground in a clean and efficient manner, without additional water consumption after filling the system.The performance of the cooling system was experimentally tested by implementing it, for the first time, in a single-axis solar tracking isolated photovoltaic facility. Extensive tests were carried out in Spain, between September 2021 and August 2022 under a wide variety of environmental conditions. The efficiency improvement system has demonstrated its technical feasibility over a one-year period, showing a peak net efficiency improvement up to 13.4 %. Moreover, a positive net efficiency improvement has been demonstrated all year long, even during the winter months.

Seasonal Affective Disorder (SAD)

It is common for people to experience brief episodes of sadness or feeling unlike themselves. Such mood swings may persist with changing seasons, become more severe, and impact a person's feelings, thoughts, and actions. Although the leading cause of it is unclear, Seasonal affective disorder (SAD) is a common mood disorder that people face in winter months due to the brain chemistry reactions to reduced sunlight and shorter days (Johns Hopkins Medicine, 2021). As students of Boston University’s (BU) Graphic Medicine Club (GMC), we wanted to find ways to improve health literacy amongst BU students and provide the necessary health resources to help students. Two content creators of GMC worked together to create this comic and split the task of typography and illustration. This comic utilizes visuals and text to explain the common symptoms and treatment methods for SAD. Through our work at the intersection of art and medicine, we hope to offer a creative avenue for conversations about health topics such as SAD and provide informative narratives to others.

Geo-visualizing the hotspots of smog-induced health effects in district Gujranwala, Pakistan: a community perspective.

This study aims to examine the health effects of smog on different age groups in Gujranwala and its associated health effects. To achieve this, primary data was gathered through a questionnaire survey focused on health issues faced by elderly individuals during the smog season. The results of the survey revealed that older adults in Gujranwala are particularly vulnerable to a range of health problems during this period, including coughing, throat infections, irritated eyes, runny noses, shortness of breath, chest pain while breathing, wheezing, asthma, heart problems, and respiratory issues. In order to analyze the spatial distribution of these health concerns, spatial and geo-statistical methods were employed utilizing ArcGIS 10.5. By integrating field data and secondary sources, hotspot and cold spot zones were identified. Employing the statistical model within ArcMap 10.5, hotspot analysis was performed to determine areas with elevated air quality index (AQI) values and associated health problems. The application of the inverse distance weighted approach, incorporating the Z value, facilitated a visual representation of areas with heightened and reduced AQI and health-related issues. The study's outcomes underscore the prevalence of health challenges among older adults during the winter months in Gujranwala, particularly linked to smog-induced throat infections, irritated eyes, and runny noses. The research identified zones with escalated AQI values, encompassing regions such as Gujranwala, Chandaqella, Alam Chowk, Khali Shahpur, Sialkot Bypass, and Pindi Bypass. It was established that industrial pollutants and vehicular emissions are the primary contributors to smog in the area. Given the detrimental consequences of pollution on individuals of all age groups, it is imperative to take action to mitigate its impact. This can be achieved through addressing pollution sources, implementing effective emission control measures, and fostering public awareness. By adopting proactive measures, the adverse health effects of pollution can be minimized, thereby fostering a healthier and safer environment for the entire population. This study offers valuable insights for policymakers and environmentalists to implement targeted interventions and improve air quality, ultimately safeguarding the health of local populations.

Investigating the different forms of premenstrual syndrome in Kursk students

Background: Premenstrual Syndrome (PMS) is a complex of symptoms experienced by women before their menstrual period, which can significantly impact daily functioning and quality of life. While the prevalence of PMS varies globally, detailed studies on its manifestation among medical students are limited. This research aims to fill this gap by investigating the prevalence and types of PMS among female medical students at Kursk State Medical University. Methods and Materials: A descriptive cross-sectional study was conducted using a sample of 128 female medical students aged 18 to 25 years. Participants were surveyed using a validated PMS questionnaire, which classifies symptoms into four categories: psychological, behavioral, physical, and atypical. Data on demographic variables and lifestyle factors were also collected to explore potential correlations. Results: The study found that 84% of participants experienced some form of PMS, with 25% reporting severe symptoms. Psychological symptoms were the most prevalent, followed by physical, behavioral, and atypical symptoms. The incidence of PMS was higher among older students and those with less physical activity. Seasonal variations also influenced symptom severity, with winter months showing a higher incidence rate. Conclusion: The findings suggest a high prevalence of PMS among medical students at Kursk State Medical University, with significant impacts on their academic and personal lives. These results underscore the need for targeted educational programs and support systems to help manage PMS effectively. Further research is recommended to explore intervention strategies and to assess their efficacy in this population.

Resemblance of the global depth distribution of internal-tide generation and cold-water coral occurrences

Abstract. Internal tides are known to be an important source of mixing in the oceans, especially in the bottom boundary layer. The depth of internal-tide generation therefore seems important for benthic life and the formation of cold-water coral mounds, but internal-tide conversion is generally investigated in a depth-integrated sense. Using both idealized and realistic simulations on continental slopes, we found that the depth of internal-tide generation increases with increasing slope steepness and decreases with intensified shallow stratification. The depth of internal-tide generation also shows a typical latitudinal dependency related to Coriolis effects. Using a global database of cold-water corals, we found that, especially in Northern Hemisphere autumn and winter, the global depth pattern of internal-tide generation correlates (rautumn = 0.70, rwinter = 0.65, p < 0.01) with that of cold-water corals: shallowest near the poles and deepest around the Equator, with a decrease in depth around 25° S and N, and shallower north of the Equator than south. We further found that cold-water corals are situated significantly more often on topography that is steeper than the internal-tide beam (i.e. where supercritical reflection of internal tides occurs) than would be expected from a random distribution: in our study, in 66.9 % of all cases, cold-water corals occurred on a topography that is supercritical to the M2 tide whereas globally only 9.4 % of all topography is supercritical. Our findings underline internal-tide generation and the occurrence of supercritical reflection of internal tides as globally important for cold-water coral growth. The energetic dynamics associated with internal-tide generation and the supercritical reflection of internal tides likely increase the food supply towards the reefs in food-limited winter months. With climate change, stratification is expected to increase. Based on our results, this would decrease the depth of internal-tide generation, possibly creating new suitable habitat for cold-water corals shallower on continental slopes.

Epidemiology of Adenovirus Infection in Hospitalized Children in the United States From 1997 to 2019.

The study aimed to explore the prevalence, clinical features, resource utilization, temporal trends and outcomes associated with adenoviral infections in hospitalized children. A retrospective analysis using the Healthcare Cost and Utilization Project's Kids' Inpatient Database from 1997 to 2019 was performed. Children aged 29 days to 17 years with adenoviral infection were selected. Chi-square, Kruskal-Wallis tests, linear trend analysis and multivariable analysis were used for data analysis. A total of 40,135 children under 18 years of age with adenoviral infection were discharged in the United States with an overall prevalence of 18.9 per 10,000 discharges and 6.9 children per 100,000 population. By linear trend analysis, the hospitalization rate has significantly increased with the highest prevalence in 2019. Adenoviral infection was more prevalent in Black children, in winter months, in the Midwest region, in children with government insurance and in the lowest income quartile. The majority (85%) of adenovirus-related hospitalizations occurred under 6 years of age. Mechanical ventilation, extracorporeal membrane oxygenation support, acute kidney injury and liver failure were documented in 11.9%, 0.4%, 2.7% and 0.4%, respectively. The overall case fatality rate was 1.4%, which decreased from 1997 to 2019 (P < 0.05). By regression analysis, an increased mortality rate was associated with the need for mechanical ventilation, the presence of complex chronic conditions, immune deficiency, central nervous system infection and pneumonia/bronchiolitis. Most human adenovirus infections occur in children under 6 years of age and cause mild illness. Human adenovirus can lead to serious illness in children with complex chronic conditions and immune deficiency conditions.

Fishpond Water Potential on Vineyard Soil Health: An Exploratory Study of a Circular System

Climate variabilities continue to hinder sustainable food production with an increasing need to use resources such as water and soil efficiently. The quest for these efficiencies in agriculture systems drives innovations among farmers. However, limited data on farm practices, such as irrigating with fishpond water and their effects on soil health, hinder their adoption as climate-smart innovations. In a nearly twenty-year-old vineyard with two distinct irrigation practices (irrigation with recycled fishpond water and irrigation with ditch water), this study was carried out as an exploratory study to investigate the influence of recycling fishpond water on soil health parameters and yield. Soil samples were taken from two different irrigation fields in summer and winter for lab analysis on soil health parameters (organic matter and carbon, nitrogen, phosphorus, microbial biomass, and microbial respiration). Averages over the two seasons of field measurements indicate that long-term irrigation using recycling fishpond water increased the measured soil health parameters (organic matter (13%), organic carbon (30%), nitrogen (17%), phosphorus (46%), microbial biomass (18%), and microbial respiration (56%)) in both summer and winter months when compared to fields receiving just ditchwater irrigation. Using water in a way that can improve soil health increases biodiversity and improves the efficiency of our limited water resources in semi-arid agricultural lands, and this strategy is a climate-smart tool that can help reduce water risks in dry agricultural regions such as Arizona.

A National Database Analysis: Does Cold Weather Affect the Surgical Intervention Rate for Developmental Dysplasia of the Hip in Children Under Five Years?

Background Cold weather in the first few months of life may increase the risk of a late diagnosis of developmental dysplasia of the hip (DDH). Early detection of DDH can often be treated non-surgically. The purpose of this study is to observe whether the rates of surgical intervention for DDH differ based on average outdoor temperatures in the winter months. Methods A retrospective observational study of DDH patients diagnosed from 2010 to 2021 was conducted using a national administrative database. Five geographic regions were defined based on the average temperatures in the coldest quarter of the year. The rates of DDH-related surgeries were compared across these temperature regions. Results A total of 55,911 patients ≤5 years old with a DDH diagnosis from 2010 to 2021 were identified in the database. When compared to the warmest region (Group 5), the coldest region (Group 1) had higher rates of open reduction (4.59% vs. 2.06%, p<0.001), adductor tenotomy (6.95% vs. 2.91%, p<0.001), femoral osteotomy (5.75% vs. 2.04%, p<0.001), pelvic osteotomy (5.27% vs. 2.04%, p<0.001), and total DDH surgeries (11.42% vs. 5.03%, p<0.001). Conclusion Children living in states with an average winter temperature of -6.17°C had an increased likelihood of requiring surgical intervention for DDH within the first five years of life.

Analyzing Air Pollution in Urban Delhi: A Quantitative Assessment of Particulate Matter (PM) Concentrations

Air pollution poses significant challenges to urban environments, with particulate matter (PM) concentrations being a major concern due to their adverse effects on public health and the environment. This research paper aims to quantitatively assess PM concentrations in urban Delhi, focusing on spatial, temporal, and seasonal variations across diverse urban microenvironments. The research design involved mobile air quality monitoring using real-time PM sensors mounted on a vehicle, coupled with Geographic Information System (GIS) analysis to map pollution hotspots and assess correlations with urban features. The key findings of the study reveal significant spatial variability in PM concentrations, with industrial zones and busy intersections emerging as hotspots for pollution. Seasonal variations in PM levels, with elevated concentrations during winter months and lower levels during the monsoon season, underscore the influence of meteorological factors on air quality dynamics. The study also identifies correlations between PM concentrations and respiratory disease cases, highlighting the adverse health effects of air pollution. The implications of these findings extend to air quality management strategies and public health interventions, emphasizing the need for targeted measures to mitigate pollution levels and protect public health in urban environments.

Syndromic gastrointestinal panel diagnostic tests have changed our understanding of the epidemiology of Yersinia enterocolitica—Foodborne Diseases Active Surveillance Network, 2010–2021

Abstract Background In the United States, Yersinia enterocolitica causes a diarrheal disease historically associated with winter months and understood to predominantly occur among Black or African American infants and Asian children. Clinical laboratory adoption of culture-independent diagnostic tests (CIDTs), in place of culture methods has led to marked increases in diagnoses. Methods We describe laboratory-diagnosed infections caused by Y. enterocolitica in 10 state health departments of the Foodborne Diseases Active Surveillance Network. A counterfactual random forest model was used to identify individual, and community-level social determinants of health associated with the type of test used to detect Y. enterocolitica. Results Annual reported incidence of Y. enterocolitica infection increased from 0.3 per 100,000 in 2010 to 1.3 per 100,000 in 2021. The proportion of infections detected by CIDT increased from 3% in 2012 to 89% in 2021. Nearly all (97%) CIDT-positive infections were detected by commercially available syndromic gastrointestinal panel tests. Reported incidence increased for adults ≥18 years, regardless of race and ethnicity. Nearly half of infections occurred during May to September in 2016–2021. The probability of CIDT-detected infection increased with age and was greater for White compared with Asian persons. In addition to year, an ill person’s location of residence had a significant impact on odds of infection detection by CIDT versus culture method. Conclusions Improved detection due to increased use of CIDTs has altered our understanding of yersinosis epidemiology. Our findings suggest that yersinosis diagnosis quantitatively varies between demographic groups by diagnostic method and that differential access to CIDTs may still affect our understanding of yersinosis epidemiology.

Seasonal variation and concentration of PAHs in Lake Balaton sediment: A study on molecular weight distribution and sources of pollution

The temporal and spatial variations of 16 Polycyclic Aromatic Hydrocarbons (PAHs) were examined at multiple sites around Lake Balaton from February 2023 to January 2024. The results indicated that the concentrations of PAHs in sediment were high during the winter months, 448.35 to 619.77 ng/g dry weight, and low during the summer months, 257.21 to 465.49 ng/g dry weight. The concentration of high molecular weight PAHs (HMWPAHs), consisting of 5–6 rings, was greater than that of low molecular weight PAHs (LMWPAHs), which had 2–3 rings. The total incremental lifetime cancer risk (ILCR) for both dermal and ingestion pathways was high for both adults and children during the four seasons, with the highest records as the following: winter > spring > summer > autumn. The ecological effects of the 16 PAHs were negligible except for acenaphthylene (Acy) and fluorene (Fl), which displayed slightly higher concentrations during the autumn and spring, respectively.

Acesulfame and other artificial sweeteners in a wastewater treatment plant in Alberta, Canada: Occurrence, degradation, and emission

Acesulfame (ACE), sucralose (SUC), cyclamate (CYC), and saccharin (SAC) are widely used artificial sweeteners that undergo negligible metabolism in the human body, and thus ubiquitously exist in wastewater treatment plants (WWTPs). Due to their persistence in WWTPs, ACE and SUC are found in natural waters globally. Wastewater samples were collected from the primary influent, primary effluent, secondary effluent, and final effluent of a WWTP in Alberta, Canada between August 2022 and February 2023, and the artificial sweeteners concentrations were measured by LC-MS/MS. Using wastewater-based epidemiology, the daily per capita consumption of ACE in the studied wastewater treatment plant catchment was estimated to be the highest in the world. Similar to other studies, the removal efficiency in WWTP was high for SAC and CYC, but low or even negative for SUC. However, ACE removal remained surprisingly high (>96%), even in the cold Canadian winter months. This result may indicate a further adaptation of microorganisms capable of biodegrading ACE in WWTP. The estimated per capita discharge into the environment of ACE, CYC, and SAC is low in Alberta due to the prevalent utilization of secondary treatment throughout the province, but is 17.4–18.8 times higher in Canada, since only 70.3% of total discharged wastewater in Canada undergoes secondary treatment.

Stochastic Flow Analysis for Optimization of the Operationality in Run-of-River Hydroelectric Plants in Mountain Areas

The highly temporal variability of the hydrological response in Mediterranean areas affects the operation of hydropower systems, especially in run-of-river (RoR) plants located in mountainous areas. Here, the water flow regime strongly determines failure, defined as no operating days due to inflows below the minimum operating flow. A Bayesian dynamics stochastic model was developed with statistical modeling of both rainfall as the forcing agent and water inflows to the plants as the dependent variable using two approaches—parametric adjustments and non-parametric methods. Failure frequency analysis and its related operationality, along with their uncertainty associated with different time scales, were performed through 250 Monte Carlo stochastic replications of a 20-year period of daily rainfall. Finally, a scenario analysis was performed, including the effects of 3 and 30 days of water storage in a plant loading chamber to minimize the plant’s dependence on the river’s flow. The approach was applied to a mini-hydropower RoR plant in Poqueira (Southern Spain), located in a semi-arid Mediterranean alpine area. The results reveal that the influence of snow had greater operationality in the spring months when snowmelt was outstanding, with a 25% probability of having fewer than 2 days of failure in May and April, as opposed to 12 days in the winter months. Moreover, the effect of water storage was greater between June and November, when rainfall events are scarce, and snowmelt has almost finished with operationality levels of 0.04–0.74 for 15 days of failure without storage, which increased to 0.1–0.87 with 3 days of storage. The methodology proposed constitutes a simple and useful tool to assess uncertainty in the operationality of RoR plants in Mediterranean mountainous areas where rainfall constitutes the main source of uncertainty in river flows.

Performance evaluation of deep learning based stream nitrate concentration prediction model to fill stream nitrate data gaps at low-frequency nitrate monitoring basins

Accurate and frequent nitrate estimates can provide valuable information on the nitrate transport dynamics. The study aimed to develop a data-driven modeling framework to estimate daily nitrate concentrations at low-frequency nitrate monitoring sites using the daily nitrate concentration and stream discharge information of a neighboring high-frequency nitrate monitoring site. A Long Short-Term Memory (LSTM) based deep learning (DL) modeling framework was developed to predict daily nitrate concentrations. The DL modeling framework performance was compared with two well-established statistical models, including LOADEST and WRTDS-Kalman, in three selected basins in Iowa, USA: Des Moines, Iowa, and Cedar River. The developed DL model performed well with NSE >0.70 and KGE >0.70 for 67% and 79% nitrate monitoring sites, respectively. DL and WRTDS-Kalman models performed better than the LOADEST in nitrate concentration and load estimation for all low-frequency sites. The average NSE performance of the DL model in daily nitrate estimation is 20% higher than that of the WRTDS-Kalman model at 18 out of 24 sites (75%). The WRTDS-Kalman model showed unrealistic fluctuations in the estimated daily nitrate time series when the model received limited observed nitrate data (less than 50) for simulation. The DL model indicated superior performance in winter months' nitrate prediction (60% of cases) compared to WRTDS-Kalman models (33% of cases). The DL model also better represented the exceedance days from the USEPA maximum contamination level (MCL). Both the DL and WRTDS-Kalman models demonstrated similar performance in annual stream nitrate load estimation, and estimated values are close to actual nitrate loads.