Evaluation of Snowmelt Estimation Techniques for Enhanced Spring Peak Flow Prediction

Water resources management and planning requires accurate and reliable spring flood forecasts. In cold and snowy countries, particularly in snow-dominated watersheds, enhanced flood prediction requires adequate snowmelt estimation techniques. Whereas the majority of the studies on snow modeling have focused on comparing the performance of empirical techniques and physically based methods, very few studies have investigated empirical models and conceptual models for improving spring peak flow prediction. The objective of this study is to investigate the potential of empirical degree-day method (DDM) to effectively and accurately predict peak flows compared to sophisticated and conceptual SNOW-17 model at two watersheds in Canada: the La-Grande River Basin (LGRB) and the Upper Assiniboine river at Shellmouth Reservoir (UASR). Additional insightful contributions include the evaluation of a seasonal model calibration approach, an annual model calibration method, and two hydrological models: McMaster University Hydrologiska Byrans Vattenbalansavdelning (MAC-HBV) and Sacramento Soil Moisture Accounting model (SAC-SMA). A total of eight model scenarios were considered for each watershed. Results indicate that DDM was very competitive with SNOW-17 at both the study sites, whereas it showed significant improvement in prediction accuracy at UASR. Moreover, the seasonally calibrated model appears to be an effective alternative to an annual model calibration approach, while the SAC-SMA model outperformed the MAC-HBV model, no matter which snowmelt computation method, calibration approach, or study basin is used. Conclusively, the DDM and seasonal model calibration approach coupled with the SAC-SMA hydrologic model appears to be a robust model combination for spring peak flow estimation.

Integrated system of approach for the control of ixodid ticks in the western region of Ukraine

For the control of ixodid ticks it is necessary to develop an integrated system of approach that provide a scientific and practical component. The integrated method is the most effective way to control arthropods. The research was conducted during 2018-2020 in the western region of Ukraine (Khmelnytsky, Chernivtsi, Vinnytsia regions). Based on data obtained in previous studies, as well as on the study of factors such as ticks species (Ixodes ricinus, Dermacentor reticulatus), environmental conditions and the possibility of certain measures in this region, an integrated system of measures to regulate the number of ixodid ticks in Western Ukraine were developed. In each region, two experimental private farms and one control farm were selected; the territory of the farms was about 20,000 m2. During the entire study period, 379 D. reticulatus ticks and 165 I. ricinus ticks were collected in all areas. In 2019, farms that were located at a distance of 1-1.5 km from swamps, lowlands and shrubs in open, dry, sunny areas showed the lowest frequency of ticks on animals. So, in May 2019, on average, in experimental farms on dogs, 9, 7 and 11 ticks were found on one animal in the Khmelnytsky, Chernivtsi and Vinnitsa regions, respectively. During acarological examination of farms in the Khmelnytsky region, the average density of ticks was 8, in Chernivtsi - 5, in Vinnitsa - 7 ticks / 1000 m2 in the spring peak of tick activity. In addition, taking into account the seasonal dynamics of ticks activity during 2018, mechanical cleaning of the territory and acaricidal treatments of vegetation were carried out from autumn 2019 to autumn 2020 - in spring (March, May) and autumn (September). According to the results of our research, the use of acaricidal treatments provided a decrease in the number of ticks populations by 50-90 % within 6-8 weeks. When collecting ticks for the flag in experimental plots of the Khmelnytsky region in 2020, the average density of ticks was 4, Chernivtsi - 2, Vinnitsa - 1 tick / 1000 m2 in the spring peak of tick activity. We also found that during the complex acaricidal treatment of the territory and the use of drops or sprays based on fipronil in 2020, half as many ticks were found on dogs than in 2019, which averaged 4 ticks in the Khmelnytsky region, in Chernivtsi - 3 and 5 ticks in the Vinnytsia region. In addition, it was found that mechanical cleaning of the area also helped to reduce the attractiveness of the area for small mammals.

Dynamics of microalgae development in the under-ice period in Southern Baikal

Spring peak of phytoplankton vegetation in Lake Baikal starts in under-ice period. This article presents the results of a study of the microalgae composition at the “ice – water” phases in different ecological zones in South Baikal over five years.

Epidemiology, aetiology and seasonality of infectious diarrhoea in adult outpatients through active surveillance in Shanghai, China, 2012–2016: a cross-sectional study

ObjectivesThis study aimed to identify the epidemiology, clinical characteristics, aetiology and seasonality of sporadic infectious diarrhoea in adults in Shanghai.SettingThis study was based on a city-wide, active continuous hospital-based diarrhoea surveillance network established by Shanghai Municipal Center for Disease Control and Prevention. There were 22 sentinel hospitals in all 16 districts (9 primary-level hospitals, 6 secondary-level hospitals and 7 tertiary-level hospitals) which were selected using probability proportionate to size sampling method.ParticipantsFrom 1 May 2012 to 31 May 2016, 90 713 patients were included in this study. Among 8797 patients whose stool samples were collected and detected, 4392 patients were male.ResultsThe positive rate was 47.96%. Bacterial and viral infections accounted for 27.19% and 69.07% separately. Norovirus was the most common pathogen (43.10%), followed by rotavirus,Vibrio parahaemolyticus, diarrhoeagenicEscherichia coli(DEC) andSalmonellaspp. Patients between 30–44 and 45–59 years were more likely to have infectious diarrhoea and viral diarrhoea. Those aged 30–44 years were the most likely to get infected withV. parahaemolyticus(adjusted OR, aOR vs 60+ years: 2.04, 95% CI 1.47 to 2.78) and norovirus (aOR vs 60+ years: 1.32, 95% CI 1.12 to 1.56). Bacterial (exceptV. parahaemolyticus) diarrhoea was characterised by fever, abdominal pain and loose stool; while viral diarrhoea was characterised by nausea, vomiting and watery stool. A seasonal distribution of infectious diarrhoea was observed with larger peaks in winter and smaller peaks in summer. Winter peaks were mainly due to norovirus and rotavirus, and summer peaks were due to bacterial infections. An emerging spring peak of norovirus around March was observed in the past 3 years.ConclusionViral infections were predominant, and norovirus played a leading role. A seasonal distribution was observed and an emerging spring peak of norovirus was noted. Our findings highlight the necessity for conducting an active, comprehensive surveillance in adults, to monitor changing dynamics in the epidemiology and aetiology of infectious diarrhoea.

Frequency of floods in a changing climate: a case study from the Red River in Manitoba, Canada

Spring flooding in the Red River basin is a recurrent issue in the Province of Manitoba, Canada. There have been a number of flood events in recent years and climate change has been suggested as a potential cause. This paper employs a relatively simple model for predicting changes in the frequency distribution of annual spring peak discharge of the Red River as a response to increased GHG concentrations. A regression model is used to predict spring peak flow from antecedent precipitation in the previous fall, winter snow accumulation, and spring precipitation. Data from the Coupled Model Intercomparison Project – Phase 5 (CMIP5) are used to estimate changes in the predictor variables and this information is then employed to derive flood distributions for future climate conditions. Most climate models predict increased precipitation during winter months but this trend is partly offset by a shorter snow accumulation period and higher winter evaporation rates. The means and medians of an ensemble of 16 climate models do not suggest a particular trend toward more or less frequent floods of the Red River. However, the ensemble range is relatively large, highlighting the difficulties involved in estimating changes in extreme events.

On the origin of the occasional spring nitrate peak in Greenland snow

Ice core nitrate concentrations peak in the summer in both Greenland and Antarctica. Two nitrate concentration peaks in one annual layer have been observed some years in ice cores in Greenland from samples dating post-1900, with the additional nitrate peak occurring in the spring. The origin of the spring nitrate peak was hypothesized to be pollution transport from the mid-latitudes in the industrial era. We performed a case study on the origin of a spring nitrate peak in 2005 measured from a snowpit at Summit, Greenland, covering 3 years of snow accumulation. The effect of long-range transport of nitrate on this spring peak was excluded by using sulfate as a pollution tracer. The isotopic composition of nitrate (δ15N, δ18O and Δ17O) combined with photochemical calculations suggest that the occurrence of this spring peak is linked to a significantly weakened stratospheric ozone (O3) layer. The weakened O3 layer resulted in elevated UVB (ultraviolet-B) radiation on the snow surface, where the production of OH and NOx from the photolysis of their precursors was enhanced. Elevated NOx and OH concentrations resulted in enhanced nitrate production mainly through the NO2 + OH formation pathway, as indicated by decreases in δ18O and Δ17O of nitrate associated with the spring peak. We further examined the nitrate concentration record from a shallow ice core covering the period from 1772 to 2006 and found 19 years with double nitrate peaks after the 1950s. Out of these 19 years, 14 of the secondary nitrate peaks were accompanied by sulfate peaks, suggesting long-range transport of nitrate as their source. In the other 5 years, low springtime O3 column density was observed, suggesting enhanced local production of nitrate as their source. The results suggest that, in addition to direct transport of nitrate from polluted regions, enhanced local photochemistry can also lead to a spring nitrate peak. The enhanced local photochemistry is probably associated with the interannual variability of O3 column density in the Arctic, which leads to elevated surface UV radiation in some years. In this scenario, enhanced photochemistry caused increased local nitrate production under the condition of elevated local NOx abundance in the industrial era.

SPATIO-TEMPORAL VARIATIONS OF MACRO-INVERTEBRATES IN RIFFLES AND POOLS OF MARDI AND VIJAYPUR STREAMS POKHARA, NEPAL

Present paper deals with the spatio-temporal variations in diversity and density of macro invertebratesin riffles and pools of the Mardi and the Vijayapur streams, Pokhara, Nepal. It was the pioneeringwork to study the biotic assemblage. Altogether 47 genera (32 from the riffles and 34 from the pools)belonging to 38 families and 12 orders were recorded during the study period. The taxa richness washigher (38 genera) in the Mardi stream than in the Vijayapur stream (30 genera). Total density at bothsites observed major peak and down fall in the spring and summer seasons, respectively. The averagetotal density during the spring peak was higher (967.42 m-2 in riffle and 652.10 m-2 in pool) at Site 1(Mardi stream) than at Site 2 (Vijaypur stream) (541.02 m-2 in riffle and 537.43 in pool). This peakwas mainly contributed by the order ephemeroptera. Ephemeroptera, diptera and trichoptera werefound predominant orders comprising 11, 8 and 8 genera, respectively. Heptagenidae, baetidae andleptophlebidae; chironomidae, ceratopogonidae and tipulidae, and hydropsychidae, psychomyidaeand polycentropodidae were dominant families among ephemeroptera, diptera and trichopterarespectively. The dominant genera were, Heptagenia Walsh, Rhithrogena Eaton and Baetis Leach;Tendipes Meigen, Culicoides Latreille and Simulium Hagen; Hydropsyche Pictet and PsychomyiaPictet; Psephenus Haldeman and Heterlimnius Hinton; Octogomphus Selys and Argia Rambur andPlanaria Girard among ephemeroptera, diptera, trichoptera, plecoptera, coleoptera, odonata andtricladida, respectively. The lower taxa richness at Site 2 having urban influence reflects theperturbation of stream environment due to urbanization, industrialization and application of inorganicfertilizers and pesticides in the agricultural lands, which needs regular ecological monitoring andmeasures to control further deterioration.DOI: http://dx.doi.org/10.3126/eco.v20i0.11442ECOPRINTAn International Journal of EcologyVol. 20, 2013Page: 61-70