Wintertime snow and precipitation conditions in the Willow Creek watershed above Ririe Dam, Idaho

The Ririe Dam and Reservoir project is located on Willow Creek near Idaho Falls, Idaho, and is important for flood risk reduction and water supply. The current operating criteria is based on fully storing a large winter runoff event. These winter runoff events are generally from large storm events, termed atmospheric rivers, which produce substantial precipitation. In addition to the precipitation, enhanced runoff is produced due to frozen soil and snowmelt. However, the need for additional water supply by local stakeholders has prompted the U.S. Army Corps of Engineers to seek to better understand the current level of flood risk reduction provided by Ririe Dam and Reservoir. Flood risk analysis using hydrologic modeling software requires quantification of the probability for all of the hydrometeorologic inputs. Our study develops the precipitation, SWE, and frozen ground probabilities that are required for the hydrologic modeling necessary to quantify the current winter flood risk.

Seasonal and spatial variability of the ammonium nitrogen content in the Amur River near Khabarovsk in 2018–2019

Представлены результаты наблюдений за содержанием аммонийного азота в воде р. Амур у г. Хабаровск в 2018–2019 гг. Максимальные значения установлены в правобережной и средней части русла в 2018 г. в начале ледостава (0.37 мг N/дм3), в 2019 г. в конце ледостава (0.32 мг N/дм3). Наименьшие значения зимой отмечены в левобережной части русла Амура из-за влияния зарегулированных рек Зея и Бурея. Показано постепенное снижение концентрации аммонийного азота в течение зимнего периода в 1.5 раза в 2018 г. и возрастание в 2.4 раза в 2019 г. Выявлено снижение концентраций в зимнюю межень 2018–2019 гг. по сравнению с периодом 2011–2013 гг. в 1.9 раза, что свидетельствует об улучшении качества воды р. Сунгари, а соответственно и Среднего Амура. В период открытого русла содержание аммонийного азота по сравнению с зимней меженью ниже и не превышает 0.1 мг N/дм3. Наибольшие значения наблюдаются в правобережной и средней части русла во время половодья и на подъеме паводков, сформированных в бассейнах рек Уссури и Сунгари. Показано, что на гребне катастрофического паводка, сформированного в Забайкальском крае в 2018 г., и очень сильного паводка в 2019 г. содержание аммонийного азота не превышало 0.05 мг N/дм3. Установлено, что содержание аммонийного азота в левобережной части русла, а в межпаводочный период по всей ширине Амура находится ниже предела обнаружения. The results of observations over the content of ammonium nitrogen in the water of the Amur River near Khabarovsk in 2018–2019 are presented. The maximum values were determined in the right-bank and middle parts of the riverbed in 2018 at the beginning of ice formation (0.37 mg of N/dm3) and in 2019 at the end of ice formation (0.32 mg of N/dm3). The minimum values were observed in winter in the left-bank part of the Amur riverbed due to effect of the regulated rivers of Zeya and Bureya. The gradual decline in the concentration of ammonium nitrogen 1.5 times during the winter season of 2018 and growth 2.4 times in 2019 are shown. The decrease in concentrations 1.9 times during the winter runoff low of 2018–2019 in comparison with period of 2011–2013 was revealed which gives evidence of the water quality improvement in Sungari River and, respectively, in the middle reaches of Amur River. In the period of free channel, the content of ammonium nitrogen is lower in comparison with the same during winter low-water level and does exceed 0.1 mg of N/dm3. The maximum values are observed in the right-bank and middle parts of the riverbed during high water and on the rise of floods formed in the catchments of the Ussuri and Sungari Rivers. It was demonstrated that in the top of the catastrophic flood formed in the Trans-Baikal Territory in 2018 and very strong flood in 2019, the content of ammonium nitrogen did not exceed 0.05 mg of N/dm3. It has been established that the content of ammonium nitrogen in the left-bank part of riverbed and in the peak-flood interval across the whole width of the Amur River is below detection limit.

Analysis of the Factors Determining Many-year Changes of Runoff from Oligotrophic Bogs

The article presents results of the analysis of interaction of the factors determining the process of the winter and spring runoff formation on the basis of integrated hydro/meteorological observations at the Lammin-Suo (Leningrad Oblast) and ILass (Archangel Oblast) oligotrophic bogs during the period of stabilization (1950-980) and the period of climate change (1981-2018). We have stated that the freezing depth is a factor that regulates the ratio between the winter runoff and spring runoff. It has been shown that the layer of the winter runoff-forming moisture increase with its decrease and, consequently, the winter runoff is increasing while the spring runoff is decreasing. Analysis of results of the observation over the hydrological regime of the bogs of the north and north-west of Russia has shown that it is exactly the 1978-1980 period that is the boundary, which the freeze depth decrease and the change of the characteristics of runoff from bogs can be observed.

MODERN TRANSFORMATION OF SEASONAL RUNOFF DISTRIBUTION OF THE SIVERSKYI DONETS RIVER BASIN

The annual runoff distribution of the Siverskyi Donets River Basin in the period of modern climate change was estimated. The annual runoff distribution of the Siverskyi Donets Basin was researched for two characteristic periods (from the beginning of observations to 1988 and from 1989 to 2018). The assessment was performed for three water year types: wet year, average year and dry year. The research was performed for three groups of rivers depending on their affiliation to a particular part of the Basin. During the research, the average monthly runoff of the hydrological gauges, which we selected for the study were averaged. The annual runoff distribution was leveled in the current period. The Siverskyi Donets Basin is characterized by the peculiar physico-geographical conditions, so the annual runoff distribution is somewhat different for different part of the Basin. Differences in the annual runoff distribution of the right-bank tributaries, the left-bank tributaries and the Siverskyi Donets River were revealed. For the left-bank tributaries, which are less affected by anthropogenic load, climate change has led to a significant increase in runoff of the winter and summer-autumn low period. For the right-bank tributaries of the Siverskyi Donets, flowing within the industrial part of Donbas, the share of low period runoff has not changed, or even decreased. This is due to the reduction of mine drainage, due to the reduction of industrial production in the region. Instead, the share of autumn-winter period in the annual runoff has increased for the right-bank tributaries and the Siverskyi Donets River itself. It is established that the share of spring floods from the annual volume of runoff has significantly decreased and the share of the summer-autumn period for the rivers of the Siverskyi Donets Basin in the modern period has increased. The winter runoff of the left-bank tributaries of the modern period is characterized by an increase. The right-bank tributaries of the Basin are characterized by a decrease in winter runoff. Currently, in dry years, spring flood is practically not allocated on the annual hydrograph; the share of runoff in the limited months has significantly increased. At the present stage of climate change, the annual runoff distribution of the Siverskyi Donets River Basin has undergone significant changes.

Impact of projected 21st century climate change on basin hydrology and runoff in the Delaware River Basin, USA

A gridded hydrologic model was developed to assess the impact of projected climate change on future Delaware River Basin (DRB) hydrology. The DRB serves as a water supply resource to over 15 million people. Model evaluation statistics for both water year and monthly runoff projections indicate that the model is able to capture well the hydrologic conditions of the DRB. Basinwide, annual temperature is projected to increase from 2.0 to 5.5 °C by 2080–2099. Correspondingly, potential and actual evapotranspiration, precipitation, rainfall, and runoff are all projected to increase, while snowfall, snow water storage, snowmelt, and subsurface moisture are all projected to decrease. By 2080–2099, basinwide summer subsurface moisture is projected to decrease 7–18% due to increased evapotranspiration, while winter runoff is projected to increase 15–43% due to increased precipitation and snowmelt and a conversion of snowfall to rainfall. Significant spatial variability in future changes to hydrologic parameters exists across the DRB. Changes in the timing and amount of future runoff and other hydrologic conditions need to be considered for future water resource management.

Long-term dynamics and trend of ion sink of Amur river In the winter low-water period near Khabarovsk, Russia

The long-term dynamics and trend of the ion sink of the Amur River near Khabarovsk, Russia, in the winter low-water period were studied. The hydrological and hydrochemical characteristics of the main tributaries are given. The spatial heterogeneity of the distribution of mineralization along the length and width of the Amur is noted. The influence of large floods on the winter runoff of solutes has been established. The long-term increasing trend of ion sink in the winter low-water period due to hydropower construction is shown.

Assessment of changes in the Viliya River runoff in the territory of Belarus

The research results of runoff changes in the River Viliya at 3 stations (Steshitsy Village, Vileyka Town and Mihalishki village) during the period 1946–2014 for the average annual, maximum, minimum summer-autumn and winter runoff are presented. It has been concluded that heterogeneity in the time series of the river runoff is caused by natural-climatic and anthropogenic factors. At Mihalishki Village the average annual runoff is about 59.7 m3 s–1, the maximum 1570 m3 s–1, minimum summer–autumn is 22.0 m3 s–1, the minimum winter runoff is 17.3 m3 s–1, and the environmental runoff is 21.1 m3 s–1. A forecast of runoff changes for the River Viliya, depending on forecasted climate change using the “Atlas of Global and Regional Climate Projections” was made on the basis of four scenarios RCP8.5, RCP6.0, RCP4.5, RCP2.6. The results of research indicate that significant changes in runoff will not occur as the forecasted climatic parameters did not change significantly. A forecasted decrease in spring runoff was investigated, thus reducing the minimum runoff is not essential. In the event of possible low water periods the Vileyka reservoir resources, involving the Olkhovskoye and the Snigyanskoye water reservoirs, can be used for compensation measures, which may be considered as the most reliable backup source of industrial water supply for the Belarusian Nuclear Power Plant.

Onsite Reuse of Reclaimed Wastewater in Winter to Determine Potential for Pollutant Runoff

The objectives of this study were to determine the impact of reclaimed wastewater irrigation in freezing conditions on the quality of runoff and to observe how soils respond to irrigation in freezing temperatures. Onsite irrigation systems were constructed on 6 bermed lots on a hillside in Coshocton County, Ohio. All runoff was collected in gutters at the bottom of the hill. Two lots were irrigated with artificial reclaimed wastewater, 2 with well water, and 2 were unirrigated. Runoff was collected through an average winter (2013) and a severe winter (2014). The infiltrative capacity of the plots was maintained during the average winter and yielded runoff on only one day. During the severe winter, runoff occurred on 11 days; of the regulated pollutants, only ammonia was significantly higher than the control plots. The volumes that ran off were lower than what was applied and the contaminate concentrations were lower than what was applied and did not exceed National Pollutant Discharge Elimination System (NPDES) effluent limits. The indication is that even in the worst-case scenario most of the pollutants were assimilated on site.