Snowmelt Water Research Articles

Integrated hydrogeological and hydrogeochemical dataset of an alpine catchment in the northern Qinghai–Tibet Plateau

Abstract. Climate warming has significantly changed the hydrological cycle in cold regions, especially in areas with permafrost or seasonal frost. Groundwater flow and its interactions with surface water are essential components of the hydrological process. However, few studies or modeling works have been based on long-term field observations of groundwater level, temperature, hydrogeochemistry, or isotopic tracers from boreholes due to obstacles such as remote locations, limited infrastructure, and harsh work conditions. In the Hulugou catchment, an alpine catchment in the headwater region of the Heihe River on the northern Qinghai–Tibet Plateau (QTP), we drilled four sets of depth-specific wells and monitored the groundwater levels and temperatures at different depths. Surface water (including river water, glacier meltwater, and snow meltwater), precipitation, groundwater from boreholes, spring water, and soil water were sampled to measure the abundances of major and minor elements, dissolved organic carbon (DOC), and stable and radioactive isotopes at 64 sites. This study provides a dataset of these groundwater parameters spanning 6 consecutive years of monitoring/measurements. These data can be used to investigate groundwater flow processes and groundwater–surface water interactions on the QTP under global climate change. The dataset provided in this paper can be obtained at https://doi.org/10.5281/zenodo.6296057 (Ma et al., 2021b) and will be subject to further updates.

Controlling Factors and Characteristics of Peak Runoff in an Alpine Headwater Under the Asian Monsoon Climate

Understanding the mountain hydrological cycle, including runoff processes, is important for water-related disaster prevention. Although the process of peak runoff generation is closely related to water hazards, this process has not been clarified in alpine headwaters with large amounts of precipitation. In this study, we conducted hydrological observations to clarify runoff characteristics and factors that determine peak runoff in an alpine headwater under the Asian monsoon climate. Total precipitation during the summer period (3 months) was 1581.4 mm, and the water runoff responded quickly and clearly to rainfall events. Focusing on baseflow, the runoff was terminated when the snow cover area decreased. This suggested that snowmelt water plays an important role in maintaining baseflow in alpine headwaters under the Asian monsoon climate, like other alpine areas worldwide. In addition, peak runoff was not significantly correlated with soil wetness (as indicated by the antecedent precipitation index), whereas it was correlated with the amount of rainfall just before the generation of peak runoff. Therefore, the amount of rainfall before peak runoff in a single event was important in determining peak runoff. Focusing on the snowmelt season, we confirmed that the runoff increased even during small rainfall events. This indicated that snowpack melting is another factor determining peak runoff when the snowpack remains in the catchment. Considering the immediate runoff generation after rainfall events, direct observation of hydrometeorological data in situ is crucial to predict water-related disasters and consider countermeasures in alpine regions.

Contribution of Spring Snowmelt Water to Soil Water in Northeast China and Its Dynamic Changes

Snowmelt water in spring is an important source of soil water, which is critical to supporting crop growth. Quantifying the contribution of snowmelt water to soil water and its dynamic changes is essential for evaluating soil moisture and allocating agricultural water resources. In this paper, through controlled outdoor experiments, different snow depths and soil depth gradients were set; and snow, precipitation, and soil samples were collected regularly. To analyze the contribution of snowmelt water to soil water and its dynamic changes, the MAT-253 stable isotope ratio mass spectrometer was adopted for hydrogen and oxygen isotope analyses. The results showed that the snowmelt water for snow depths of 10 cm, 30 cm, and 50 cm all contributed to the 0–30 cm soil layer. The contribution increased with soil depth, contributing 8.13%, 8.55%, and 11.24%, respectively. The contribution of the snow cover at the same depth to the soil moisture at different depths also varied, i.e., the contribution increased with increasing soil depth. The snowmelt water retention time at depths of 10 cm, 30 cm, and 50 cm was inconsistent, i.e., it was the longest at 0–10 cm (average of 69 days), followed by 20–30 cm (average of 59 days), and the shortest at 10–20 cm (average of 54 days). The greater the snow depth, the shorter the retention time of the snowmelt water in the different soil layers. For surface soil, the contribution of the snowmelt water at greater depths was significantly different; while for deep soil, the contribution was more sensitive to the snow depth. Regardless of snow depth, soil contributions at different depths were significantly different. Precipitation also affected the contribution of the snowmelt water to the soil water, exhibiting different effects at different depths.

Morphodynamic evolution of paraglacial spit complexes on a tide-influenced Arctic fjord delta (Dicksonfjorden, Svalbard)

Recent global warming triggered pronounced geomorphic changes such as coastal retreat and delta progradation along the coastlines of the Arctic regions. Coastal morphodynamics and associated sediment transport at the Arctic fjord head remain relatively unexplored due to the logistically limited accessibility to the field area, especially at short-term temporal scales. A repeat survey using an unmanned aerial vehicle (UAV)-assisted photogrammetry was conducted to quantify the annual morphodynamics of gravel spit complexes developed on the tidal delta plain of the deglaciated Dicksonfjorden, Svalbard of Arctic. Results show that the spit morphodynamics varies in time and space with an overall downfjord increase in the growth and migration rate of the spits. The youngest spits elongated 22 m yr−1 and migrated landward 4.3 m yr−1 between 2015 and 2019, marking the most pronounced spit morphodynamics documented to date in the Svalbard fjord systems. The spit morphodynamics is driven primarily by longshore drift and to a lesser degree by overwash processes. Gravels constituting the spits originate from the unconsolidated debris-flow deposits of old alluvial fans, which locally retreat 0.5 m yr−1. The growth of the spit complexes is also fed by snow meltwater discharge on the alluvial fans, accounting for a downfjord imbrication of angular gravel layers that are intercalated with interlaminated sands and muds on the landward sides of the spits. The breached spits at the most upfjord location have remained stationary during the study period and presumably since the 1930s. Rapid delta progradation combined with an isostatic rebound after the Little Ice Age (LIA) has decreased spit morphodynamics on the tidal delta plain upfjord in Dicksonfjorden with infrequent and insignificant wave influence. Sparse distribution of the isolated spits signifies the intermittent spit development, which is constrained by the proximity to the protruded alluvial fans. The spit complexes in Dicksonfjorden highlight that climate change accelerates coastal geomorphic changes at the fjord head by enhancing wave intensity and regulating episodic sediment delivery that led to the downfjord shift in the locus of wave shoaling.

Mechanism of snowmelt infiltration coupled with salt transport in soil amended with carbon-based materials in seasonally frozen areas

In midlatitude seasonally frozen areas, the freeze–thaw cycle affects the movement of soil water, which increases the uncertainty in salt transport and aggravates the risk of soil salinization. Based on this, a two-year field study was established on the Songnen Plain, a seasonally frozen area in northern China. Four treatments were set up: (i) control, (ii) corn stover, (iii) biochar, and (iv) combined (joint application of biochar and corn stover). The modified soil underwent seasonal freeze–thaw cycling, accompanied by the evaporation and infiltration of snowmelt water, and the soil salt migration and diffusion characteristics were determined. Both biochar and corn stover regulated the pore structure of the soil and enhanced the infiltration capacity of snowmelt water; notably, the maximum soil moisture contents in the corn stover, biochar and combined treatments increased by 9.33%, 22.12% and 16.37%, respectively, compared with that in the control group. However, biochar with abundant functional groups increased the cation exchange capacity and promoted the migration of salt ions (i.e., Na+, K+ and Cl−), and the surface soil salt content in the biochar treatment was 0.12–0.53 g/kg lower than that for the other three modes during the infiltration period. Additionally, soil water evaporation carried salts upwards, which greatly increased the salt content of the surface soil. Conversely, biochar presented a strong water-holding capacity, which reduced the ineffective evaporation of soil water, while stover acted as a barrier to hinder the return of salt. Among the treatments, the synergistic transport ability of soil salt and water was the lowest in the combined treatment. Overall, the combination of biochar and corn stover had advantages in terms of soil salt leaching and offered a healthy, effective strategy for soil salinization control in cold areas.

A Novel Approach for Monitoring the Ecoenvironment of Alpine Wetlands using Big Geospatial Data and Cloud Computing

Alpine wetlands in western Sichuan plateau (WSCP) are located on the eastern edge of the Qinghai-Tibet Plateau (QTP), where the ecological environment is very sensitive to global climate change. Being naturally driven coupled with unreasonable human development activities, alpine wetlands have experienced serious ecological and environmental issues such as drought, inversion, and desertification. However, due to the limitations of data sources and calculation models, it is impossible for us to deeply understand the change mechanism and spatial difference of the ecological environment of the alpine wetland (EEAW) in previous studies. In view of this, an innovative approach for monitoring the EEAW change has been proposed in this paper. We employ the approach to perform the EEAW change trend analysis, and some meaningful characteristics were founded. Specifically, it includes the fol1owing aspects. The air temperature increase is relatively significant, while the precipitation change has obvious spatial differentiation, and even some region’s precipitation experienced a decrease especially in plot1. In Haizishan, Lugu Lake, and Bari Lake, we explored an interesting phenomenon that the precipitation increases first and then decrease, and the turning point occurred around 1999. Increases in air temperature and evaporation have aggravated the drought in high-latitude areas. The drought situation has been alleviated in high-altitude areas due to the acceleration of snow melt water. Wetland vegetation and biomass presented an overall increasing trend, but the degradation also occurs in some area, including Zoige and Lugu Lake area. The human activity disturbances of wetland degradation mainly include the settlements expansion, agricultural development, and the ecotourism prosperity. Among them, targeted poverty alleviation projects have accelerated the urbanization in WSCP, and the development of agriculture and tourism has increased the interference of wetlands. Additionally, we have used Landsat images and national wetland survey data (1999, 2013, and 2020 year) from the past two decades to verify the EEAW trend and confirm the reliability of the analysis results using this approach.

Влияние урбанизированных территорий на митотическую активность клеток меристемы корней лука репчатого (Allium cepa L.)

The article presents the results of the use of cytogenetic methods in assessing the impact of urbanized territories on the mitotic activity of cells of the onion root meristem Allium cepa L. The research was carried out on 4 sites with different anthropogenic load. The Allium test research method is based on the analysis of the values of the mitotic index of the meristem cells of the Allium cepa L. root sprouted on the melted snow water of the studied points. The study showed that pollution of urbanized territories has a mutagenic effect, causing the formation of chromosomal aberrations and other types of mitosis pathology in the cells of the apical meristem of the roots of Allium cepa L. Keywords: CYTOGENETIC METHODS, MITOTIC INDEX, ALLIUM TEST, ONION, URBANIZED TERRITORIES

Hydrogeological, hydrodynamic and anthropogenic factors affecting the spread of pharmaceuticals and pesticides in water resources of the Granada plain (Spain)

The anthropogenic organic contaminants contemplated in the environmental legislation, as well as those of emerging concern, threaten the quality of water resources to a degree that remains largely unknown. Contaminant exposure in the aquatic environment is a crucial element if a full understanding of the risk is pursued. There are still many uncertainties about the occurrence of organic pollutants and behavior in the hydro(geo)logical media in large scale areas. The case study of the unconfined aquifer of the Granada Plain (approximately 200 km2) is presented here. Two surface and groundwater monitoring campaigns were conducted (March 2017 and June 2018). In total, 41 out of 171 target organic pollutants were detected, at least once: 17 pharmaceuticals or drugs of abuse, 21 pesticides or their metabolites and three polyaromatic hydrocarbons. In addition, physico-chemical parameters were measured during the monitoring campaigns and hydrochemical parameters and stable isotopes (δ2H, δ18O, δ13C) were analyzed. Statistical tests confirmed the significance of seasonal changes for some of these parameters (e.g., EC, Cl-, F-, δ18O, δ13C), revealing the influence from snowmelt water input on streams and the intensification of irrigation. In March 2017, the group of pesticides (largely represented by triazines) predominated, whereas the frequency of detection of pharmaceuticals increased substantially in June 2018. Results suggest four main factors affecting the spatial and seasonal variation of organic pollutants in the aquifer: the anthropogenic factor determining the period of contaminant release throughout the year (pesticide application period and growth of tourism) along with irrigation practices that include reclaimed wastewater; unsaturated zone thickness; hydraulic gradient and river-groundwater hydraulic connection. The latter can be especially important in the case of those contaminants whose main path of entry into the aquatic environment occurs through wastewater discharge into streams (i.e., pharmaceuticals).

Adaptability of MODIS Daily Cloud-Free Snow Cover 500 m Dataset over China in Hutubi River Basin Based on Snowmelt Runoff Model

Global warming affects the hydrological characteristics of the cryosphere. In arid and semi-arid regions where precipitation is scarce, glaciers and snowmelt water assume important recharge sources for downstream rivers. Therefore, the simulation of snowmelt water runoff in mountainous areas is of great significance in hydrological research. In this paper, taking the Hutubi River Basin in the Tianshan Mountains as the study area, we used the “MODIS Daily Cloud-free Snow Cover 500 m Dataset over China” (MODIS_CGF_SCE) to carry out the Snowmelt Runoff Model (SRM) simulation and evaluated the simulation accuracy. The results showed that: (1) The SRM preferably simulated the characteristics of the average daily flow variation of the Hutubi River from May to October, from 2003–2009. The monthly total runoff was maximum in July and minimum in October. Extreme precipitation events influenced the formation of flood peaks, and the interannual variation trend of total runoff from May to October was increased. (2) The mean value of the volume difference (DV) during the model validation period was 8.85%, and the coefficient of determination (R2) was 0.73. In general, the SRM underestimates the runoff of the Hutubi River, and the simulation accuracy is more accurate in the normal water period than in the high-water period. (3) By analyzing MODIS_CGF_SCE from 2003 to 2009, areas above 3200 m elevation in the Hutubi River Basin were classified as permanent snow areas, and areas below 3200 m were classified as seasonal snow areas. In October, the snow area in the Hutubi River Basin gradually increased, and the increase in snow cover in the permanent snow area was greater than that in the seasonal snow area. The snowmelt period was from March to May in the seasonal snow area and from May to early July in the permanent snow area, and the minimum snow cover was 0.7%.

Comparing headwater stream thermal sensitivity across two distinct regions in Northern California

AbstractThermal regimes in headwater streams are critical for freshwater ecological condition and habitat resilience to disturbance, and to inform sustainable forest management. However, stream temperatures vary depending on characteristics of the stream, catchment, or region. To improve our knowledge of stream thermal regimes, we collected stream and air temperature data along eight headwater streams in two regions in Northern California. Five streams were in the Coast Range, which is characterized by permeable sandstone lithology, rain dominated precipitation regime, and dense coast redwood forests. Three streams were in the Cascade Range, which is characterized by fractured and resistant basalt lithology, snow dominated precipitation, and low to moderate density pine forests. We instrumented each stream with 12 stream temperature and four air temperature sensors during summer 2018. We compared stream thermal regimes and thermal sensitivity—slope of the linear regression between daily stream and air temperature—within and between study regions. Mean daily stream temperatures were ~4.7°C warmer in the Coast Range but were less variable (SD = 0.7°C) compared to the Cascade Range (SD = 2.3°C). Median thermal sensitivity was 0.33°C °C−1 in the Coast Range and 0.23°C °C−1 in the Cascade Range. We posit that the volcanic lithology underlying the Cascade streams likely supported discrete groundwater discharge locations of cold snowmelt water, which dampened thermal sensitivity. At locations of apparent groundwater discharge in these streams, median stream temperatures rapidly decreased by 2.0–7.0°C relative to locations 70–90 m upstream. In contrast, thin friable soils in the Coast Range likely contributed warmer, rain dominated baseflow from shallow subsurface sources, which strongly co‐varied with air temperature and generally warmed downstream (up to 2.1°C km−1). Our study revealed distinct longitudinal thermal regimes in streams with contrasting lithology, precipitation regimes, and stand densities suggesting that streams in these different regions may respond differentially to forest disturbances or climate change.

Earlier snowmelt predominates advanced spring vegetation greenup in Alaska

Snow is considered a vital component in the northern climate system, however, our understanding of the impacts of snowmelt on spring phenological shifts is still limited for high-latitude ecosystems. In this study, we analyzed the start of growing season (SOS) and its response to the process of snowmelt over 2000–2019 using multiple ground observations, satellite data products, and climate datasets in Alaska and part of Canada Yukon among five ecoregions. We found that the earlier snowmelt resulting from warming spring dominates the advanced spring vegetation phenology in the region. Spring vegetation greenup follows the start of snowmelt (SOM). During 2000–2019, the SOM and SOS advanced in a similar spatial pattern across the ecoregions, and SOS experienced further advancement than SOM. On average, SOS advanced about 0.49 days per day of SOM advancement. The impacts of snowmelt on vegetation phenology are largely driven by the snowmelt-induced synergistic changes in soil temperature and soil water content. As snowmelt starts, the infiltration of snowmelt water and insulation of the remaining snow cover stimulate the vegetation activities below the snow. The responses of SOS to the snowmelt phenology varied among the different ecoregions are associated with the varied climate backgrounds and vegetation types. Greater SOS and SOM advancements were found in the taiga-tundra ecotone, while lower changes were detected over the tundra. This study suggests that the snow cover and snowmelt phenology should be considered to better understand the vegetation seasonality under climate change in the high latitudes.

Potential recharge sources and origin of solutes in groundwater in the central Qinghai–Tibet Plateau using hydrochemistry and isotopic data

Study regionThe Nagqu River Basin in the central part of the Qinghai–Tibet Plateau, China. Study focusGroundwater flow systems in permafrost regions are characterized by a unique circulation. Understanding the groundwater circulation mechanism is essential for studying the hydrological effect of permafrost degradation in alpine regions. In this study, potential water sources and origin of solutes in the groundwater of a typical alpine region were studied using hydrochemistry, 18O, 2H and 3H analyses. This research is essential for studying the hydrological effects of permafrost degradation. New hydrological insights for the regionUpon moving from the mountainous region to the plains, the renewal rate decreases from 10.5% to 0.6% and the mean transit time increases from 5–30 to 20–32 years. Groundwater is mainly recharged by ground ice meltwater and infiltration of glacier meltwater, snow meltwater and precipitation in mountainous areas, and by deep groundwater near faults. Discharge to surface water, evaporation, and overflow into springs are the main drainage modes. Water/ice–rock/soil interactions, such as dissolution of aluminosilicate minerals, are the main factors affecting the hydrochemical evolution. This study provides a data-driven approach for understanding groundwater recharge and evolution in similar systems.

Factors controlling the rise and fall of groundwater level during the freezing-thawing period in seasonal frozen regions

Freezing- and thawing-induced variations of groundwater level and the corresponding changes in water storage in the saturated zone have been observed in regions with a shallow water table. However, the vertical migration of water under the effect of the freezing-thawing process on shallow groundwater has not been accurately quantified and the influencing factors of groundwater level dynamics during the freezing-thawing period remain unclear. Reasonable representation of this process on the field scale is very important for improving our understanding of water budgets during the freezing-thawing cycle. In this study, we investigated the main factors controlling groundwater level fluctuations during the freezing-thawing period at two sites in Northeast China through comparative analyses of long-term field observations of air temperature, precipitation, snow depth, liquid soil water content, soil water temperature, and fluctuations of groundwater level. We found that the seasonal variations in groundwater table coincided with the soil frost freezing-thawing seasonal cycle, which exhibited a “V” shape. Freezing-induced groundwater decline occurred only when the maximum depth of effect of freezing and thawing overlapped with the maximum height of capillary rise in unconfined groundwater. Moreover, the decline was controlled by air temperature, snow cover, soil media properties, and soil water distribution. By comparing the change trends of groundwater level and calculating the water budget, the process of the rise of groundwater level could be further divided into three stages, during which groundwater was recharged by frost melt water and snowmelt water. Among them, snowmelt water had a limited contribution, accounting for less than 20% of the total recharge. The results have potential applications in the development of reasonable water-management plans for irrigation, using which soil salt can be washed out and suitable soil thermal and moisture conditions can be maintained for winter crops or farming in the next year.

Effects of snow manipulation on larch trees in the taiga forest ecosystem in northeastern Siberia

Changes in winter precipitation (snow) may greatly affect vegetation by altering hydrological and biochemical processes. To understand the effects of changing snow cover depth and melt timing on the taiga forest ecosystem, a snow manipulation experiment was conducted in December 2015 at the Spasskaya Pad experimental larch forest in Eastern Siberia, which is characterized by a continental dry climate with extreme cold winters and hot summers. Variables including soil temperature and moisture, oxygen and hydrogen isotope ratios of soil moisture and stem water, foliar nitrogen and carbon contents and their isotopes, phenology, and soil inorganic nitrogen were observed at snow removal (SNOW−), snow addition (SNOW+), and CONTROL plots. After snow manipulation, the soil temperature at the SNOW− plot decreased significantly compared to the CONTROL and SNOW+ plots. At SNOW− plot, snowmelt was earlier and soil temperature was higher than at other plots during spring because of low soil moisture caused by less snowmelt water. Despite the earlier snowmelt and higher soil temperature in the SNOW− plot in the early growing season, needle elongation was delayed. Leaf chemistry also differed between the CONTROL and SNOW− plots. The needle nitrogen content in the SNOW− plot was lower in the middle of July, whereas no difference was observed among the three plots in August. The soil inorganic nitrogen content of each plot corresponded to these results. The amount of soil ammonium was lower in the SNOW− plot than in the other plots at the end of July, however, once production started in August, the amount of soil ammonium in the three plots was comparable. Extremely low soil temperatures in winter and freeze–thaw cycles in spring and dry soil condition in spring and early summer at the SNOW− plot may have influenced the phenology and production of soil inorganic nitrogen.

Geochemical studies of snow over mineral accumulations under conditions of their overlap by sedimentary rocks of the platform cover

In geochemical exploration, the seasonal snow cover is a convenient natural material for identifying under deep covered mineral accumulations. Snow has shielding and accumulating properties sufficient for the occurrence of dispersion of geochemical halos. The snow horizon of geochemical sampling is protected from atmospheric and landscape factors of replenishment of its chemical composition for most of the winter. The filtrate of snow melted water is cleaned of large-sized solid material, and chemical compounds are in the dissolved and finely dispersed solid phase of submicron dimension. Therefore, in terms of the physical and chemical properties of the analyzed substance, snow geochemical survey is close to selective methods. Test surveys were carried out on single profiles of snow sampling at two ore occurrences (Au, Pb-Zn) and an oil field within the West Siberian plate. Concentrations of a wide range of chemical elements in snowmelt water filtrate were determined by the ICP-MS method. As a result of statistical processing of geochemical data, a low variability of concentrations of chemical elements has been established. Correlation and regression analyzes demonstrate the presence of linear dependences in the distribution of trace elements, which reflect the ability of elements to form easily soluble and hardly soluble occurrence forms. The variability of the local geochemical background is mainly due to the content of hardly soluble phases that entered the snow layer during its deposition on the ground. Presumably, they are represented by particles of aeolian dust, needles and scales of tree bark captured by snow from tree and shrub crowns. In the area of study with high heterogeneity of elementary landscapes, the influence of this factor is comparable in amplitude to the contrast of superimposed geochemical halos. Normalization of the concentrations of trace elements by the sum of rare earth elements (REE) allows to strengthen the useful geochemical signal. Geochemical anomalies detected in snow in space quite accurately coincide with the position of mineral deposits buried the platform cover terrains, and also find confirmation in the chemical composition of soils and soil air. The good potential of snow metallometric surveying for prospecting of deep-seated mineral resources needs to be confirmed by studying the vertical and lateral migration of chemical elements in the snow cover.

Растительность суффозионных западин на севере подтаежной подзоны Западной Сибири

Suffusion depressions are closed relief depressions on the flat surfaces of watersheds and terraces. They are formed during water erosion (suffusion) of loesses and loess-like loams. Therefore, the distribution of the depressions is associated with that of the soil-forming rocks - along the south of the taiga zone and further south in the subtaiga, forest-steppe, and steppe. The depressions are islands of preserved natural vegetation, since flat surfaces were plowed over a large area. Previous studies have shown an increase in moisture from the edge to the center of the depressions, and a rather high trophicity of habitats due to the richness in nutrients of loesslike loams. Birch and aspen forests along the edges of the depressions are actively studied. Wet plant communities in the inner parts of the depressions are less studied -mainly in the center of the subtaiga and to the south. The purpose of our work is to study vegetation of the depressions in the northern part of the subtaiga of Western Siberia. The study area is the southeastern part of the West Siberian Plain (55°30'-56°55N, 83°27'-84°45'E) (See Fig. 1). The diameter of the depressions is 20-100 m, the depth usually does not exceed 1.5 m. In spring, the depressions are usually flooded with snow-melt waters until the end of May (sometimes mid-June). The releves of plant communities were made with reference to the relief elements (slope and center). A total of 120 releves were used to describe the vegetation of the depressions, including a list of the species which each layer of the community comprises, and their abundance (projective cover, %). An ecological-floristic classification was carried out using the Braun-Blanquet method. Environmental factors (soil moisture, soil trophicity, soil nitrogen concentration, and soil acidity) were assessed by the phytoindication method using the indicator values of plants developed by Tsyganov. The data were processed and calculated in Excel. We identified five types of depressions with different series of plant communities depending on their shape and drainage properties of soils (See Fig. 3). Based on these five types, a generalized hydrological series of plant communities in the depressions was identified. However, with account to the richness and availability of nutrients in soils, two variants of the hydrological series were considered. Under poorer (meso-trophic) and weakly acidic conditions, the communities of the class Brachypodio-Betuletea on the edge (in the upper part of the slope) of the depressions are further replaced by the swampy communities of the class Alnetea glutinosae on the slope and also in the center (See Fig. 3, a, c, e). In richer (mesoeutrophic) and near-neutral conditions on the slopes of the depressions, the communities of the class Brachypodio- Betuletea on the edge are replaced by the communities of the class Alno-Populetea on the slope and further by the communities of the class Alnetea glutinosae in the center of the depression (See Fig. 3, b, d). The location of the suffusion depressions in the north of the subtaiga and the associated relatively high moistening of habitats determine the structure of the hydrological series where mesophilic communities of the class Brachypodio-Betuletea occupy only the upper part of the slope (See Fig. 4, a). Hygromesophilic and hygrophilic communities of the classes Alno-Populetea and Alnetea glutinosae are formed in the rest of the slope and in the center. Eutrophic species in the plant communities of the depressions are not abundant due to the low mineralization of soil and ground waters. The article contains 4 Figures, 1 Table, and 40 References. The Authors declare no conflict of interest.

Development of the snowmelt prediction model using Artificial Intelligence (AI)

Droughts and abnormal heavy rains have frequently occurred in Japan due to the effects of climate change in recent years, and flexible operations that maximize the functions of dams are required. Especially in cold snowy regions, snowmelt water is stored in a dam to cover water demand from early spring to early summer, but during the snowmelt season, a sudden rise in temperature and heavy rain could cause large-scale floods. Therefore, the highly accurate prediction of dam inflow during the snowmelt season is extremely important from the viewpoint of effective use of water resources and prevention of snowmelt floods. On the other hand, in recent years, research utilizing Artificial Intelligence (AI) has also been promoted in the hydrological field. This study clarified the problems of the conventional physical model (rainfall runoff model) and the prediction model by AI for the inflow of the dam during the snowmelt season in order to support efficient dam management. Then, by constructing a semi-physical model that complements the problems of the physical model and the AI model, we developed a more accurate model for predicting the inflow of snowmelt water during the snowmelt season compared to the single model.

An Improved Zhang's Dynamic Water Balance Model Using Budyko‐Based Snow Representation for Better Streamflow Predictions

AbstractUnderstanding the water balance of a catchment in relation to its regional climate forcings and catchment characteristics is critical for predicting current and future water resources amid changing climate and land cover. This study intends to improve Zhang's monthly water balance model (a physics‐based conceptual hydrologic model) that reflects the physical partitioning process of the hydrological cycle at the basin level based on regional climate and catchment characteristics. The existing model does not include snow process and has confronted evident limitations in snow‐affected areas, which is a critical aspect since snowmelt water has been a significant source of water resources for many regions, especially in the temperate and frigid zones. We introduce a snow module based on surface energy balance and Budyko‐limits on melting and combine it with the existing water balance equations. Moreover, monthly parameterization is applied to the model to better explain the time‐varying hydrological characteristics of a catchment. The proposed model involves five different monthly parameters, which determine the physical partitioning process of the hydrological cycle, and they are regionally calibrated and validated under Budyko‐type constraints. The model is applied to 1,210 basins across the continental United States (CONUS), and the simulated streamflow is compared to the observed data. The proposed model significantly outperformed the original model, improving the median NSE by 31% (from 0.51 to 0.67) and increasing the number of catchments with an acceptable NSE by 58%. The spatial variability of the basin characteristics across the CONUS is also investigated based on the calibrated parameters.

Variation in water supply leads to different responses of tree growth to warming

Global climate change, characterized by changes in precipitation, prolonged growing seasons, and warming-induced water deficits, is putting increased pressure on forest ecosystems globally. Understanding the impact of climate change on drought-prone forests is a key objective in assessing forest responses to climate change. In this study, we assessed tree growth trends and changes in physiological activity under climate change based on measurements of tree ring and stable isotopes. Additionally, structural equation models were used to identify the climate drivers influencing tree growth for the period 1957–2016. We found that the mean basal area increment decreased first and then increased, while the water use efficiency showed a steady increase. The effects of climate warming on tree growth switched from negative to positive in the period 1957–2016. Adequate water supply, especially snowmelt water available in the early critical period, combined with an earlier arrival of the growing season, allowed to be the key to the reversal of the effects of warming on temperature forests. The analysis of structural equation models (SEM) also demonstrated that the growth response of Pinus tabuliformis to the observed temperature increase was closely related to the increase in water availability. Our study indicates that warming is not the direct cause of forest decline, but does indeed exacerbate droughts, which generally cause forest declines. Water availability at the beginning of the growing season might be critical in the adaptation to rising temperatures in Asia. Temperate forests may be better able to withstand rising temperatures if they have sufficient water, with boosted growth even possible during periods of rising temperatures, thus forming stronger carbon sinks.

Surface flow of melted snow water on the central Russian upland

In areas with a pronounced relief, water erosion causes great harm to agriculture and other sectors of the national economy. It leads to the destruction of the soil cover, a reduction in the area of arable land, a decrease in fertility, the removal of erosion products into floodplains, the siltation of ponds and rivers and the destruction of the road network. The scientific goal was to identify the influence of the main natural factors (snow reserves, freezing and soil moisture) on the formation of the spring melt water runoff on the plow. To study the questions raised, the water-balance method was used with the use of runoff sites. Observations showed that the formation of the melt water runoff depended on the depth of soil freezing. With shallow soil freezing up to 50 cm, there was no runoff. All the melt water was absorbed by the soil. As a result of 30 years of research (1991-2020), it was found that the average annual runoff on the plow was very weak - 3.8 mm on the scale of Surmach, the runoff coefficient is 0.05, shallow soil freezing - 19-28 cm, duration of snow melting - 16 days.