Runoff Characteristics Research Articles

Thin foil body-shield resuscitation barrier device to protect from blood: an experimental study

In times of collective concern about pandemics, body-shield resuscitation barrier devices are more and more considered to protect against transmission of different pathogens between rescuers and patients. The objective of this experimental study was to investigate the characteristics of blood drops dispersed on the surface of four different foils suitable for blanketing patients during resuscitation. We analyzed run-off characteristics of blood stains depending on surface properties of polyvinyl chloride, polyethylene, polyethylene terephthalate and aluminum-coated polyethylene terephthalate. Confocal fluorescence microscopy revealed less cellular density and lack of fibrin networks in blood stains on the four foil surfaces than on paper towel. Delayed clotting went along with larger areas of contamination indicating a greater likelihood of coming into contact with potential germs but a smaller chance of contracting an infection. Space blankets as obligatory components of first aid kits are readily available for rescuers and serve as a mechanical barrier between rescuers and patients during resuscitation.

Effects of grass density on the runoff hydraulic characteristics and sediment yield in gully headcut erosion processes

AbstractVegetation plays a crucial role in gully headcut erosion. However, little is known about how grass influences runoff hydraulics, soil erosion and headcut erosion processes. A series of rainfall and scouring experiments were conducted on four plots to elucidate the effect of the density of Agropyron cristatum (L.) Gaertn (planting spaces: 20 × 20 cm2, GA1; 15 × 15 cm2, GA2; 10 × 10 cm2, GA3; bare land as control, BL) on runoff hydraulics and soil erosion during gully headcut erosion. The velocity, Reynolds number (Re), runoff shear force (τ) and stream power (ω) of the BL increased exponentially with time (P < 0.01). However, for the grassland, most parameters increased linearly with time (P < 0.01). The Froude number (Fr) of the BL and grassland significantly decreased linearly and exponentially, respectively, with time (P < 0.01). For τ, the grass tableland needed to develop for a period of time to restrain it. The runoff of the BL tableland and gully head was supercritical turbulent, while that of the grassland was more dispersed. The existence of a gully head increased the jet velocity by 2.97%–67.19%, which increased the dispersion degree of the runoff. The runoff energy showed a significant exponential increase with time (P < 0.05). Compared with that of the BL, the energy consumption of the runoff from the grassland increased by 4.10%–31.81%. During gully headcut erosion, the BL was primarily cut down to the tableland by runoff, while the grassland was cut down to the headwall by on‐wall flow. As the density increased, the benefit of sediment reduction increased, reaching a maximum of 66.79%. The collapse of the BL primarily occurred in the upper part of the headwall during the early experimental stage. The frequency and space–time ranges of the collapse of the grassland were larger than those of the BL. The gravity erosion types of the BL were headwall collapse and gully bank collapse, while those of the grasslands were headwall collapse and root‐soil composite collapse.

Lithologic control on parameters of conceptual rainfall-runoff model and runoff characteristics: a case study of the Xinanjiang model

Lithologic control on parameters of conceptual rainfall-runoff model and runoff characteristics: a case study of the Xinanjiang model

Lithologic control on parameters of conceptual rainfall-runoff model and runoff characteristics: a case study of the Xinanjiang model

Lithologic control on parameters of conceptual rainfall-runoff model and runoff characteristics: a case study of the Xinanjiang model

Morphometric Analysis of Chilenahalli Micro-watershed in the North-eastern Dry Zone of Karnataka using GIS and Remote Sensing Techniques

The structure and landform of watershed and their associated stream networks are described mainly by their morphometric parameters and Watershed analysis based on morphometric parameters is very important for watershed planning, since it gives an idea about the basin characteristics regarding slope, topography, soil condition, runoff characteristics, surface water potential and quantify the linear, areal and relief aspects of watershed. Geographic information system and remote sensing techniques were employed for the identification of morphological features, drainage pattern and its planning in basin area. The Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) 30m resolution was used to digitize study watershed and generate drainage pattern and analysis done using GIS software and excel spreadsheet. The study reveals that Chilenahalli micro-watershed designated as 4thstream order and drainage indicate dendritic pattern with mature geomorphic stage and stream order verifies the Horton’s law of stream number. The Mean Bifurcation Ratio was found to be 4.46, which indicates low rainfall, shallow weathering and low dissection of the valley and it shows low to medium relief aspect during investigation of the basin. This can be visualised using DEM, relief ratio, ruggedness number, and slope maps of the study area. The drainage density was found to be 2.13 km/km2which indicate a low class Dd value, thereby indicating a poorly drained watershed with low response to hydrological parameters. The texture ratio of the micro-watershed is 3.52, which indicated coarse texture of drainage basin and the values of Form Factor, Circulatory ratio and Elongation ratio may imply an oval shape of the basin with a slightly elongated main stream and the length of overland flow values in this study is 0.23 km which shows moderate infiltration and percolation characteristics of soil. The study which also helps in planning erosion control strategy, prioritization of watershed and management practices for soil and rainwater conservation. The research study helps to formulate the selection and adoption of crop management practices by preparing soil map of the watershed in future.

Characteristics of runoff and infiltration processes on slope with intergrown biocrusts and herbs

Biocrusts and herbs coexist in arid and semi-arid areas, playing an important role in soil and water conservation. However, the combined effects of biocrusts and herbs on process and mechanism of runoff and infiltration on slope are still unclear. In this study, simulated rainfall experiments with four treatments, including bare soil, biocrusts, Stipa bungeana and S. bungeana+biocrusts, were designed to investigate runoff, infiltration process and hydrodynamic characteristics of herbs and biocrusts on slope. The results showed that the runoff under the two treatments with biocrusts was stable. The total runoff of four treatments was in the following order: biocrusts > S. bungeana+biocrusts > bare soil > S. bungeana, indicating that biocrusts could inhibit soil infiltration and S. bungeana could promote soil infiltration. At soil depths of 16 cm and 24 cm, the cumulative infiltration of biocrusts treatment was significantly less than that of S. bungeana+biocrusts treatment, suggesting that with the increases of soil depth, S. bungeana reduced the negative effect of biocrusts on soil infiltration. The Froude number was greater than 1 under bare soil and less than 1 under other treatments, which was subcritical flow. Compared with the runoff kinetic energy of the bare soil treatment, the treatments of biocrusts, S. bungeana, and S. bungeana+biocrusts were reduced by 83.3%, 59.5%, and 88.1%, respectively. The variations of hydrodynamic parameters indicated that the role of biocrusts is greater than S. bungeana in regulating runoff.

Riparian buffer strips influence nitrogen losses as nitrous oxide and leached N from upslope permanent pasture

Riparian buffer strips can have a significant role in reducing nitrogen (N) transfers from agricultural land to freshwater primarily via denitrification and plant uptake processes, but an unintended trade-off can be elevated nitrous oxide (N2O) production rates. Against this context, our replicated bounded plot scale study investigated N2O emissions from un-grazed ryegrass pasture served by three types of riparian buffer strips with different vegetation, comprising: (i) grass riparian buffer with novel deep-rooting species, (ii) willow (young trees at establishment phase) riparian buffer, and (iii) deciduous woodland (also young trees at establishment phase) riparian buffer. The experimental control was ryegrass pasture with no buffer strip. N2O emissions were measured at the same time as total oxidized N in run-off, and soil and environmental characteristics in the riparian buffer strips and upslope pasture between 2018 and 2019. During most of the sampling days, the no-buffer control treatment showed significantly (P < 0.05) greater N2O fluxes and cumulative N2O emissions compared to the remainder of the treatments. Our results also showed that the grass riparian buffer strip is a sink of N2O equivalent to − 2310.2 g N2O-N ha−1 day−1 (95% confidence interval:−535.5 to 492). Event-based water quality results obtained during storms (12 November 2018 and 11 February 2019) showed that the willow riparian buffer treatment had the highest flow-weighted mean N concentrations (N-FWMC) of 0.041 ± 0.022 and 0.031 ± 0.015 mg N L−1, when compared to the other treatments. Our 9-month experiment therefore, shows that riparian buffer strips with novel deep-rooting grass can therefore potentially address emissions to both water and air. The results imply that over a shorter timeline similar to the current study, the grass riparian buffer strip can potentially address N emission to both air and water, particularly when serving a permanent pasture in similar settings as the current experiment.

Runoff of Russian Rivers under Current and Projected Climate Change: a Review 2. Climate Change Impact on the Water Regime of Russian Rivers in the XXI Century

The present overview is the second part of the article “Runoff of Russian Rivers Under Current and Projected Climate Change: A Review,” which focuses on modern assessment of possible changes in the runoff characteristics of Russian rivers in the XXI century under projected global climate change. The article considers two assessment groups: based on (1) climate models and (2) hydrological models, using data of climate model simulations. The review mainly presents works that have been published over the last 7−8 years, since the release of the previous IPCC Assessment Report and the National Assessment Report of Roshydromet. It is noted that, in recent years, there has been a shift regarding the methodology of assessment of hydrological consequences of projected climate change—from simulations based on climate models to simulations based on regional hydrological models that allow one to simulate characteristics of the water regime of rivers over a historical period more accurately and to assess their possible changes in the future with lower uncertainty than climate models.

ПРОСТРАНСТВЕННО-ВРЕМЕННАЯ СТРУКТУРА ПОЛЕЙ РЕЧНОГО СТОКА В БАССЕЙНЕ ДОНА В УСЛОВИЯХ ИЗМЕНЕНИЯ КЛИМАТА

Changes in the spatial structure of runoff fields in the Don River basin due to the revealed non-stationarity of the hydrological regime are investigated. It is shown that the spatial correlation of the spring flood runoff layers, winter and summer-autumn low runoff, as well as snow storage have changed significantly. The chaotic pattern of the spatial correlation was gained, as a result of which the fields of the studied runoff characteristics became heterogeneous and anisotropic.

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.

The relationships between basin conditions and long-term runoff characteristics in Japanese basins with little snow by comparing tank model parameters

The relationships between basin conditions and long-term runoff characteristics in Japanese basins with little snow by comparing tank model parameters

Laboratory Investigation on Pollutant Removal Effect of Purification Materials for Porous Asphalt Pavement

Purification materials have been widely applied as filter media in best management measures including wetlands, bioretention systems, and so forth, whereas their application in permeable pavement is limited and needs further research. This paper aims to explore the feasible applications of water purification materials in permeable pavement materials and structures. Based on laboratory rainfall test and static adsorption test, the possible application of three types of water purification materials, including diatomite, quartz sand, and straw biochar, in porous asphalt pavement and their pollutant removal effect were investigated. The results show that the filter layers can effectively increase the total suspended solids removal rate to 60%–80%. And when the purification materials are applied as alternative fillers in porous asphalt mixture (PA), they can enhance the removal effect of dissolved pollutants, especially heavy metals, by their special chemical properties and the positive influence on microscopic pore structures of PA. The adsorption effect of PA on pollutants is closely related to the environment temperature. The PA adsorption of nutrients and Cu increases with the increase of temperature, but the adsorption effect of Cr is better at lower temperatures. The pseudo-first-order model and the pseudo-second-order model can properly describe the adsorption process of heavy metals Cu and Cr by PA, respectively. The purification schemes that present purification effects under different runoff pollution characteristics are recommended as well.

Analysis on the Source Tracing and Pollution Characteristics of Rainfall Runoff in the Old Urban Area of Nanning City

Rainfall runoff is one of the important sources of urban river pollution. In order to understand the pollution characteristics of rainfall runoff, the synchronous sampling and monitoring of rainfall runoff in the old urban area of Nanning were carried out; the pollution condition, initial scouring effect, and pollution contribution ratio of different underlying surfaces under different rainfall conditions were analyzed; and the calculation method and influence factor analysis of initial scouring of runoff pollution were discussed. According to the underlying surface of the vegetable market in the old urban area, the selection standard and necessity of the underlying surface of rainfall runoff were discussed. The results showed that the average concentration (EMC) of COD and TSS in roads and vegetable markets were greater than those in green spaces and roofs in the runoff pollution of the old urban area of Nanning, and the EMC values of nutrient pollutants in field rainfall runoff were ranked in decreasing order as vegetable markets, green spaces, roofs, and roads. Under the condition of heavy rain, each underlying surface had an obvious initial scouring effect, the average value of initial scouring coefficient (b) was 0.67, and there were many pollutants transported by roads and green spaces at the initial stage. Under light rain and moderate rain conditions, there was no obvious initial scouring effect, and the average b values were 0.83 and 0.94, respectively. The b value calculated by the whole process was preferred for evaluating the scouring effect. Based on multivariate statistical analysis, the EMC value of TSS in road runoff was significantly positively correlated with the total rainfall duration (RD), and the EMC value of TN in green land runoff was significantly negatively correlated with the average rainfall intensity (ARI). Whether the vegetable market was considered as the underlying surface had a great impact on the calculation results of nutrient pollution load but had little impact on the calculation results of COD and TSS load. The difference percentage of nutrient pollution load under heavy rain reached 80%. Under this condition, the difference percentage of pollutant EMC between the road and vegetable market reached 1012%.

Surface-subsurface hydrological processes of rainwater harvesting project in karst mountainous areas indicated by stable hydrogen and oxygen isotopes

Rainwater harvesting (RWH) projects in a decentralized way are significant measures to deal with the water scarcity dilemma in rural areas of the karst mountains in Southwest China at present. Due to the differences in cistern construction features and geomorphological positions, the water sources of cisterns were characterized by marked spatial variability, and the recharge stability of cisterns was strongly influenced by precipitation seasonality. Nevertheless, in hydrological processes on karst hillsides, the identification of different runoff types of RWH has not been sufficiently studied. The stable isotopes of hydrogen and oxygen of eleven cisterns and epikarst springs in subtropic cockpit karst landforms were monitored from 2020 to 2021 to investigate the runoff characteristics in RWH. Evaporative fractionation in different hydrological cycles is the predominant factor regulating the stable isotopic signature of cistern water. The results indicated that the typical roles that occurred in the recharge process contributed differently to water harvesting, with surface runoff (SR) and subsurface runoff (SSR) contributing much more than rainwater (RW) and epikarst runoff (ER). Three mixing patterns were proposed by end-member analysis in which SR + SSR, ER, and RW were three end members with indicators of isotopic value and the total dissolved solids (TDS). The recharge of SR + SSR was the predominated source, which contributed to 64% of the total water resources collected through RWH in the rainy season. In addition, the influence of various runoffs on the recharge stability of the cistern can be reflected by the multiple statistical analysis of isotopic fluctuation. Poor recharge stability is caused by excessive SR + SSR, whereas a higher percentage of ER and RW leads to better recharge stability. The applied method of hydrological process analysis is significant to the cistern water resources management in rural areas of the karst mountains.

Particle size characteristics of sediment by sheet erosion and their responses to related parameters on a Loess hillslope: a plot-scale study

Abstract Particle size distribution (PSD) of sediment by sheet erosion not only indicates erosion behaviors, but also provides a basis for potential nutrient losses. PSDs are significantly influenced by topographic, rainfall, and associate runoff characteristics, such as rainfall intensity (I), rainfall kinetic energy (KE), slope gradient (S), runoff velocity (v), and stream power (Ω), while their effects have not been fully understood so far. To fill this research gap, in this study, simulated rainfall experiments were conducted to investigate the characteristics of effective and ultimate PSDs of sediments, as well as their responses to related parameters, under five levels of I and S. The results showed that (1) for effective PSDs, there was a significant enrichment of clay-sized and silt-sized fractions (P&amp;lt;2μm and P2–50μm) in sediment (percentage range: 12.11–20.64% and 57.09–65.94%), whereas there was a depletion of sand-sized fractions (P50–250μm and P250–2000μm). The ultimate PSDs of sediment were, however, similar to the soil matrix under experimental conditions. (2) With an increase in I and S, P&amp;lt;2μm and P2–50μm decreased exponentially or logarithmically, and P50–250μm and P&amp;gt;250μm increased correspondingly. The contribution rates (PCs) of the effect of I on clay-, silt-, fine-sand-, and coarse-sand-sized fractions in sediment were 23.44, 35.45, 29.09, and 56.82%, respectively, whereas the PCs of that of S were 56.54, 24.42, 59.89, and 31.47%, respectively, indicating that S plays a more pivotal role in influencing P&amp;lt;2μm and P50–250μm, whereas P2–50μm and P&amp;gt;250μm were more sensitive to I than to S. (3) The aggregation ratio (AR) for the fractions of different sizes indicated that clay-sized particles tend to be transported as aggregates, while silt-sized particles tend to be transported as primary particles. A higher I or steeper S leads to a larger proportion of particles being transported as aggregates. (4) KE, Ω, and unit stream power (U) were the most correlated parameters influencing effective PSDs. Equations were finally established using KE, Ω, and U to predict the effective PSDs of sediment by sheet erosion. This study can further the understanding of the sheet erosion process and provide a scientific basis for the establishment of a sheet erosion model.

Research of possibility of application of catchment complex geo/morphological characteristic for determination of a wide spectrum of hydrological characteristics

The situation that arises when calculating the hydrological characteristics of poorly studied and unexplored rivers is characterized. The possibility of using the "flow rate" value to determine the runoff characteristics is considered. A calculation method is proposed with the Transbaikal Kray Amur River basin as a study case.

Effect of land use land cover change on runoff characteristics using curve number: a GIS and remote sensing approach

Effect of land use land cover change on runoff characteristics using curve number: a GIS and remote sensing approach

Explaining the Variability in High‐Frequency Nitrate Export Patterns Using Long‐Term Hydrological Event Classification

AbstractRunoff events play an important role in nitrate export from catchments, but the variability of export patterns between events and catchments is high and the dominant drivers remain difficult to disentangle. Here, we rigorously asses if detailed knowledge on runoff event characteristics can help to explain this variability. To this end, we conducted a long‐term (1955–2018) event classification using hydro‐meteorological data, including rainfall characteristics, soil moisture and snowmelt, in six neighboring mesoscale catchments with contrasting land use. We related these event characteristics to nitrate export patterns from high‐frequency nitrate concentration monitoring (2013–2017) using concentration‐discharge (CQ) relationships. Our results show that low‐magnitude rainfall‐induced events with dry antecedent conditions exported lowest nitrate concentrations and loads but exhibited highly variable CQ relationships. We explain this by a low fraction of active flow paths, revealing the spatial heterogeneity of nitrate sources within the catchments and by an increased impact of biogeochemical retention processes. In contrast, high‐magnitude rainfall or snowmelt‐induced events exported highest nitrate concentrations and loads and converged to similar chemostatic export patterns across all catchments, without exhibiting source limitation. We explain these homogeneous export patterns by high catchment wetness that activated a high number of flow paths and by higher nitrate availability during high‐flow seasons. Long‐term hydro‐meteorological data indicated an increased number of events with dry antecedent conditions in summer and a decreased number of snow‐influenced events. These trends will likely continue and cause increased nitrate concentration variability during low‐flow seasons and changes in the timing of nitrate export peaks during high‐flow seasons.

Characteristics of discharge frequency and their effects on flood channel formation in the middle and lower reaches of the Yangtze River before/after the impoundment of the Three Gorges Reservoir

三峡水库蓄水前后长江中下游流量特征变化及其对造床作用的影响一直受到学者的关注.采用枝城等6个水文站日均流量资料，分别统计了各站流量的经验频率分布，检验了8种概率密度函数的适用性，并讨论了三峡水库蓄水前后流量频率分布特征与造床流量的关系.研究表明：长江中下游干流洪中枯各级流量的频率分布具有分段特性，无法用皮尔逊Ш型或对数正态等常见函数来整体描述，但中洪流量区段符合分段幂函数；拟合得到的分段幂函数转折点可近似反映造床流量，包括临界值在内的函数特征参数受洞庭湖等调蓄作用影响，在螺山站上下游差异较大；三峡水库蓄水后，洪水削减使得各站的流量频率分段特性增强，分段幂函数仍然适用；由于三峡水库蓄水后流量过程变化和频率调整的影响，枝城、沙市、监利站造床流量将变为蓄水前的0.79、0.73、0.74倍，螺山、汉口、大通站造床流量将变为蓄水前的0.89、0.90、0.93倍.本文的方法和认识对于长江中下游径流特征分析和造床流量计算具有参考价值.;The variations of flow characteristics and their effects on channel formation in the middle and lower reaches of the Yangtze River before and after the impoundment of the Three Gorges Reservoir (TGR) have drawn much concern. Based on the data of the average daily discharge at six hydrological stations including Zhicheng Station, the empirical flow frequency distributions were calculated, and the applicabilities of eight probability density functions were tested. Furthermore, the relationships between the flow frequency distribution characteristics and the channel-forming discharges before and after the impoundment of the TGR were discussed. The results show that the flow frequency distributions in the study reach are segmented, which cannot be described as a whole by common functions such as Pearson Ш or Lognormal distribution. However, the frequency distributions of the medium-high flow conform to the broken power-law (BPL). The turning point of the BPL obtained by fitting approximately reflects the channel-forming discharge. Moreover, affected by the regulation and storage of Lake Dongting, the characteristic parameters including the critical values quite differently in the upper and lower reaches of Luoshan Station. After the TGR is impounded, the subsection characteristics of the flow frequency distributions are enhanced by the flood reduction, and the applicability of BPL are still considerable. Due to the influence of the flow process change and frequency adjustment by the impoundment of the TGR, the channel-forming discharge at Zhicheng, Shashi, Jianli, Luoshan, Hankou and Datong stations will be 0.79, 0.73, 0.74, 0.89, 0.90 and 0.93 times of that before the impoundment, respectively. The method presented in this paper are of reference value for the analysis of runoff characteristics and the calculation of channel-forming discharge in the middle and lower reaches of the Yangtze River.

Effects of geological differences on rainfall–runoff characteristics based on field measurements

Effects of geological differences on rainfall–runoff characteristics based on field measurements