Dependence of discharge, channel area, and flow velocity on river stage and a refutation of Manning’s equation

ABSTRACT Field data reveal how the discharge (Q), channel area (A), and average water velocity (Vavg) of natural streams functionally depend on the effective stage (h) above channel bottom. A graphical technique allows the level that corresponds to a dry channel, denoted “h0,” to be determined, permitting the dependent variables Q, A, and Vavg to all be expressed as simple functions of h, equal to hL– h0, where hL is the local stage that is typically reported relative to an arbitrary, site-specific datum. Once h0 is known, plots of log Q, log A, and log Vavg versus log h can be constructed using available data. These plots define strong, nearly linear trends for which the slopes (1) quantify the power relationships among these variables; (2) show that Vavg varies nearly linearly with h, unlike behaviors assumed in the Chezy and Manning equations; (3) distinguish the individual contributions of A and Vavg to discharge, which is their product; (4) provide quantitative means with which to compare different sites; and (5) offer new insights into the character and dynamics of natural streams.

Pathogenicity of Phytophthora × alni Isolates Obtained from Symptomatic Trees, Soil and Water against Alder

Phytophthora alni complex (P. × alni, P. × multiformis, P. uniformis) are pathogens attacking alder seedlings and trees, causing significant losses in nurseries and natural tree stands. Decay of alder trees has been observed in Poland for over a dozen years. Overall, 25 Polish isolates of P. × alni obtained from symptomatic alder trunks, rhizosphere soil surrounding infected trees, and nearby natural streams were compared with isolates from symptomatic trunks obtained in France, Belgium and Hungary. Morphologic characterization of mycelium, vegetative and generative organs, temperature effect on mycelium growth, and their pathogenicity were studied. The mycelium growth rate of isolates from symptomatic plants was fastest on Carrot Agar (CA) medium, and from soil and water on Vegetable Agar (V8A) medium. The sizes of zoosporangia varied depending on their origin. The isolates that originated from the soil had the largest zoosporangia. The diameter of the oogonia and antheridia did not differ regardless of their origin. The results of pathogenicity tests of P. × alni isolates obtained from different sources showed that the soil isolates were the most aggressive in each test, followed by the isolates from the trunks and water. A simple test of leaf colonization can give an idea of the aggressiveness of the isolate towards the shoots and roots. No morphological or physiological markers of aggressiveness have been found.

Detection Of Change In Land Cover In Jabalpur District From 1991-2021 Using Remote Sensing

Land use/ land cover is an important component in understanding the interactions of human activities with the environment and thus it is necessary to monitor and detect the changes to maintain a sustainable environment. In this paper, an attempt has been made to study the changes in land use and land cover of Jabalpur district in the last 4 decades from 1991 to 2021 classifying majorly in Forest (Medium to Dense), Trees, Waterbody, Settlements & Agricultural fields. The study was carried out through the Remote Sensing and GIS approach using High-resolution Imagery from Google Earth, and LANDSAT 8, 7, 5 imagery of 2021, 2011, 2001, 1991 respectively. The land use/land cover classification was performed based on the Supervised Classification approach available in ArcGIS. GIS software is used to prepare the thematic maps and ground truth observations were also performed to check the accuracy of the classification. The present study has brought out that the Tree cover has been decreased from 12.97–5.40% during 1991-2021 showing a considerable decrease in Forest area as well. The settlement area increased from 4.26% in 1991 to 12.46% in 2021. The areas under natural streams, have shown no significant change and can be considered as a positive sign for sustainable development.

Urban Drool Water Quality in Denver, Colorado: Pollutant Occurrences and Sources in Dry-Weather Flows

Dry-weather flows in urban channels and streams, often termed “urban drool”, represent an important source of urban surface water impairment, particularly in semi-arid environments. Urban drool is a combination of year-round flows in urban channels, natural streams, and storm-sewer systems (runoff from irrigation return flow, car washes, street cleaning, leakage of groundwater or wastewater into streams or storm sewers, etc.). The purpose of this study was to better understand the extent and sources of urban drool pollution in Denver, Colorado by identifying relationships between urban catchment characteristics and pollutants. Water-quality samples were taken throughout Denver at urban drainage points that were representative of a variety of urban characteristics. Samples were analyzed for total suspended solids (TSS), coliforms, Escherichia Coli (E. coli), nutrients (nitrate, phosphorus, and potassium), dissolved and total organic carbon, and dissolved and total recoverable metals. Results from this study were as follows: (1) most contaminants (nitrate, phosphorus, arsenic, iron, manganese, nickel, selenium, and zinc) were concluded to be primarily loaded from shallow groundwater; (2) anthropogenic effects likely exacerbated groundwater pollutant concentrations and contributions to surface water; (3) nitrate, nickel, and manganese may be partially contributed by industrial inputs; (4) medical marijuana cultivation sites were identified as a potential source of nutrient and zinc pollution; (5) E. coli was a ubiquitous contaminant in all urban waterways; (6) erosion of contaminated urban soils, presumably from construction, was found to significantly increase concentrations of TSS, total phosphorus, and total metals. Increasing urbanization and predicted drier climates suggest that dry-weather flows will become more important to manage; the results from this study provide insight on dry-weather water quality management for the City and County of Denver.

Uncertainty Quantification of Granular Computing-neural Network Model for Prediction of Pollutant Longitudinal Dispersion Coefficient in Aquatic Streams

Discharge of pollution loads into natural water systems remains a global challenge that threatens water/food supply as well as endangers ecosystem services. Natural rehabilitation of the polluted streams is mainly influenced by the rate of longitudinal dispersion (Dx), a key parameter with large temporal and spatial fluctuates that characterizes pollution transport. The large uncertainty in estimation of Dx in streams limits evaluation of water quality in natural streams and design of water quality enhancement strategies. This study develops a sophisticated model coupled with granular computing and neural network models (GrC-ANN) to provide robust prediction of Dx and its uncertainty for different flow-geometric conditions with high spatiotemporal variability. Uncertainty analysis of Dx GrC-ANN model was based on the alteration of training data fed to tune the model. Modified bootstrap method was employed to generate different training patterns through resampling from a 503 global database of tracer experiments in streams. Comparison between the Dx values estimated by GrC-ANN to those determined from tracer measurements show the appropriateness and robustness of the proposed method in determining the rate of longitudinal dispersion. GrC-ANN model with the narrowest bandwidth of estimated uncertainty (bandwidth-factor =0.56) that brackets the most percentage of true Dx data (i.e., 100%) is the best model to compute Dx in streams. Given considerable inherent uncertainty reported in other Dx models, the Dx GrC-ANN model is suggested as a proper tool for further studies of pollutant mixing in turbulent flow systems such as streams.

A global algorithm for identifying changing streamflow regimes: application to Canadian natural streams (1966–2010)

Climate change affects natural streamflow regimes globally. To assess alterations in streamflow regimes, typically temporal variations in one or a few streamflow characteristics are taken into account. This approach, however, cannot see simultaneous changes in multiple streamflow characteristics, does not utilize all the available information contained in a streamflow hydrograph, and cannot describe how and to what extent streamflow regimes evolve from one to another. To address these gaps, we conceptualize streamflow regimes as intersecting spectrums that are formed by multiple streamflow characteristics. Accordingly, the changes in a streamflow regime should be diagnosed through gradual, yet continuous changes in an ensemble of streamflow characteristics. To incorporate these key considerations, we propose a generic algorithm to first classify streams into a finite set of intersecting fuzzy clusters. Accordingly, by analyzing how the degrees of membership to each cluster change in a given stream, we quantify shifts from one regime to another. We apply this approach to the data, obtained from 105 natural Canadian streams, during the period of 1966 to 2010. We show that natural streamflow in Canada can be categorized into six regime types, with clear hydrological and geographical distinctions. Analyses of trends in membership values show that alterations in natural streamflow regimes vary among different regions. Having said that, we show that in more than 80 % of considered streams, there is a dominant regime shift that can be attributed to simultaneous changes in streamflow characteristics, some of which have remained previously unknown. Our study not only introduces a new globally relevant algorithm for identifying changing streamflow regimes but also provides a fresh look at streamflow alterations in Canada, highlighting complex and multifaceted impacts of climate change on streamflow regimes in cold regions.

Field variations in mass at metamorphosis in a stream frog, Odorrana splendida, and their relationship with the stream environment

Animals with complex life cycles, such as amphibians, shift their habitats when they metamorphose. Metamorphosing traits (e.g., size at, and timing of, metamorphosis) at an early stage can affect the growth, reproduction, and survival in the adult stage. Thus, metamorphosing traits are important factors that affect the fitness of the individuals. Although size at metamorphosis in the field has been investigated in amphibians, its relationship with environmental factors has been scarce. We aimed to quantify variations in the mass at metamorphosis of a stream frog, Odorrana splendida, among multiple streams, and show the relationship of these variations with environmental conditions. We searched for metamorphs in 11 field streams and measured their body size. We then examined the relationship between environmental conditions of each stream and the mass at metamorphosis to reveal the factors determining the mass. We found 229 metamorphs over three years. The estimated mass at metamorphosis ranged from 0.17 g to 1.44 g, with a coefficient of variation among streams of 0.38. The size at metamorphosis significantly differed among streams, and was found to be positively affected by water temperature and chlorophyll a concentration, and negatively affected by altitude, slope gradient, and the number of adult calls. We showed that O. splendida has a large variation in mass at metamorphosis within and among natural streams. A lower mass at metamorphosis may correlate with scarce food resources in the stream and higher competition during the larval stages, resulting from a higher number of mating adults.

Study of Cadmium Desorption Kinetics from Riverine Sediments

In natural streams, the majority of heavy metal ions are generally associated ‎with ‎sediment particles. Under some environmental conditions, these metal ions may release from ‎the ‎sediment particles.‎ In such conditions, the desorption rate of heavy metals is very important for decision-makers of ‎water quality assessment. In this study, the effect of cadmium desorption ‎from the river bed ‎sediments has been ‎experimentally investigated. Artificially contaminated sediments were used ‎for performing batch desorption ‎experiments. The experiments were conducted by adding 1 gr of contaminated ‎sediment (D50 = 0.53 mm) with a known concentration and shaking until observing a ‎roughly ‎constant cadmium concentration in the solution. It was concluded that the cadmium ions were strongly bond to the river bed sediment; meanwhile, at the ‎equilibrium time, up to about 7 to 29 percent of cadmium ions were ‎released from the‎ artificially contaminated sediments. The experiments were followed by ‎two agitation rates of 100 and 200 rpm. It was revealed that by increasing the flow turbulence, the amount ‎of desorbed cadmium is slightly increased. Besides, the desorption kinetics was evaluated using eight models of Zero-, first-, second-, third-order, ‎parabolic diffusion, double parabolic diffusion, two constant rate, and simple Elovich. The results of the evaluation showed that simple Elovich (with R2 = 0.991), double parabolic diffusion (with R2 = 0.9882), two constant rate (with R2 = 0.983) and parabolic diffusion models (with R2 = 0.846) have respectively the best performance in calculation of Cd desorption rate from the sediments.

Design of Canal by Closing out Debits of Current Canal System

Canals are natural streams channels, or manmade streams, for water movement, or to support water movement, or to support water transport vehicles. Fundamental capacity of waterway is to convey water from water assets for irrigation or domestic utilization of water. The whole water movement framework for water system, containing the fundamental channel, branch waterways, major and minor distributaries. Water is a valuable asset. It is needed by human in doing distinctive day by day exercises. This valuable asset while going through the canal is lost from the channels through leakage from the sides and lower part of the canals and by evaporation from the top water surface of the canals. This project aims at modelling a canal section using HEC-RAS conducting flow analysis such that there is no silting and scouring in the canal. HEC-RAS is a computer program that help model the hydraulics of water flow through natural rivers and artificial or natural channels. The objective is to estimate evaporation and seepage losses and suggest necessary remedies in order to avoid these water debits from the canals.