Estimating river water-quality trends under different flow conditions

2021 ◽  
Author(s):  
Qian Zhang ◽  
James Webber ◽  
Douglas Moyer ◽  
Jeffrey Chanat
Keyword(s):  
Water Quality ◽  
River Water ◽  
Total Nitrogen ◽  
Nitrogen Concentration ◽  
High Flow ◽  
River Water Quality ◽  
Low Flow ◽  
Flow Conditions ◽  
Particulate Nitrogen ◽  
Water Quality Trends

<p>A number of statistical approaches have been developed to quantify the overall trend in river water quality, but most approaches are not intended for reporting separate trends for different flow conditions. We propose an approach called FN<sub>2Q</sub>, which is an extension of the flow-normalization (FN) procedure of the well-established WRTDS (“Weighted Regressions on Time, Discharge, and Season”) method. The FN<sub>2Q</sub> approach provides a daily time series of low-flow and high-flow FN flux estimates that represent the lower and upper half of daily riverflow observations that occurred on each calendar day across the period of record. These daily estimates can be summarized into any time period of interest (e.g., monthly, seasonal, or annual) for quantifying trends. The proposed approach is illustrated with an application to a record of total nitrogen concentration (632 samples) collected between 1985 and 2018 from the South Fork Shenandoah River at Front Royal, Virginia (USA). Results show that the overall FN flux of total nitrogen has declined in the period of 1985–2018, which is mainly attributable to FN flux decline in the low-flow class. Furthermore, the decline in the low-flow class was highly correlated with wastewater effluent loads, indicating that the upgrades of treatment technology at wastewater treatment facilities have likely led to water-quality improvement under low-flow conditions. The high-flow FN flux showed a spike around 2007, which was likely caused by increased delivery of particulate nitrogen associated with sediment transport. The case study demonstrates the utility of the FN<sub>2Q</sub> approach toward not only characterizing the changes in river water quality but also guiding the direction of additional analysis for capturing the underlying drivers. The FN<sub>2Q</sub> approach (and the published code) can easily be applied to widely available river monitoring records to quantify water-quality trends under different flow conditions to enhance understanding of river water-quality dynamics. <span>(Journal article: https://doi.org/10.1016/j.scitotenv.2020.143562; R code and data release: https://doi.org/10.5066/P9LBJEY1).</span></p>

scholarly journals Unfolding Water Quality Status During COVID-19 Lockdown for the Highly Polluted Santiago River in Jalisco, Mexico

2021 ◽  
Author(s):  
Gurusamy Kutralam-Muniasamy ◽  
Fermín Pérez-Guevara ◽  
Ignacio Elizalde Martinez ◽  
Shruti Venkata Chari
Keyword(s):  
Water Quality ◽  
River Water ◽  
Total Nitrogen ◽  
Surface Water Quality ◽  
Quality Parameters ◽  
River Water Quality ◽  
Organic Load ◽  
The Government ◽  
Temporary Closure

Abstract The Santiago River is one of Mexico's most polluted waterways and evaluating its surface water quality during the COVID-19 outbreak is critical to assessing the changes and improvements, if any, from the nationwide lockdown (April-May 2020). Hence, the data for 12 water quality parameters from 13 sampling stations during April-May 2020 (lockdown) were compared with the levels for the same period of 2019 (pre-lockdown) and with the same interval of previous eleven-years (2009-2019). The values of BOD (14%), COD (29%), TSS (7%), f. coli (31%), t. coli (14%) and Pb (20%) declined, while pH, EC, turbidity, total nitrogen and As enhanced by 0.3-21% during the lockdown compared to the pre-lockdown period suggesting decrements of organic load in the river due to the temporary closure of industrial and commercial activities. An eleven-year comparison estimated the reduction of pH, TSS, COD, total nitrogen and Pb by 1-38%. The analysis of water quality index estimates showed short-term improvements of river water quality in the lockdown period, compared to pre-lockdown and eleven-year trend as well as indicated very poor quality of the river. The contamination sources identified by factor analysis were mainly related to untreated domestic sewage, industrial wastewaters and agriculture effluents influencing the river water quality. Overall, our findings demonstrated positive responses of COVID-19 imposed lockdown on water quality of the Santiago River during the study period, providing a foundation for the government policy makers to identify the sources of pollution, to better design environmental policies and plans for water quality improvements.

scholarly journals An approach for decomposing river water-quality trends into different flow classes

2021 ◽  
Vol 755 ◽  
pp. 143562
Author(s):  
Qian Zhang ◽  
James S. Webber ◽  
Douglas L. Moyer ◽  
Jeffrey G. Chanat
Keyword(s):  
Water Quality ◽  
River Water ◽  
River Water Quality ◽  
Water Quality Trends

scholarly journals Geochemical characteristics of dissolved heavy metals in Zhujiang River, Southwest China: spatial-temporal distribution, source, export flux estimation, and a water quality assessment

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6578 ◽  
Author(s):  
Jie Zeng ◽  
Guilin Han ◽  
Qixin Wu ◽  
Yang Tang
Keyword(s):  
Heavy Metals ◽  
Water Quality ◽  
River Water ◽  
Southwest China ◽  
Hazard Index ◽  
Temporal Distribution ◽  
High Flow ◽  
Low Flow ◽  
Dissolved Heavy Metals ◽  
Zhujiang River

To investigate the sources and spatial-temporal distribution of dissolved heavy metals in river water, and to evaluate the water quality, a total of 162 water samples were collected from 81 key sampling points in high and low flow seasons separately in the Zhujiang River, Southwest China. Ten dissolved heavy metals (V, Cr, Mn, Co, Ni, Cu, Mo, Cd, Ba, and Pb) in the Zhujiang River water exhibit little variation at temporal scale, but vary with a significant spatial heterogeneity. Furthermore, different metals present different variation trends along the main channel of the Zhujiang River. Our results suggest that Ba (14.72 μg L−1 in low flow season and 12.50 μg L−1 in high flow season) and Cr (6.85 μg L−1 in low flow season and 7.52 μg L−1 in high flow season) are consistently the most abundant metals in the two sampling periods. According to the water quality index (WQI values ranged from 1.3 to 43.9) and health risk assessment, metals investigated in Zhujiang River are below the hazard level (all hazard index (HI) < 1). Application of statistical approaches, including correlation matrix and principal component analysis (PCA), identify three principal components that account for 61.74% of the total variance, the results conclude that the anthropogenic heavy metals (V, Cr, Ni, and Cu) are greatly impacted by the dilution effect, and the heavy metals in Zhujiang River are mainly presented a natural sources signature from the perspective of entire basin. Moreover, our results reveal that the estimated export budget of several heavy metals including V (735.6 t year−1), Cr (1,561.1 t year−1), Ni (498.2 t year−1), and Mo (118.9 t year−1) to the ocean are higher than the world average.

Novel bacterial ratio for predicting faecal age

2003 ◽  
Vol 47 (3) ◽  
pp. 45-49 ◽  
Author(s):  
J. Nieman ◽  
G.M. Brion
Keyword(s):  
Water Quality ◽  
River Water ◽  
Total Coliform ◽  
River Water Quality ◽  
Low Flow ◽  
Quality Data ◽  
Water Quality Data ◽  
Ongoing Research ◽  
Kentucky River ◽  
Survival Studies

This study presents an extension of ongoing research into the utility of the ratio of colonies isolated on membrane filters during the total coliform test using m-Endo broth media. Investigations into the relative shifts in concentrations of indicator bacterial populations over time, in laboratory-based survival studies conducted with filtered river water, were undertaken. Also, analysis of Kentucky River water quality data collected from the inlet of a local water treatment plant was carried out. Survival studies found that the ratio between the raw concentrations of atypical colonies (AC) and total coliform colonies (TC) was directly related to the amount of time coliform spiked river water had been held in open jars in the laboratory. The AC/TC ratio in the jars would rise from &lt;1 at the time of coliform spiking to &gt;200 within 4d. The rise in AC/TC ratio with time in river water was confirmed in the analysis of two years of Kentucky River water quality data where the average AC/TC ratio during months with high river flow (rain) was 3.37 and rose to an average of 27.58 during months with low flow. The average AC/TC ratio during high flow months compared to that of raw human sewage (3.9) and the ratio increased to values associated with animal impacted urban runoff (18.9) during low flow months.

River water quality modeling using continuous high frequency data allows disentangling whole-stream nitrogen uptake and release pathways

2020 ◽  
Author(s):  
Jingshui Huang ◽  
Michael Rode
Keyword(s):  
Water Quality ◽  
River Water ◽  
High Frequency ◽  
N Uptake ◽  
Benthic Algae ◽  
Water Quality Modeling ◽  
River Water Quality ◽  
Low Flow ◽  
High Frequency Data ◽  
Quality Modeling

&lt;p&gt;River water quality models offer studying spatio-temporal variation and processes of nitrogen (N) turnover. However, the infrequent temporal resolution of monitoring data commonly limit the reliability of modeling instream N processing. These limitations of the temporal data resolution can result in equifinality of model parameter sets and considerable uncertainties due to insufficient ability of validating internal turnover processes. The combination of emerging high frequency monitoring techniques and water quality modeling may support continuous quantification of instream N processing pathways with higher reliability.&lt;/p&gt;&lt;p&gt;In this study, we set up a hydrodynamic and river water quality model (WASP 7.5.2) in the 27.4-km reach of the 5&lt;sup&gt;th&lt;/sup&gt; order river Bode in Central Germany for a 5-year period (2014-2018). High frequency data (15-min interval) of discharge, nitrate, dissolved oxygen (DO) and Chlorophyll-a (Chl-a) at the upstream and downstream station were used as model inputs and for model testing, respectively. Chl-a and DO data were used for disentangling uptake via phytoplankton and benthic algae. Furthermore we identified the most important N-removal and release processes including denitrification, excretion from phytoplankton and benthic algae at daily, seasonal and annual scales.&lt;/p&gt;&lt;p&gt;The PBias of lower than 20% between the simulated and measured high-frequency values for the four variables showed general good performance of the model. Results showed that on an annual scale, net N uptake efficiency ranged from 0.2-17.2% and increased with decreasing discharge resulting in highest value for the extreme low-flow year 2018. Among seasons, net uptake efficiency was found to be the highest in summer. Over 50% of the N loading was taken up at the extreme low flow in the summer of 2018. The contributions of each pathway to total N uptake decreased from assimilatory uptake via benthic algae, denitrification, and assimilatory uptake via phytoplankton. However, in the extreme low-flow summer of 2018, the importance of denitrification was largely increased compared to former years. Besides, in autumn, the reach became a net N source, because remineralization of N from benthic algae surpassed uptake processes.&lt;/p&gt;&lt;p&gt;Our study highlights the value of high frequency data to support river water quality modeling allowing continuous quantification of whole-stream N uptake and release pathways.&lt;/p&gt;

Groundwater inputs towards surface water: quantification and impact on the river water quality using chemical and isotope fingerprints (87Sr/86Sr), example of the Loire River (France)

2021 ◽  
Author(s):  
Emmanuelle Petelet-Giraud ◽  
Philippe Negrel ◽  
Joël Casanova
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
River Water ◽  
Groundwater Discharge ◽  
Thermal Infrared ◽  
River Water Quality ◽  
Low Flow ◽  
Isotopic Tracers ◽  
The Impact ◽  
Loire River

&lt;p&gt;Within the Critical Zone, the river water quality plays a key role for the related ecosystems. The impact of contaminants delivered to surface water from groundwater inputs are often neglected, while they can constitute the major loads of nutrients or pesticides in some specific river sections. In this study, we focus on a limited section of the Loire River in France, downstream Orleans city, where the increase of the river discharge cannot be attributed to the confluence of the small tributaries. Indeed, previous studies have pointed out the role of the groundwater discharge from the large Beauce aquifer located to the north of the river, mainly focusing on the quantitative aspects.&lt;/p&gt;&lt;p&gt;Based here on geochemical and isotopic tracers, we first confirm groundwater inputs to the Loire River and we clearly attributed those inputs to the Beauce carbonate aquifer using the relationship between &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr and the Cl/Sr ratios. Secondly, the conservative tracers (Sr isotopes and Cl concentrations) allow assessing the groundwater contribution to the river to around 20% of the total discharge during low flow periods. This proportion is in full agreement with the previous studies based on heat budget method, where the river temperature is estimated with satellite thermal infrared images. Lalot et al. (2015) showed that the main groundwater discharge is concentrated along a 9 km transect just downstream of Orl&amp;#233;ans city with a discharge of 5.3 and 13.5 m&lt;sup&gt;3&lt;/sup&gt;.s&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; during summer and winter times, respectively. This is roughly in agreement with the calculations based on groundwater modelling (calculated groundwater discharge: 0.6 to 0.9 m&lt;sup&gt;3&lt;/sup&gt;.s&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;.km&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;). Finally, we pointed out the quality impact of these groundwaters especially regarding nitrates. Groundwater impacts on surface water quality have recently been considered as a potential vector of surface water contamination but they are still weakly studied and quantified. Here, we show pics of nitrates concentrations that rapidly decrease in the Loire River (especially in low flow period) after the groundwaters inputs enriched in NO&lt;sub&gt;3&lt;/sub&gt; coming from the highly anthropized Beauce aquifer because of intensive agriculture practices. The nitrate decrease in the river is probably due to a nitrate removal processes (plant/microbial uptake?). The impact of these inputs into the Loire but also into the small tributaries of the Loire River should be further investigated, especially regarding pesticides loads and fates, and their potential impact on the related ecosystems.&lt;/p&gt;&lt;p&gt;Lalot, E., Curie, F., Wawrzyniak, V., Baratelli, F., Schomburgk, S., Flipo, N., Piegay, H., Moatar, F., 2015. Quantification of the contribution of the Beauce groundwater aquifer to the discharge of the Loire River using thermal infrared satellite imaging. Hydrol. Earth Syst. Sci. 19, 4479&amp;#8211;4492.&lt;/p&gt;

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