Evaluation of a Method of Estimating Low-Flow Frequencies from Base-Flow Measurements at Indiana Streams

AbstractEstimation of aquifer recharge is key to effective groundwater management and protection. In mountain hard-rock aquifers, the average annual discharge of a spring generally reflects the vertical aquifer recharge over the spring catchment. However, the determination of average annual spring discharge requires expensive and challenging field monitoring. A power-law correlation was previously reported in the literature that would allow quantification of the average annual spring discharge starting from only a few discharge measurements in the low-flow season, in a dry summer climate. The correlation is based upon the Maillet model and was previously derived by a 10-year monitoring program of discharge from springs and streams in hard-rock aquifers composed of siliciclastic and calcareous turbidites that did not have well defined hydrogeologic boundaries. In this research, the same correlation was applied to two ophiolitic (peridotitic) hard-rock aquifers in the Northern Apennines (Northern Italy) with well-defined hydrogeologic boundaries and base-outflow springs. The correlation provided a reliable estimate of the average annual spring discharge thus confirming its effectiveness regardless of bedrock lithology. In the two aquifers studied, the measurable annual outputs (i.e. sum of average annual spring discharges) could be assumed equal to the annual inputs (i.e. vertical recharge) based on the clear-cut aquifer boundaries and a quick groundwater circulation inferable from spring water parameters. Thus, in such setting, the aforementioned correlation also provided an estimate of the annual aquifer recharge allowing the assessment of coefficients of infiltration (i.e. ratio between aquifer recharge and total precipitation) ranging between 10 and 20%.

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Multiple causes of nonstationarity in the Weihe annual low-flow series

Hydrology and Earth System Sciences ◽

10.5194/hess-22-1525-2018 ◽

2018 ◽

Vol 22 (2) ◽

pp. 1525-1542 ◽

Cited By ~ 8

Author(s):

Bin Xiong ◽

Lihua Xiong ◽

Jie Chen ◽

Chong-Yu Xu ◽

Lingqi Li

Keyword(s):

Frequency Analysis ◽

Driving Forces ◽

Potential Evapotranspiration ◽

Aridity Index ◽

Base Flow ◽

Low Flow ◽

Distribution Model ◽

Flow Index ◽

Explanatory Variables ◽

Distribution Parameters

Abstract. Under the background of global climate change and local anthropogenic activities, multiple driving forces have introduced various nonstationary components into low-flow series. This has led to a high demand on low-flow frequency analysis that considers nonstationary conditions for modeling. In this study, through a nonstationary frequency analysis framework with the generalized linear model (GLM) to consider time-varying distribution parameters, the multiple explanatory variables were incorporated to explain the variation in low-flow distribution parameters. These variables are comprised of the three indices of human activities (HAs; i.e., population, POP; irrigation area, IAR; and gross domestic product, GDP) and the eight measuring indices of the climate and catchment conditions (i.e., total precipitation P, mean frequency of precipitation events λ, temperature T, potential evapotranspiration (EP), climate aridity index AIEP, base-flow index (BFI), recession constant K and the recession-related aridity index AIK). This framework was applied to model the annual minimum flow series of both Huaxian and Xianyang gauging stations in the Weihe River, China (also known as the Wei He River). The results from stepwise regression for the optimal explanatory variables show that the variables related to irrigation, recession, temperature and precipitation play an important role in modeling. Specifically, analysis of annual minimum 30-day flow in Huaxian shows that the nonstationary distribution model with any one of all explanatory variables is better than the one without explanatory variables, the nonstationary gamma distribution model with four optimal variables is the best model and AIK is of the highest relative importance among these four variables, followed by IAR, BFI and AIEP. We conclude that the incorporation of multiple indices related to low-flow generation permits tracing various driving forces. The established link in nonstationary analysis will be beneficial to analyze future occurrences of low-flow extremes in similar areas.

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Abstract TP112: Mechanism of Recurrent Stroke in Patients with Atherosclerotic Vertebrobasilar Disease in Relation to Hemodynamics

Stroke ◽

10.1161/str.48.suppl_1.tp112 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Joanna D Schaafsma ◽

Frank L Silver ◽

Scott E Kasner ◽

Louis R Caplan ◽

Linda Rose-Finnell ◽

...

Keyword(s):

Recurrent Stroke ◽

Posterior Circulation ◽

Low Flow ◽

Flow Measurements ◽

Quantitative Mr ◽

Perforating Artery ◽

Recurrent Strokes ◽

Stroke Mechanism ◽

Prospective Longitudinal ◽

Distal Flow

Objectives: Patients with symptomatic atherosclerotic vertebrobasilar disease are at high risk for recurrent stroke and we have demonstrated that distal flow status is independently associated with this risk. Our aim was to assess the mechanism of recurrent strokes in these patients related to their distal flow status. Methods: Patients with symptomatic atherosclerotic vertebrobasilar disease were enrolled in a prospective longitudinal cohort study (VERiTAS) with a median follow-up of 23 months. Large-vessel flow in the posterior circulation distal to the stenosis and/or occlusion was measured on quantitative MR angiography and dichotomized into normal or low flow. Three observers, who were blinded to the distal flow status, independently reviewed the imaging done at the time of the recurrent stroke to classify the most likely stroke mechanism. Results: Ten out of 72 enrolled patients had a recurrent stroke in the posterior circulation. Four patients were determined to have embolic infarcts, four patients had infarcts caused by plaques that occluded a branch or perforating artery (junctional plaques), and two patients had imaging that suggested hemodynamic infarction. Five of the ten patients with recurrent strokes had low distal flow. Of these, two patients had hemodynamic infarcts, one patient had an embolic infarct, and two patients had a junctional plaque. None of the five patients with normal flow had hemodynamic infarcts, three patients had embolic infarcts, and two patients had a junctional plaque. Conclusion: Despite the small numbers, there seems to be a higher risk of hemodynamic infarction in patients with low flow distal to symptomatic vertebrobasilar disease than in the presence of normal distal flow. This would confirm the hypothesis that in addition to embolic strokes and those related to junctional plaque, patients with low distal flow are at risk for hemodynamic infarction. Further studies are required to determine whether flow measurements could be used to select patients who may benefit from endovascular treatment of atherosclerotic vertebrobasilar disease.

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Estimation of base flow recession constant and regression of low flow indices in eastern Japan

Hydrological Sciences Journal ◽

10.1080/02626667.2021.2003368 ◽

2021 ◽

Author(s):

Andrew C. Whitaker ◽

Stanley N. Chapasa ◽

Cristencio Sagras ◽

Uwitonze Theogene ◽

Ronald Veremu ◽

...

Keyword(s):

Base Flow ◽

Low Flow ◽

Recession Constant ◽

Eastern Japan

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Forecasting Low Stream Flow Rate Using Monte—Carlo Simulation of Perigiali Stream, Kavala City, NE Greece

Proceedings ◽

10.3390/proceedings2110580 ◽

2018 ◽

Vol 2 (11) ◽

pp. 580 ◽

Cited By ~ 1

Author(s):

Thomas Papalaskaris ◽

Theologos Panagiotidis

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Flow Rate ◽

Stream Flow ◽

Simulation Method ◽

Base Flow ◽

Low Flow ◽

Rate Data ◽

Storm Flow ◽

Management Plans

A small number of scientific research studies with reference to extremely low flow conditions, have been conducted in Greece, so far. Predicting future low stream flow rate values is an essential and of paramount importance task when compiling watershed and drought management plans, designing water reservoirs and general hydraulic works capacity, calculating hydrological and drought low flow values, separating groundwater base flow and storm flow of storm hydrographs etc. The Monte-Carlo simulation method generates multiple attempts to define the anticipated value of a random (hydrological in this specific case) variable. The present study compiles, correspondingly, artificial low stream flow time series of both the same part of the year (2016) as well as a part of the calendar year (2017), based on the stream flow data observed during the same two different interval periods of the years 2016 and 2017, using a 3-inches U.S.G.S. modified portable Parshall flume, a 3-inches conventional portable Parshall flume, a 3-inches portable Montana (short Parshall) flume and a 90° V-notched triangular shaped sharp crested portable weir plate. The recorded data were plotted against the fitted one and the results were demonstrated through interactive tables providing us the ability to effectively evaluate the simulation procedure performance. Finally, we plot the observed against the calculated low stream flow rate data, compiling a log-log scale chart which provides a better visualization of the discrepancy ratio statistical performance metric and calculate statistics featuring the comparison between the recorded and the forecasted low stream flow rate data.

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A multi-functional and multi-compartment constructed wetland to support urban waterway restoration

Water Practice & Technology ◽

10.2166/wpt.2018.086 ◽

2018 ◽

Vol 13 (4) ◽

pp. 764-770 ◽

Cited By ~ 2

Author(s):

T. M. Adyel ◽

M. R. Hipsey ◽

C. Oldham

Keyword(s):

Constructed Wetland ◽

Flow System ◽

Surface Flow ◽

Base Flow ◽

Low Flow ◽

Nutrient Loads ◽

Storm Events ◽

Flow Conditions ◽

Storm Flow ◽

Diverse Area

Abstract This study assessed the significance of a multi-functional and multi-compartment constructed wetland (CW) implemented to restore a degraded urban waterway in Western Australia. The wetland was initially constructed as a surface flow system, then modified through the incorporation of the additional laterite-based subsurface flow system, with the potential for operation of a recirculation scheme and groundwater top-up during low water flows in summer. The CW performance was assessed by comparing nitrogen (N) and phosphorus (P) attenuation during base flow, high flow and episodic storm flow conditions. The performance varied from approximately 41% total nitrogen (TN) and 66% total phosphorus (TP) loads reduction during storm events, increasing up to 62% TN and 99% TP during low flow and summer recirculation periods. In overall, the CW attenuated about 45% TN and 65% TP loads from being delivered to the downstream sensitive river between 2009 and 2015. The CW design proved to be not only highly effective at reducing nutrient loads, but also improved the ecological services of the urban waterway by providing a diverse area for habitat and recreational activities.

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Passive Control of Unstable Characteristics of a High Specific Speed Diagonal-Flow Fan by an Annular Wing

Volume 1: Turbomachinery ◽

10.1115/90-gt-159 ◽

1990 ◽

Cited By ~ 1

Author(s):

Kenji Kaneko ◽

Toshiaki Setoguchi ◽

Masahiro Inoue

Keyword(s):

Flow Rate ◽

Geometrical Parameter ◽

Energy Input ◽

Passive Control ◽

Internal Flow ◽

Flow Region ◽

Low Flow ◽

Performance Tests ◽

Flow Measurements ◽

Specific Speed

A passive control of an unstable characteristics of a high specific speed diagonal-flow fan has been proposed. It is possible to eliminate the unstable characteristics of pressure-flow rate curve in a low flow region without deterioration of performance at design point. The control action is done naturally (passively) without any energy input. The inlet nozzle of an ordinary diagonal-flow fan was replaced by an annular wing with Göttingen 625 airfoil section. The mechanism of the passive control and the optimum geometrical parameter are discussed on the basis of the performance tests and internal flow measurements.

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Intraoperative use of transit time flow measurement improves patency of newly created radiocephalic arteriovenous fistulas in patients requiring hemodialysis

The Journal of Vascular Access ◽

10.1177/1129729820916561 ◽

2020 ◽

Vol 21 (6) ◽

pp. 990-996

Author(s):

Anna E Cyrek ◽

Johannes Bernheim ◽

Benjamin Juntermanns ◽

Peri Husen ◽

Arkadius Pacha ◽

...

Keyword(s):

Blood Flow ◽

Arteriovenous Fistula ◽

Transit Time ◽

Intraoperative Ultrasound ◽

Low Flow ◽

Flow Measurements ◽

Technical Problems ◽

Arteriovenous Fistulas ◽

Time Flow ◽

Observation Period

Background: The autologous arteriovenous fistula is the primary choice to establish hemodialysis access without high failure rates. Intraoperative ultrasound flow measurements of newly created autologous arteriovenous fistulas represent a possibility of quality control and may therefore be a tool to assess their functionality. The aim of our study was to correlate intraoperative blood flow with access patency. Methods: Between March 2012 and March 2015, intraoperative transit time flow measurements were collected on 89 patients. Measurements were performed 5–10 min after the creation of a standardized anastomosis using 3–6 mm flow probes. To examine the correlation between intraoperative blood flow and access patency, groups of patients with high (> 200 mL/min) versus low flow (< 200 mL/min) were enrolled. Patients were assessed clinically and with ultrasound every 3 months. Data were analyzed retrospectively. Results: In the current short-term follow-up, including 89 patients (age 62 ± 3 years), 61 (68.5%) of the autologous arteriovenous fistulas were currently being used in an observation period ranging from 3 months to 3 years (mean observation period 546 ± 95 days) postoperatively. The intraoperative blood flow in patients with functioning autologous arteriovenous fistula (78) was significantly higher than that of patients without functioning autologous arteriovenous fistulas (407 ± 25 vs 252 ± 42 mL/min, respectively; p < 0.005) (11). Conclusion: The intraoperative measurement of blood flow is a useful tool to predict the outcome of maturation in autologous arteriovenous fistula. With this method, technical problems can be detected and corrected intraoperatively. Routine implementation of intraoperative flow measurements has to be examined by prospective controlled trials.

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