scholarly journals Time-variability of the fraction of young water in a small headwater catchment

2019 ◽  
Author(s):  
Michael P. Stockinger ◽  
Heye R. Bogena ◽  
Andreas Lücke ◽  
Christine Stumpp ◽  
Harry Vereecken
Keyword(s):  
Time Series ◽  
Time Window ◽  
High Sensitivity ◽  
Annual Runoff ◽  
Nutrient Loss ◽  
Time Variability ◽  
Short Term ◽  
Sampling Campaign ◽  
The Mean ◽  
One Year

Abstract. The time precipitation needs to travel through a catchment to its outlet is an important descriptor of a catchment's susceptibility to pollutant contamination, nutrient loss and hydrological functioning. The fast component of total water flow can be estimated by the fraction of young water (Fyw) which is the percentage of streamflow younger than three months. Fyw is calculated by comparing the amplitudes of sine waves fitted to seasonal precipitation and streamflow tracer signals. This is usually done for the complete tracer time series available neglecting annual differences in the amplitudes of longer time series. Considering inter-annual amplitude differences, we here employed a moving time window of one-year length in weekly time steps over a 4.5-years δ18O tracer time series to calculate 189 Fyw results. The results were then tested against the following null hypotheses, defining 2 % difference in Fyw as significant based on results of previous studies: (1) Fyw does not deviate more than ±2% from the mean of all Fyw results indicating long-term invariance. Larger deviations would indicate either flow path changes or a change in the relative contribution of different flow paths; (2) for any four-week window Fyw does not change more than ±2 % indicating short-term invariance. Larger deviations would indicate a high sensitivity of Fyw to a 1–4 weeks shift in the start of a one-year sampling campaign; (3) for a given calendar month Fyw does not change more than ±2 % indicating seasonal invariance of Fyw. In our study, all three null hypotheses were rejected. Thus, the Fyw results were time-variable, showed a high variability in the chosen sampling time and had no pronounced seasonality. Based on high short-term variability of Fyw when the mean adjusted R² was below 0.2 we recommend that a low R2 should be regarded as indicating potentially highly uncertain Fyw results. Furthermore, while investigated individual meteorological factors could not sufficiently explain variations of Fyw, the runoff coefficient showed a moderate negative correlation of r = −0.54 with Fyw. This indicated that when annual runoff exceeded precipitation the catchment received the water deficit from storage which is old water causing a decrease in Fyw. The results of this study suggest that care must be taken when comparing Fyw of catchments that were based on different calculation time periods.

scholarly journals Time variability and uncertainty in the fraction of young water in a small headwater catchment

2019 ◽  
Vol 23 (10) ◽  
pp. 4333-4347 ◽  
Author(s):  
Michael Paul Stockinger ◽  
Heye Reemt Bogena ◽  
Andreas Lücke ◽  
Christine Stumpp ◽  
Harry Vereecken
Keyword(s):  
Time Series ◽  
Goodness Of Fit ◽  
Time Window ◽  
High Sensitivity ◽  
Nutrient Loss ◽  
Time Variability ◽  
Flow Paths ◽  
Relative Contribution ◽  
Sampling Campaign ◽  
The Mean

Abstract. The time precipitation needs to travel through a catchment to its outlet is an important descriptor of a catchment's susceptibility to pollutant contamination, nutrient loss, and hydrological functioning. The fast component of total water flow can be estimated by the fraction of young water (Fyw), which is the percentage of streamflow younger than 3 months. Fyw is calculated by comparing the amplitudes of sine waves fitted to seasonal precipitation and streamflow tracer signals. This is usually done for the complete tracer time series available, neglecting annual differences in the amplitudes of longer time series. Considering inter-annual amplitude differences, we employed a moving time window of 1 year in weekly time steps over a 4.5-year δ18O tracer time series to calculate 189 Fyw estimates and their uncertainty. They were then tested against the following null hypotheses: (1) at least 90 % of Fyw results do not deviate more than ±0.04 (4 %) from the mean of all Fyw results, indicating long-term invariance. Larger deviations would indicate changes in the relative contribution of different flow paths; (2) for any 4-week window, Fyw does not change more than ±0.04, indicating short-term invariance. Larger deviations would indicate a high sensitivity of Fyw to a 1-week to 4-week shift in the start of a 1-year sampling campaign; (3) the Fyw results of 1-year sampling campaigns started in a given calendar month do not change more than ±0.04, indicating seasonal invariance. In our study, all three null hypotheses were rejected. Thus, the Fyw results were time-variable, showed variability in the chosen sampling time, and had no pronounced seasonality. We furthermore found evidence that the 2015 European heat wave and including two winters into a 1-year sampling campaign increased the uncertainty of Fyw. Based on an increase in Fyw uncertainty when the mean adjusted R2 was below 0.2, we recommend further investigations into the dependence of Fyw and its uncertainty to goodness-of-fit measures. Furthermore, while investigated individual meteorological factors did not sufficiently explain variations of Fyw, the runoff coefficient showed a moderate negative correlation of r=-0.50 with Fyw. The results of this study suggest that care must be taken when comparing Fyw of catchments that were based on different calculation periods and that the influence of extreme events and snow must be considered.

Zooplankton Sample Variation on the Scotian Shelf

1978 ◽  
Vol 35 (9) ◽  
pp. 1207-1222 ◽  
Author(s):  
D. D. Sameoto
Keyword(s):  
Time Series ◽  
Fish Larvae ◽  
Geographic Area ◽  
Scotian Shelf ◽  
Tidal Cycles ◽  
Zooplankton Sample ◽  
Single Station ◽  
The Mean ◽  
One Year ◽  
Abundance And Distribution

Zooplankton sampling experiments on the Scotian Shelf during September 1973 and August 1974 using vertical tows demonstrated that numbers of many zooplankton species had a periodic fluctuation over 26 h. The fluctuations appeared related to the tide during 1974 but not in 1973. The periodic fluctuations accounted for a major portion of the sample variation in many species during both years. The mean numbers of small forms of zooplankton (copepods) obtained from the 26-h time series on a single station were very similar to means obtained during the same cruise over a wide area of the shelf. This suggested that a single station sampled over a period of two tidal cycles may be representative of the sample variation encountered over a wide geographic area of many hundreds of kilometres. Only Calanus and Pseudocalanus were correlated during all the experiments and from year to year. The abundance and distribution of the other species of zooplankton compared from one year to the next were not significantly correlated. This suggested the species populations were independent of one another. Key words: zooplankton, sample variation, time series, Scotian Shelf, fish larvae, Copepoda, tide

Methods for determining "reference changes" from serial measurements: plasma lipid-bound sialic acid.

1989 ◽  
Vol 35 (6) ◽  
pp. 972-974 ◽  
Author(s):  
S Shahangian ◽  
H A Fritsche ◽  
J I Hughes ◽  
D A Johnston
Keyword(s):  
Time Series ◽  
Sialic Acid ◽  
Healthy Subjects ◽  
Plasma Lipid ◽  
Autoregressive Time Series ◽  
The Mean ◽  
One Year ◽  
Mean Variance ◽  
Serial Measurements ◽  
Colorectal Adenocarcinomas

Abstract Lipid-bound sialic (neuraminic) acid (LSA) was measured in EDTA-treated plasma of 26 healthy subjects at three-month intervals for up to one year. The change in LSA concentration for consecutive measurements ranged from -54 to 42 mg/L (mean, -2.1 mg/L; SD, 19.6 mg/L; n = 56). The "reference change" for plasma LSA (+/- 2 SD), calculated from distribution of the differences, was +/- 39 mg/L. The 88th percentile of the intra-individual variance was 338 mg2/L2 and the mean variance was 159 mg2/L2. Using the homeostatic, autoregressive time-series model, a reference change of +/- 51 mg/L between two consecutive measurements was determined to be statistically significant (i.e., expected by chance no more than 5% of the time) in 88% of the healthy subjects. Only 73% of the healthy subjects would have had intra-individual variances corresponding to the reference change of +/- 39 mg/L according to the autoregressive model. The concentration of LSA in plasma was significantly decreased upon surgery in five of 10 patients with colorectal adenocarcinomas of Dukes stages A-C when we used +/- 39 mg/L as the reference change, but in only two of the 10 when we used +/- 51 mg/L as the reference change.

The effect of season and the introduction of rams on oestrous activity in Somali, Nandi, Merino, Karakul and New Zealand Romney Marsh ewes in Kenya

1986 ◽  
Vol 43 (3) ◽  
pp. 447-457 ◽  
Author(s):  
A. B. Carles ◽  
W. A. K. Kipngeno
Keyword(s):  
Time Series ◽  
Seasonal Variation ◽  
New Zealand ◽  
Time Series Analysis ◽  
Oestrous Cycle ◽  
Significant Source ◽  
Short Term ◽  
Series Analysis ◽  
The Mean

ABSTRACTA study was made of the levels of oestrous activity of two indigenous breeds of sheep (Somali and Nandi) and three exotic breeds of sheep (Merino, Karakul and New Zealand Romney Marsh) over a period of 3 years, in an equatorial environment. Breed was the only significant source of variation for the length of the oestrous cycle (P < 0·01). The mean lengths of the oestrous cycle were 17·2 (s.d. 3·21), 17·5 (s.d. 2·24), 17·9 (s.d. 2·99), 17·5 (s.d. 2·57) and 16·5 (s.d. 3·41) days for the Somali, Nandi, Merino, Karakul and Romney Marsh breeds, respectively.The mean percentage of ewes of the different breeds showing oestrus in 20-day periods were 69·8 (s.d. 22·57), 49·9 (s.d. 18·67), 63·4 (s.d. 25·70), 79·2 (s.d. 20·30) and 33·2 (s.d. 23·50) % for the Somali, Nandi, Merino, Karakul and Romney Marsh breeds, respectively. Time-series analysis did not detect any evidence of seasonal variation in oestrous activity, although there was an indication that the Merino and Romney Marsh breeds showed a marked increase in oestrous activity following, the introduction of rams. It was concluded that the variation in level of oestrous activity was short term and random.

ADAPTATION AND APPLICATION OF THE KARAZEV METHOD TO THE RATIONALIZATION OF QUEBEC'S HYDROMETRIC BASIC NETWORK

1974 ◽  
Vol 5 (4) ◽  
pp. 213-228
Author(s):  
M. LECLERC ◽  
B. BOBÉE ◽  
J. P. VILLENEUVE
Keyword(s):  
Spatial Distribution ◽  
Research Program ◽  
Annual Runoff ◽  
Time Variability ◽  
Actual Knowledge ◽  
Rational Development ◽  
The Mean ◽  
Basic Network

In a research program carried out by I.N.R.S.-Eau, certain principles inherent to the rational development of hydrometric networks were applied to the Quebec network. This study describes an application of a method specific to the development of a basic network. The method used to establish the number of stations required is based on the actual knowledge of the spatial distribution and time variability of the mean annual runoff. A modified version of Karazev's (1968) method applied originally to a study of the hydrographic basins in the USSR was found to be particularly suitable to regions of little hydrologic information and particularly to Quebec.

TIME SERIES ANALYSIS AND FORECAST ESTIMATES FOR THE MEAN ANNUAL RIVERINE WATER RUNOFF WITHIN THE UKRAINIAN PART OF THE PRUT AND SIRET BASINS

2020 ◽  
Author(s):  
O. Lukianets ◽  
◽  
O. Obodovskyi ◽  
V. Grebin ◽  
O. Pochaievets ◽  
...  
Keyword(s):  
Time Series ◽  
Annual Runoff ◽  
Water Runoff ◽  
Cyclic Structure ◽  
Deviation Probability ◽  
Riverine Water ◽  
Random Functions ◽  
Integral Curves ◽  
The Mean ◽  
Annual Water

The systematization, generalization, estimation of the variability of time series of the mean annual water runoff of rivers in of the Prut and Siret basins has been carried out, and its cyclic structure has been revealed. For this purpose, a database of average annual discharges water with 12 of hydrological observing stations on the rivers in of the Prut and Siret basins from the beginning of observations to 2015 have been created. Number of years under observation by the annual runoff values for river Prut near city of Chernivtsi is 121. Their representativeness and homogeneity for practical calculations has been evaluated. To identify and formalize the cyclic structure of time series of the mean annual water runoff of rivers in of the Prut and Siret basins used the methods of mathematical statistics and theory of random functions: a function of mathematical expected value; a function of dispersion values or standard deviation; probability distribution function; autocorrelation function. Also have been involved different of the standard mathematical criteria (criteria homogeneity, criteria of the series and of the longest series), integral curves of the differences. As a result, the structure of cyclic oscillations is revealed of the mean annual water runoff of rivers in the Prut and Siret basins and that is what made it possible to provide forecast estimates until 2050.

scholarly journals One Year Follow-Up of Patient Reported Outcomes Following Third Generation Minimally Invasive Chevron Akin Osteotomies (MICA) in Hallux Valgus Surgery

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0032
Author(s):  
Thomas L. Lewis ◽  
Robbie Ray ◽  
David Gordon
Keyword(s):  
Minimally Invasive ◽  
Hallux Valgus ◽  
Patient Reported Outcomes ◽  
Case Series ◽  
Third Generation ◽  
Short Term ◽  
Patient Reported ◽  
The Mean ◽  
One Year

Category: Bunion Introduction/Purpose: The aim of this study was to explore the short-term results of third generation (using screw fixation) Minimally Invasive Chevron and Akin osteotomies (MICA) for hallux valgus correction. There is a paucity of published data regarding the outcomes of this relatively new technique. We present the largest series in the literature, using three separate validated patient-reported outcome measures (EQ-5DL, VAS Pain and Manchester Oxford Foot Questionnaire (MOXFQ), for this time point. Methods: A single surgeon case series of patients with hallux valgus underwent primary third generation minimally invasive chevron and akin osteotomies (MICA) for hallux valgus correction. Between August 2015 and January 2019, 430 MICAs were performed in 295 patients that were eligible for 1 year follow up. Baseline and 1 year post-operative patient reported outcomes were collected for 242 feet in 194 patients (182 females; 12 males). Paired t-tests were used to determine the statistical significance of the difference between pre- and post-operative scores. Results: The mean age was 55.9 (range 16.3-84.9, standard deviation (s.d.) 12.5). At one year follow up, the mean MOXFQ scores had improved for each domain: Pain; baseline 41.9 (range 0-100, s.d. 21.8), reduced to 13.8 (range 0-90, s.d. 17.7, p<0.001); Walking; baseline 34.6 (range 0-100, s.d. 24.3) reduced to 9.8 (range 0-89.0, s.d. 18.0, p<0.001); Social interaction; baseline 45.4 (range 0-100, s.d. 22.8), reduced to 8.2 (range 0-75.0, s.d. 14.7, p<0.001). Mean VAS Pain score improved from 29.8 (range 0.0-90.0, s.d. 22.1) to 8.2 (range 0.00-64.0, s.d. 12.8, p<0.001). Mean EQ-5D index score improved from 0.755 (range 0.066-1.000, s.d. 0.136) to 0.891 (range 0.350-1.000, s.d. 0.124, p<0.001). Mean EQ-5D VAS score improved from 83.4 (range 28- 100, s.d. 12.4) to 85.6 (range 0-100, s.d. 14.2, p=0.047). Conclusion: This is the largest prospective case series of short-term patient reported outcomes using a validated assessment method for hallux valgus, following third generation MICA to date. These data show that this technique is effective at improving foot and ankle specific patient reported outcomes at 1 year. This cohort is being followed over the longer term.

scholarly journals Prevalence of Asymptomatic Brucellosis in Children 7 to 12 Years Old

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
Mohammad Aghaali ◽  
Siamak Mohebi ◽  
Hosein Heydari
Keyword(s):  
Demographic Data ◽  
Clinical Manifestations ◽  
Asymptomatic Infection ◽  
Short Term ◽  
Disease Symptoms ◽  
Blood Samples ◽  
Asymptomatic Children ◽  
The Mean ◽  
One Year

Background. Brucellosis is one of the most common diseases of humans and animals and its clinical manifestations differ from asymptomatic infection to chronic illness associated with recurrence of symptoms. This study aimed to evaluate the prevalence of brucellosis in asymptomatic children 7 to 12 years old in Kahak, Iran.Methods. In this study, 186 children 7 to 12 years old were evaluated. Demographic data and exposure to the brucellosis agent were recorded and blood samples for the Wright, Coombs, and 2ME tests were collected. All the study subjects were followed up for one year about the appearance of symptoms.Results. The mean age was 10 ± 1.72 years and 51% were boys. Family history was positive for brucellosis in 15% of children. A total of 8 children were brucellosis seropositive and, in subsequent follow-up, 6 of them showed the disease symptoms.Conclusion. This study showed that approximately 4.3% of children in endemic areas can have asymptomatic brucellosis and many of these children may be symptomatic in short term.

scholarly journals Water Infiltration after Prescribed Fire and Soil Mulching with Fern in Mediterranean Forests

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 95
Author(s):  
Bruno Gianmarco Carrà ◽  
Giuseppe Bombino ◽  
Pietro Denisi ◽  
Pedro Antonio Plaza-Àlvarez ◽  
Manuel Esteban Lucas-Borja ◽  
...  
Keyword(s):  
Prescribed Fire ◽  
Time Window ◽  
Water Repellency ◽  
Infiltration Rate ◽  
Water Infiltration ◽  
Mediterranean Forests ◽  
Runoff Generation ◽  
Short Term ◽  
Peak Flows ◽  
One Year

Prescribed fire is commonly used to reduce the wildfire risk in Mediterranean forests, but the soil’s hydrological response after fire is contrasting in literature experiences. The mulch treatment can limit the increases in runoff and erosion in the short term after a fire. The use of fern is preferable to straw, due its large availability in forests. However, no experiences of post-fire treatment with fern mulch have been found in the literature and therefore the mulching effectiveness has not been evaluated. This study has measured water infiltration rate (IR) and water repellency (SWR) using a rainfall simulator in three Mediterranean forest stands (pine, oak and chestnut) of Calabria (Southern Italy) after a prescribed fire and mulching treatment with fern in comparison to unburned soil. Prescribed fire reduced water infiltration in all forests in the short term compared to the unburned conditions, and increased SWR in pine and oak forests. These reductions in IR in the time window of disturbance after fire increased the runoff generation capacity in all soils, but had a lower effect on peak flows. However, soil mulching with fern limited the runoff rates and peak flows compared to the burned soils, but this treatment was less effective in pine forest. One year after fire, IR increased in burned soils (treated or not) over time, and SWR disappeared. The effects of mulching have disappeared after some months from fire. The study confirms the usefulness of mulching in broadleaves forest in the short term, in order to control the hydrological effects of prescribed fire in Mediterranean forests. Both post-fire management techniques should be instead adopted with caution in conifer forests.

scholarly journals Time Series Analysis of Mean Monthly Temperature in the Far Western Ethiopia, Assosa District

2020 ◽  
Author(s):  
Tigabu Hailu Kassa ◽  
Shewayiref Geremew Gebremichael
Keyword(s):  
Time Series ◽  
Arima Model ◽  
Descriptive Statistics ◽  
Mean Annual Temperature ◽  
Temperature Pattern ◽  
First Order ◽  
Monthly Temperature ◽  
The Mean ◽  
One Year ◽  
Western Ethiopia

Abstract BackgroundThis study investigated the mean monthly temperature pattern of the Assosa district, Western Ethiopia. The objective of this study was to analyze the mean monthly temperature patterns in the Assosa district for the period from January 2012 to December 2016 based on data from meteorological stations in the Assosa district.MethodsDescriptive statistics and univariate Box-Jenkins methodology to build the seasonal ARIMA model were used.ResultsThe results showed that the mean annual temperature of Assosa was 28.025 degree Celsius. The original series was found to be seasonally non-stationary, as indicated by the ACF plot of the series. After using first-order seasonal differencing, the series was found to be stationary. A time-series model for the Assosa station was adjusted, processed, diagnostically checked, and finally, an ARIMA (3.0.1) model is established and this model is used to forecast one-year mean monthly temperature values. ConclusionThe forecasted mean temperature values showed a similar pattern to previous recordings.

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