A Statistical Evaluation of Trends in the Water Quality of the Niagara River

El‐Shaarawi, A. H.; Esterby, Sylvia R.; Kuntz, K.W.

doi:10.1016/s0380-1330(83)71892-7

Cited by 37 publications

(12 citation statements)

References 3 publications

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“…In addition, unequal spacing between observations does not present a problem as the day of observation is incorporated directly into the model. A similar approach was used by El-Shaarawi et al (1983). A simple linear regression model was used to test the relationship between selected chemical determinands included in this study.…”

Section: Discussionmentioning

confidence: 99%

Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

Helliwell¹,

Ferrier²,

Johnston³

et al. 2001

Hydrol. Earth Syst. Sci.

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The long term response of surface waters to changes in sulphur deposition and afforestation is investigated for three upland river systems in the Galloway region of south-west Scotland. From 1984-1999, these rivers exhibited a statistically significant decline in non-marine sulphate concentrations in response to reduced acid deposition. This reduction in non-marine sulphate was, however, insufficient to induce a pH recovery over the period. A statistically significant increase in river pH was observed between 1956-1970 (0.05 yr -1 ) when subsidised agricultural lime payments were at a maximum. In 1976, this subsidy ceased and surface waters have progressively acidified. In addition, climatic change is found to influence long-term trends in pH. Mean annual pH was greatest during a dry period between 1969-1973 when total annual discharge was low. Thereafter, pH declined gradually in response to higher rainfall and increased total annual discharge. Overall, surface waters draining the afforested catchments of the Rivers Cree and Bladnoch are more acid than those draining the moorland catchment of the Luce. These results indicate that in afforested catchments, current reductions in sulphur emissions have not led to an observed improvement in the acid status of surface waters. Forestry, therefore, represents a confounding factor with regard to chemical recovery from acidification in this region.

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Section: Discussionmentioning

confidence: 99%

Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

Helliwell¹,

Ferrier²,

Johnston³

et al. 2001

Hydrol. Earth Syst. Sci.

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“…The advantages of nonparametric procedures are fewer assumptions on the underlying quantity distributions, less sensitive to a small percent of outliers, invariant to power transformation (e.g., MK tests give the same p-values when applied to the original time series and the log-transformed series), and simplicity in application (Helsel and Hirsch, 1992;Shadmani et al, 2012). Therefore, in climatological and hydrological applications where the normality and independence of observations are often not satisfied, nonparametric trend test methods, such as Mann-Kendall (Lins and Slack, 1999;Zhang et al, 2001Zhang et al, , 2006Kahya and Kalaycı, 2004;Wu et al, 2008;Birsan et al, 2014) and Spearman's rank correlation coefficient (El-Shaarawi et al, 1983;Hipel and McLeod, 1994;Yue et al, 2002;Khaliq et al, 2009) are preferred. Yue et al (2002) showed that the MK and SR have similar power for trend analysis in both normally distributed and highly skewed time series.…”

Section: Trend Analysismentioning

confidence: 99%

Spatial and Temporal Variations in Eastern U.S. Hydrology: Responses to Global Climate Variability

Feng

Beighley

Hughes

et al. 2016

J American Water Resour Assoc

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Coastal ecosystems are dependent on terrestrial freshwater export which is affected by both climate trends and natural climate variability. However, the relative role of these factors is not clear. Here, both climate trends and internal climate variabilities at different time scales are related to variations in terrestrial freshwater export into the eastern United States (U.S.) coastal region. For the recent 35‐year period, the intensified hydro‐meteorological processes (annual precipitation or evapotranspiration) may explain the observed streamflow variability in the northeast. However, in the southeast, streamflow is positively correlated with climate variability induced by the Pacific Ocean conditions (El Nino‐Southern Oscillation [ENSO] and Pacific Decadal Oscillation) rather than Atlantic Ocean conditions (Atlantic Multi‐decadal Oscillation and North Atlantic Oscillation). The centroid location for volume of terrestrial freshwater export integrated along the eastern U.S. has a positive temporal trend and is negatively correlated with ENSO conditions, suggesting the northward trend in freshwater export to U.S. eastern coast may be disturbed by the natural climate variability, especially ENSO conditions, i.e., the center of freshwater mass moves southward (northward) during El Nino (La Nina) years. The results indicate the spatial and temporal variations in freshwater export from the eastern U.S. are affected by both climate change and inter‐annual climate variability during the recent 35‐year period (1980‐2014).

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“…Another rank-based nonparametric test, the Spearman's rho (SR) test (Lehmann, 1975;Sneyers, 1990), has sometimes been applied to detect trends in hydrological data (e.g. Lettenmaier, 1976;El-Shaarawi et al, 1983;Pilon et al, 1985;McLeod et al, 1991;Hipel & McLeod, 1994). The study of documented that these two tests have almost the same power to identify trends in time series.…”

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confidence: 99%

A comparison of the power of thettest, Mann-Kendall and bootstrap tests for trend detection / Une comparaison de la puissance des teststde Student, de Mann-Kendall et du bootstrap pour la détection de tendance

Yue

Pilon

2004

Hydrological Sciences Journal

335

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PO Box 5050, Burlington, Ontario L7R 4A6, Canada Abstract Monte Carlo simulation is applied to compare the power of the statistical tests: the parametric t test, the non-parametric Mann-Kendall (MK), bootstrap-based slope (BS-slope), and bootstrap-based MK (BS-MK) tests to assess the significance of monotonic (linear and nonlinear) trends. Simulation results indicate that (a) the t test and the BS-slope test, which are slope-based tests, have the same power; (b) the MK and BS-based MK tests, which are rank-based tests, have the same power; (c) for normally-distributed data, the power of the slope-based tests is slightly higher than that of the rank-based tests; and (d) for non-normally distributed series such as time series with the Pearson type III (P3), Gumbel, extreme value type II (EV2), or Weibull distributions, the power of the rank-based tests is higher than that of the slope-based tests. The power of the tests is slightly sensitive to the shape of trend. Practical assessment of the significance of trends in the annual maximum daily flows of 30 Canadian pristine river basins demonstrates a similar tendency to that obtained in the simulation studies. (BS-MK). Les résultats de simulation indiquent que (a) les tests t de Student et BS-pente, basés sur la pente, ont la même puissance; (b) les tests MK et BS-MK, basés sur le rang, ont la même puissance; (c) pour des données présentant une distribution normale, la puissance des tests basés sur la pente est légèrement supérieure à celle des tests basés sur le rang; et (d) pour des séries présentant une distribution non-normale, comme une distribution de Pearson III, de Gumbel, de valeur extrême type II, ou de Weibull, la puissance des tests basés sur le rang est supérieure à celle des tests basés sur la pente. La puissance des tests est légèrement sensible à la forme de la tendance. L'estimation pratique de la signification des tendances est similaire pour les études par simulation et pour l'analyse des données de maxima annuels de débits journaliers de 30 bassins vierges canadiens. Mots clefs détection de tendance; test t de Student; test de Mann-Kendall; test bootstrap; puissance d'un test; valeur de P; forme de tendance; analyse statistique Key words INTRODUCTIONThe rank-based nonparametric Mann-Kendall (MK) test (Mann, 1945;Kendall, 1975) has been commonly used to assess the significance of monotonic trends in hydroSheng Yue & Paul Pilon 22 meteorological time series (e.g. ven Belle & Hughes, 1984;Cailas et al., 1986;Hipel et al., 1988;Hipel & McLeod, 1994;Taylor & Loftis, 1989;Demarée & Nicolis, 1990;Zetterqvist, 1991;Chiew & McMahon, 1993;Yu et al., 1993;Hirsch et al., 1993;Lettenmaier et al., 1994;Burn, 1994;Yulianti & Burn, 1998;Gan, 1998;Lins & Slack, 1999;Douglas et al., 2000;Yue et al., 2003; and others). Another rank-based nonparametric test, the Spearman's rho (SR) test (Lehmann, 1975;Sneyers, 1990), has sometimes been applied to detect trends in hydrological data (e.g. Lettenmaier, 1976;El-Shaarawi et al., 1983;Pilon et al., 1985;McLeod et al....

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A Statistical Evaluation of Trends in the Water Quality of the Niagara River

Cited by 37 publications

References 3 publications

Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

Spatial and Temporal Variations in Eastern U.S. Hydrology: Responses to Global Climate Variability

A comparison of the power of thettest, Mann-Kendall and bootstrap tests for trend detection / Une comparaison de la puissance des teststde Student, de Mann-Kendall et du bootstrap pour la détection de tendance

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