A Nonparametric Trend Test for Seasonal Data With Serial Dependence

Hirsch, Robert M.; Slack, James Richard

doi:10.1029/wr020i006p00727

Cited by 1,403 publications

(875 citation statements)

References 12 publications

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“…The non-parametric Seasonal Kendall test (Hirsch and Slack, 1984;Loftis et al 1991) was used for detecting monotonic trends over the study period in the throughfall, soil water, groundwater, and streamwater chemistry time series. For tests of trends for the combined data (Loftis et al 1991) from all four IM sites, an Excel-program developed by Anders Grimvall, SLU and further extended and modified by Jens Fölster and Jan Seibert, SLU was used for the calculations (Fölster et al 2003a).…”

Section: Statistical Testsmentioning

confidence: 99%

Recovery of Soil Water, Groundwater, and Streamwater From Acidification at the Swedish Integrated Monitoring Catchments

Löfgren

Aastrup

Bringmark

et al. 2011

AMBIO

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Recovery from anthropogenic acidification in streams and lakes is well documented across the northern hemisphere. In this study, we use 1996-2009 data from the four Swedish Integrated Monitoring catchments to evaluate how the declining sulfur deposition has affected sulfate, pH, acid neutralizing capacity, ionic strength, aluminum, and dissolved organic carbon in soil water, groundwater and runoff. Differences in recovery rates between catchments, between recharge and discharge areas and between soil water and groundwater are assessed. At the IM sites, atmospheric deposition is the main human impact. The chemical trends were weakly correlated to the sulfur deposition decline. Other factors, such as marine influence and catchment features, seem to be as important. Except for pH and DOC, soil water and groundwater showed similar trends. Discharge areas acted as buffers, dampening the trends in streamwater. Further monitoring and modeling of these hydraulically active sites should be encouraged.

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Section: Statistical Testsmentioning

confidence: 99%

Recovery of Soil Water, Groundwater, and Streamwater From Acidification at the Swedish Integrated Monitoring Catchments

Löfgren

Aastrup

Bringmark

et al. 2011

AMBIO

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“…Limitations of the MK test are that there must be no serial correlation for the resulting p-values to be correct, and that data must be monotonic. A few of authors mention the use of modifications of the MK method that account for autocorrelation [63,67,70,74]; the most usual modification is the one proposed by Hirsch and Slack [111]. It is not excluded that others account for autocorrelation without mentioning it.…”

Section: Trend Detection and Quantificationmentioning

confidence: 99%

Long-term Trends of Organic Carbon Concentrations in Freshwaters: Strengths and Weaknesses of Existing Evidence

Filella

Rodríguez-Murillo

2014

Water

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Many articles published in the last few years start with the assumption that the past decades have seen an increase in dissolved organic carbon (DOC) concentrations in the rivers and lakes of the Northern Hemisphere. This study analyses whether the existing evidence supports this claim. With this aim, we have collected published studies where long series of organic carbon concentrations (i.e., longer than 10 years) were analyzed for existing trends and have carefully evaluated the 63 articles found. Information has been collated in a comprehensive and comparable way, allowing readers to easily access it. The two main aspects considered in our analysis have been the analytical methods used and the data treatment methods applied. Both are sensitive issues because, on the one hand, the difficulties associated with correctly determining organic carbon concentrations in surface waters are well known, while, on the other, dealing with real environmental data (i.e., lack of normality, censoring, missing values, etc.) is an extremely intricate matter. Other issues such as data reporting and the geographical location of the systems studied are also discussed. In conclusion, it is clear that organic carbon concentrations have increased in some surface waters in the Northern Hemisphere since the 1990s. However, due to a lack of data in many parts of the world, it is not known whether this phenomenon is general and, more importantly, in the areas for which such data do exist, the reporting and methodological problems in the published studies prevent any conclusion on the existence of a general temporal behavior of organic carbon from being drawn.

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“…(2) (after Hirsch and Slack, 1984). For cases the sample size n is larger than 10, the standard normal variate p is computed by using the following equation (see Douglas et al, 2000)…”

Section: Trends In Rainfall and Stream Flowmentioning

confidence: 99%

Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin – Ethiopia

Rientjes

Haile

Kebede

et al. 2011

Hydrol. Earth Syst. Sci.

170

140

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Abstract. In this study we evaluated changes in land cover and rainfall in the Upper Gilgel Abbay catchment in the Upper Blue Nile basin and how changes affected stream flow in terms of annual flow, high flows and low flows. Land cover change assessment was through classification analysis of remote sensing based land cover data while assessments on rainfall and stream flow data are by statistical analysis. Results of the supervised land cover classification analysis indicated that 50.9 % and 16.7 % of the catchment area was covered by forest in 1973 and 2001, respectively. This significant decrease in forest cover is mainly due to expansion of agricultural land.By use of a change detection procedure, three periods were identified for which changes in rainfall and stream flow were analyzed. Rainfall was analyzed at monthly base by use of the Mann-Kendall test statistic and results indicated a statistically significant, decreasing trend for most months of the year. However, for the wet season months of June, July and August rainfall has increased. In the period 1973-2005, the annual flow of the catchment decreased by 12.1 %. Low flow and high flow at daily base were analyzed by a low flow and a high flow index that is based on a 95 % and 5 % exceedance probability. Results of the low flow index indicated decreases of 18.1 % and 66.6 % for the periods 1982-2000 and 2001-2005 respectively. Results of high flows indicated an increase of 7.6 % and 46.6 % for the same periods. In this study it is concluded that over the period 1973-2005 stream flow has changed in the Gilgel Abbay catchment by changes in land cover and changes in rainfall.

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A Nonparametric Trend Test for Seasonal Data With Serial Dependence

Cited by 1,403 publications

References 12 publications

Recovery of Soil Water, Groundwater, and Streamwater From Acidification at the Swedish Integrated Monitoring Catchments

Recovery of Soil Water, Groundwater, and Streamwater From Acidification at the Swedish Integrated Monitoring Catchments

Long-term Trends of Organic Carbon Concentrations in Freshwaters: Strengths and Weaknesses of Existing Evidence

Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin – Ethiopia

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