Improved Seasonal Mann–Kendall Tests for Trend Analysis in Water Resources Time Series

Zhang, Y.; Cabilio, Paul; Nadeem, Khurram

doi:10.1007/978-1-4939-6568-7_10

Cited by 19 publications

(8 citation statements)

References 23 publications

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“…Changes in RWT will directly impact the ecological conditions of habitats and the variability of fish populations in freshwater ecosystems [15][16][17]. However, the reaction of rivers differs depending on the hydrological properties and environmental conditions of catchment areas, which makes it difficult to generalize the strength and direction of their temperature trends in large spatial scales and for distinct river types [18,19].…”

Section: Introductionmentioning

confidence: 99%

Detecting Patterns of Changes in River Water Temperature in Poland

Graf

Wrzesiński

2020

Water

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The study determined water temperature trends of rivers in Poland in the period 1971–2015, and also their spatial and temporal patterns. The analysis covered daily water temperature of 53 rivers recorded at 94 water gauge stations and air temperature at 43 meteorological stations. Average monthly, annual, seasonal and maximum annual tendencies of temperature change were calculated using the Mann–Kendall (M–K) test. Regional patterns of water temperature change were determined on the basis of Ward’s hierarchical grouping for 16 correlation coefficients of average annual water temperature in successive 30-year sub-periods of the multi-annual period of 1971–2015. Moreover, regularities in monthly temperature trends in the annual cycle were identified using 12 monthly values obtained from the M–K Z test. The majority of average annual air and water temperature series demonstrate statistically significant positive trends. In three seasons: spring, summer and autumn, upward tendencies of temperature were detected at 70%–90% of the investigated water gauges. In 82% of the analysed rivers, similarity to the tendencies of change of monthly air temperature was concluded, with the climatic factor being recognised as of decisive importance for the changes in water thermal characteristics of the majority of rivers in Poland. In the winter months, positive trends of temperature were considerably weaker and in general statistically insignificant. On a regional scale, rivers with a quasi-natural thermal regime experienced temperature increases from April to November. In the other cases, different directions of change in river water temperature (RWT) were attributed to various forms of human impact. It was also found that for the majority of rivers the average annual water temperature in the analysed 30-year sub-periods displayed upward trends, statistically significant or close to the significance threshold. Stronger trends were observed in the periods after 1980, while a different nature of water temperature change was detected only in a couple of mountainous rivers or rivers transformed by human impact. In the beginning of the analysed period (1971–2015), the average annual water temperature of these rivers displayed positive and statistically significant trends, while after 1980 the trends were negative. The detected regularities and spatial patterns of water temperature change in rivers with a quasi-natural regime revealed a strong influence of climate on the modification of their thermal regime features. Rivers characterised by a clearly different nature of temperature change, both in terms of the direction of the tendencies observed and their statistical significance, were distinguished by alterations of water thermal characteristics caused by human activity. The results obtained may be useful in optimising the management of aquatic ecosystems, for which water temperature is a significant indicator of the ongoing environmental changes.

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Section: Introductionmentioning

confidence: 99%

Detecting Patterns of Changes in River Water Temperature in Poland

Graf

Wrzesiński

2020

Water

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“…In addition, most of the hydro-climatic series do not follow a Gaussian distribution leading to a possible misinterpretation of the dependency between the variables when using linear measures [ 24 , 25 , 26 ]. As a result, the non-parametric rank-based correlation metrics of Kendall’s tau and Spearman’s rho are applied to quantify the relationship between two given variables [ 27 , 28 , 29 ]. However, even though the associations evaluated by these two metrics are independent of any probability distribution assumptions, they are more successful in detecting the monotonous relationships between any two variables.…”

Section: Introductionmentioning

confidence: 99%

Information Entropy Suggests Stronger Nonlinear Associations between Hydro-Meteorological Variables and ENSO

Mishra

Konapala

2018

Entropy

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Abstract:Understanding the teleconnections between hydro-meteorological data and the El Niño-Southern Oscillation cycle (ENSO) is an important step towards developing flood early warning systems. In this study, the concept of mutual information (MI) was applied using marginal and joint information entropy to quantify the linear and non-linear relationship between annual streamflow, extreme precipitation indices over Mekong river basin, and ENSO. We primarily used Pearson correlation as a linear association metric for comparison with mutual information. The analysis was performed at four hydro-meteorological stations located on the mainstream Mekong river basin. It was observed that the nonlinear correlation information is comparatively higher between the large-scale climate index and local hydro-meteorology data in comparison to the traditional linear correlation information. The spatial analysis was carried out using all the grid points in the river basin, which suggests a spatial dependence structure between precipitation extremes and ENSO. Overall, this study suggests that mutual information approach can further detect more meaningful connections between large-scale climate indices and hydro-meteorological variables at different spatio-temporal scales. Application of nonlinear mutual information metric can be an efficient tool to better understand hydro-climatic variables dynamics resulting in improved climate-informed adaptation strategies.

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“…Relative importance (the rank of words in all vocabularies each year) was used to evaluate the changes in attention given to different words over the years [28]. The patterns of interannual variation in these phrases were tested using Mann-Kendall trend analysis [29]. The Mann-Kendall trend analyses were performed using "Kendall" [30].…”

Section: Discussionmentioning

confidence: 99%

Research Characteristics on Cyanotoxins in Inland Water: Insights from Bibliometrics

Wang

Zhang

et al. 2022

Water

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Eutrophication is a long-standing ecological and environmental problem, and the severity of harmful algal blooms continues to increase, causing large economic losses globally. One of the most important hazards created by harmful algal blooms is the production of cyanotoxins. This study aimed to analyze the characteristics and development trends of cyanotoxin research through bibliometric analysis. A total of 3265 publications from 1990 to 2020 on cyanotoxins were retrieved from the Science Citation Index (SCI) Expanded database, Web of Science. Over the past 30 years, most research has been concentrated in China (21.4%) and the USA (21.3%). Throughout the study period, microcystin was the focus of the research, accounting for 86% of the total number of publications. A word frequency analysis revealed that as people became more aware of drinking water safety and the construction of large-scale water conservation facilities, “reservoirs” and “rivers” became hot words for researchers, while “lakes” have always been important research objects. Nonmetric multidimensional scaling (NMDS) analysis of studies from the five countries with the largest numbers of publications showed that Chinese researchers typically associate eutrophication with Microcystis, while research subjects in other countries are more extensive and balanced. The development of cyanotoxin research around the world is not even, and we need to push for more research on major lakes that are outside of North America, Europe and China.

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Improved Seasonal Mann–Kendall Tests for Trend Analysis in Water Resources Time Series

Cited by 19 publications

References 23 publications

Detecting Patterns of Changes in River Water Temperature in Poland

Detecting Patterns of Changes in River Water Temperature in Poland

Information Entropy Suggests Stronger Nonlinear Associations between Hydro-Meteorological Variables and ENSO

Research Characteristics on Cyanotoxins in Inland Water: Insights from Bibliometrics

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