Spatial-temporal rainfall trend and variability assessment in the Upper Wabe Shebelle River Basin, Ethiopia: Application of innovative trend analysis method

Harka, Arus Edo; Jilo, Nura Boru; Behulu, Fiseha

doi:10.1016/j.ejrh.2021.100915

Cited by 44 publications

(54 citation statements)

References 63 publications

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“…According to Şen [35], the segmentation into three categories (weak, average and strong) provides detailed information about the structure of the internal tendency of the series considered. Other authors, who used the ITA method in other regions, confirmed that the method is more adapted to detect tendencies within the series [28,37,38]. The results obtained with the ITA method are important because they enable better comprehension of the hydroclimatic context and provide elements for water resource management [28].…”

Section: Long-term Tendencies Of Precipitationmentioning

confidence: 89%

“…During the last years, numerous research studies have used parametric and nonparametric tests to define tendencies within chronological series [22][23][24][25][26][27][28][29][30][31] The most commonly used are the Mann-Kendall [32,33] and Sen [34] tests. More recently, Sen [35] developed a new methodological approach, the innovative trend analysis (ITA), to detect tendencies in chronological data series.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to the other methods mentioned above, the advantages of this method are: (1) the dataset does not require any hypothesis to be verified and (2) it is based only on the comparison of the two halves of the original temporal series [36]. This method has been used, for example, in Turkey [37], Nepal [38] and Ethiopia [28]. For instance, Girma et al [39] applied the ITA method to the upper basin of the Huai River in China to show that the basin's precipitation is characterized by a high variation coefficient during the summer season, and that the annual rainfall had a statistically significant increasing tendency at the Fuyang station during the period 1960-2016.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Long-Term Evolution of Rainfall and Its Consequences on Water Resources: Application to the Watershed of the Kara River (Northern Togo)

Ani

Jaunat

Marin

et al. 2022

Water

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The Kara River watershed (KRW), northern Togo, is facing climate-change impacts that have never been clearly characterized. Six decades of rainfall data (1961–2020) from six measuring stations ideally distributed across the watershed were used in this study. The flow records from two stations situated in contrasting locations on the KRW were also used. Statistical tests were conducted to assess the spatial and temporal variability of the rainfall and to detect tendencies within these meteorological series. The water balance method and calculation of the dry-off coefficient and of the groundwater volume drained by rivers allowed evaluating the impact of climatic evolution on surface flow and on groundwater volumes during the six decades studied. The results showed contrasting spatiotemporal variability of rainfall (and of aquifer recharge) over the watershed with a decreasing tendency upstream and an increasing one downstream. At the same time, the water volume drained by the aquifer to sustain the river’s base flow decreased from −22% to −36% depending on the measuring station. These results constitute a decision-making tool for Togolese water resource managers and are of primary importance for characterizing the fate of water resources worldwide in regions subject to severe droughts.

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Section: Long-term Tendencies Of Precipitationmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Long-Term Evolution of Rainfall and Its Consequences on Water Resources: Application to the Watershed of the Kara River (Northern Togo)

Ani

Jaunat

Marin

et al. 2022

Water

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“…LOESS appears to be "more sensitive" to the number of data points, thereby identifying more grids with significant trends when the entire series is cut in half. If eliminating the influence of the amount of significant grids (i.e., ignoring the dots in Figures 8,9,11,and 12), we can still find that the two smoothing methods can maintain good consistency of the trend patterns. Another notable difference between the trend detection method using first derivatives and LOESS that should be addressed is the number of fitted data points used for deriving the trend statistics: the former has to make use of the first derivatives at all the points by design, while the latter takes only the first three and last three fitted values into account (see Sections 3.3.2 and 3.3.3).…”

Section: Trends In the Earlier And Later 30 Yearsmentioning

confidence: 95%

“…Apart from these classical methods, some new methods for trend detection have been developed as well: ref. [11] developed and used the innovative trend analysis method in conjunction with the MK test and Sen's slope estimate for trend analysis on rainfall in the Upper Wabe Shebelle River Basin in Ethiopia.…”

Section: Introductionmentioning

confidence: 99%

Meaningful Trend in Climate Time Series: A Discussion Based On Linear and Smoothing Techniques for Drought Analysis in Taiwan

2022

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Finding significant trends in hydroclimate time series has been deemed an essential task in numerous studies. Despite the existence of various trend detection methods, statistical significance is mostly examined for linear trends and related to the meaningfulness of the found trends. We wish to draw attention to a more general definition of meaningful trends by cross-referencing not only linear but also smoothing techniques. We apply linear regression (LR) and two smoothing techniques based on regularized minimal-energy tensor-product B-splines (RMTB) to the trend detection of standardized precipitation index (SPI) series over Taiwan. LR and both RMTB-based methods identify an overall upward (wetting) trend in the SPI series across the time scales in Taiwan from 1960 to 2019. However, if dividing the entire time series into the earlier (1960–1989) and later (1990–2019) sub-series, we find that some downward (drying) trends at varied time scales migrate from southcentral–southwestern to eastern regions. Among these significant trends, we have more confidence in the recent drying trend over eastern Taiwan since all the methods show trend patterns in highest similarity. We also argue that LR should be used with great caution, unless linearity in data series and independence and normality in residuals can be assured.

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Assessment of temporal and spatial variations of water quality parameters in the Zarafshan River basin

Shoergashova,

Liu,

Ibrokhimova

et al. 2024

CLEAN Soil Air Water

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River ecosystems in Central Asia face significant stress from environmental changes and pollution. This study assesses temporal and spatial variations in water quality parameters within the Zarafshan River Basin using retrospective data and field measurements. Water quality indicators, including electrical conductivity (EC), total suspended solids (TSS), ammonium nitrogen (N‐NH4), nitrite nitrogen (N‐NO2), nitrate nitrogen (N‐NO3), temperature (T), chemical oxygen demand (COD), dissolved oxygen (DO), and discharge, were analyzed using the Pearson's correlation coefficient and ANOVA, with the Mann–Kendall (MK) test detecting trends over time. Obtained results indicate significant seasonal effects with elevated TSS during summer, increasing sediment load and changing aquatic habitats. The strong inverse correlation (–0.89) between DO and N‐NH4 signifies ecological challenges particularly in low DO concentrations during summer (3.25 mg L–1). Long‐term analysis identifies Navoiazot chemical factory as a major pollution hotspot. Spatial analyses based on extended sampling have revealed the Siab and Dargom canals and Samarkand City as major pollution sources of elevated N‐NO2 and COD, respectively. Trends at various gauging stations (MK‐test) show increasing EC (τ = 0.72) and N‐NH4 (τ = 0.46) levels, with decreasing TSS, N‐NO3, T, and COD levels over time. Recommendations include targeted measures to reduce pollution at the Navoiazot factory and downstream, introducing sustainable agriculture practices, increasing public awareness for environmental conservation, and improving urban wastewater treatment to meet water quality requirements for different users.

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Spatial-temporal rainfall trend and variability assessment in the Upper Wabe Shebelle River Basin, Ethiopia: Application of innovative trend analysis method

Cited by 44 publications

References 63 publications

Long-Term Evolution of Rainfall and Its Consequences on Water Resources: Application to the Watershed of the Kara River (Northern Togo)

Long-Term Evolution of Rainfall and Its Consequences on Water Resources: Application to the Watershed of the Kara River (Northern Togo)

Meaningful Trend in Climate Time Series: A Discussion Based On Linear and Smoothing Techniques for Drought Analysis in Taiwan

Assessment of temporal and spatial variations of water quality parameters in the Zarafshan River basin

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