Analysis of Hydrological Drought Trends in the Gap Region (Southeastern Turkey) by Mann-Kendall Test and Innovative Şen Method

Yılmaz, Barış

doi:10.15666/aeer/1702_33253342

“…This method commonly used in the science of hydrology and climatology for testing randomness of the temporal variation in hydro-meteorological data series. It is widely applied in detecting the significant changes in trends of a time series (Yilmaz, 2019;Xing etal., 2018). MK is a rankbased technique, it is not influence by the extremes and therefore best suited for skewed data i.e., it is not affected by the outliers like the simple linear regression method.…”

Section: Mann-kendall Trend Analysismentioning

confidence: 99%

Spatial-temporal Assessment of historical and projected drought events over Isiolo County, Kenya using Self Calibrating Palmer Drought Severity Index

Ochieng

¹

,

Nyandega

²

,

Wambua

³

2021

Preprint

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This study was to determine the spatiotemporal characteristics of historical and projected drought events throughout Isiolo County, Kenya, through using self-calibrating Palmer drought severity index (scPDSI). The scPDSI is a complex and robust drought index that applies the water balance model by incorporating the role played by evapotranspiration and soil properties on drought analysis therefore making it appropriate to identify the linkages between meteorological, agricultural and hydrological droughts. The historical scPDSI was computed at a monthly timescale using a 39-year long monthly mean precipitation data from Climate Hazard Group Infrared Precipitation with Station (CHIRPS) and monthly average temperature data from the Climate Research Unit (CRU). The climatological (1950-1996) available water holding capacity (AWHC) of the soil was obtained from Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) for biochemical dynamics at a spatial resolution of 1o x 1o. The projected scPDSI under Representative Concentration Pathways (RCPs) was computed using bias corrected monthly temperature and precipitation model output data from Coordinated Regional Climate Downscaling Experiment (CORDEX). The datasets were extracted for ten grid points in the County. The scPDSI was used to assess the historical and projected duration, severity, and intensity of droughts. The major significant historical and projected drought events and their characteristics were clearly identified using the run theory. ScPDSI runs have shown that more severe drought events dominated the period between 1980 and 2000. ScPDSI had the longest dry event duration of 61 months and a severity of 126.412 with adverse effects on the eastern locations. The projected drought events identified Mar 2046 –Mar 2048 under RCP4.5 to be the most severe drought lasting for 25 months with severity of 59.292 while under RCP8.5 run Nov 2042 – Nov 2046 is identified as the most severe, 114.362 with the duration of water stress anticipated to last for 49 months. To examine the spatial variability of the drought events in the County, the Empirical Orthogonal Analysis (EOF) was applied to the historical and projected scPDSI time series. The EOF results indicated that the two leading eigen vectors accounted for over 85% of the spatial variability for both historical and projected droughts under the RCPs. Subsequently, the Mann-Kendall (MK) test was applied to the projected scPDSI, temperature and precipitation timeseries in order to determine the local expected drought trends. The MK test of the identified significant increase in trend for temperatures under RCP8.5 and precipitation under RCP4.5 towards the end of the last decade under the study period considered. Both scenarios showed a decline in trends of drought events in Isiolo County from 2020-2050.

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“…It is also a commonly used method to test the evolution trend and sequence mutation of variables. It is easy to test non-normally distributed variables such as hydrological and meteorological elements and less disturbed by variable abnormal values, so it has been widely used in meteorology, hydrology and other fields (Yilmaz 2019). The M-K trend test method and the M-K mutation test method were used to test and analyze the trend and mutation of the SPI/SRI sequence respectively.…”

Section: Drought Evaluation Indexmentioning

confidence: 99%

Evolution Characteristics and Relationship of Meteorological and Hydrological Droughts from 1961 to 2018 in Hanjiang River Basin, China

Wang

¹

,

Zhang

²

,

Elmahdi³

et al. 2021

Preprint

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In the context of global warming and increasing human activities, the acceleration of the water cycle will increase the risk of basin drought. In this study, to analyze the spatial and temporal evolution characteristics of hydrological and meteorological droughts over the Hanjiang River Basin (HRB); the Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI) were selected and applied for the period 1961–2018. In addition, the cross-wavelet method was used to discuss the relationship between hydrological drought and meteorological droughts. The results and analysis indicated that: (1) the meteorological drought in the HRB showed a complex cyclical change trend of flood-drought-flood from 1961 to 2018. The basin drought began to intensify from 1990s and eased in 2010s. The characteristics of drought evolution in various regions are different based on scale. (2) During the past 58 years, the hydrological drought in the HRB has shown a significant trend of intensification, particularly in autumn season. Also, the hydrological droughts had occurred frequently since the 1990s, and there were also regional differences in the evolution characteristics of drought in various regions. (3) Reservoir operation reduces the frequency of extreme hydrological drought events. The effect of reducing the duration and intensity of hydrological drought events by releasing water from the reservoir is most obvious at Huangjiagang Station, which is the nearest to Danjiangkou Reservoir. (4) The hydrological drought and meteorological drought in the HRB have the strongest correlation on the yearly scale. After 1990, severe human activities and climate change are not only reduced the correlation between hydrological drought and meteorological drought in the middle and lower reaches of the basin, but also reduced the lag time between them. Among them, the hydrological drought in the upper reaches of the basin lags behind the meteorological drought by 1 month, and the hydrological drought in the middle and lower reaches of the basin has changed from 2 months before 1990 to 1 month lagging after 1990.

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“…It is also a commonly used method to test the evolution trend and sequence mutation of variables. It is easy to test nonnormally distributed variables such as hydrological and meteorological elements and less disturbed by variable abnormal values, so it has been widely used in meteorology, hydrology and other fields (Yilmaz 2019). The M-K trend test method and the M-K mutation test method were used to test and analyze the trend and mutation of the SPI/SRI sequence respectively.…”

Section: Drought Evaluation Indexmentioning

confidence: 99%

Evolution characteristics and relationship of meteorological and hydrological droughts from 1961 to 2018 in Hanjiang River Basin, China

Wang

¹

,

Zhang

²

,

Elmahdi³

et al. 2021

Journal of Water and Climate Change

View full text Add to dashboard Cite

In the context of global warming and increasing human activities, the acceleration of the water cycle will increase the risk of basin drought. In this study, to analyze the spatial and temporal evolution characteristics of hydrological and meteorological droughts over the Hanjiang River Basin (HRB); the Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI) were selected and applied for the period 1961–2018. In addition, the cross-wavelet method was used to discuss the relationship between hydrological drought and meteorological droughts. The results and analysis indicated that: (1) the meteorological drought in the HRB showed a complex cyclical change trend of flood-drought-flood from 1961 to 2018. The basin drought began to intensify from 1990s and eased in 2010s. The characteristics of drought evolution in various regions are different based on scale. (2) During the past 58 years, the hydrological drought in the HRB has shown a significant trend of intensification, particularly in autumn season. Also, the hydrological droughts had occurred frequently since the 1990s, and there were also regional differences in the evolution characteristics of drought in various regions. (3) Reservoir operation reduces the frequency of extreme hydrological drought events. The effect of reducing the duration and intensity of hydrological drought events by releasing water from the reservoir is most obvious at Huangjiagang Station, which is the nearest to Danjiangkou Reservoir. (4) The hydrological drought and meteorological drought in the HRB have the strongest correlation on the yearly scale. After 1990, severe human activities and climate change are not only reduced the correlation between hydrological drought and meteorological drought in the middle and lower reaches of the basin, but also reduced the lag time between them. Among them, the hydrological drought in the upper reaches of the basin lags behind the meteorological drought by 1 month, and the hydrological drought in the middle and lower reaches of the basin has changed from 2 months before 1990 to 1 month lagging after 1990.

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Analysis of Hydrological Drought Trends in the Gap Region (Southeastern Turkey) by Mann-Kendall Test and Innovative Şen Method

Cited by 41 publications

References 32 publications

Spatial-temporal Assessment of historical and projected drought events over Isiolo County, Kenya using Self Calibrating Palmer Drought Severity Index

Spatial-temporal Assessment of historical and projected drought events over Isiolo County, Kenya using Self Calibrating Palmer Drought Severity Index

Evolution Characteristics and Relationship of Meteorological and Hydrological Droughts from 1961 to 2018 in Hanjiang River Basin, China

Evolution characteristics and relationship of meteorological and hydrological droughts from 1961 to 2018 in Hanjiang River Basin, China

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