Detailed Trend Analysis of Extreme Climate Indices in the Upper Geum River Basin

To investigate the recent effects of climate change in the upper Geum River basin in South Korea, a detailed trend analysis of 17 extreme climate indices based on 33 years (1988–2020) of daily precipitation, and daily (minimum and maximum) temperature data has been analyzed in this study. Out of the 17 extreme climate indices, nine (eight) indices were based on temperature (precipitation) data. Trend analysis based on detailed temporal scales (annual, seasonal, monthly) were performed through the Mann–Kendall trend test and the Theil–Sen slope method. Furthermore, the Mann–Whitney–Pettit test was also applied in this study, to detect abrupt changes in the extreme climate indices. Based on the results of this study, the climate conditions at the upper Geum River basin for the past three decades can be summarized as follows: general increase in temperature intensity, decrease in cold duration, increased heat duration, increased precipitation intensity, and increased consecutive wet and dry durations. Furthermore, a prolonged summer season (shorter spring, and autumn periods) and precipitation shifts, were detected based on trend analysis results of seasonal, and monthly time scales. The results presented in this study can provide supplementary data for improving watershed management strategies in the upper Geum River basin.

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Trends in Extreme Climate Indices in Cherrapunji for the period 1979 to 2020

10.21203/rs.3.rs-706445/v1 ◽

2021 ◽

Author(s):

Raju Kalita ◽

Dipangkar Kalita ◽

Atul Saxena

Keyword(s):

Climate Change ◽

Negative Trend ◽

Maximum Temperature ◽

Daily Minimum Temperature ◽

Daily Maximum Temperature ◽

Trend Test ◽

Climate Indices ◽

Daily Maximum ◽

Positive Trend ◽

Extreme Climate

Abstract We have used Mann-Kendall trend test and Sen’s slope estimator method to find out significant changes in extreme climate indices for daily temperature as well as precipitation over the period 1979 to 2020 in Cherrapunji. In the present study, a total of 24 precipitation and temperature based extreme climate indices were calculated using RClimDex v 1.9-3. Among 24 indices, 7 were derived from number of days above nn mm rainfall (Rnn) according to Indian Meteorological Department (IMD) convention and the rest were in accordance with the Expert Team on Climate Change Detection and Indices (ETCCDI). It was observed that, among all the indices, consecutive dry days (CDD), summer days (SU25) and very light rainfall (VLR) days increased significantly with 0.54, 1.58 and 0.14 days/year respectively, while only consecutive wet days (CWD) decreased significantly with 0.36 days/year. A slight negative trend was also observed in case of tropical nights (TR20) and among the other precipitation indices as well. Again, the indices associated with daily maximum temperature increased significantly with annual change of 0.06 to 0.07 ⁰C/year. And for indices associated with daily minimum temperature, almost no change or a slight negative change was observed, except a significant positive trend in February and significant negative trend in November for TNN only. The analysis reveals that some of the extreme climate indices which explains the climatic conditions of Cherrapunji has changed a lot over the period of 42 years and if this trend continues then Cherrapunji will be under threat when it comes to climate change.

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Assessment of the impact of climate change on the freshwater availability of Kaduna River basin, Nigeria

Journal of Water and Land Development ◽

10.2478/jwld-2018-0047 ◽

2018 ◽

Vol 38 (1) ◽

pp. 105-114 ◽

Cited By ~ 2

Author(s):

Gloria C. Okafor ◽

Kingsley N. Ogbu

Keyword(s):

Climate Change ◽

River Basin ◽

Water Availability ◽

Hydrological Cycle ◽

Temporal Trends ◽

Kendall Test ◽

Well Being ◽

Trend Test ◽

Climate Indices ◽

The Impact

AbstractChanges in runoff trends have caused severe water shortages and ecological problems in agriculture and human well-being in Nigeria. Understanding the long-term (inter-annual to decadal) variations of water availability in river basins is paramount for water resources management and climate change adaptation. Climate change in Northern Nigeria could lead to change of the hydrological cycle and water availability. Moreover, the linkage between climatic changes and streamflow fluctuations is poorly documented in this area. Therefore, this study examined temporal trends in rainfall, temperature and runoff records of Kaduna River basin. Using appropriate statistical tools and participatory survey, trends in streamflow and their linkages with the climate indices were explored to determine their amplifying impacts on water availability and impacts on livelihoods downstream the basin. Analysis indicate variable rainfall trend with significant wet and dry periods. Unlike rainfall, temperature showed annual and seasonal scale statistically increasing trend. Runoff exhibit increasing tendency but only statistically significant on annual scale as investigated with Mann–Kendall trend test. Sen’s estimator values stood in agreement with Mann–Kendall test for all variables. Kendall tau and partial correlation results revealed the influence of climatic variables on runoff. Based on the survey, some of the hydrological implications and current water stress conditions of these fluctuations for the downstream inhabitants were itemized. With increasing risk of climate change and demand for water, we therefore recommend developing adaptive measures in seasonal regime of water availability and future work on modelling of the diverse hydrological characteristics of the entire basin.

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Trend Analysis of Hydroclimatic Historical Data and Future Scenarios of Climate Extreme Indices over Mono River Basin in West Africa

10.20944/preprints201906.0267.v1 ◽

2019 ◽

Author(s):

Djan'na H. Koubodana ◽

Moustapha Tall ◽

Ernest Amoussou ◽

Muhammad Mumtaz ◽

Julien Adounkpe ◽

...

Keyword(s):

Trend Analysis ◽

River Basin ◽

Climate Model ◽

Climate Indices ◽

Climate Extreme ◽

Future Scenarios ◽

Discharge Data ◽

Climatic Indices ◽

Annual Trend ◽

Mk Test

This paper performs non-parametric Mann Kendall (MK) trend analysis of historical hydroclimatic data (1961-2016), an ensemble climate model validation and a computation of 16 Expert Team on Climate Change Detection and Indices (ETCCDI) temperature and rainfall extremes indices. The climate indices are evaluated using MK test and annual trend analysis for two Representative Concentration Pathways (RCP4.5 & RCP8.5) future scenarios from 2020 to 2045 over Mono River Basin (MRB) in Togo. The annual and seasonal trend analyses are assessed on historical potential evapotranspiration, mean temperature, rainfall and discharge data. Results show positive and negative trends of hydroclimatic data over MRB from1961 to 2016. Mean temperatures increase significantly in most of the stations while a negative non-significant trend is noticed for rainfall. Meanwhile, the discharge presents a significant seasonal and annual trend for three gauge stations (Corrokope, Nangbéto and Athiémé). Validation of the ensemble climate models reveals that the model under-estimates observations at Sokode, Atkakpamé and Tabligbo stations, however linear regression and spatial correlation coefficients are higher than 0.6. Moreover, the percentage of bias between climate model and observations are less than 15% at most of the stations. Finally, the computation of extreme climatic indices under RCP4.5 and RCP8.5 scenarios shows a significant annual trend of some extreme climatic indices of rainfall and temperature at selected stations between 2020 and 2045 in the MRB. Therefore, relevant governmental politics are needed to elaborate strategies and measures to cope with projected climate changes impacts in the country.

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Historical and future climates over the upper and middle reaches of the Yellow River Basin simulated by a regional climate model in CORDEX

Climate Dynamics ◽

10.1007/s00382-020-05617-4 ◽

2021 ◽

Cited By ~ 1

Author(s):

Xuejia Wang ◽

Deliang Chen ◽

Guojin Pang ◽

Xiaohua Gou ◽

Meixue Yang

Keyword(s):

River Basin ◽

Yellow River ◽

Yellow River Basin ◽

Global Climate Models ◽

The Yellow River ◽

Climate Indices ◽

Extreme Climate ◽

Mean Temperature ◽

Rcp 8.5 ◽

The Yellow River Basin

AbstractDespite the importance of the Yellow River to China, climate change for the middle reaches of the Yellow River Basin (YRB) has been investigated far less than for other regions. This work focuses on future changes in mean and extreme climate of the YRB for the near-term (2021–2040), mid-term (2041–2060), and far-term (2081–2100) future, and assesses these with respect to the reference period (1986–2005) using the latest REgional MOdel (REMO) simulations, driven by three global climate models (GCMs) and assuming historical and future [Representative Concentration Pathway (RCP) 2.6 and 8.5] forcing scenarios, over the CORDEX East Asia domain at 0.22° horizontal resolution. The results show that REMO reproduces the historical mean climate state and selected extreme climate indices reasonably well, although some cold and wet biases exist. Increases in mean temperature are strongest for the far-term in winter, with an average increase of 5.6 °C under RCP 8.5. As expected, the future temperatures of the warmest day (TXx) and coldest night (TNn) increase and the number of frost days (FD) declines considerably. Changes to mean temperature and FD depend on elevation, which could be explained by the snow-albedo feedback. A substantial increase in precipitation (34%) occurs in winter under RCP 8.5 for the far-term. Interannual variability in precipitation is projected to increase, indicating a future climate with more extreme events compared to that of today. Future daily precipitation intensity and maximum 5-day precipitation would increase and the number of consecutive dry days would decline under RCP 8.5. The results highlight that pronounced warming at high altitudes and more intense rainfall could cause increased future flood risk in the YRB, if a high GHG emission pathway is realized.

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Comparative assessment of extreme climate variability and human activities on regional hydrologic droughts in the Weihe River basin, North China

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-369-141-2015 ◽

2015 ◽

Vol 369 ◽

pp. 141-146

Author(s):

H. Shen ◽

L. Ren ◽

F. Yuan ◽

X. Yang

Keyword(s):

River Basin ◽

Human Activity ◽

Human Activities ◽

Climate Extremes ◽

Hydrologic Model ◽

Climate Indices ◽

Extreme Climate ◽

Runoff Series ◽

Weihe River ◽

Weihe River Basin

Abstract. Drought is a comprehensive phenomenon not only resulting from precipitation deficits and climatic factors, but also being related to terrestrial hydrologic conditions and human activities. This paper investigated the relationships among regional hydrologic drought, climate extremes and human activities in the Weihe River basin, northwest China, where is also called Guanzhong Plain. First, the study period was divided into baseline and variation period according to the runoff trend analysis. Subsequently, the variable infiltration capacity (VIC) macroscale distributed hydrologic model was applied to reconstruct the natural runoff series in variation period. Furthermore, the effects of climate change and human activities on runoff were separated by the modelling results. Finally, standardized runoff index (SRI) and extreme climate indices were generated to quantatively assess the relationships among hydrologic droughts, climate extremes and human activity impacts. The results indicated that human activity impacts is a remarkable source of runoff reduction and represented an in-phase pattern of SRI-based drought severity and warm days. It also showed that the SRI-based floods and droughts characteristics are in good correlation with extreme precipitation.

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PROYEKSI CURAH HUJAN DAN SUHU UDARA EKSTRIM MASA DEPAN PERIODE TAHUN 2021-2050 KOTA BANJARBARU KALIMANTAN SELATAN

Jukung (Jurnal Teknik Lingkungan) ◽

10.20527/jukung.v6i1.8237 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Presli Panusunan Simanjuntak ◽

Annisa Dwi Nopiyanti ◽

Agus Safril

Keyword(s):

Air Temperature ◽

Extreme Temperature ◽

Daily Rainfall ◽

Extreme Rainfall ◽

Maximum Temperature ◽

Future Climate Change ◽

Climate Indices ◽

Change Scenario ◽

Extreme Climate ◽

Rainfall Projection

Peningkatan konsentrasi gas rumah kaca telah menyebabkan perubahan pada kejadian iklim ekstrim. Penelitian ini menggunakan skenario RCP 4.5 sebagai skenario perubahaan iklim masa mendatang untuk mengetahui tren indeks suhu dan curah hujan ekstrim periode 2021-2050 di Kota Banjarbaru. Data suhu maksimum, suhu minimum dan curah hujan harian hasil proyeksi tahun 2021-2050 diolah dengan Software RClimDex sehingga didapatkan data indeks temperatur dan hujan ekstrim. Indeks-indeks tersebut merupakan indeks iklim ekstrim yang ditetapkan oleh ETCCDMI yang terdiri atas TN90p, , TX90p, TNn, TNx, TXn, TXx, TMAXmean, TMINmean, RX1day, RX5day, SDII, CDD dan CWD. Hasil penelitian ini menunjukkan bahwa diproyeksikan pada 2020-2050 tren suhu udara akan meningkat signifikan di kota Banjarbaru terutama suhu udara minimum selanjutnya pola prespitasi juga mengalami peningkatan terutama akumulasi curah hujan 5 hari berturut-turut. Meningkatknya jumlah hari kering dan berkurangnya jumlah hari basah, serta semakin tinggi akumulasi curah hujan harian namun hari basah yang sedikit akan menghasilkan curah hujan harian yang tinggi (ekstrim) setiap kejadian hari basah. Kata kunci: banjarbaru, curah hujan, ekstrim, suhu. ABSTRACT Increased concentrations of greenhouse gases have caused changes in extreme climate events. This study uses the RCP 4.5 scenario as a future climate change scenario to determine the temperature index and extreme rainfall trends in the 2021-2050 period in Banjarbaru. Data of maximum temperature, minimum temperature and daily rainfall projection results in 2021-2050 are processed with RClimDex Software so that the temperature and extreme rain index data are obtained. The indices are extreme climate indices determined by ETCCDMI consisting of TN90p, TX90p, TNn, TNx, TXn, TXx, TMAXmean, TMINmean, RX1day, RX5day, SDII, CDD and CWD. The results of this study indicate that it is projected that in 2020-2050 air temperature trends will increase significantly in the city of Banjarbaru especially the minimum air temperature then the pattern of prespitations will also increase especially the accumulation of rainfall for 5 consecutive days. Increasing the number of dry days and decreasing the number of wet days, as well as the higher accumulation of daily rainfall but a small wet day will produce high daily rainfall (extreme) every event of a wet day. Keywords: banjarbaru, extreme, temperature, rainfall.

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The Sensitivity of Vegetation Phenology to Extreme Climate Indices in the Loess Plateau, China

Sustainability ◽

10.3390/su13147623 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7623

Author(s):

Tingting Pei ◽

Zhenxia Ji ◽

Ying Chen ◽

Huawu Wu ◽

Qingqing Hou ◽

...

Keyword(s):

Loess Plateau ◽

Growing Season ◽

Sensitivity Coefficient ◽

Scientific Basis ◽

Maximum Temperature ◽

Climate Indices ◽

Vegetation Phenology ◽

The Loess Plateau ◽

Extreme Climate ◽

Yearly Maximum

Climate changes, especially increased temperatures, and precipitation changes, have significant impacts on vegetation phenology. However, the response of vegetation phenology to the extreme climate in the Loess Plateau in Northwest China remains poorly quantified. The research described here analyzed the spatial change in vegetation phenology and the response of vegetation phenology to climate change in the Loess Plateau from 2001 to 2018, using data from seven extreme climate indices based on the ridge regression method. The results showed that extreme climate indexes, TNn (yearly minimum value of the daily minimum temperature), TXx (yearly maximum value of the daily maximum temperature), and RX5day (yearly maximum consecutive five-day precipitation) progressively increased from 2001 to 2018 in the Loess Plateau region, but decrease trend was found in DRT (diurnal temperature range). The start of the growing season (SOS) of vegetation gradually advanced with precipitation from northwest to southeast, and the rate was +0.38 d/a. The overall vegetation end of the growing season (EOS) was delayed, and the trend was −2.83 d/a. The sensitivity of the different vegetation phenology to different extreme weather indices showed obvious spatial differences, the sensitivity coefficient of SOS being mainly positive in the region, whereas the sensitivity coefficient of EOS was negative generally. More sensitivity was found in the EOS to extreme climate indexes than in the SOS. Forest, shrubland and grassland have similar responses to DRT and TNn; namely, both SOS and EOS are advanced with the increase in DRT and delayed with the increase in TNn (the sensitivity coefficient is quite different) but have different responses to RX5day and TXx. These results reveal that extreme climate events have a greater impact on vegetation EOS than on vegetation SOS, with these effects varying with vegetation types. This research can provide a scientific basis for formulating a scientific basis for regional vegetation restoration strategies and disaster prediction on the Loess Plateau.

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Detection of Abrupt Changes in Runoff in the Weihe River Basin

Advances in Meteorology ◽

10.1155/2016/6962082 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Yanling Li ◽

Jianxia Chang ◽

Zhiliang Wang ◽

Huiling Li

Keyword(s):

River Basin ◽

Management Strategies ◽

Hydrological Regime ◽

Annual Runoff ◽

Intrinsic Mode Functions ◽

Data Set ◽

Time Frequency ◽

Abrupt Changes ◽

Weihe River ◽

Weihe River Basin

Climate change and human activities are two major driving factors for variations in hydrological patterns globally, and it is of significant importance to distinguish their effects on the change of hydrological regime in order to formulate robust water management strategies. Hilbert-Huang transform-based time-frequency analysis is employed in this study to detect abrupt changes and periods of the runoff at five hydrological stations in the Weihe River Basin, China, from 1951 to 2010. The key part of the method is the empirical decomposition mode with which any complicated data set can be decomposed into small number of intrinsic mode functions that admit well adaptive Hilbert transforms. Moreover, an attempt has been made to find out the specific reason for the abrupt point at the five hydrological stations in the Weihe River Basin. The results are presented as follows: (1) annual runoff significantly declined in the basin in intervals of 8~15 years; (2) abrupt changes occurred in 1971, 1982, and 1994 at Huaxian, 1972 and 1982 at Xianyang, 1992 at Zhangjiashan, 1990 at Zhuangtou, and 1984 at Beidao; (3) changes were more frequent and complex in the mainstream and downstream reaches than in tributaries and upstream reaches, respectively.

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Trend Analysis of Observed Precipitation, Temperature and Streamflow for Hadejia – Nguru Wetlands Catchment, Nigeria

10.21203/rs.3.rs-650459/v1 ◽

2021 ◽

Author(s):

Salisu Dan'azumi ◽

Usman Abdullahi Ibrahim

Keyword(s):

Water Resources ◽

Trend Analysis ◽

Maximum Temperature ◽

Mean Annual Precipitation ◽

Trend Test ◽

Data Series ◽

Monthly Precipitation ◽

Climate Data ◽

Annual Streamflow ◽

Increasing Trend

Abstract This study investigated trends in hydro-climate data (precipitation, maximum/minimum temperatures, and streamflow) for the period 1980–2016 in a semi-arid Hadejia-Nguru Wetlands (HNWs) catchment, Nigeria. Four meteorological stations (Bauchi, Hadejia, Kano and Nguru) and three streamflow gauge stations (Gashua, Hadejia and Katagum on Rivers Yobe, Hadejia and Jama’are respectively) covers the HNWs catchment. Anderson-Darling and Shapiro-Wilk normality tests were applied on the monthly hydro-climate data series to determine their class of distribution. A non-parametric Pettit’s test for homogeneity was employed to detect change points in the data series. An absolute homogenization method using RHtestsV4 software was applied to homogenize and (as needed) pre-whitened the data series. Trend analysis was carried out using modified Mann–Kendall trend test (trend free pre-whitening approach), while Sen’s slope was used to estimate the magnitude of the changes. Results of the study revealed that there was an increasing positive trends at all the stations for monthly minimum, average annual minimum, average annual maximum, and annual average temperature data series. While monthly maximum temperature series of Bauchi and Kano stations indicated the presence of an increasing trend with magnitude 0.00350C and 0.00190C; and no trend was detected for Hadejia and Nguru stations. For monthly precipitation, no trends was detected at all stations. However, an increasing trend was detected at Bauchi, Hadejia and Nguru stations for mean annual precipitation with magnitude 7.7960mm/yr, 8.1766mm/yr and 5.7214mm/yr respectively. A decreasing trend was detected for monthly and annual streamflow series at Hadejia gauge station with magnitude − 0.0115m3/s/month and − 3.7037m3/s/year respectively; and no trend was detected for monthly and annual streamflow series at Gashua and Katagum gauge stations. The trend analysis may be helpful to water resources managers for planning and management of water resources in the HNWs catchment and the Hadejia Jama’are Komadugu Yobe Basin at large.

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Spatial–Temporal Variability of Hydrothermal Climate Conditions in the Yellow River Basin from 1957 to 2015

Atmosphere ◽

10.3390/atmos9110433 ◽

2018 ◽

Vol 9 (11) ◽

pp. 433 ◽

Cited By ~ 5

Author(s):

Liqun Ma ◽

Haoming Xia ◽

Jiulin Sun ◽

Hao Wang ◽

Gary Feng ◽

...

Keyword(s):

River Basin ◽

Temporal Variability ◽

Yellow River ◽

Yellow River Basin ◽

Maximum Temperature ◽

The Yellow River ◽

Climate Conditions ◽

Temperature And Precipitation ◽

The Yellow River Basin ◽

Maximum Minimum

The Yellow River Basin has been affected by global climate change. Studying the spatial–temporal variability of the hydrothermal climate conditions in the Yellow River Basin is of vital importance for the development of technologies and policies related to ecological, environmental, and agricultural adaptation in this region. This study selected temperature and precipitation data observed from 118 meteorological stations distributed in the Yellow River Basin over the period of 1957–2015, and used the Mann–Kendall, Pettitt, and Hurst indices to investigate the spatial–temporal variability of the hydrothermal climate conditions in this area. The results indicated: (1) the annual maximum, minimum, and average temperatures have increased. The seasonal maximum, minimum, and average temperatures for the spring, summer, autumn, and winter have also increased, and this trend is statistically significant (p < 0.01) between 1957–2015. The rate of increase in the minimum temperature exceeded that of the maximum temperature, and diurnal warming was asymmetric. Annual precipitation and the total spring, summer, and autumn precipitations declined, while the total winter precipitation increased, although the trend was non-significant (p > 0.05). (2) Based on the very restrictive assumption that future changes will be similar to past changes, according to the Hurst index experiment, the future trends of temperature and precipitation in the Yellow River Basin are expected to stay the same as in the past. There will be a long-term correlation between the two trends: the temperature will continue to rise, while the precipitation will continue to decline (except in the winter). However, over the late stage of the study period, the trends slowed down to some extent.

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