scholarly journals Spatio-Temporal Trend Mapping of Precipitation and its Extremes Across Afghanistan (1951-2010)

2021 ◽  
Author(s):  
Quarban Aliyar ◽  
Santosh Dhungana ◽  
Sangam Shrestha
Keyword(s):  
Crop Production ◽  
Heavy Precipitation ◽  
Kendall Test ◽  
Eastern Region ◽  
Spring Precipitation ◽  
Significance Level ◽  
Northeastern Region ◽  
Spatio Temporal ◽  
Slope Estimator ◽  
Harsh Climate

Abstract The civil war, harsh climate, tough topography and lack of accurate meteorological stations has limited observed data across Afghanistan. In order to fulfill the gap, this study analyzed the trend in precipitation and its extremes using Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation (APHRODITE) daily dataset between 1951 to 2010 at the spatial resolution of 0.25˚˟0.25˚. Non-parametric modified Mann-Kendall test and Sen’s slope estimator were employed to detect trend and quantify it at the significance level of 5%. Significant decreasing trends were observed only in small clusters of southwestern regions ranging between 0 to -1.5mm/year and northeastern region between -1.5 to -6 mm/year for the annual time series. Similar trend pattern was observed in spring season decreasing at the rate of -0.15 to 0.54 mm/year in northeastern and 0 to -0.15 mm/year southwestern region. Decrease in spring precipitation is expected to affect crop production especially in northeastern region which host 22 % of the arable area. Increasing trend in eastern region at maximum of 0.16 mm/year was observed which could intensify the flooding events. Trend analysis of extreme precipitation indices indicated similar spatial distribution to the mean precipitation, concentrated around southwestern, northeastern, and eastern regions. Increasing frequency of consecutive dry days in western region and very heavy precipitation (R10mm) and extremely heavy precipitation (R20mm) in eastern region are fueling the occurrence of droughts and floods respectively. Taking these findings of erratic nature of rainfall and extreme events into consideration for sustainable management of water resources would be fruitful.

Signals of Climate Change and Spatio-temporal Analysis of Climate Extremes in the Homogeneous Climatic Zones of Pakistan During 1962-2019

2021 ◽  
Author(s):  
Firdos Khan ◽  
Shaukat Ali ◽  
Christoph Mayer ◽  
Hamd Ullah ◽  
Sher Muhammad
Keyword(s):  
Climate Change ◽  
Climate Extremes ◽  
Heavy Precipitation ◽  
Temporal Analysis ◽  
Significance Level ◽  
Temperature And Precipitation ◽  
Increasing Trend ◽  
North Pakistan ◽  
Spatio Temporal ◽  
Increasing Temperature

Abstract This study investigates contemporary climate change and spatio-temporal analysis of climate extremes in Pakistan (divided into five homogenous climate zones) using observed data, categorized between 1962–1990 and 1991–2019. The results show that on the average, the changes in temperature and precipitation are significant at 5 % significance level throughout Pakistan in most of the seasons. The spatio-temporal trend analysis of consecutive dry days (CDD) shows an increasing trend during 1991–2019 except in zone 4 indicating throughout decreasing trend. PRCPTOT (annual total wet-day precipitation), R10 (number of heavy precipitation days), R20 (number of very heavy precipitation days) and R25mm (extremely heavy precipitation days) are significantly decreasing (increasing) during 1962–1990 (1991–2019) in North Pakistan. Summer days (SU25) increased across the country, except in zone 4 with a decrease. TX10p (Cool days) decreased across the country except an increase in zone 1 and zone 2 during 1962–1990. TX90p (Warm days) has an increasing trend during 1991–2019 except zone 5 and decreasing trend during 1962–1990 except zone 2 and 5. The Mann-Kendal test indicates increasing precipitation (DJF) and decreasing maximum and minimum temperature (JJA) in the Karakoram region during 1962–1990. The decadal analysis suggests decreasing precipitation during 1991–2019 and increasing temperature (maximum and minimum) during 2010–2019 which is in line with the recently confirmed slight mass loss of glaciers against Karakoram Anomaly.

scholarly journals Analysis of Non-Parametric Trend and Climatic Parameter Homogeneity Tests in a Data-scarce Region: A Spatio-Temporal Perspective in the Tawang River Basin, Eastern Himalayas

2021 ◽  
Author(s):  
Juna Probha Devi ◽  
Chandan Mahanta ◽  
Anamika Barua
Keyword(s):  
Water Resource Management ◽  
Management Strategies ◽  
Kendall Test ◽  
Climate Impact ◽  
Mean Annual Precipitation ◽  
Homogeneity Test ◽  
Eastern Region ◽  
Positive Trend ◽  
Temporal Perspective ◽  
Spatio Temporal

Abstract This study is aimed at studying long–term historical and future (1950-2099) trends for the RCP 4.5 and RCP 8.5 on approximately 30-year timescale at annual and seasonal for precipitation and at annual, seasonal, monthly, and diurnal temperature range (DTR) for temperature maximum (T_max), temperature minimum (T_min) variations using statistical trend analysis techniques– Mann–Kendall test (MK) and Sen's slope estimator (S) and the homogeneity test using Pettitt’s test. The study is carried out in three spatial points across the Tawang Chu in the district of Tawang, Arunachal Pradesh. The summer mean precipitation for RCP 4.5 (2006-2065) shows a positive trend with a rise in precipitation between 1.56 mm to 9.94 mm in all the study points. The mean annual precipitation statistics for all the points show an increase of RCP 4.5 in 2006-2052 and 2053-2099 timescale. Both RCP 4.5 and 8.5 scenarios exhibit a uniform rise in T_min and T_max during investigation. For all the points, the results likewise reveal a rising trend in mean annual T_min and T_max. Still, the inter-decadal temperature statistical analysis shows that the increase in mean annual T_min is greater than the increase in T_max, indicating a decreasing trend in DTR. It is anticipated that this study's outcomes will contribute to a better understanding of the relationship between change in climate and the regional hydrological behaviour and will be benefitting the society to develop a regional strategy for water resource management, can serve as a resource for climate impact research scope- assessments, adaptation, mitigation, and disaster management strategies for India's north-eastern region.

scholarly journals Long–term spatio–temporal warming tendency in the Vietnamese Mekong Delta based on observed and high–resolution gridded datasets

2019 ◽  
pp. 01-16
Author(s):  
Dang Nguyen Dong Phuong ◽  
Dang Kien Cuong ◽  
Duong Ton Dam ◽  
Nguyen Kim Loi
Keyword(s):  
High Resolution ◽  
Statistical Tests ◽  
Mekong Delta ◽  
Kendall Test ◽  
Trend Detection ◽  
Homogeneity Test ◽  
Spatio Temporal ◽  
Temperature Records ◽  
Slope Estimator ◽  
Increasing Trends

The Vietnamese Mekong Delta is among the most vulnerable deltas to climate–related hazards across the globe. In this study, the annual mean and extreme temperatures from 11 meteorological stations over the Vietnamese Mekong Delta were subjected to normality, homogeneity and trend analysis by employing a number of powerful statistical tests (i.e. Shapiro–Wilk, Buishand Range test, classical/modified Mann–Kendall test and Sen’s slope estimator). As for spatio–temporal assessment, the well–known (0.5° × 0.5°) high–resolution gridded dataset (i.e. CRU TS4.02) was also utilized to examine trend possibilities for three different time periods (i.e. 1901–2017, 1951–2017 and 1981–2017) by integrating spatial interpolation algorithms (i.e. IDW and Ordinary Kriging) with statistical trend tests. Comparing the calculated test–statistics to their critical values (a = 0.05), it is evident that most of the temperature records can be considered to be normal and non–homogeneous with respect to normality and homogeneity test respectively. As for temporal trend detection, the outcomes show high domination of significantly increasing trends. Additionally, the results of trend estimation indicate that the magnitude of increase in minimum temperature was mostly greater than mean and maximum ones and the recent period (1981–2017) also revealed greater increasing rates compared to the entire analyzed period and second half of the 20th century. In general, these findings yield various evident indications of warming tendency in the Vietnamese Mekong Delta over the last three decades.

 Spatio-temporal characterization of rainfall using an innovative trend and discrete wavelet transformation approaches in Bhakra catchment, India

2021 ◽  
Author(s):  
Neha Gupta ◽  
Sagar Chavan
Keyword(s):  
Extreme Rainfall ◽  
Kendall Test ◽  
Mitigation Measures ◽  
Discrete Wavelet ◽  
Precipitation Concentration Index ◽  
Seasonal Time Series ◽  
Seasonal Basis ◽  
Spatio Temporal ◽  
Water Resources Projects ◽  
Slope Estimator

<p>Using a high-resolution daily gridded rainfall data of 0.25° from the Indian Meteorological Department (IMD), the present study investigates the detailed characteristics of rainfall in the Bhakra Catchment from 1901 to 2019. The long term spatial and temporal rainfall variations in Bhakra Catchment are not well explored. The spatial pattern of rainfall regimes in this catchment is identified by estimating index like the precipitation concentration index (PCI) and seasonality index (SI). Extreme rainfall trends on annual and seasonal basis are examined using the innovative trend analysis (ITA) method. Reliability of ITA was assessed by comparing them with widely applied Mann–Kendall (MK) or modified Mann–Kendall (mMK) test results. Furthermore, the change in two halves of rainfall series is estimated using percent bias technique for estimating changes in rainfall. Changes in slopes are estimated by using Sen’s slope estimator (Q). Discrete wavelet transform (DWT) in conjunction with Sequential Mann–Kendall test (SQMK) is employed to find out the dominant periodicity in rainfall patterns. The effectiveness of the graphical method in qualitative analysis can be seen, while DWT is found efficient in identifying periodicity. Both positive and negative trends are detected in annual and seasonal time series over the study area. The outcomes of this study may be helpful in the planning and management of water resources projects in the catchment along with the planning of mitigation measures to alleviate the effects of climate change under extreme rainfall conditions.</p>

scholarly journals Testing Possible Scenario-Based Responses of Vegetation Under Expected Climatic Changes in Khuzestan Province

2021 ◽  
Vol 14 ◽  
pp. 117862212110133
Author(s):  
Hadi Eskandari Damaneh ◽  
Meysam Jafari ◽  
Hamed Eskandari Damaneh ◽  
Marjan Behnia ◽  
Asadollah Khoorani ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Kendall Test ◽  
Baseline Period ◽  
System Model ◽  
Future Period ◽  
Khuzestan Province ◽  
Ecosystem Planning ◽  
Slope Estimator ◽  
Precipitation And Temperature

Projections of future scenarios are scarce in developing countries where human activities are increasing and impacting land uses. We present a research based on the assessment of the baseline trends of normalized difference vegetation index (NDVI), precipitation, and temperature data for the Khuzestan Province, Iran, from 1984 to 2015 compiled from ground-based and remotely sensed sources. To achieve this goal, the Sen’s slope estimator, the Mann-Kendall test, and Pearson’s correlation test were used. After that, future trends in precipitation and temperature were estimated using the Canadian Earth System Model (CanESM2) model and were then used to estimate the NDVI trend for two future periods: from 2016 to 2046 and from 2046 to 2075. Our results showed that during the baseline period, precipitation decreased at all stations: 33.3% displayed a significant trend and the others were insignificant ones. Over the same period, the temperature increased at 66.7% of stations while NDVI decreased at all stations. The NDVI–precipitation relationship was positive while NDVI–temperature showed an inverse trend. During the first of the possible future periods and under the RCP2.6, RCP4.5, and RCP8.5 scenarios, NDVI and precipitation decreased, and temperatures significantly increased. In addition, the same trends were observed during the second future period; most of these were statistically significant. We conclude that much assessments are valuable and integral components of effective ecosystem planning and decisions.

scholarly journals Kecenderungan dan Perubahan Hujan Ekstrem Harian di Pulau Madura

2020 ◽  
Vol 18 (1) ◽  
pp. 89-96
Author(s):  
Ahmad Nur Akma Juangga Fura ◽  
Retno Utami Agung Wiyono ◽  
Indarto Indarto
Keyword(s):  
Flood Hazard ◽  
Parametric Method ◽  
Extreme Rainfall ◽  
Kendall Test ◽  
Random Processes ◽  
Rain Gauge ◽  
Rainfall Trend ◽  
Significance Level ◽  
High Level ◽  
Crossing Test

Madura subject to a high level of flood hazard. One of the main causes of flood is extreme rainfall. Global warming generates changes in the amount of extreme rainfall. This research is conducted to identify and to analyze the trends, changes, and randomness of 24-hour extreme rainfall data on Madura Island. The method used is a non-parametric method which includes the Median Crossing test, the Mann-Kendall test, and the Rank-Sum test at the significance level of α =0.05. The analysis was carried out on 31 rain gauge stations. The recording period observed is between 1991-2015. The results of the analysis show that based on the Median Crossing test, most rainfall stations have data originating from random processes. The result shows also that the maximum 24-hour extreme rainfall trend is significantly decreased in a few locations, while for the majority of other stations have no experience a significant trend.

scholarly journals Historical drought patterns over Canada and their teleconnections with large-scale climate signals

2018 ◽  
Vol 22 (6) ◽  
pp. 3105-3124 ◽  
Author(s):  
Zilefac Elvis Asong ◽  
Howard Simon Wheater ◽  
Barrie Bonsal ◽  
Saman Razavi ◽  
Sopan Kurkute
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Kendall Test ◽  
Wavelet Coherence ◽  
Climate Indices ◽  
Data Sets ◽  
Canadian Prairies ◽  
Agriculture Industry ◽  
Spatio Temporal

Abstract. Drought is a recurring extreme climate event and among the most costly natural disasters in the world. This is particularly true over Canada, where drought is both a frequent and damaging phenomenon with impacts on regional water resources, agriculture, industry, aquatic ecosystems, and health. However, nationwide drought assessments are currently lacking and impacted by limited ground-based observations. This study provides a comprehensive analysis of historical droughts over the whole of Canada, including the role of large-scale teleconnections. Drought events are characterized by the Standardized Precipitation Evapotranspiration Index (SPEI) over various temporal scales (1, 3, 6, and 12 consecutive months, 6 months from April to September, and 12 months from October to September) applied to different gridded monthly data sets for the period 1950–2013. The Mann–Kendall test, rotated empirical orthogonal function, continuous wavelet transform, and wavelet coherence analyses are used, respectively, to investigate the trend, spatio-temporal patterns, periodicity, and teleconnectivity of drought events. Results indicate that southern (northern) parts of the country experienced significant trends towards drier (wetter) conditions although substantial variability exists. Two spatially well-defined regions with different temporal evolution of droughts were identified – the Canadian Prairies and northern central Canada. The analyses also revealed the presence of a dominant periodicity of between 8 and 32 months in the Prairie region and between 8 and 40 months in the northern central region. These cycles of low-frequency variability are found to be associated principally with the Pacific–North American (PNA) and Multivariate El Niño/Southern Oscillation Index (MEI) relative to other considered large-scale climate indices. This study is the first of its kind to identify dominant periodicities in drought variability over the whole of Canada in terms of when the drought events occur, their duration, and how often they occur.

Evaluation of spatio-temporal trends of groundwater quality in different land uses using Kendall test

2012 ◽  
Vol 16 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Dugin Kaown ◽  
Yunjung Hyun ◽  
Gwang-Ok Bae ◽  
Chang Whan Oh ◽  
Kang-Kun Lee
Keyword(s):  
Groundwater Quality ◽  
Temporal Trends ◽  
Kendall Test ◽  
Land Uses ◽  
Spatio Temporal

scholarly journals Climatic Regionalization and the Spatio-Temporal Occurrence of Extreme Single-Year Drought Events (1500–1998) in the Interior Pacific Northwest, USA

2002 ◽  
Vol 58 (3) ◽  
pp. 226-233 ◽  
Author(s):  
Paul A. Knapp ◽  
Henri D. Grissino-Mayer ◽  
Peter T. Soulé
Keyword(s):  
Pacific Northwest ◽  
Radial Growth ◽  
Extended Period ◽  
Growth Indices ◽  
Spring Precipitation ◽  
Enso Events ◽  
Western Juniper ◽  
Northern Nevada ◽  
The Pacific ◽  
Spatio Temporal

AbstractTree-ring records from western juniper (Juniperus occidentalis var. occidentalis Hook.) growing throughout the interior Pacific Northwest identify extreme climatic pointer years (CPYs) (i.e., severe single-year droughts) from 1500–1998. Widespread and extreme CPYs were concentrated in the 16th and early part of the 17th centuries and did not occur again until the early 20th century. The 217-yr absence of extreme CPYs may have occurred during an extended period of low variance in the Pacific Decadal Oscillation. We mapped climatic boundaries for the interior Pacific Northwest based on the location of sites with similar precipitation variability indices. Three regions, the Northwest (based on chronologies from nine sites), the Southwest (four sites), and the East (five sites) were identified. Our results suggest that western juniper radial growth indices have substantial interannual variability within the northwestern range of the species (central Oregon), particularly when compared with western juniper growing in its eastern range (eastern Oregon, southeastern Idaho, and northern Nevada) and southwestern range (southern Oregon and northeast California). We suspect that the substantial differences in the variability of western juniper radial growth indices are linked to the influence of ENSO events on winter/spring precipitation amounts.

scholarly journals Deficit Irrigation in Peach Orchards under Water Scarcity Conditions

2020 ◽  
Author(s):  
António Canatário Duarte ◽  
Abel Veloso ◽  
António Ramos ◽  
Dora Ferreira ◽  
Maria Paula Simões
Keyword(s):  
Water Supply ◽  
Deficit Irrigation ◽  
Crop Production ◽  
Dilution Effect ◽  
Soluble Solids ◽  
Eastern Region ◽  
Total Production ◽  
Fruit Firmness ◽  
Total Soluble Solids ◽  
Average Production

The irrigation patterns in two peach orchards, located in the central eastern region of Portugal, called “Beira Interior”, and the effect of different amounts of irrigation on the total production and fruit quality were evaluated. The experiment was conducted in 2016, in two different orchards, and included three treatments correspondent to three different flow rates per tree: 8, 12 and 16 l/hour. The water balance, which included the water supplied by rain and irrigation and the crop evapotranspiration, was developed. At harvest, crop production, pulp firmness and percentage of the total soluble solids were evaluated. There were no significant differences between treatments in the average production per tree. However, in one of the orchards production increased with the volume of irrigation. In the same orchard, fruit firmness decreased with the increasing water supply. Total soluble solids had decreased with the increasing water supply in both orchards, probably as a consequence of the dilution effect due, directly, to the water incorporated in the fruits, or, indirectly, to the larger fruits produced by the trees that were irrigated more. In general, the treatments used in this study as well as in the farmers’ practices, the supplied water was in deficit, but the farmers tend empirically to follow closely the evolution of evapotranspiration. Keywords: Deficit irrigation, Peach tree, Production, Total soluble solids, Fruit firmness

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