Spatiotemporal Variation of the Meteorological and Groundwater Droughts in Central Taiwan

Extreme Drought ◽

Water Shortages ◽

Level Data ◽

Groundwater Drought ◽

Central Taiwan ◽

In recent years, Taiwan has been facing severe water shortages due to extreme drought. In addition, changes in rainfall patterns have resulted in an increasingly notable drought phenomenon, which affects the management and utilization of water resources. Therefore, this work examines basins in Central Taiwan. Long-term records from 13 rainfall and 17 groundwater stations were selected. The Standardized Precipitation Index (SPI) and Standardized Groundwater Level Index (SGI) were used to analyze the drought characteristics of this region. The rainfall and groundwater level data from basins in Central Taiwan were analyzed in this study. The results show that the year 2015 experienced extreme drought conditions due to a correlation with SPI and SGI signals. In addition, with regard to groundwater drought, more drought events occurred in the Da'an River basin; however, the duration and intensity of these events were relatively low, in contrast to those of the Wu River basin. Finally, the correlation between SPI and SGI was observed to vary in different basins, but a certain degree of correlation was observed in all basins. The results show that drought intensity increases with longer drought durations. Moreover, severe droughts caused by rainfall tend to occur at a greater frequency than those caused by groundwater.

Extreme Droughts Change in the Mekong River Basin: A Multidisciplinary Analysis Based on Satellite Data

Water ◽

10.3390/w13192682 ◽

2021 ◽

Vol 13 (19) ◽

pp. 2682

Author(s):

Vo Tuong ◽

Thanh-Van Hoang ◽

Tien-Yin Chou ◽

Yao-Min Fang ◽

Chun-Tse Wang ◽

...

Keyword(s):

River Basin ◽

Regional Climate ◽

Extreme Drought ◽

Mekong River ◽

Drought Duration ◽

Mekong River Basin ◽

Drought Period ◽

Mk Test ◽

This study evaluates droughts in the Mekong River Basin (MKB) based on a multidisciplinary method, mainly using the Standardized Precipitation Index (SPI) and Mann–Kendall (MK) test. Precipitation data corresponding to the seasonality of the regional climate were retrieved from Integrated Multi-satellitE Retrievals for Global Precipitation Measurement from 2001 to 2020, at a monthly temporal scale and 0.1 degree spatial resolution. Drought events and their average interval, duration, and severity were determined based on Run theory. Our results revealed the most extreme drought period was in January 2014, at the time the lowest precipitation occurred. Spatial extreme drought results indicated that Zone 2 in the upstream MKB has the highest frequency of drought, with 44 events observed during 19 years, and experiences the most severe droughts, whereas Zone 24 in the downstream MKB has the most prolonged drought duration of seven months. The periods and locations of extreme drought were identified using the SPI, corresponding to historic droughts of the MKB. Furthermore, the MK test shows an increasing trend of droughts in the lower MKB and the cluster analysis identified six clusters of times series. Overall, our study provides essential findings for international and national water resource stakeholders in identifying trends of extreme drought in the MKB.

Long-term meteorological and hydrological dryness and wetness conditions in the Zhujiang River Basin, South China

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-9-10525-2012 ◽

2012 ◽

Vol 9 (9) ◽

pp. 10525-10562

Author(s):

T. Fischer ◽

M. Gemmer ◽

B. Su ◽

T. Scholten

Keyword(s):

Time Series ◽

River Basin ◽

Principal Component ◽

Economic Losses ◽

Xijiang River ◽

The Xijiang River ◽

Spatio Temporal ◽

Abstract. Floods and droughts are frequently causing large economic losses in China. These conditions vary in space, time, and magnitude. In this study, long-term meteorological and hydrological dryness and wetness conditions are analyzed for the Xijiang River Basin which is the largest tributary of the Zhujiang (Pearl) River. A very similar inter-annual course of precipitation and discharge can be observed. The standardized precipitation index (SPI) is used to show dryness and wetness pattern in the six sub-basins of the Xijiang River. The SPI-24 correlates high with the standardized discharge index (SDI-24) for Gaoyao hydrological station at the mouth of Xijiang River. Distinct long-term dryness and wetness sequences are found in the time series for the SPI-24 and SDI-24. The principal component analysis reveals many spatial interdependencies in dryness and wetness conditions for the sub-basins and explains some spatio-temporal disparities. Moderate dryness conditions have a larger spatial impact than moderate wetness conditions in the sub-basins. The loading pattern of the first principal component shows that the correlation with the entire Xijiang River Basin is highest in the eastern and lowest in the western sub-basins. Further spatial dipole conditions explain the spatio-temporal heterogeneity of dryness and wetness conditions. Accordingly, the precipitation in the eastern sub-basins contributes more to the hydrological wetness conditions than in the western sub-basins, which mainly contribute to dryness patterns. The spectral analysis for the SPI-24 (entire Xijiang River Basin) and SDI-24 shows similar peaks for periods of 11–14.7 yr, 2.8 yr, 3.4–3.7 yr, and 6.3–7.3 yr. The same periods can be found for the SPI-24 of Xijiang River's six sub-basins with some variability in the magnitude. The wavelet analysis shows that the most significant periods are stable over time since the 1980s. The extrapolations of the reconstructed time series do not suggest any spatial or temporal changes in the occurrence of dryness and wetness conditions in the next two decades but a continuation of the observed cycles at given magnitude. It can be concluded that long-term hydrological dryness and wetness conditions are directly caused by periodic cycles of meteorological conditions (i.e. precipitation). The applied methodologies prove to be able to identify spatial interdependencies and corresponding regional disparities, and to detect significant periodicities in long-term dryness and wetness conditions in the Xijiang River Basin.

Hydrological long-term dry and wet periods in the Xijiang River basin, South China

Hydrology and Earth System Sciences ◽

10.5194/hess-17-135-2013 ◽

2013 ◽

Vol 17 (1) ◽

pp. 135-148 ◽

Cited By ~ 29

Author(s):

T. Fischer ◽

M. Gemmer ◽

B. Su ◽

T. Scholten

Keyword(s):

River Basin ◽

South China ◽

Principal Component ◽

Spatial Disparities ◽

Xijiang River ◽

Daily Precipitation Data ◽

The Xijiang River ◽

Abstract. In this study, hydrological long-term dry and wet periods are analyzed for the Xijiang River basin in South China. Daily precipitation data of 118 stations and data on daily discharge at Gaoyao hydrological station at the mouth of the Xijiang River for the period 1961–2007 are used. At a 24-month timescale, the standardized precipitation index (SPI-24) for the six sub-basins of the Xijiang River and the standardized discharge index (SDI-24) for Gaoyao station are applied. The monthly values of the SPI-24 averaged for the Xijiang River basin correlate highly with the monthly values of the SDI-24. Distinct long-term dry and wet sequences can be detected. The principal component analysis is applied and shows spatial disparities in dry and wet periods for the six sub-basins. The correlation between the SPI-24 of the six sub-basins and the first principal component score shows that 67% of the variability within the sub-basins can be explained by dry and wet periods in the east of the Xijiang River basin. The spatial dipole conditions (second and third principal component) explain spatiotemporal disparities in the variability of dry and wet periods. All sub-basins contribute to hydrological dry periods, while mainly the northeastern sub-basins cause wet periods in the Xijiang River. We can also conclude that long-term dry events are larger in spatial extent and cover all sub-basins while long-term wet events are regional phenomena. A spectral analysis is applied for the SPI-24 and the SDI-24. The results show significant peaks in periodicities of 11–14.7 yr, 2.8 yr, 3.4–3.7 yr, and 6.3–7.3 yr. The same periodic cycles can be found in the SPI-24 of the six sub-basins but with some variability in the mean magnitude. A wavelet analysis shows that significant periodicities have been stable over time since the 1980s. Extrapolations of the reconstructed SPI-24 and SDI-24 represent the continuation of observed significant periodicities at given magnitudes until 2030. The projected hydrological long-term dry and wet periods can be used for planning purposes in water resources management. The applied methodologies prove to be able to identify spatial disparities, and to detect significant periodicities in hydrological long-term dry and wet periods in the Xijiang River basin.

Proceedings of the 7th International Scientific Conference Rural Development 2015 ◽

DROUGHT OCCURRENCE UNDER LITHUANIAN CLIMATIC CONDITIONS

10.15544/rd.2015.059 ◽

2015 ◽

Cited By ~ 1

Author(s):

Laima TAPARAUSKIENĖ ◽

Veronika LUKŠEVIČIŪTĖ

Keyword(s):

Meteorological Data ◽

Vegetation Period ◽

Climatic Conditions ◽

Precipitation Record ◽

Calculation Step ◽

Drought Conditions ◽

The Standardized Precipitation Index ◽

June July

This study provides the analysis of drought conditions of vegetation period in 1982-2014 year in two Lithuanian regions: Kaunas and Telšiai. To identify drought conditions the Standardized Precipitation Index (SPI) was applied. SPI was calculated using the long-term precipitation record of 1982–2014 with in-situ meteorological data. Calculation step of SPI was taken 1 month considering only vegetation period (May, June, July, August, September). The purpose of investigation was to evaluate the humidity/aridity of vegetation period and find out the probability of droughts occurrence under Lithuanian climatic conditions. It was found out that according SPI results droughts occurred in 14.5 % of all months in Kaunas region and in 15.8 % in Telšiai region. Wet periods in Kaunas region occurred in 15.8 %, and in Telšiai region occurrence of wet periods was – 18.8 % from all evaluated months. According SPI evaluation near normal were 69.7 % of total months during period of investigation in Kaunas and respectively – 65.5 % in Telšiai. The probability for extremely dry period under Lithuania climatic conditions are pretty low – 3.0 % in middle Lithuania and 2.4 % in western part of Lithuania.

Rescue of groundwater level time series: how to identify and treat errors

10.5194/egusphere-egu21-9877 ◽

2021 ◽

Author(s):

Jānis Bikše ◽

Inga Retike ◽

Andis Kalvāns ◽

Aija Dēliņa ◽

Alise Babre ◽

...

Keyword(s):

Time Series ◽

Groundwater Level ◽

Monitoring Network ◽

Observation Data ◽

Automatic Data ◽

Mean Values ◽

Temporal Prediction ◽

National Monitoring ◽

Groundwater Drought

Groundwater level time series are the basis for various groundwater-related studies. The most valuable are long term, gapless and evenly spatially distributed datasets. However, most historical datasets have been acquired during a long-term period by various operators and database maintainers, using different data collection methods (manual measurements or automatic data loggers) and usually contain gaps and errors, that can originate both from measurement process and data processing. The easiest way is to eliminate the time series with obvious errors from further analysis, but then most of the valuable dataset may be lost, decreasing spatial and time coverage. Some gaps can be easily replaced by traditional methods (e.g. by mean values), but filling longer observation gaps (missing months, years) is complicated and often leads to false results. Thus, an effort should be made to retain as much as possible actual observation data.In this study we present (1) most typical data errors found in long-term groundwater level monitoring datasets, (2) provide techniques to visually identify such errors and finally, (3) propose best ways of how to treat such errors. The approach also includes confidence levels for identification and decision-making process. The aim of the study was to pre-treat groundwater level time series obtained from the national monitoring network in Latvia for further use in groundwater drought modelling studies.This research is funded by the Latvian Council of Science, project &#8220;Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change&#8221;, project No. lzp-2019/1-0165.

Using integrated meteorological and hydrological indices to assess drought characteristics in southern Taiwan

Hydrology Research ◽

10.2166/nh.2019.120 ◽

2019 ◽

Vol 50 (3) ◽

pp. 901-914 ◽

Cited By ~ 3

Author(s):

Hsin-Fu Yeh

Keyword(s):

River Basin ◽

Drought Index ◽

Assessment Method ◽

Drought Indices ◽

Trend Test ◽

Integrated Analysis ◽

Drought Assessment ◽

Southern Taiwan ◽

Abstract Numerous drought index assessment methods have been developed to investigate droughts. This study proposes a more comprehensive assessment method integrating two drought indices. The Standardized Precipitation Index (SPI) and the Streamflow Drought Index (SDI) are employed to establish an integrated drought assessment method to study the trends and characteristics of droughts in southern Taiwan. The overall SPI and SDI values and the spatial and temporal distributions of droughts within a given year (November to October) revealed consistent general trends. Major droughts occurred in the periods of 1979–1980, 1992–1993, 1994–1995, and 2001–2003. According to the results of the Mann–Kendall trend test and the Theil–Sen estimator analysis, the streamflow data from the Sandimen gauging station in the Ailiao River Basin showed a 30% decrease, suggesting increasing aridity between 1964 and 2003. Hence, in terms of water resources management, special attention should be given to the Ailiao River Basin. The integrated analysis showed different types of droughts occurring in different seasons, and the results are in good agreement with the climatic characteristics of southern Taiwan. This study suggests that droughts cannot be explained fully by the application of a single drought index. Integrated analysis using multiple indices is required.

Long-Term, Gridded Standardized Precipitation Index for Hawai‘i

Data ◽

10.3390/data5040109 ◽

2020 ◽

Vol 5 (4) ◽

pp. 109

Author(s):

Matthew P. Lucas ◽

Clay Trauernicht ◽

Abby G. Frazier ◽

Tomoaki Miura

Keyword(s):

High Spatial Resolution ◽

Precipitation Index ◽

Drought Indices ◽

Drought Severity ◽

Spatially Explicit ◽

Historical Period ◽

The Standardized Precipitation Index ◽

Climatic Information

Spatially explicit, wall-to-wall rainfall data provide foundational climatic information but alone are inadequate for characterizing meteorological, hydrological, agricultural, or ecological drought. The Standardized Precipitation Index (SPI) is one of the most widely used indicators of drought and defines localized conditions of both drought and excess rainfall based on period-specific (e.g., 1-month, 6-month, 12-month) accumulated precipitation relative to multi-year averages. A 93-year (1920–2012), high-resolution (250 m) gridded dataset of monthly rainfall available for the State of Hawai‘i was used to derive gridded, monthly SPI values for 1-, 3-, 6-, 9-, 12-, 24-, 36-, 48-, and 60-month intervals. Gridded SPI data were validated against independent, station-based calculations of SPI provided by the National Weather Service. The gridded SPI product was also compared with the U.S. Drought Monitor during the overlapping period. This SPI product provides several advantages over currently available drought indices for Hawai‘i in that it has statewide coverage over a long historical period at high spatial resolution to capture fine-scale climatic gradients and monitor changes in local drought severity.

Natural and Human-Induced Drivers of Groundwater Sustainability: A Case Study of the Mangyeong River Basin in Korea

Sustainability ◽

10.3390/su11051486 ◽

2019 ◽

Vol 11 (5) ◽

pp. 1486 ◽

Cited By ~ 2

Author(s):

Jae Lee ◽

Eun Kwon ◽

Nam Woo

Keyword(s):

Water Quality ◽

River Basin ◽

Groundwater Level ◽

Groundwater Monitoring ◽

Temporal Variations ◽

Quality Data ◽

Monitoring Wells ◽

Groundwater Sustainability ◽

Groundwater Drought ◽

Drought Conditions

The sustainability of rural areas depends on the availability of water resources. The Mangyeong River Basin (MRB) in Korea faces a water supply shortage for agriculture and industry. Based on 11-year (2005–2015) precipitation and groundwater monitoring data, groundwater sustainability was evaluated in terms of natural and man-made factors and their spatio-temporal variations. A precipitation time-series revealed a declining trend, but there were different seasonal trends between wet and dry periods, with declining and rising trends, respectively. Groundwater hydrographs from five national groundwater monitoring wells showed temporal variations. Groundwater wells located in downstream areas showed both recharge from upgradient areas and local man-made impacts (e.g. from pumping), resulting in an ambiguous relationship between precipitation and water levels. However, other monitoring wells in the upstream areas displayed water level responses to precipitation events, with a declining trend. Using the standardized precipitation index at a time scale of 12 months (SPI-12) and the standardized groundwater level anomaly, meteorological and groundwater drought conditions were compared to infer the relationship between precipitation deficit and groundwater shortage in the aquifer. The SPI results indicated severely dry to extremely dry conditions during 2008–2009 and 2015. However, the standardized groundwater level anomaly showed various drought conditions for groundwater, which were dependent on the site-specific hydrogeological characteristics. Finally, groundwater sustainability was assessed using water budget modelling and water quality data. Presently, if groundwater is used above 39.2% of the recharge value in the MRB, groundwater drought conditions occur throughout the basin. Considering water quality issues, with nitrate being elevated above the natural background, this critical abstraction value becomes 28.4%. Consequently, in the MRB, sustainable groundwater management should embrace both natural and human-induced factors to regulate over-exploitation and prevent contamination.

Analysis of Drought in the Northern Region of Bangladesh Using Standardized Precipitation Index (SPI)

Journal of Environmental Science and Natural Resources ◽

10.3329/jesnr.v11i1-2.43387 ◽

2019 ◽

Vol 11 (1-2) ◽

pp. 199-216

Author(s):

R Afrin ◽

F Hossain ◽

SA Mamun

Keyword(s):

Extended Period ◽

Northern Region ◽

Precipitation Index ◽

Rainfall Data ◽

Extreme Drought ◽

Severe Drought ◽

Drought Analysis ◽

Dry Conditions ◽

Drought is an extended period when a region notes a deficiency in its water supply. The Standardized Precipitation Index (SPI) method was used in this study to analyze drought. Northern region of Bangladesh was the area of study. Monthly rainfall data of northern region of Bangladesh was obtained from the Meteorological Department of Bangladesh. Obtained rainfall data was from 1991 to 2011 and values from 2012 to 2026 were generated using Markov model. Then SPI values from 1991 to 2026 were calculated by using SPI formula for analyzing drought. Analysis with SPI method showed that droughts in northern region of Bangladesh varied from moderately dry to severely dry conditions and it may vary from moderately dry to severely dry conditions normally in future but in some cases extreme drought may also take place. From the study, it is observed that the northern region of Bangladesh has already experienced severe drought in 1991, 1992, 1994, 1995, 1997, 1998, 2000, 2003, 2005, 2007, 2009 and 2010. The region may experience severe drought in 2012, 2015, 2016, 2018, 2019, 2021, 2022, 2023, 2024, 2025 and 2026 and extreme drought in 2012, 2014, 2016, 2023 and 2024. J. Environ. Sci. & Natural Resources, 11(1-2): 199-216 2018

Evaluation of temporal drought variation and projection in a tropical river basin of Kerala

Journal of Water and Climate Change ◽

10.2166/wcc.2020.240 ◽

2020 ◽

Vol 11 (S1) ◽

pp. 115-132 ◽

Cited By ~ 1

Author(s):

M. A. Jincy Rose ◽

N. R. Chithra

Keyword(s):

River Basin ◽

Drought Severity ◽

Climate Projections ◽

Severe Drought ◽

Tropical River ◽

The Past ◽

Drought Conditions ◽

The Future ◽

Abstract Temperature is an indispensable parameter of climate that triggers evapotranspiration and has vital importance in aggravating drought severity. This paper analyses the existence and persistence of drought conditions which are said to prevail in a tropical river basin which was once perennial. Past observed data and future climate projections of precipitation and temperature were used for this purpose. The assessment and projection of this study employ the Standardized Precipitation Evapotranspiration Index (SPEI) compared with that of the Standardized Precipitation Index (SPI). The results indicate the existence of drought in the past and the drought conditions that may persist in the future according to RCP 4.5 and 8.5 scenarios. The past drought years identified in the study were compared with the drought declared years in the state and were found to be matching. The evaluation of the future scenarios unveils the occurrence of drought in the basin ranging from mild to extreme conditions. It has been noted that the number of moderate and severe drought months has increased based on SPEI compared to SPI, indicating the importance of temperature in drought studies. The study can be considered as a plausible scientific remark helpful in risk management and application decisions.