A comparison of weather systems in 1870 and 1956 leading to extreme floods in the Murray–Darling Basin

2019 ◽  
Vol 69 (1) ◽  
pp. 84
Author(s):  
Jeff Callaghan

This research is the extension of a project studying the impact of 19th century severe weather events in Australia and their relation to similar events during the 20th and 21st century. Two floods with the worst known impacts in the Murray–Darling Basin (MDB) are studied. One of these events which occurred during 1956 is relativelywell known and the Bureau of Meteorology archives contain good rainfall data covering the period. Additionally, information on the weather systems causing this rainfall can be obtained. Rainfall, flood and weather system data for this event are presented here and compared with a devastating event during 1870. Although archived Australian rainfall data is negligible during 1870 and there is no record of weather systems affecting Australia during that year, a realistic history of the floods and weather systems in the MDB during 1870 is created. This follows an extensive search through newspaper archives contained in the National Library of Australia’s web site. Examples are presented showing how the meteorological data in 19th century newspapers can be used to create weather charts. Six such events in 1870 are demonstrated and three of these had a phenomenal effect on the Murray–Darling system. The 1870 floods followed drought type conditions and it is remarkable that it was worse in many ways than the 1956 event which followed flood conditions in the MDB during the previous year. The events in 1870 caused much loss of life from drowning in the MDB in particular froman east coast low (ECL) in April 1870 and two Victorian weather systems in September and October 1870. In 1956, there were also record-breaking events especially during March when all-time record monthly rainfall were reported in New South Wales. Overall the greatest impact from flooding across the whole MDB was associated with the 1870 flooding. Analyses of heavy rainfall areas in the MDB showed a linear trend increase from 1900 to 2018. Analysing the same data using an 8-year moving average highlighted three peaks around the five highest annual rainfall years. The largest peak occurred around 1950 and 1956, the second largest around 1973 and 1974 and the third around 2010. Each of these 5 years occurred during negative phases of the Interdecadal Pacific Oscillation (IPO) and positive phases of the Southern Oscillation Index (SOI). Studies have shown that the SOI is a climate driver in the MDB along with a persistent blocking high-pressure systems south of Australia along longitude 140°E with a low to its north. Three major blocking events with record rainfall and flooding in the MDB occurred in 1983, 1984 and 1990. Thiswas during the period 1977–1990 when blocking was conducive to heavy rain in the MDB and was coincidentwith a positive phase of the IPO, thus helping conflictwith the IPO–MDB heavy rainfall relationship. Persistent and unexplained middle level westerly winds kept subtropical Queensland clear of tropical cyclones during the negative phases of the IPO from 1999 to 2009 and during the 1960s, influencing low rainfall in the MDB during those periods.

2019 ◽  
Vol 8 (4) ◽  
pp. 9287-9290

Vrishabhavathi valley is a part of river Arkavathi. It covers parts of Bengaluru Urban and Ramanagara districts with an area of 381.46 sq. kms. Due to rapid urbanization in Bengaluru lot of pervious strata is converted into non-pervious concrete or asphalt surfaces. Rainfall is a major event, which is resulting flood in Bengaluru city. Recently observed heavy rainfall, rapid urbanization, encroachment of streams and water bodies are the major causes of flooding in Bengaluru. Disturbance to human activities and damages to properties has been observed in Vrishabhavathi valley region due to heavy rainfall especially in heavy rain events. Rainfall data analysis has been carried out statistically and graphically on Vrishabhavathi valley from 1970 to 2018. Rainfall analysis was made on converting daily rainfall data to monthly average data and seasonal analysis of rainfall has made for three different monsoon seasons Pre- monsoon, South- West and North- East monsoon, distribution and frequency of rainfall has been analyzed and results are represented graphically. From the annual rainfall study it is observed that less rainfall variations till 1990 and rainfall pattern seem to be increasing constantly from 1990’s onwards till 2018, particularly in the months of August, September and October. The rainfall contribution during south-west monsoon is almost equal to 50% of total annual rainfall. Rainfall analysis is essential to develop appropriate flood prediction models utilizing latest rainfall data collected (KSNDMC Telemetric station data) and available geospatial data to address the issues of urban flood observed in many locations in Vrishabhavathi valley region and in Bengaluru.


2021 ◽  
Vol 6 (1) ◽  
pp. 289-297
Author(s):  
Ricky Anak Kemarau ◽  
Oliver Valentine Eboy

The El Niño–Southern Oscillation (ENSO) event is a climate event that has an impact on the world climate. The effects of ENSO are often associated with prolonged droughts and floods since 1980 following global climate change. In addition to causing flooding and drought. Indirectly, the occurrence of ENSO causes health problems, environmental destruction, affecting economic activities such as agriculture and fisheries. Many studies on ENSO have been conducted. However, there is still a lack of research on the effect of ENSO on temperature in local knowledge areas, especially urban areas because the urban environment especially building materials that can absorb and release heat. In addition, previous studies have focused on large-scale areas. Beside that there still gap to understand and increase knowledge about the effect of ENSO on local temperatures, especially in urban areas. This study uses meteorological data and Oceanic Nino Index (ONI) from 1988 to 2019. This study found that the occurrence of ENSO has an effect on the value of daily temperature but differs based on the value of the ONI index. In addition, this study uses linear regression in predicting the effect of ENSO on temperature. The results of this study are useful to those responsible for understanding the impact of ENSO on temperature in urban areas to provide infrastructure in reducing the impact of ENSO as well as adjustment measures during the occurrence of ENSO.


2021 ◽  
Vol 8 (1) ◽  
pp. 23-35
Author(s):  
Ahmad Cahyadi ◽  
Eko Haryono ◽  
Tjahyo Nugroho Adji ◽  
Margaretha Widyastuti ◽  
Indra Agus Riyanto ◽  
...  

Karst area is highly susceptible to changes to climate parameters. One of the parameters is rainfall variability. In addition to shaping the condition of water resources, rainfall in the Gunung Sewu karst area determines the nature of crop and livestock of the agriculture sectors―the local population's main economic activities, warranting the significance of the rainfall variability studies. Rainfall variability in karst areas also affects disaster conditions such as drought and floods. However, due to insufficient meteorological data in quality and quantity, there has been no rainfall variability studies conducted in this locality. The research intended to analyze rainfall variability in the Gunung Sewu karst area in 1979‒2013 by utilizing rainfall predictions from satellite images that many scholars had tested in different locations and recognized as having good quality. In the analysis, mean monthly rainfall was calculated, and the trends of annual rainfall and average rainfall intensity, dry and rainy seasons, the number of rainy days, and the effect of ENSO (El Niño Southern Oscillation) on rainfall were analyzed. The research data were 35 years of daily rainfall records derived from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR). The analysis results showed that the mean rainfall, number of rainy days, and rainfall intensity had an increasing trend. Also, El Niño quantitatively influenced the rain in the Gunung Kidul karst area.


Author(s):  
Dr. Sumit M. Dhak

Abstract: A detailed trend analysis of monthly and annual rainfall for Tehsils of Palghar district were carried out using 22 years (1998-2019) daily rainfall data taken from Department of Agriculture, Maharashtra State. In this study, to analyse the trend, the non-parametric test (Mann-Kendall test) and Sen’s slope estimator were used. For developing a functional relationship between variables, a linear trend of rainfall data for the studied area evaluated using the linear regression. The results showed that the trend analysis of monthly rainfall has a varied trend of rainfall in the rainy months in tehsil of Palghar District. The month of July significant increasing trend was observed at Jawhar (42.91 mm/year), Vikramgad (29.90 mm/year), Wada (24.06 mm/year), Talasari (31.36 mm/year), Palghar (25.299 mm/year), Mokhada (29.96 mm/year) and Dahanu (38.14 mm/year), whereas non-significant increasing trend 2.76 mm/year was observed at Vasai tehsil of Palghar District during 1998-2019. The month of June, August, September and October rainfall did not show any significant trend in tehsil of Palghar District and non significant decreasing as well as non significant increasing trend was observed in tehsil of Palghar District during 1998 – 2019. The result concluded that annual rainfall trend was increased in Jawhar, Vikramgad, Wada, Talasari, Palghar, Mokhada and Dahanu; whereas Vasai tehsil rainfall trend was decreased in tehsil of Palghar District during 1998 -2019. Keywords: Rainfall, Trend Analysis, Mann Kendall’s Test, Sen Slopes, Regression


2020 ◽  
Author(s):  
Elżbieta Lasota ◽  
Riccardo Biondi ◽  
Florian Ladstädter ◽  
Andrea K. Steiner

<p>Recent studies have shown an increase of stratospheric aerosol optical depth in the last 20 years despite the absence of large volcanic eruptions in the same period, contributing to supporting the hypothesis that several minor eruptions could impact the atmospheric variability as a large one. November 2010 was a relatively active volcanic period in the tropical belt, three eruptions with Volcanic Explosivity Index higher than 3 occurred in a time span of about 3 weeks: Merapi, Tengger Caldera and Tungurahua. Merapi was the largest eruption of the three, directly overshooting the stratosphere and injecting a large amount of sulfur dioxide. In this study, we analyse the impact of this series of eruptions on the temperature derived from radio occultation observations in upper troposphere lower stratosphere at the local, regional and global scale. The impact of the Quasi‐Biennial Oscillation, El Niño–Southern Oscillation, and linear trend on temperature is estimated and removed from temperature time series using multiple linear regression. Signatures of volcanic eruptions in temperature are analysed using post fit residuals. The results show significant warming in the lower stratosphere between 10°S and 0° for a period of 7 months after the eruptions with a maximum anomaly amplitude of about 1.4 K at 18 km altitude. Whilst the maximum warming in Merapi’s vicinity occurred 4 months after the eruption and reached the magnitude of almost 4 K.</p>


Author(s):  
David Nash

Precipitation levels in southern Africa exhibit a marked east–west gradient and are characterized by strong seasonality and high interannual variability. Much of the mainland south of 15°S exhibits a semiarid to dry subhumid climate. More than 66 percent of rainfall in the extreme southwest of the subcontinent occurs between April and September. Rainfall in this region—termed the winter rainfall zone (WRZ)—is most commonly associated with the passage of midlatitude frontal systems embedded in the austral westerlies. In contrast, more than 66 percent of mean annual precipitation over much of the remainder of the subcontinent falls between October and March. Climates in this summer rainfall zone (SRZ) are dictated by the seasonal interplay between subtropical high-pressure systems and the migration of easterly flows associated with the Intertropical Convergence Zone. Fluctuations in both SRZ and WRZ rainfall are linked to the variability of sea-surface temperatures in the oceans surrounding southern Africa and are modulated by the interplay of large-scale modes of climate variability, including the El Niño-Southern Oscillation (ENSO), Southern Indian Ocean Dipole, and Southern Annular Mode.Ideas about long-term rainfall variability in southern Africa have shifted over time. During the early to mid-19th century, the prevailing narrative was that the climate was progressively desiccating. By the late 19th to early 20th century, when gauged precipitation data became more readily available, debate shifted toward the identification of cyclical rainfall variation. The integration of gauge data, evidence from historical documents, and information from natural proxies such as tree rings during the late 20th and early 21st centuries, has allowed the nature of precipitation variability since ~1800 to be more fully explored.Drought episodes affecting large areas of the SRZ occurred during the first decade of the 19th century, in the early and late 1820s, late 1850s–mid-1860s, mid-late 1870s, earlymid-1880s, and mid-late 1890s. Of these episodes, the drought during the early 1860s was the most severe of the 19th century, with those of the 1820s and 1890s the most protracted. Many of these droughts correspond with more extreme ENSO warm phases.Widespread wetter conditions are less easily identified. The year 1816 appears to have been relatively wet across the Kalahari and other areas of south central Africa. Other wetter episodes were centered on the late 1830s–early 1840s, 1855, 1870, and 1890. In the WRZ, drier conditions occurred during the first decade of the 19th century, for much of the mid-late 1830s through to the mid-1840s, during the late 1850s and early 1860s, and in the early-mid-1880s and mid-late 1890s. As for the SRZ, markedly wetter years are less easily identified, although the periods around 1815, the early 1830s, mid-1840s, mid-late 1870s, and early 1890s saw enhanced rainfall. Reconstructed rainfall anomalies for the SRZ suggest that, on average, the region was significantly wetter during the 19th century than the 20th and that there appears to have been a drying trend during the 20th century that has continued into the early 21st. In the WRZ, average annual rainfall levels appear to have been relatively consistent between the 19th and 20th centuries, although rainfall variability increased during the 20th century compared to the 19th.


MAUSAM ◽  
2021 ◽  
Vol 47 (2) ◽  
pp. 157-162
Author(s):  
A. S. M. SABBIR AHMED ◽  
A. A. MUNIM ◽  
Q. N. BEGUM ◽  
A.M. Choudhury

In the present study, an attempt has been made to examine the variations of rainfall over Bangladesh and to find possible correlation with EI-Nino/Southern Oscillation (ENSO). Four stations have been chosen from four different climatic regions of Bangladesh for this purpose, namely  Jessore, Dhaka. Barisal and Srimangal. The regions have been classified according to annual rainfall amounts. The rainfall data for forty three years, (1950-1992) have been analysed. The yearly mean rainfall shows a distinct negative decreasing tendency with the occurrence of ENSO.The seasonal rainfall analysis shows a somewhat better correlation.  


Author(s):  
Mwinyihija M.

Africa’s renaissance is inevitable and rapidly emerging as a reality in tandem with the continent’s continued exploration of its natural resources in a more sustained way than previously done. Currently, the clarion call is to value add, avoid plundering and involve its population through the SME’s to adapt modern methods of entrepreneurship. During the study, critical aspects that are envisaged to trigger the growth and development of Africa, included the entry of major countries of the continent into the global emerging markets such as MINT (Mexico, Indonesia, Nigeria and Turkey) and BRICS (Brazil, Russia, India, China and South Africa). For the leather sector, certain socioeconomic indicators such as the youthful participation in the value chain, ownership status, literacy levels and acquired experiences are all contributing to a vibrant sector. It was observed that these indicators if well aligned with individual member states of African Union Commission and structured than productivity and competitiveness of leather products will be attained. As such, ease of either foreign direct investment, local recapitalization and development of the SME’s could become feasible. Indeed, with the emergence of over 300 million youth at middle level income level is construed to start building on the impact of the continents purchasing power. Therefore, Africa needs to respond by address on development of ICT, develop affordable financial support to provide stimulus packages to SME’s (Small and Medium Enterprises) to transform, improve on inter and intra trade to optimize on unexplored synergies and enhance mobility of persons with in Africa as preamble to Africa’s renaissance.


2013 ◽  
Vol 12 (2) ◽  
pp. 119-125

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.


2015 ◽  
Vol 15 (2) ◽  
pp. 37-52
Author(s):  
Mahpud Sujai

This paper is intended to analyze the effect of oil price changes on potential output and actual output in the state budget cycle and identifies the output gap which is the difference between potential output and actual output. The research methodology uses a quantitative approach to analyze problems that occur related to the impact of oil price changes to the state budget cycle. Data analysis was carried out through the approach cyclically adjusted fiscal balance with a simplified approach. This research identified that the potential output is likely to continue increasing in line with Indonesia's oil price trends which is continue to rise following the world oil price movements. In calculating the output gap using a linear trend and HP filter, the result is fuctuating depend on the percentage changes in both potential output and actual output. This paper concludes that Indonesian oil price (ICP) has a significant impact on changes in the state budget cycle. If oil prices rise, the output gap between potential output and actual output is greater, and vice versa. This will make the budget vulnerable to shock that occurs as an external infuence.


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