PEAK OVER THRESHOLD ANALYSIS OF HEAVY PRECIPITATION IN

Peak Over Threshold Analysis Of Heavy Precipitation In-Free PDF

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to be more than one extreme precipitation event 2 1 2. in a given location during a given year so this, method is most appropriate for the evaluation of 1 1. extremes in this region The ninety fifth 1,percentile of all data including days with zero. precipitation was chosen as the threshold for Next a Generalized Pareto Distribution GPD. each dataset Days with precipitation totals was fit to the exceedance data The shape. greater than the threshold were extracted from and scale parameters from the GPD fit along. the dataset for further analysis Extreme with were used to compute the return period. precipitation events in Texas are often due to curve for N 1 to 100 years using Equation 2. multi day frontal or upper level low pressure,systems Such systems often lead to multiple. successive days of high precipitation totals To 1,ensure independence of each event in the 2. database these clusters were treated as single, events with the peak day in the event 4 RESULTS AND DISCUSSION.
representing the entire event The extremal When linear regressions were fit to the raw. index Equation 1 was used to estimate the daily precipitation data for each season at each. portion of data which existed outside of these station trend in the magnitude but not the. clusters and then to scale the resulting return frequency of extreme precipitation could be. period curve based upon this amount evaluated Over the course of the study period. nine stations saw an increase in the magnitude,of extreme precipitation events during the winter. Table 1 Stations and periods of study months College Station was the only station to. Station Period s of Study see a decline in the magnitude of extreme. events during the winter with San Antonio,Abilene 28 Dec 1949 31 Dec 2017. Austin and Brownsville reporting no change in, Alpine 29 Sep 1911 1 Oct 1960 extreme precipitation Seven of thirteen stations. 5 Oct 1965 28 Sep 2014 reported an increase during the autumn months. Amarillo 28 Dec 1949 31 Dec 2017 with no regional dependence evident Spring. and summer were variable with regard to,Austin 5 Oct 1904 28 Sep 1953. extreme precipitation trend and also exhibit no,28 Dec 1949 31 Dec 2017 regional dependence.
Blanco 6 Oct 1900 29 Sep 1949,5 Oct 1965 28 Sep 2014. Brownsville 6 Oct 1900 29 Sep 1949,5 Oct 1965 0 28 Sep 2014. College Station 1 Oct 1901 29 Sep 1949,5 Oct 1965 0 28 Sep 2014. El Paso 28 Dec 1949 31 Dec 2017,Houston 6 Oct 1921 28 Sep 1972. 28 Dec 1949 1 Dec 2017,Kingsville 6 Oct 1902 29 Sep 1951.
5 Oct 1965 28 Sep 2014,Lubbock 28 Dec 1949 31 Dec 2017. San Antonio 5 Sep 1946 1 Jan 2016,San Marcos 6 Oct 1902 29 Sep 1949. 5 Oct 1965 28 Sep 2014 Figure 1 Raw data divided into four seasons for the Blanco. Texarkana 6 Oct 1900 29 Sep 1949 station,5 Oct 1965 28 Sep 2014. Fitting a Weibull distribution to the whole,dataset all seasons including days with no. precipitation enabled comparison of the,frequency of extreme events between the early.
and late datasets for stations with sufficiently,long records Weibull distribution fits to the. whole precipitation dataset for each site,indicated a change in the 1 day precipitation. dataset at the heavy to extreme end of the,distribution between the early and late periods. Figures 2 6 Weibull fits indicate a higher,number of heavy and extreme precipitation. events for later data compared with earlier data,for five stations Austin Elgin Lockhart and San.
Marcos Of the remaining stations three,Brownsville Kingsville and Texarkana repored. fewer extreme precipitation events based on the Figure 4 Weibull fits for the early and late periods for the. Weibull fits College Station s early and late Houston data. data Weibull fits did not indicate a trend between. the early and late periods, Figure 5 Weibull fits for the early and late periods for the San. Marcos data, Figure 2 Weibull fits for the early and late periods for the Austin. Figure 6 Weibull fits for the early and late periods for the. Texarkana data, Figure 3 Weibull fits for the early and late periods for the. Brownsville data Tabular recurrence interval data in Table 2. which were generated using the peak over,threshold method reflect a regional dependence.
for the daily precipitation totals for each station. This result was expected given the diverse,range of precipitation climates in Texas Lower. values were found in the arid and semi arid,locations in the western and northwestern parts. of the state with 20 year return period single trend in daily precipitation values at a given. day totals of 2 5 in 3 8 in 2 0 in and 3 9 in for recurrence interval For Brownsville College. Alpine Amarillo El Paso and Lubbock Station Houston and San Marcos daily. respectively Larger totals were found for more precipitation totals at a given recurrence interval. temperate environments on the eastern side of increased between the early and late period. the state 6 8 in and 7 1 in for College Station For Austin Blanco and Texarkana the daily. and Houston The highest return period total in precipitation total for a given recurrence interval. the dataset occurred in San Marcos with single decreased between the early and late period In. day precipitation totals of 6 8 in 7 6 in and 9 3 several cases this trend is opposite what was. in for the 10 20 and 100 year recurrence observed for the Weibull fits For example. intervals Weibull fit data for both Austin and Blanco. Table 3 lists daily precipitation totals for three indicates an increase in the frequency of events. recurrence intervals for the early and late at the heavy and extreme end of the daily. periods The magnitudes of daily precipitation precipitation spectrum but return period curves. values at the 10 20 and 100 year levels for for the same stations indicate a decrease in. the Austin Blanco and Texarkana stations daily precipitation totals for given recurrence. decrease between the early and late period intervals over the same period In other words. Brownsville Houston and San Marcos each had for these stations the number of extreme events. an increase in daily precipitation totals at the 10 has increased between the early and late period. 20 and 100 year return periods but the total precipitation occurring during each. of those events has declined Other stations, Table 2 Return period values 10 20 and 100 year in experienced an increasing trend in both. inches for the late time period for each site,frequency of extreme events and the daily. City 10 year 20 year 100 year precipitation total associated with a given. Abilene 4 5 4 9 5 8 recurrence interval College Station whose. Alpine 2 1 2 5 3 1 Weibull fits for the early and late periods. indicated no temporal trend in extreme event, Amarillo 3 5 3 8 4 4 frequency experienced an increase in daily.
Blanco 5 2 5 5 6 2 precipitation total at a given recurrence interval. Brownsville 4 3 5 0 6 7 Brownsville s Weibull fit data indicated a. College Station 5 7 6 8 9 3 decrease in the number of extreme events while. return period curves indicated an increase in, El Paso 1 8 2 0 2 3 daily precipitation totals associated with a given. Houston 6 3 7 1 8 5 recurrence interval, Kingsville 4 0 4 6 6 0 Some preliminary regional dependencies. Lubbock 3 6 3 9 4 7,begin to appear in this analysis The three. Central Texas stations Blanco Austin and San, San Marcos 6 8 7 6 9 3 Marcos all experienced an increase in the. Texarkana 5 2 5 9 7 3 frequency of extreme events between the early. and late periods San Marcos which has seen,numerous notable flash flooding events in the.
Table 3 Return period values 10 20 and 100 year in past decade has experienced an increase in. inches for the early and late time periods,both frequency and quantity of extreme. 10 year 20 year 100 year precipitation Houston and College Station both. Early Late Early Late Early Late situated in East Texas both experienced an. increase in return period values between the,Austin 7 0 5 5 7 8 5 9 9 5 6 7. early and the late period Texarkana was the, Blanco 5 3 5 2 5 7 5 5 6 5 6 2 only station to report a decrease in both. Brownsville 2 4 4 3 3 0 5 0 4 4 6 7 frequency and quantity of extreme precipitation. Historical data from stations in the western and,Houston 5 5 6 3 6 0 7 1 7 0 8 5. northern parts of the state would allow for further. San Marcos 6 4 6 8 7 1 7 6 8 5 9 3 evaluation of regional trends in extreme. Texarkana 5 8 5 2 6 4 5 9 7 6 7 3 precipitation,Return period curves for the early and late.
periods Figures 7 13 also indicate a temporal, Figure 7 Return period curves for early and late Austin data Figure 10 Return period curves for early and late College. Station data, Figure 8 Return Period curves for the early and late Blanco. data Figure 11 Return period curves for early and late Houston. Figure 9 Return period curves for the early and late. Brownsville data Figure 12 Return period curves for early and late San. Marcos data,more data from the western and northern. portions of the state Enhancing the resolution,of the data network will facilitate evaluation of. regional trends and allow for more detailed,analysis of trends in frequency and daily.
precipitation totals,REFERENCES,Acero F Garc a J Gallego M 2011 Peaks over. Threshold Study of Trends in Extreme Rainfall over. the Iberian Peninsula Journal Of Climate 24 4 pp,1089 1105 Academic Search Complete EBSCOhost. viewed 26 February 2018,Bosart L Cordeira J Galarneau T Moore B. Figure 13 Return period curves for early and late Texarkana Archambault H 2012 An Analysis of Multiple. Predecessor Rain Events ahead of Tropical Cyclones. Ike and Lowell 10 15 September 2008 Monthly, 5 CONCLUSIONS Weather Review 140 4 pp 1081 1107 Academic. Fourteen precipitation records varying in Search Complete EBSCOhost viewed 22 February. length from fifty to one hundred years from cities 2018. across the state of Texas were evaluated for, temporal and regional dependences using the Furl C Sharif H El Hassan A Mazari N Burtch D.
peak over threshold method for generating Mullendore G 2015 Hydrometeorological Analysis. return period curves As expected some of Tropical Storm Hermine and Central Texas Flash. Flooding September 2010 Journal Of,regional dependence was apparent including. Hydrometeorology 16 6 pp 2311 2327 Academic, higher single day precipitation totals for the 10 Search Complete EBSCOhost viewed 22 February. 20 and 100 year recurrence intervals for 2018,stations located in the central and eastern. portions of the state The largest single day Nielsen E Schumacher R Keclik A The Effect of the. precipitation totals were found in the central part Balcones Escarpment on Three Cases of Extreme. of the state San Marcos For those stations Precipitation in Central Texas Monthly Weather. whose records were long enough to evaluate Review serial online January 2016 144 1 119 138. both an early and a late period temporal Available from Academic Search Complete Ipswich. MA Accessed February 22 2018,changes in single day precipitation total. distribution were identified in comparisons of Shen S P S O Wied A Weithmann T Regele B. both Weibull fits and return period curves A Bailey and J H Livermore 2016 Six temperature. Blanco Austin San Marcos and Houston all and precipitation regimes of the contiguous United. experienced an increase in frequency of States between 1895 2001 Theoretical Applied. extreme precipitation events between the two Climatology 125 197 2011. periods Trends in the return period curves for, those stations were not as straightforward with Venkataraman K S Tummuri A Medina and J.
decrease in values at a given recurrence interval Perry 2016 21 century drought outlook for major. climate divisions of Texas based on CMIP5,reported for Blanco and Austin Texarkana and. multimodel ensemble Implications for water resource. Brownsville both reported a decrease in the management Journal of Hydrology 534 300 316. frequency of extreme events with Texarkana, also reporting a decrease in recurrence interval Villarini G and J A Smith Flooding in Texas. values and Brownsville reporting an increase Examination of Temporal Changes and Impacts of. Notably Houston and San Marcos cities which Tropical Cyclones Journal of the American Water. have experienced multiple noteworthy flooding Resources Association 49 825 837. events in the past decade both reported an, increase in both the frequency and the return Zhao G H Gao and L Cuo 2016 Effects of. Urbanization and Climate Change on Peak Flows,period values over the past century. over the San Antonio River Basin Texas Journal of,Hydrometeorology 17 2371 2389.
6 FUTURE WORK,This study will benefit from a denser network. of historical precipitation observations as well as. Alpine 29 Sep 1911 1 Oct 1960 5 Oct 1965 28 Sep 2014 Amarillo 28 Dec 1949 31 Dec 2017 Austin 5 Oct 1904 28 Sep 1953 28 Dec 1949 31 Dec 2017 Blanco 6 Oct 1900 29 Sep 1949 5 Oct 1965 28 Sep 2014 Brownsville 6 Oct 1900 29 Sep 1949 5 Oct 1965 0 28 Sep 2014 College Station 1 Oct 1901 29 Sep 1949 5 Oct 1965 0 28 Sep 2014

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