Tesis sobre el tema "Annual rainfall"
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1
Sreenivasan, K. R. "Structural Analysis And Forecasting Of Annual Rainfall Series In India". Thesis, Indian Institute of Science, 2001. http://hdl.handle.net/2005/262.
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The objective of the present study is to forecast annual rainfall taking into account the periodicities and structure of the stochastic component.
This study has six Chapters. Chapter 1 presents introduction to the problem and objectives of the study. Chapter 2 consists of review of literature. Chapter 3 deals with the model formulation and development. Chapter 4 gives an account of the application of the model. Chapter 5 presents results and discussions. Chapter 6 gives the conclusions drawn from the study.
In this thesis the following model formulations are presented in order to achieve the objective.
Fourier analysis model is used to identify periodicities that are present in the rainfall series.1 These periodic components are used to obtain discrotized ranges which is an essential input for the Fourier series model.
Auto power regression model is developed for estimation of rainfall and hence to compute the first order residuals errlt The parameters of the model are estimated using genetic algorithm. The auto power regression model is of the form,
( Refer the PDF File for Formula)
where αi and βi are parameters and M indicates modular value.
Fourier series model is formulated and solved through genetic algorithm to estimate the parameters amplitude R, phase Φ and periodic frequency wj for the residual series errlt. The ranges for the parameters R, Φ and wj were obtained from Fourier analysis model.
errl't= /µerrlt+ Σj Rcos(wjt+ Φ)
Further, an integrated auto power regression and Fourier series model developed (with parameters of the model being known from the above analysis) to estimate new rainfall series
Zesťt=Zµ Σ t αi(ZMi-t ) βi+µerrl+ Σj Rcos(wjt+ Φ)
and the second order residuals, err2t is computed using,
err2t = (zt –Zesťt)
Thus, the periodicities are removed in the errlt series and the second order residuals err'2f obtained represents the stochastic component of the actual rainfall series.
Auto regressive model is formulated to study the structure of the stochastic component err2t. The auto regressive model of order two AR(2) is found to fit well. The parameters of the AR(2) model were estimated using method of least squares.
An exponential weighting function is developed to compute the weight considering weight as a function of AR{2) parameters. The product of weight and Gaussian white noise N(0, óerr2) is termed as weighted stochastic component.
Also, drought analysis is performed considering annual (January to December) and summer monsoon (June to September) rainfall totals, to determine average drought interval (idrt) which is used in assigning signs to the random component of the forecasting model.
In the final form of the forecasting model.
Zest”t = Z µ Σ t αi(ZMi-t ) βi+µerrl+ Σj Rcos(wjt+ Φ) ± WT(Φ1, Φ2)N(0, óerr2)
The weighted stochastic component is added or subtracted considering two criteria. Criterion I is used for all rainfall series except all-India series for which criterion II is used. The criteria also consider average drought interval Further, it can be seen that a ± sign is introduced to add or subtract the weighted stochastic component, albeit the stochastic component itself can either be positive or negative. The introduction of ± sign on the already signed value (instead of absolute value) is found to improve the forecast in the sense of obtaining more number of point rainfall estimates within 20 percent error.
Incorporating significant periodicities, and weighted stochastic component along with
average drought interval into the forecasting formulation is the main feature of the model.
Thus, in the process of rainfall prediction, the genetic algorithm is used as an efficient tool in estimating optimal parameters of the auto power regression and the Fourier series models, without the use of an expensive nonlinear least square algorithm.
The model application is demonstrated considering different annual rainfall series
relating to IMD-Regions (RI...R5), all-india (AI), IMD-Subdivisions (S1...S29), Zones (Z1...Z10) and all-Karnataka (AK).
The results of the proposed model are encouraging in providing improved forecasts. The model considers periodicity, average critical drought frequency and weighted stochastic component in forecasting the rainfall series. The model performed well in achieving success-rate of 70 percent with percentage error less than 20 percent in 4 out of 5 IMD Regions (R2 to R5), all-India, 17 out of 29 IMD Subdivisions (S1 to S5, S7 to S9, S18, S19, S21, S24 to S29) and all-Karnataka rainfall series. The model performance for Zones was not that-satisfactory as only 2 out of 10 Zones [Z1 and Z2) met the criterion.
In a separate study, an effort was made to forecast annual rainfall using IMSL subroutine SPWF -which estimates Wiener forecast parameters. Monthly data is considered for the study. The Wiener parameters obtained were used to estimate monthly rainfall. The annual estimates obtained by simple aggregation of the monthly estimates compared extremely well with the actual annual rainfall values. A success rate of more than 80 percent with percentage error less than 10 percent is achieved in 4 out of 5 IMD Regions (R2 to R5), all-India, 18 out of 29 IMD Subdivisions (S1 to S8, S14, S18, S19, S22 to S24, S26 to S29) and all-Karnataka rainfall series. Whereas a success rate of 80 percent within 20 percent error is achieved in 4 out of 5 IMD Regions (except R1), all-India, 25 outof 29 IMD Subdivisions (except S10, S11, S12 and S17), all- Karnataka and 8 out of 10 Zones (except Z6 and Z8)(Please refer PDF File for Formulas)
2
Moses, Godfrey. "The establishment of the long-term rainfall trends in the annual rainfall patterns in the Jonkershoek Valley, Western Cape, South Africa". Thesis, University of the Western Cape, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6556_1263520811.
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The overall aim of this project was to establish whether there is a long-term decline of rainfall collected in rainfall gauges within the Jonkershoek Valley that have the longest and best quality records.
3
Maldonado, Tito. "Inter-annual variability of rainfall in Central America : Connection with global and regional climate modulators". Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-304656.
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Central America is a region regularly affected by natural disasters, with most of them having a hydro-meteorological origin. Therefore, the understanding of annual changes of precipitation upon the region is relevant for planning and mitigation of natural disasters. This thesis focuses on studying the precipitation variability at annual scales in Central America within the framework of the Swedish Centre for Natural Disaster Science. The aims of this thesis are: i) to establish the main climate variability sources during the boreal winter, spring and summer by using different statistical techniques, and ii) to study the connection of sea surface temperature anomalies of the neighbouring oceans with extreme precipitation events in the region. Composites analysis is used to establish the variability sources during winter. Canonical correlation analysis is employed to explore the connection between the SST anomalies and extreme rainfall events during May-June and August-October. In addition, a global circulation model is used to replicate the results found with canonical correlation analysis, but also to study the relationship between the Caribbean Sea surface temperature and the Caribbean low-level jet. The results show that during winter both El Niño Southern Oscillation and the Pacific Decadal Oscillation, are associated with changes of the sea level pressure near the North Atlantic Subtropical High and the Aleutian low. In addition, the El Niño Southern Oscillation signal is intensified (destroyed) when El Niño and the Pacific Decadal Oscillation have the same (opposite) sign. Sea surface temperature anomalies have been related to changes in both the amount and temporal distribution of rainfall. Precipitation anomalies during May-June are associated with sea surface temperature anomalies over the Tropical North Atlantic region. Whereas, precipitation anomalies during August-September-October are associated with the sea surface temperature anomalies contrast between the Pacific Ocean and the Tropical North Atlantic region. Model outputs show no association between sea surface temperature gradients and the Caribbean low-level jet intensification. Canonical correlation analysis shows potential for prediction of extreme precipitation events, however, forecast validation shows that socio-economic variables must be included for more comprehensive natural disaster assessments.
4
Köchy, Martin. "Opposite trends in life stages of annual plants caused by daily rainfall variability : interaction with climate change". Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2007/1469/.
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Global Circulation Models of climate predict not only a change of annual precipitation amounts but also a shift in the daily distribution. To improve the understanding of the importance of daily rain pattern for annual plant communities, which represent a large portion of semi-natural vegetation in the Middle East, I used a detailed, spatially explicit model. The model explicitly considers water storage in the soil and has been parameterized and validated with data collected in field experiments in Israel and data from the literature. I manipulated daily rainfall variability by increasing the mean daily rain intensity on rainy days (MDI, rain volume/day) and decreasing intervals between rainy days while keeping the mean annual amount constant. In factorial combination, I also increased mean annual precipitation (MAP). I considered five climatic regions characterized by 100, 300, 450, 600, and 800 mm MAP. Increasing MDI decreased establishment when MAP was >250 mm but increased establishment at more arid sites. The negative effect of increasing MDI was compensated by increasing mortality with increasing MDI in dry and typical Mediterranean regions (c. 360–720 mm MAP). These effects were strongly tied to water availability in upper and lower soil layers and modified by competition among seedlings and adults. Increasing MAP generally increased water availability, establishment, and density. The order of magnitudes of MDI and MAP effects overlapped partially so that their combined effect is important for projections of climate change effects on annual vegetation. The effect size of MAP and MDI followed a sigmoid curve along the MAP gradient indicating that the semi-arid region (≈300 mm MAP) is the most sensitive to precipitation change with regard to annual communitie
5
Akachuku, A. E. "Intra-Annual Variation in Wood Density in Gmelina Arborea from X-Ray Densitometry and its Relationship with Rainfall". Tree-Ring Society, 1985. http://hdl.handle.net/10150/261361.
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The variation in wood density within growth rings was determined from X-ray negative images of wood samples of Gmelina arborea. The within-tree and between-tree comparisons showed that no two growth rings had exactly similar patterns of variation in the radial direction. The proportions of wood in four within-ring density classes were estimated. The variations in the proportions of wood in the four classes with age were nonlinear. On the average, the proportion of low density wood decreased with increasing age, while the proportion of high density wood increased with age. Regression analysis testing different curvilinear models showed that 37 to 99 per cent of the variations in the proportions of wood were associated with variations in age. Maximum and minimum ring density were negatively correlated with dry season rainfall. Variations in the proportion of high density wood and mean ring density were not associated with corresponding variation in dry season rainfall. The proportions of low and high density wood, mean ring density, maximum ring density and minimum ring density were not determined by annual rainfall.
6
Burns, Kit Alexander. "Characterisation of rhizobia for the new annual pasture legume Scorpiurus muricatus targeted for medium-to-low rainfall areas of southern Australia". Thesis, Burns, Kit Alexander (2019) Characterisation of rhizobia for the new annual pasture legume Scorpiurus muricatus targeted for medium-to-low rainfall areas of southern Australia. Honours thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/53975/.
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Legumes play an integral role in increasing agricultural productivity, particularly in low input agricultural systems in Australia, due to their ability to form symbiotic interactions with a group of soil bacteria called rhizobia. However, in medium-to-low rainfall areas of southern Australia, there is a lack of suitable annual pasture legumes, which is limiting agricultural productivity and profitability in these farming systems. Scorpiurus muricatus is an annual legume from the Mediterranean which possesses high nutritive value and palatability for livestock, is high yielding, capable of self-seeding and is well-adapted to hot and dry summers. As such, S. muricatus is currently being evaluated as a new pasture legume for southern Australia. Crucial to the success of introducing this legume will be the availability of a highly effective rhizobial inoculant strain. This thesis therefore sought to characterise the phylogeny, free-living and symbiotic phenotype of a range of bacteria isolated from Scorpiurus spp.
A total of 19 strains were investigated, with 16s rRNA sequencing demonstrating that 18 of these strains belonged to the genus Mesorhizobium, with the remaining strain (WSM1184) most closely related to Agrobacterium tumefaciens. Analysis of nifH and nodC symbiosis genes further showed that the characterised Mesorhizobium strains generally shared highly similar sequences for these loci, indicating a comparatively high degree of genetic similarity. In particular, WSM1343 (isolated from Scorpiurus sulcatus growing in Morocco) and WSM1386 (isolated from S. sulcatus in Manjimup, Western Australia) were shown to share highly similar symbiosis genes, but divergent 16S rRNA genes, suggesting the possibility that these strains may contain symbiosis genes on mobile Integrative and Conjugative Elements (ICEs).
While the temperature tolerance and apparent optimum growth temperature of the test strains of 28°C was consistent with that commonly reported for Mesorhizobium spp., their growth rate was atypical for this genus, with 15 of the 18 strains having a growth rate on YMA at 28°C slower than that generally described for Mesorhizobium. This slower growth rate may be a common feature of rhizobia from S. muricatus nodules and therefore should be considered when isolating organisms from this legume.
Symbiotic effectiveness experiments showed all Mesorhizobium strains nodulated S. muricatus and fixed N2 on this host, with the most effective strain producing 67.5% of the mean shoot dry weight of the N-fed control plants. Host range experiments demonstrated a subset of the Mesorhizobium strains nodulate existing Australian commercial pasture legumes Biserrula pelecinus and Lotus corniculatus, with the effectiveness data suggesting these strains fix N2 poorly on both hosts. In contrast, none of the strains tested were able to nodulate the grain legume Cicer arietinum.
While this thesis has characterised the phylogeny, free-living and symbiotic phenotype of a range of S. muricatus microsymbionts, further work is required before a suitable commercial inoculant strain can be recommended for this pasture legume. First, all the strains tested in this thesis were isolated from S. sulcatus plants or soils with Scorpiurus spp. present, rather than S. muricatus and it is not known whether strains from either species are cross-compatible for effective N2 fixation. Future studies may therefore locate more effective N2-fixing rhizobia for S. muricatus by isolating microsymbionts from this host in the field. Second, experiments testing the ability of commercial inoculants for already-established pasture legumes B. pelecinus (WSM1497), Lotus sp. (SU343, CC829) and the grain legume C. arietinum (CC1192) to nodulate and fix N2 on S. muricatus need to be conducted to determine whether these inoculants will interact with this legume. Finally, the data strongly suggest that S. muricatus-nodulating Mesorhizobium spp. may contain symbiosis genes on mobile symbiosis ICEs. Given that the phenomenon of ICE transfer has led to the evolution of poorly effective microsymbionts for B. pelecinus, it is imperative that these S. muricatus strains be interrogated for the presence and transfer of symbiosis ICEs, in order to manage this mobility in any future commercial inoculant strain that is released for this pasture legume species.
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Smemoe, Christopher M. "Floodplain Risk Analysis Using Flood Probability and Annual Exceedance Probability Maps". Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd379.pdf.
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Mokhtarnejad, Siamak N. "Storm Water Management Using a High Density Rainfall Network Along With Long Term Records". ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/903.
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The United States Weather Bureau had published Technical Paper No. 40 (TP-40) in 1961 which provides a rainfall atlas for the United States. These rainfall frequencies have been used by engineers throughout the United States including Jefferson Parish, Louisiana. Rainfall from Audubon and the New Orleans International Airport rain gauge stations were used with the Log Pearson Method to provide rainfall frequency for Jefferson Parish, Louisiana. The results from the frequency rainfall that were developed for this research along with the current Jefferson Parish design storm rainfall were applied to a typical urban development to evaluate the extent of flooding.
9
Kabine, Ezekiel Simon. "Evaluation of different temperature winter fodder species (Festulolium hybrids, dactylis species, lolium hybrids) and grass-legume mixtures in the warmer summer rainfall areas of South Africa". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1808.
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Thesis (MSc. (Pasture Science)) -- University of Limpopo, 2016South Africa is regarded as a semi-arid area; only 28% of the country receives more than 600 mm rainfall recorded annually. Sustainable utilization of cool season fodder grasses in summer rainfall areas to produce winter animal feed remains a major problem. Farmers are affected by a shortage of adequate, good quality herbage for livestock during winter and dry periods on commercial farms. The study aimed to evaluate and compare the production potential of six Festulolium hybrids, three Dactylis species, and five Lolium hybrids and three grass-legume mixtures in the summer rainfall area. A total of 17 cultivars were evaluated for their DM production under the treatment of different fertilizer levels on three planting dates (16 March 2011, 21 April 2011 and 4 April 2012). The study was carried out at Hygrotech Seed Company (Experimental site), Dewagensdrift in Moloto Village outside Pretoria in the Gauteng Province. Data was collected on a monthly basis from sub-plots of 1 m x 1 m (m2) in 51 plots of 1.5 m x 6 m (9 m2), with nine rows that were 10 cm apart arranged under RCBD with three replicates per cultivar. Harvested fresh samples were taken, weighed, dried at 60ºC until they reached a constant dry weight and weighed to determine DM content. A Fischer’s protected LSD at the 5 % level was performed to compare the treatment means. Over a period of three years of study, it shows that the low fertilizer level resulted in the lowest DM production, with no significant difference occurring between medium and high fertilizer levels. To achieve optimum DM production with minimum cost medium fertilizer is recommended. The cultivars responded differently to the three different planting dates. The time of planting had an effect on DM production in winter. It is recommended that Festulolium hybrids and Lolium hybrids be planted earlier (March) for better DM production in winter.
National Research Foundation (NRF)
10
Alsadi, Aram. "Dynamiken hos organiskt kol i Mälarens avrinningsområde : flöden, drivande faktorer och modellering". Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256490.
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I denna rapport undersöks hur mängden organiskt kol, TOC (Totalt organiskt kol), varierar i tid och rum i Mälarens avrinningsområde, samt vad det är som styr TOC-halten i Mälaren. Det är viktigt att förstå dynamiken hos TOC i Mälaren och i dess avrinningsområde eftersom ökat TOC i vattnet påverkar vattenkvaliteten och orsakar problem vid beredning av dricksvatten. TOC kan bland annat reagera med klor/UV-ljus och bilda cancerframkallande ämnen. Det kan också öka antal mikrober i vattnets distributionssystem. Arbetet omfattar analys av samband mellan elementen, transportberäkningar per ytenhet av elementen till Mälaren och en modelleringsansats för ett av avrinningsområdena. Rapporten innehåller även en jämförelse mellan de olika vattenföringsmodellerna samt uppmätt vattenföring för analys av eventuella systematiska skillnader mellan dessa som påverkar beräkningen av TOC och de andra elementens transport till Mälaren. Analysen av sambanden mellan variablerna TOC (mg/l), kaliumpermanganat förbrukning (KMnO4, mg/l), absorbans_F (F=filtrerad), järn (mg/l), mangan (mg/l) och SO4_IC (sulfat mätt med hjälp av jonkromatografi, mg/l), visade att vissa av dessa variabler är korrelerade med varandra. TOC mot KMnO4 och TOC mot absorbans_F hade de bästa anpassningarna med respektive R2- värden 0,65 och 0,59 och p-värden <0,001. Årsnederbörd är positivt korrelerad med TOC per ytenhet för Kolbäcksån med R2-värde 0,63 och p-värde <0,01, vilket innebär att sambandet är signifikant. Ökad årsnederbörd leder till ökad tillförsel av TOC till Mälaren. Det finns däremot inget signifikant samband mellan TOC-transport per ytenhet och årsmedeltemperatur. Arealflödesberäkningar tyder på att den största tillförseln av TOC- transport per ytenhet kommer från den nordöstra delen av Mälaren. Fyrisån står för den största tillförseln av TOC. Hydrologiska, kemiska och meteorologiska data inkluderades i modeller för att kunna skatta TOC-halten i Mälaren. Temperatur-, evapotranspirations- och nederbördsdata användes i en hydrologisk modell, HBV- modellen, för att simulera vattenföringen från avrinningsområdet. Sedan användes en processbaserad modell, INCA- C, som drivs av hydrologisk data och beräknade grundvattenbildning och markfuktighet för att simulera tidsmässiga mönster i TOC. Invariablerna till INCA-modellen, markfuktigheten och HER (grundvattenbildning), simulerades med hjälp av HBV- modellen. Dessa modeller tillämpades i Kolbäcksån (ett av Mälarens största avrinningsområden). Modelleringen av Kolbäcksåns TOC- halt resulterade i en modell som anpassade dynamiken mellan 1996 och 2009, men missar den mellan 2009 och juni 2010, med bäst anpassning mellan 2006 och 2008. R2- och NS värden som erhölls för modellen var 0,086 och -0,059.In this report, it has been investigated how the amount of organic carbon, TOC, varies in time and space in the basin of Mälaren, and what controls the TOC content in the lake. It is important to understand the dynamics of the TOC in the lake and its catchment because increased TOC in the water affects water quality and causes problems in the preparation of drinking water. Particularly, it can react with chlorine / UV- light and form carcinogenic substances. It can also increase the number of microbes in water distribution systems. In addition the work includes analysis of the relation between water chemistry variables, annual fluxes calculations (g/m2/year) of element flows to the lake and a modeling approach to a watershed. Annual fluxes calculations (g/m2/year) indicate that the largest supply of TOC to the lake comes from the northeast of the lake. Fyrisån accounts for the largest input of TOC to the lake. The high TOC-flux is due to a small proportion of open water in the catchment. Hydrological, chemical and meteorological data have been included in models to estimate the TOC content in the Mälaren. Input data processing, especially precipitation data, has been an important part of the work as it affects the whole model. Temperature, evapotranspiration and precipitation data were used in a hydrological model, HBV model, to simulate the flow from the catchment area. Then a process-based model, INCA-C, operated by the hydrological data and soil moisture, has been used to simulate the temporal patterns in TOC. The input variables to INCA-C- model, soil moisture and HER (Hydrological effective rainfall), have been simulated using the HBV- model. Those models were applied in Kolbäcksån, one of the lake's largest catchments. The modeling of Kolbäcksån resulted in a model that captured the dynamics of a few periods of the whole time series. The modeling of Kolbäcksån TOC-concentration resulted in a model that captured the dynamics between 1996 and 2009, but misses it between 2009 and June 2010. R2 and NS values obtained for the model were 0.086 and -0.059, respectively.
11
Mahlalela, Precious. "Revisiting the links between the Southern Annular Mode and rainfall over the Western Cape region of South Africa". Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29208.
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The winter rainfall region of South Africa displays considerable interannual variability and prevalence to prolonged dry periods. Although not completely understood, a wide range of factors have been highlighted to contribute to this interannual variability. The relatively poor understanding of rainfall variability in this region is of concern considering the low rainfall received in 2015-2017, resulting in the City of Cape Town enforcing severe water restrictions due to dam levels falling dangerously low. The focus of this thesis is on the influence of the Southern Annular Mode (SAM) on rainfall over the region, the possible influence of El Niño Southern Oscillation (ENSO) is also considered. To achieve this, a correlation analysis was conducted using the Marshal (2003) SAM index and station rainfall anomalies over the region for the period 1979 to 2016. The results show that five (three) of the six driest (wettest) years were associated with a positive (negative) SAM phase. However, the relationship is found to be statistically insignificant at a 95% significance level. The relationship is also found to show spatial variability, with strong negative correlations over the West Coast, while a weak positive correlation is observed over the South Coast. Furthermore, a decadal analysis in the relationship found it to be statistically insignificant (at the 95 th significance level) for most of the study period, with an exception of the early winter over the West Coast which shows a strong negative correlation after 2015. A composite analysis showed that dry (wet) winters tend to be associated with a positive (negative) SAM pattern superimposed with a wave number 3 anomaly. In addition, there are La Niña (El ivNiño) – like SST anomalies in the tropical Pacific. These circulation and SST patterns are more or less observed during the generally dry 2015-2017 winters except that winter 2015 shows an El Niño SST anomaly.
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Blumenthal, Barbara. "Nederbördsintensitet och andra faktorer som påverkar skyfallsskador". Licentiate thesis, Karlstads universitet, Centrum för klimat och säkerhet (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-70173.
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I Sverige inträffar många skyfall och intensiva regn under sommarmånaderna. Det finns inga uppenbara geografiska mönster, vilket är en skillnad gentemot älv- eller sjööversvämningar där det vanligtvis är känt vilka områden som kan komma att översvämmas vid en viss vattennivå eller ett visst vattenflöde. För individer och samhällsaktörer innebär en skyfallshändelse i många fall en stor överraskning då skyfall utvecklas snabbt och dagens meteorologiska prognossystem i stort inte lyckas att prognosticera extrema regn korrekt med avseende på mängd, tid och plats. Vädervarningar kommer med kort varsel eller uteblir helt. Konsekvenserna av intensiv nederbörd och skyfall är främst översvämningar och erosionsskador på byggnader och infrastruktur, men även störningar och avbrott i olika samhällsfunktioner som kan påverka samhället och individer utanför det drabbade området. I denna avhandling har 15 år av försäkringsskadedata använts för att undersöka samband mellan nederbördsintensitet och skyfallsskador. Även påverkan av andra faktorer som topografi, bebyggelse och socioekonomiska aspekter har undersökts. Resultaten visar att regnintensitet under ett 60 minuters intervall i kombination med korta perioder av extrem intensitet, tillsammans med topografiska faktorer spelar en betydande roll vid uppkomsten av skador.
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Chang, Chan-Hua y 張展華. "Characteristics of Annual rainfall and Maximum one day rainfall in Kao-Ping Area". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/58162691719786829098.
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碩士國立屏東科技大學
水土保持系
91
Five frequency analysis methods were used in this study for the Maximum one day rainfall and annual from the data issued by Central Weather Bureau(CWB) of weather observation station in December, 2000(5th edition) and data in annual book about 188 weather observation stations of CWB in Kaohsiung and Pingtung. As the results of analysis shown, it is suggested to use Pearson type Ⅲ method for predicting frequency analysis of annual rainfall in Kaohsiung City, Kaohsiung County, Pingtung County, and the whole region of Kaohsiung and Pingtung; for the Maximum one day rainfall,Log Natural Distribution for predicting frequency analysis is suggested to use in Kaohsiung City, Log Pearson type Ⅲ method in Kaohsiung County, Pingtung County, and the whole region of Kaohsiung and Pingtung. Based on the distributions from applicable theories, the most applicable theory for each station was found. Then, use the hydrological frequency analysis to estimate the hydrological parameters of 5-yr, 20-yr, 25-yr, 50-yr and 100-yr, and draw the rainfall contour map accordingly for the reference for different requirements. The rainfall contour map shows that the rainfall increases as the elevation increases, but it is hard to estimate the increase rate. By taking each village, town, city and district as the regional units, the frequency regression equations, R squares and standard deviations were obtained, which can provide the relevant engineers an easy way to obtain the hydrological parameters for the reference of construction design. As for the relationship of rainfalls and elevations of station, it can be found from the results of this study that the more the year number of record, the closer the relationship between the average annual rainfall and the maximum one day rainfall. Therefore, as the year number of record increases, the reliability of the hydrological frequency analysis increases. However, the average annual rainfall and the maximum one day rainfall increase as the elevation of the stations increases, but there is no fixed increase trend. The average annual rainfall and maximum one day rainfall have no conspicuous relationship with the elevations of the stations. Especially, the relationship of the maximum one day rainfall and the elevation is worse.
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林立恆. "Regional frequency analysis of annual maximum 24-hour rainfall". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/9wcbb3.
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碩士逢甲大學
水利工程與資源保育學系
104
Regional analysis is a very important part of the design in hydraulic engineering. Base on measured data from the past,this study can find correlations between the stations.Therefore, regional analysis solve the situation inadequate data, and creates a partition for each of rainfall in Taiwan. This study used two cluster approaches, Cluster analysis and self-organizing map (SOM) with the reference of 127 raingauge data (recorded over 20-years). Hydrological factors presented annual maximum 24-hour rainfall data (mean, standard deviation, skewness and kurtosis), and Physiographical factor displayed station locations and elevation.After this study established each rainfall characteristics partitions, this study detected partition information by L-moment method.The results showed that after adjusting rainfall characteristics data, the two classifications were likely uniformity. Next, this study used the goodness-of-fit measurement to select the best regional probability distributions of rainfall.The Cluster Analysis results show that the best regional probability distribution for 2 normal distribution ,the Gumbel I and the Pearson type III distribution were the best for 1 region.On the other hand, SOM only shows 3 normal distributions and 2 Gumbel I distributions.Finally, this study used SOM results and with Thiessen polygons method dividing Taiwan rainfall characteristics into several partition. In the absence of rainfall frequency analysis information, this storm frequency analysis results will provide a reference for the design of future project planning.
15
Wen-HongHuang y 黃文宏. "Trend and distribution-change analysis of annual rainfall in Taiwan". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/81473423351194911447.
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碩士國立成功大學
水利及海洋工程學系碩博士班
101
Extreme climatic events have frequently observed in Taiwan recently. Such unusual extreme events often cause severe economic damages. Many studies report that intensified events caused by climate change are occurred frequently. Declining rainfall would induce insufficient water supplies, while increasing rainfall would cause flooding. Understanding trend of rainfall characteristics thus becomes an important task in water resources planning and management. This study aims to detect trend and distribution-change of annual rainfall by using statistical methods, including linear regression, Mann-Kendall test, and quantile regression. The data used in this study is the annual rainfall with at least 54 years (from 1947 to 2000) of 23 rainfall gauge stations in Taiwan. Quantile regression can identify the linear regression lines at various quantiles. An approach is proposed in this study to integrate changes of all quantiles from quantile regression model in terms of changes of probability density function (PDF) to detect distributional changes of annual rainfall. Linear regression and Mann-Kendall test show that the Taipei station has an increasing trend, while Wukuai, Likang, and Tawu have descending trend. The results of quantile regression also show that the above 4 stations have significant trend at some quantiles. There are 19 stations exhibit non-significant trend by the linear regression model and Mann-Kendall test. However, significant trend at some quantiles are observed by quantile regression for 7 stations. That is, such trends are not detected by linear regression model and Mann-Kendall test. In terms of PDF-change, the PDF of annual rainfall in North region has no shift, the PDF in Central and South regions has leftward shift and concentrates in a narrower rage, and half of PDF in East region has no shift and the other half PDF has left shift.
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Frost, Andrew James. "Spatio-temporal hidden Markov models for incorporating inter-annual variability in rainfall". Diss., 2004.
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Thesis (Ph. D.) -- University of Newcastle, 2004.School of Engineering. Discipline of Civil, Surveying and Environmental Engineering. Includes bibliographical references (leaves 205 - 217). Also available online.
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Wu, Zheng Ji y 吳正吉. "Study on regional frequency analysis for annual maximun daily rainfall of southern Taiwan". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/74234249607040395665.
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LIU, ZHEN-ZHONG y 劉振忠. "A study of hydrologic frequency analysis in Taiwan (annual maximum rainfall and streamflow)". Thesis, 1991. http://ndltd.ncl.edu.tw/handle/15306140112081053125.
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Fan, Chen-Shuo y 范辰碩. "Inter-annual Rainfall Variability of Specific Area In The Eastern Equatorial Pacific Ocean". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/jeeyw7.
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碩士國立中央大學
大氣科學學系
105
This research is inspired by Floating City Project which is going to be implemented by American and Netherland Cooperated Institution in 2020. The floating city has been planned to construct over the eastern equatorial Pacific Ocean near Central America in the project. Consider to the future water resource problem of the floating city, this research is dedicated to understand inter-annual precipitation variation over Target Area (6N-12N, 86W-94W) in rainy season. Target Area is actually a place where the floating city would be built in 2020. In this research, climatology rainy season of Target Area has been classified as three periods. Period-1, Period-2 and Period-3 are represent of May-June, July-August and September-October respectively. Wet years and dry years are picked up in each period, then analysis of atmospheric and oceanic gridded datasets would be conducted through composite analysis method according to these wet and dry years. Follow the diagnostic results of moisture budget over Target Area, Period-1 and Period-2 has dry advection and downward motion anomaly contribution for less precipitation in Dry year. Conversely, wet advection and upward motion anomaly contributed for more precipitation in Wet year. With regard to Period-3, contribution intensity of vertical motion anomaly is much higher than Period-1 and Period-2, but for advection term contribution is much less than former two periods. From the results of correlation analysis between global sea surface temperatures (SST) and Target Area precipitation, precipitation has found to have related with Pacific and Atlantic SST. Therefore, this research further applied Empirical Orthogonal Function (EOF) with SST datasets to separate out the most three significant climate oscillation signals of Pacific and Atlantic Ocean. Through correlation and multi-regression analysis of climate oscillation signals and precipitation, Period-1 and Period-2 precipitation are demonstrated that affected by Central Pacific ENSO (CP), Eastern Pacific ENSO (EP) and North Atlantic Oscillation (NAO). When getting into Period-3, precipitation only affected by CP and EP in this time. Especially for Walker Circulation variation during CP and EP events, Atlantic Subtropical High variation during NAO event, these phenomenon are the main cause of vertical motion and advection anomaly contribution, it is also consistent with the diagnostic results of moisture budget.
20
Pei-SyunWu y 巫佩勳. "Exploring nonstationary characteristics of distributions of annual rainfall indices in Taiwan using GAMLSS". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/eama56.
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碩士國立成功大學
水利及海洋工程學系
107
Global climate change would induce changes of the rate of hydrologic cycles and intensify the frequency and intensity of hydrologic extreme events. Changes in rainfall characteristics lead to the hypothesis of stationary in traditional hydrologic analysis no longer applicable. Nonstationary analysis of rainfall characteristics thus becomes one of the important issues in water resources management. In this study, the generalized additive models for location, scale, and shape (GAMLSS) is adopted for the nonstationary analysis of the annual rainfall indices in Taiwan. Ten annual rainfall indices are used to detect alterations of the magnitude, duration, and extreme of annual rainfall regime at eight rainfall stations in the north, central, south, and east regions of Taiwan. The results indicate that 55% of the annual rainfall indices are nonstationary, and the characteristics of regional similarities are not found in most of the annual rainfall indices. Trends of some annual rainfall indices are observed at different stations. Annual 1-day maximum rainfall and annual 2-day maximum rainfall have upward trend in the past 30 years at Taipei, Hengchun, and Dawu stations. Annual maximum consecutive rain days has downward changes in the south and east regions. Daily rainfall intensity has rising trend in the past 40 years at most stations except for Sun Moon Lake and Chengkung stations. Annual dry days has increasing trend at Taipei, Hengchun, and Dawu stations, while the downward trend in recent years has been observed at Yilan, Taichung, and Chengkung stations in recent years.
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Singh, Charu. "The Changing Nature Of Rainfall Annual Cycle And The Propagation Characteristics Of The Intraseasonal Oscillations In Flood And Drought Years Of The Indian Monsoon". Thesis, 2008. http://hdl.handle.net/2005/850.
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Using a 50-year (1951-2000) gridded (1-degree) daily rainfall data set over the Indian land region, we study two main aspects of the Indian monsoon. The first aspect deals with the changing nature of the rainfall annual cycle. This, to our knowledge, is the first attempt at studying the changing behaviour of the Indian monsoon rainfall annual cycle in a systematic way. The annual cycle is defined as a combination of the first few Fourier harmonics of daily rainfall. We then identify five attributes of the annual cycle for each year and location (grid): (a) the day of maximum intensity (peak day); (b) maximum intensity (peak value); (c) beginning; (d) end; and (e) duration of the annual cycle. An extensive statistical analysis of these five attributes over the central Indian region (16.5 – 26.5N; 74.5 – 86.5E) shows that the probability distributions of all attributes, barring the peak value, show a significant change in the last 25 years (1976-2000) compared to the first 25 years (1951-1975). The second issue addressed in this thesis deals with the behaviour of the intraseasonal oscillations in flood and drought years. Previous studies on this issue have been limited to only specific flood or drought years. Our analysis confirms earlier findings such as the northwestward propagation of the 10-20 day ISO. However, we also find, for the first time, based on 9 flood and 9 drought years, that the 20-60 day has an eastward propagation during drought years and remains stationary in flood years. The analysis is primarily statistical in nature, and providing a physical explanation for some of our findings is beyond the scope of our work. Finally, it is worth noting here that without the long-term gridded data, it would have been difficult to assess coherent changes over a large region and long time-period.
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Kanetsi, Khahiso. "Annual peak rainfall data augmentation - A Bayesian joint probability approach for catchments in Lesotho". Thesis, 2017. https://hdl.handle.net/10539/25567.
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A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2017The main problem to be investigated is how short duration data records can be augmented using existing data from nearby catchments with data with long periods of record. The purpose of the investigation is to establish a method of improving hydrological data using data from a gauged catchment to improve data from an ungauged catchment. The investigation is undertaken using rainfall data for catchments in Lesotho. Marginal distributions describing the annual maximum rainfall for the catchments, and a joint distribution of pairs of catchments were established. The parameters of these distributions were estimated using the Bayesian – Markov Chain Monte Carlo approach, and using both the single-site (univariate) estimation and the two-site (bivariate) estimations. The results of the analyses show that for catchments with data with short periods of record, the precision of the estimated location and scale parameters improved when the estimates were carried out using the two-site (bivariate) method. Rainfall events predicted using bivariate analyses parameters were generally higher than the univariate analyses parameters. From the results, it can be concluded that the two-site approach can be used to improve the precision of the rainfall predictions for catchments with data with short periods of record. This method can be used in practice by hydrologists and design engineers to enhance available data for use in designs and assessments.
CK2018
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Mashinye, Mosedi Deseree. "Long term seasonal and annual changes in rainfall duration and magnitude in Luvuvhu River Catchment, South Africa". Diss., 2018. http://hdl.handle.net/11602/1152.
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MESHWRDepartment of Hydrology and Water Resources
This study was aimed at investigating the long term seasonal and annual changes in rainfall duration and magnitude at Luvuvhu River Catchment (LRC). Rainfall in this catchment is highly variable and is characterised of extreme events which shift runoff process, affect the timing and magnitude of floods and drought, and alter groundwater recharge. This study was motivated by the year to year changes of rainfall which have some effects on the availability of water resources. Computed long term total seasonal, annual rainfall and total number of seasonal rainy days were used to identify trends for the period of 51 years (1965- 2015), using Mann Kendal (MK), linear regression (LR) and quantile regression methods. The MK, LR and quantile regression methods have indicated dominance of decreasing trends of the annual, seasonal rainfall and duration of seasonal rainfall although they were not statistically significant. However, statistical significant decreasing trends in duration of seasonal rainfall were identified by MK and LR at Matiwa, Palmaryville, Levubu, and Entabeni Bos stations only. Quantile regression identified the statistically significant decreasing trends on 0.2, 0.5 and 0.7 quantiles only in the Palmaryville, Levubu and Entabeni Bos, respectively. Stations with non-statistically significant decreasing trends of annual and seasonal rainfall had magnitude of change ranging from 0.12 to 12.31 and 0.54 to 6.72 mm, respectively. Stations with non-statistically increasing trends of annual and seasonal rainfall magnitude had positive magnitude of change ranging from 1.51 to 6.78 and 2.05 to 6.51 mm, respectively. The Study recommended further studies using other approaches to determine the duration of rainfall to improve, update and compare the results obtained in the current study. Continuous monitoring and installation of rain gauges are recommended on the lower reaches of the catchment for the findings to be of complete picture for the whole catchment and to also minimize the rainfall gaps in the stations. Water resources should be used in a sustainable way to avoid water crisis risk in the next generations.
NRF
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Huang, Liang-Yun y 黃亮芸. "Frequency Analysis of Annual Maximum 1-Day Rainfall for Ungauged Sites in Taiwan Using Regionalization Approach". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/79724791308063577030.
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碩士淡江大學
水資源及環境工程學系碩士班
95
The purpose of the study aims to estimate frequencies of annual maximum 1-day rainfall for ungauged sites in Taiwan using regionalization approach. The index flood method with parameters estimated by L-moments is used to establish the regional frequency model. Kriging is then employed to estimate the mean annual maximum 1-day rainfall of ungauged sites in order to analyze the rainfall magnitudes of various frequencies. Delineation of homogeneous regions is determined by cluster analysis in this study based on the coordinates of the rainfall gauge stations, the means and coefficient of variation of the annual maximum 1-day rainfall. The L-moment based discordancy, heterogeneity, and goodness-of-fit measures are then used to detect unusual sites and select the optimal regional probability models. In this study, a total of 77 rainfall gauge stations are used as the basis to estimate the frequencies of the annual maximum 1-day rainfall for ungauged sites. The number of homogeneous regions derived by cluster analysis is 3. The best regional probability model for one region is Pearson type Ⅲ distribution, and generalized Pareto distribution is the best model for the other two regions. Frequency analysis for ungauged sites needs to establish the variogram models of the mean and coefficient of variation of the annual maximum 1-day rainfall first. The obtained variogram models is then used to estimate the mean annual maximum 1-day rainfall for the ungauged sites. The ungauged sites belong to which homogeneous region depend on the minimum distance to the centroid of the homogeneous regions. Combined with the derived regional frequency model and estimated mean annual maximum 1-day rainfall, the computing procedures of frequency analysis for ungauged sites are identical with the procedures of gauged sites.
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LIN, JIAN-YI y 林賢義. "Studies on hydrologic frequency analysis in Taiwan (Annual maximum 1-hr., 2-hr.,3-hr. rainfall)". Thesis, 1992. http://ndltd.ncl.edu.tw/handle/47930029565003731701.
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Frost, Andrew James. "Spatio-temporal hidden Markov models for incorporating interannual variability in rainfall". Thesis, 2004. http://hdl.handle.net/1959.13/24868.
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Two new spatio-temporal hidden Markov models (HMM) are introduced in this thesis, with the purpose of capturing the persistent, spatially non-homogeneous nature of climate influence on annual rainfall series observed in Australia. The models extend the two-state HMM applied by Thyer (2001) by relaxing the assumption that all sites are under the same climate control. The Switch HMM (SHMM) allows at-site anomalous states, whilst still maintaining a regional control. The Regional HMM (RHMM), on the other hand, allows sites to be partitioned into different Markovian state regions. The analyses were conducted using a Bayesian framework to explicitly account for parameter uncertainty and select between competing hypotheses. Bayesian model averaging was used for comparison of the HMM and its generalisations. The HMM, SHMM and RHMM were applied to four groupings of four sites located on the Eastern coast of Australia, an area that has previously shown evidence of interannual persistence. In the majority of case studies, the RHMM variants showed greatest posterior weight, indicating that the data favoured the multiple region RHMM over the single region HMM or the SHMM variants. In no cases does the HMM produce the maximum marginal likelihood when compared to the SHMM and RHMM. The HMM state series and preferred model variants were sensitive to the parameterisation of the small-scale site-to-site correlation structure. Several parameterisations of the small-scale Gaussian correlation were trialled, namely Fitted Correlation, Exponential Decay Correlation, Empirical and Zero Correlation. Significantly, it was shown that annual rainfall data outliers can have a large effect on inference for a model that uses Gaussian distributions. The practical value of this modelling is demonstrated by the conditioning of the event based point rainfall model DRIP on the hidden state series of the HMM variants. Short timescale models typically underestimate annual variability because there is no explicit structure to incorporate long-term persistence. The two-state conditioned DRIP model was shown to reproduce the annual variability observed to a greater degree than the single state DRIP.PhD Doctorate
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Frost, Andrew James. "Spatio-temporal hidden Markov models for incorporating interannual variability in rainfall". 2004. http://hdl.handle.net/1959.13/24868.
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Two new spatio-temporal hidden Markov models (HMM) are introduced in this thesis, with the purpose of capturing the persistent, spatially non-homogeneous nature of climate influence on annual rainfall series observed in Australia. The models extend the two-state HMM applied by Thyer (2001) by relaxing the assumption that all sites are under the same climate control. The Switch HMM (SHMM) allows at-site anomalous states, whilst still maintaining a regional control. The Regional HMM (RHMM), on the other hand, allows sites to be partitioned into different Markovian state regions. The analyses were conducted using a Bayesian framework to explicitly account for parameter uncertainty and select between competing hypotheses. Bayesian model averaging was used for comparison of the HMM and its generalisations. The HMM, SHMM and RHMM were applied to four groupings of four sites located on the Eastern coast of Australia, an area that has previously shown evidence of interannual persistence. In the majority of case studies, the RHMM variants showed greatest posterior weight, indicating that the data favoured the multiple region RHMM over the single region HMM or the SHMM variants. In no cases does the HMM produce the maximum marginal likelihood when compared to the SHMM and RHMM. The HMM state series and preferred model variants were sensitive to the parameterisation of the small-scale site-to-site correlation structure. Several parameterisations of the small-scale Gaussian correlation were trialled, namely Fitted Correlation, Exponential Decay Correlation, Empirical and Zero Correlation. Significantly, it was shown that annual rainfall data outliers can have a large effect on inference for a model that uses Gaussian distributions. The practical value of this modelling is demonstrated by the conditioning of the event based point rainfall model DRIP on the hidden state series of the HMM variants. Short timescale models typically underestimate annual variability because there is no explicit structure to incorporate long-term persistence. The two-state conditioned DRIP model was shown to reproduce the annual variability observed to a greater degree than the single state DRIP.PhD Doctorate
28
Réis, Délia Canha Gouveia. "Statistical modelling of extreme rainfall in Madeira Island". Doctoral thesis, 2014. http://hdl.handle.net/10400.13/869.
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Extreme rainfall events have triggered a significant number of flash floods in Madeira Island along its past and recent history. Madeira is a volcanic island where the spatial rainfall distribution is strongly affected by its rugged topography. In this thesis, annual maximum of daily rainfall data from 25 rain gauge stations located in Madeira Island were modelled by the generalised extreme value distribution. Also, the hypothesis of a Gumbel distribution was tested by two methods and the existence of a linear trend in both distributions parameters was analysed. Estimates for the 50– and 100–year return levels were also obtained. Still in an univariate context, the assumption that a distribution function belongs to the domain of attraction of an extreme value distribution for monthly maximum rainfall data was tested for the rainy season. The available data was then analysed in order to find the most suitable domain of attraction for the sampled distribution. In a different approach, a search for thresholds was also performed for daily rainfall values through a graphical analysis. In a multivariate context, a study was made on the dependence between extreme rainfall values from the considered stations based on Kendall’s τ measure. This study suggests the influence of factors such as altitude, slope orientation, distance between stations and their proximity of the sea on the spatial distribution of extreme rainfall. Groups of three pairwise associated stations were also obtained and an adjustment was made to a family of extreme value copulas involving the Marshall–Olkin family, whose parameters can be written as a function of Kendall’s τ association measures of the obtained pairs.
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Hou, Ju-Chen y 侯如真. "A Frequency-Factor Based Approach for Bivariate Gamma Simulation and Its Application for Assessment of Climate Change Impact on Annual Typhoon Rainfall". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/30389918061073903260.
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博士臺灣大學
生物環境系統工程學研究所
98
Many studies related to climate change focused on global, continental or regional scale effect in space and annual or seasonal scale effect in time. However, for practical planning and engineering design, it is necessary to deal with local (spatial) and event (temporal) scales. However, the mathematical expressions of many previous stochastic simulation models are complex with a large number of parameters to be calibrated from the observed rainfall data and have computational limitations. In this dissertation, a continuous stochastic storm-rainfall simulation model (SRSM) is presented to accommodate the aforementioned scales and provide quantitative assessment of the impact on annual typhoon rainfall under given scenarios of climate change. The SRSM is a parametric stochastic simulation model which considers random processes of four major storm types: frontal rainfall, Mei-Yu, convective storms and typhoons occurring annually in Taiwan. Random process of a storm rainfall event is characterized by (1) inter-arrival time of storm events and (2) joint probability distribution of storm duration and total rainfall depth. Occurrences of storm events of a certain storm type can be modeled as a Poisson process and the inter-arrival time is modeled as a random variable with exponential distribution. A frequency-factor based bivariate gamma distribution model is proposed for generating random sample pairs (duration and total depth), which have not only the desired marginal densities of component random variables but also their correlation coefficient. Under certain scenarios of climate change, i.e. when the average number of typhoon events for the study site increases or decreases, we can assess the impact of climate change on annual typhoon rainfall from a stochastic point of view.
30
CHEN, XIU-JUAN y 陳秀娟. "Studies on Wakeby distribution and its application on the annual 1-day, 2-day and 3-day maximum rainfalls in Taiwan area". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/45224137978327178894.
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碩士淡江大學
水資源及環境工程研究所
81
Houghton(1978)提出威克拜分布(Wakeby Distribution) ，本研究將其與頻率分析中 常用之分布(TN、LN2、LN3、EV1、PT3及LPT3)作一詳盡之比較，究中使用合成資以模 擬各迴歸周期之理論值及模擬隨機樣本值兩者來探討威克拜分布之性，並分析台灣年 一日、二日及三日最大暴兩量，探討威克拜分布之適用性。合成資之研究結果顯示威 克拜分布無論於推估各頻率理論值或擬合樣本值上，其精確度均較六種常用分布為高 ，同時，實測資料研究結果亦顯示威克拜分布較其他常用分布更適合模擬台灣暴雨資