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Characterisation of Urban Rainfall in Kuala Lumpur, Malaysia

Desa Mohamed, Mohamed Nor bin LU (1997)
Abstract (Swedish)
Popular Abstract in Swedish

Arbetet avser studier av regnkarakteristik i tid och rum i Kuala Lumpur, Malaysia. I storskalig betraktelse studerades ett 550 km2 område för att bl.a. finna påverkan av monsuner. I skalan av ett avrinningsområde avsåg arbetet en studie av regnets dynamiska egenskaper och rumsliga korrelationsstrukturer. I en enpunktskala, för ett 23 km2 stort område framtogs sannolikheter för extremt höga regnintensiteter. Signifikansen av rums- och tidsvariation av regn undersöktes med användning av krosskorrelationer utförda på långtidsdata från sex regnmätare täckande ett område av 450 km2. Krosskorrelationsstrukturer gjorda på månadsdata uppvisade en uttalad påverkan under två monsunsäsonger. Regnvariation... (More)
Popular Abstract in Swedish

Arbetet avser studier av regnkarakteristik i tid och rum i Kuala Lumpur, Malaysia. I storskalig betraktelse studerades ett 550 km2 område för att bl.a. finna påverkan av monsuner. I skalan av ett avrinningsområde avsåg arbetet en studie av regnets dynamiska egenskaper och rumsliga korrelationsstrukturer. I en enpunktskala, för ett 23 km2 stort område framtogs sannolikheter för extremt höga regnintensiteter. Signifikansen av rums- och tidsvariation av regn undersöktes med användning av krosskorrelationer utförda på långtidsdata från sex regnmätare täckande ett område av 450 km2. Krosskorrelationsstrukturer gjorda på månadsdata uppvisade en uttalad påverkan under två monsunsäsonger. Regnvariation är mest uttalad längs en riktning parallell med monsunens rörelse, dvs i rät vinkel till kustlinjen. Variationskoefficienten för månadsnederbördsdata är dubbelt så stor som för årsnederbördsdata. Åtta kortvariga (60 minuters) regnhändelser registrerade på ett 23 km2 stort område användes för att ta fram areella reduktionsfaktorer. Resultat påvisar att strukturen av enstaka regnceller inte är markant olika för sådana strukturer i andra klimatiska regioner.Dynamiska regnegenskaper studerades med användning av fullt synkroniserade data från 30 regnhändelser. Resultatet påvisar signifikansen av en korrelation mellan observerad regnhastighet och vindhastighet på maken. Regnrörelsen i Kuala Lumpur är långsam. Medelhastigheten beräknades till 2.6 m/sek jämförd med 12 m/sek som visats av andra vara en typisk regnhastighet för områden på höga latituder.Tvådimensionell advektion-diffusion modell applicerades till data från två regnhändelser för att prognosera regnintensiteter för en, två och fem minuter framåt i tiden. Resultatet ger möjlighet att fysikaliskt förklara värden av modellparametrar. Modellering med användning av endast advektionstermen ger sämre resultat.Partiella varaktighetsserier av kortvarig regn från sju mätare analyserades för att ta fram empiriska samband i vilka regnvolymer och intensiteter betraktades som beroende, och varaktigheter som oberoende variabler. Intensitet-varaktighet-återkomst samband såväl som volym-varaktighet-återkomst samband applicerades på omkringliggande områden. Resultatet påvisar att intensitet-varaktighet-återkomst samband relaterade till statistiskt framtagna 1-times regn från aktuell plats ger bättre resultat än tradiotionella volym-varaktighet-återkomst samband. (Less)
Abstract
Rainfall characteristics of Kuala Lumpur, Malaysia, are studied in space and time; on a large scale, 550 km2, and long term scale to find out the monsoon influence, and on urban basin scale, 23 km2, to determine dynamic properties of rainfalls and spatial correlations, and on a point scale to determine the probabilities of very high rain intensities.



The importance of spatial and temporal variability of rainfall was investigated applying cross correlation on long term historical rainfalls from Kuala Lumpur, Malaysia. Data from six rain gauges distributed over an area of 450 km2 were used. The annual and monthly rainfall correlation structures depict a pronounced effect of the monsoon. The variability of rainfall is... (More)
Rainfall characteristics of Kuala Lumpur, Malaysia, are studied in space and time; on a large scale, 550 km2, and long term scale to find out the monsoon influence, and on urban basin scale, 23 km2, to determine dynamic properties of rainfalls and spatial correlations, and on a point scale to determine the probabilities of very high rain intensities.



The importance of spatial and temporal variability of rainfall was investigated applying cross correlation on long term historical rainfalls from Kuala Lumpur, Malaysia. Data from six rain gauges distributed over an area of 450 km2 were used. The annual and monthly rainfall correlation structures depict a pronounced effect of the monsoon. The variability of rainfall is parallel to the monsoon direction, which is perpendicular to the sea coast. The coefficient of variation for the monthly rainfalls is higher than for the annual rainfalls by a factor of two. Eight short term rainfall storms of 60 minute duration over the 23 km2 urban basin were studied to derive the average areal reduction factor curve. The results indicate that the structure of single rainfall cells is not very different from that in other climate regions. The areal reduction was well pronounced for a small urban catchment used in this study.



Dynamic properties of 30 fully synchronised short term rainfall storms were investigated. The results showed significant correlation between storm velocities and observed wind velocities on the ground. The storm movements were rather slow. There was no correlation between storm movement and high altitude wind direction. The average storm velocity was 2.6 m/s compared to a mean velocity of 12 m/s obtained in high latitude regions by other investigators.



A two-dimensional advection diffusion model was applied to two short term rainfall events for predicting rainfall intensities of one, three and five minutes ahead. The results enabled a reasonable physical explanation of model parameters. In addition, advection of the two rainfall events was carried out. However the results were not promising for prediction purposes.



Partial duration series of short term rainfall storms recorded by seven rain gauges were analysed and empirical relationships for rainfall depths and intensity ratios as dependent variables against duration time as the independent variable were determined. The intensity-duration-frequency and the depth-duration-frequency relationship were applied to a surrounding area. Results showed that a modified intensity-duration-frequency relationship accounting for hourly rainfall intensities at the position under consideration is better than the depth-duration-frequency relationship. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Schilling, Wolfgang, Department of Hydraulic and Environmental Engineering, Norwegian Institute of Technology, S.P. Andersen vei 5, Norway
organization
publishing date
type
Thesis
publication status
published
subject
keywords
geographical and geological engineering, Hydrogeology, velocity, vector, monsoon, Malaysia, thunderstorm, Hydrogeologi, teknisk geologi, teknisk geografi, Geophysics, physical oceanography, meteorology, Geofysik, fysisk oceanografi, meteorologi
pages
182 pages
publisher
Department of Water Resources Engineering, Lund Institute of Technology, Lund University
defense location
Hörsal V:C
defense date
1997-03-13 10:15
external identifiers
  • other:ISRN: LUTVDG/(TVVR-1017)/(1997)
ISSN
1101-9824
language
English
LU publication?
yes
id
7bca852f-4ed2-490e-988e-dd3f0c7c1a24 (old id 29044)
date added to LUP
2007-06-14 08:48:50
date last changed
2016-09-19 08:44:58
@phdthesis{7bca852f-4ed2-490e-988e-dd3f0c7c1a24,
  abstract     = {Rainfall characteristics of Kuala Lumpur, Malaysia, are studied in space and time; on a large scale, 550 km2, and long term scale to find out the monsoon influence, and on urban basin scale, 23 km2, to determine dynamic properties of rainfalls and spatial correlations, and on a point scale to determine the probabilities of very high rain intensities.<br/><br>
<br/><br>
The importance of spatial and temporal variability of rainfall was investigated applying cross correlation on long term historical rainfalls from Kuala Lumpur, Malaysia. Data from six rain gauges distributed over an area of 450 km2 were used. The annual and monthly rainfall correlation structures depict a pronounced effect of the monsoon. The variability of rainfall is parallel to the monsoon direction, which is perpendicular to the sea coast. The coefficient of variation for the monthly rainfalls is higher than for the annual rainfalls by a factor of two. Eight short term rainfall storms of 60 minute duration over the 23 km2 urban basin were studied to derive the average areal reduction factor curve. The results indicate that the structure of single rainfall cells is not very different from that in other climate regions. The areal reduction was well pronounced for a small urban catchment used in this study.<br/><br>
<br/><br>
Dynamic properties of 30 fully synchronised short term rainfall storms were investigated. The results showed significant correlation between storm velocities and observed wind velocities on the ground. The storm movements were rather slow. There was no correlation between storm movement and high altitude wind direction. The average storm velocity was 2.6 m/s compared to a mean velocity of 12 m/s obtained in high latitude regions by other investigators.<br/><br>
<br/><br>
A two-dimensional advection diffusion model was applied to two short term rainfall events for predicting rainfall intensities of one, three and five minutes ahead. The results enabled a reasonable physical explanation of model parameters. In addition, advection of the two rainfall events was carried out. However the results were not promising for prediction purposes.<br/><br>
<br/><br>
Partial duration series of short term rainfall storms recorded by seven rain gauges were analysed and empirical relationships for rainfall depths and intensity ratios as dependent variables against duration time as the independent variable were determined. The intensity-duration-frequency and the depth-duration-frequency relationship were applied to a surrounding area. Results showed that a modified intensity-duration-frequency relationship accounting for hourly rainfall intensities at the position under consideration is better than the depth-duration-frequency relationship.},
  author       = {Desa Mohamed, Mohamed Nor bin},
  issn         = {1101-9824},
  keyword      = {geographical and geological engineering,Hydrogeology,velocity,vector,monsoon,Malaysia,thunderstorm,Hydrogeologi,teknisk geologi,teknisk geografi,Geophysics,physical oceanography,meteorology,Geofysik,fysisk oceanografi,meteorologi},
  language     = {eng},
  pages        = {182},
  publisher    = {Department of Water Resources Engineering, Lund Institute of Technology, Lund University},
  school       = {Lund University},
  title        = {Characterisation of Urban Rainfall in Kuala Lumpur, Malaysia},
  year         = {1997},
}