Leong, Weng Chin
(2007)
Study On Malaysian Urban Rainfall-Runoff Characteristics:
Case Study Of Sungai Kayu Ara, Damansara, Selangor.
Masters thesis, Perpustakaan Hamzah Sendut.
Abstract
Knowledge on the rainfall spatial and temporal distribution, as well as the
rainfall-runoff response, is vital in engineering practices for developing area in the
humid tropics. Nevertheless, this study will primarily discuss the runoff response due to
varying rainfall within small urban catchment in Malaysia. Daily totals rainfall and 10-
min intervals rainfall and runoff data from year 1996 to 2004 had been analysed. The
result shows that greater rainfall volume fell on developed area, compared to
suburban/rural area. This is proven that most of proportion of annual rainfall extent is
contributed by strong convective storm during the inter-monsoon season. The
relationship between direct runoff and mean areal rainfall was developed and validated
using statistical model (SPSS®). To verify the representativeness of rainfall-runoff
response, rainfall concentration between the developed area and suburban/rural area
was determined. Analyses of constant loss rates indicate that the generation of
cumulative direct runoff can be attributed to the constant rainfall intensities. The
correlation between the derived runoff coefficients and rainfall intensities was made.
This was to assess the Design Chart 14.3 for peak flow estimation in the Malaysian
Urban Stormwater Management Manual (MSMA). The distribution percentage of
observed data among classified land uses in the relevant design chart is found to have
corresponded quite well with the degree of land use covers, estimated from digital
topographic information. This implies that, the runoff coefficient versus intensity chart
adopted from the Australian Rainfall and Runoff 1977 is still in the suitable range for
use in Malaysian urban condition. To ensure a future need for higher design
requirement in urban stormwater control facilities, the catchment response subjected to
development was determined. Factors such as rainfall volume and its temporal and
spatial distribution of rainfall were taken into account for this purpose. The increasing peak flow with corresponding time-to-peak resulted from seven (7) to eight (8) years'
urbanization had been successfully identified.
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