Spatial and temporal characteristics of rainfall over a forested river basin in NW Borneo
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ORIGINAL PAPER
Spatial and temporal characteristics of rainfall over a forested river basin in NW Borneo H. Vijith1 · D. Dodge‑Wan1 Received: 18 January 2019 / Accepted: 22 November 2019 © Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract The spatial and temporal patterns of rainfall over the Baram River Basin (BR) in Sarawak (Malaysian Borneo) were characterised through cluster analysis and multivariate statistics for the 25 year period from 1990 to 2014. Baram River Basin recorded an average annual rainfall of 3654 mm with high spatial and temporal variations. Ward’s method based analytical hieratical clustering (AHC) identified three homogeneous clusters (HC’s) of rain gauging stations (HC-I, HC-II, and HC-III). Rain gauges in HC-I are located in high rainfall domain, HC-II gauges are in moderate rainfall domain and HC-III gauges are in low rainfall domains. The moderate elevation regions in the Baram basin recorded the highest amounts of rainfall compared to lower and upper elevated regions. Multivariate statistics show variation in the distribution of monthly and annual rainfall within and between individual HC’s. Mean annual rainfall recorded at individual HC’s varies by around 1000 mm. Though the mean monthly rainfall distribution in HC’s varies by more than 70 mm, all clusters show a common pattern of high and low rainfall seasons related to monsoon characteristics of the region. The northeast monsoon (NEM) is the wettest period with highest mean rainfall falling in the months of November and December at all stations. In comparison, the southwest monsoon (SWM) is the driest season with the lowest mean rainfall falling in July. It was also noted that the inter-monsoon periods are actually wetter than the SWM season. Overall, rainfall in the Baram shows high inter-annual variability with dominant low rainfall domain in the lower (coastal) and upper (plateau) reach with highly localised high rainfall domain surrounded by fluctuating moderate rainfall areas in the middle reaches of the river basin. The localised nature of high rainfall domain in the central (south and southwest) part of the basin suggests that the surrounding elevated mountains and hills in that region influence the high rainfall recorded. The findings of the present research will aid in formulating water resource management plans, large scale plantation and agricultural practices and any other hydrological development projects in the region.
1 Introduction Precipitation or rainfall, is the most dynamic hydrometeorological variable which controls the existence of ecosystems and also the agricultural, industrial, and economic development of a country and may show high variability in its distribution. Understanding the spatial and temporal distribution of rainfall is critical for framing and implementing better agricultural and industrial development projects (Sombroek 2001; Haile 2005; Arvor et al. 2014). Numerous studies Responsible Editor: A.-P. Dimri. * H. Vijith [email protected] 1
Department of Applied Geology, Fa
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