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GIS Application in Evaluating Land Use-Land Cover Change and its Impact on Hydrological Regime in Langat River Basin, Malaysia
M. R. Vijaindra
M.Tech, Student, Birla Institute of Technology, Ranchi
C2, Kendriya Vidyalaya ASC Staff Quarters, Victoria Road,
Bangalore: 560047, Karnataka, India
Tel: (080) 5561128
Email: mrvijaindra@yahoo.co.in
Dr. Sudha Ravindranath
Scientist, Regional Remote Sensing Service center, Bangalore
Email: raviatri@hotmail.com
Dr. M. S. Nathawat
Head, Department of Remote Sensing, Birla Institute of Technology, Ranchi
Introduction
Urban expansion has increased the exploitation of natural resources and has changed land use and land cover patterns. In 1900, only 15 percent of the world’s population lived in the cities, however now more than 50% do so, with the United Nations forecasting that between 1990 and 2050, the urban population will rise to over 5 billions (Maksimovic & Tucci, 2001). In Malaysia, for example, the total urban population has increased to 58.8 per cent in the year 2000 (Samad Hadi, 2000) and some of the states in the Peninsular has achieved the urbanisation level of developed countries i.e. 80 percent of the total population. Foreign and local investment in the agricultural, commercial and mining sectors were the main factors leading to the growth of the urban population in Malaysia.
Most urban areas in developing countries are located on the coast or on major rivers as in Malaysia. The uncontrolled growth of urban development has adversely affected Malaysian river basin ecosystems (Jamaluddin Jahi & Nordin Hassan, 1996) especially their capacity to regulate streamflow. About 2.5 million urban dwellers in Malaysia are exposed to flood hazards due to their settlements in the flood plain (Mohd Ekhwan, 2000). According to Chan, N.W (1996), the flood risks and community vulnerability have increased since 1985 due to the onslaught of urban development in river corridors.
The increase in urban population density and built up areas (Hall, 1984) directly or indirectly affects hydrological processes, through : a) Change in total runoff or streamflow b) Alteration of peak flow characteristics, c) Decline in water quality and d) Changes in river’s amenities. Basically, urbanisation could lead the alteration in streamflow characteristics by the expansion of built up areas, modification of natural channel through channelisation processes and the interferences from the artificial drainage or sewer system to the natural drainage system. The information of the changing LULC within a watershed is vital for evaluating the current ecosystem health. The impact of LULC change on hydraulic and stream stability, with special reference to the urban built-up areas (including impervious surfaces) has been discussed widely in academic literatures. The recent results regarding impact of LULC on hydrological regime has been discussed in Jennings & Jarnagin (2002), De Roo et.al (2001), Lahmer, et.al (2001) and Acreman (2000).
The application of computer systems and information technology in handling geographic and spatial data is a necessity. Thus, the Geographic Information systems (GIS) and coupling with the deterministic or stochastic process models will accelerate the field of research and development in spatial science. The application of GIS will facilitates new avenues of exploratory spatial data analysis that were previously not feasible and also enables the integration of data collected by different media thereby substantially increasing the communications capabilities of those involved in urban management (Masser, 2001).
Using the Arc-View Spatial Analyst with the Patch Analysis extension, the assesment of spatial landscape diversity and land use changes in watershed could be more easier and faster (Whelan, F. 1999). Some of the researchers coupled their efforts in hydrological analysis with GIS and other hydrological model that available. As such, the coupling of GIS and hydrological modelling can be seen in Brun and Band (2000), Nelson and Jones (1996) and Saunders and Maidments (1996), Campana and Tucci (2001) in very recent research.
The objective of this study were (1) to identify spatial patterns of Langat Basin within 1984 and 1997 and, (2) to analyse the change in flow behaviour due to the impact of urbanisation. In this study, we related the impact of urban LULC change, especially the built-up areas upon the daily streamflow discharge, and focusses in detail of the changing pattern in surface runoff and streamflow responses.
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