Land Use Dynamics and Landscape Change Pattern in a Mountain Watershed in Nepal Ambika P. Gautam School of Environment, Resources and Development Asian Institute of Technology P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand Mail Box # 43 Tel.: (66 2) 524 5615 Fax: (66 2) 524 6431 E-mail: nip007227@ait.ac.th Edward L. Webb, Ganesh P. Shivakoti and Michael A. Zoebisch School of Environment, Resources and Development Asian Institute of Technology P.O. Box 4 Klong Luang Pathum Thani 12120 Thailand 1. Introduction Watershed management has become an increasingly important issue in many countries including Nepal as government agencies and non-governmental groups struggle to find appropriate management approaches for improving productions from natural resource systems. Principles, concepts and approaches related to watershed management have experienced a vast change during the past few years but yet there is no universal methodology for achieving effective watershed management (Naiman et al., 1997; Bhatta et al., 1999). It is generally agreed that sustainable development and management of upland natural resources for the welfare of local populations should be the key objective of watershed management, which includes sustainable utilization and conservation of forest resources at community or watershed level as one of its important components (Sharma and Krosschell, 1996). To provide foundations for effective management of forest and other natural resources, an understanding of the variability in time and space of the resources and the role of human cultures and institutions in bringing those variations are some of the fundamental requirements (Naiman et al., 1997). In addition to area coverage, the shape of land use patches is an important characteristic for evaluating the processes and effects of land use change at landscape and watershed level. The concept is related to edge effects (physical and biotic phenomena) associated with increase in patch complexity due to habitat fragmentation and is emerging as an important field in the management and conservation of fragmented ecosystems at the local as well as regional level (Laurance and Bierregaard, 1997). Patchiness in forested area is of special importance because it serves as an important indicator of natural habitat fragmentation (Kammerbauer and Ardon, 1999). This is particularly important in Nepal where forest fragmentation has been a common phenomenon in the past few decades and most of the surviving forests in the hills consist systems of small patches, which are increasingly coming under community-based forest management in recent years (Gautam and Webb, 2001). There are various methods that can be used in the collection, analysis and presentation of resource data but the use of remote sensing and geographic information system (RS/GIS) technologies can greatly facilitate the process. Repeated satellite images and/or aerial photographs are useful for both visual assessment of natural resources dynamics occurring at a particular time and space as well as quantitative evaluation of land use/land cover changes overtime (Tekle and Hedlund, 2000). Analysis and presentation of such data, on the other hand, can be greatly facilitated through the use of GIS technology (ESCAP, 1997). A combined use of RS/GIS technology, therefore, can be invaluable to address a wide variety of resource management problems including land use and landscape changes. This study is part of a broader research designed to assess the role of community-based forestry institutions in determining the status of forests in the study area. Within this broad framework, the objectives of this study were: i) to detect and document changes in major land use in general and forests in particular in a representative mountain watershed in central Nepal in between 1976 and 2000, and ii) to analyze patterns of changes in landscape of the study area during the period, with special focus on forest fragmentation. The study used RS/GIS with substantial input from the filed to achieve the stated objectives. 2. Study Area The site of this study, Upper Roshi Watershed (85.39 – 85.57 E, 27.54 – 27.70 N), is situated in the western part of Kabhrepalanchok district in the Middle Hills of Nepal (Figure 1). The watershed covers an area of 15,335 hectares. The altitude varies between 1,420 m to 2,820 m above sea level. Climate is monsoonal with a dry season normally spanning from November to May and rainy season from June to October. Warm-temperate humid temperature and moisture regime prevails in most part of the watershed except at higher elevation (above 2000 m) where the climate is cool-temperate type. Microclimate varies considerably with elevation and aspect. The south-facing slopes and lower slopes are generally hotter and drier and the north-facing slopes and upper slopes are cooler and moister. Three rivers namely Punyamata, Bebar and Roshi along with their numerous tributaries drain the area, which latter converge at the southeastern corner of the watershed into Roshi River.  Figure 1: Location of the Upper Roshi Watershed in Kabhrepalanchok District, Nepal The watershed can be divided into fertile, relatively flat valleys along the rivers and surrounding uplands with medium to steep slopes. Agricultural lands in the valleys are under intensive management with multiple cropping systems and are mostly irrigated. Paddy, potato, wheat and vegetables are major crops cultivated in the valley. Rain-fed agriculture, with or without outward facing terraces, is practiced on rest of the agricultural lands, many of which are not suitable for crop production without strong soil and water conservation measures because of their high erodability and low productivity (ICIMOD, 1994).
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