Abstract
GIS, RS and GPS, powerful tools for surveying, mapping and monitoring land cover, were used to monitor landuse changes in Palung Sub-watershed, Makawanpur District, from 1992 to 2001. Using an orthophoto map prepared from 1992 data and an IRS1C Image from 2001, it was found that the area devoted to agriculture decreased by 12.1% in those nine years; it had had been converted to forest. Nearly all shrub land was now forest. Natural forest areas along the agricultural boundaries, however, had declined by 2.5%.

Introduction
Geographical Information Systems (GIS), remote sensing (RS) and the Global Positioning System (GPS) are powerful tools for surveying, mapping and monitoring natural resources. Satellite techniques are useful because their synoptic coverage of large areas renders them cost and time effective. Furthermore, in areas that are difficult to access, RS and GPS are perhaps the only best method of obtaining the required data speedily.

Any GIS comprises four functions--measuring, mapping, monitoring and modeling-- although most organizations in Nepal use GIS for the former two purposes only. The Bagmati Integrated Watershed Management Project (BIWMP), however, used GIS, along with RS and GPS, to monitor the changes in land use in Palung Sub-watershed, Makawanpur District, from year 1992 to 2001. The data required was taken from FINNMAP’s 1992 (orthophotomaps, 1992) and an Indian Remote Sensing Satellite (IRS1C, 2001) geocoded photo. Both are at the same scale, 1:12,500.

Study Area
Palung Watershed lies between 85º 01’30” and 85º 05’33” E longitude and 27º 36’43” and 27º 39’28” N latitude in Makwanpur District, as shown in Figure 1 and 2. The total catchment area of the watershed is 3767ha. The highest and lowest points of the catchment are 2551m and 1660m respectively. This watershed is one of eight sub-watersheds in the Kulekhani reservoir basin. There are three main tributaries of the Palung River in the sub-watershed area, namely, Phedigao Khola, Gharti Khola and Khaiti Khola. The climate of Palung Sub-watershed is warm temperate in the valley and cool temperate on the slopes and in the upper mountain area.


Figure 1. Location map of Palung sub-watershed

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