Methods

14.2.1 Study Area

Batang Merao Watershed is located in the northwest of Jambi Province: its geo-location is at 01°42’19"-02°08’14"S, 101°13’11"-101032’20"E (Fig. 14.1). The elevation ranges from 766 to 3,236 m above sea level. The total area of the study site is 67,874.48 ha. This area covers ten subregencies and 124 villages. It is situated in a tropical zone where the annual mean precipitation is 2,495 mm year-1, based on the past 20 years, and the annual mean temperature is 23.1 °C, based on the past 10 years.

14.2.2 Data

The basic data required to meet the objectives of this study were Landsat image data, Aster Global Digital Elevation Model (Aster GDEM), digital land use maps, climate data (annual rainfall), and Universal Soil Loss Equation (USLE) data. For supporting image analysis, some ancillary data were used including ground truth data acquired through a field survey on September 10-15, 2011, a digital adminis­trative map of Jambi Province provided by the Gespatial Information Agency of Indonesia, and a digital watershed boundary map of Jambi Province published by the Ministry of Forestry of Indonesia. All the supplementary data were used to assist in image classification and to collect reference data for accuracy assessment, as described in Table 14.1.