Description

Abstract: The overall Goal is to convert degrading Southeast Asia watersheds into vibrant, sustainable basins enhancing quality of life for their inhabitants. To achieve this, the research has established as its first objectives to develop an economically viable and ecologically sound integrated vegetable agroforestry (VAF) system to increase farm productivity and income through reliable supply of products and to reduce vulnerability and risks. The Soil and Water Assessment Tool (SWAT) has been selected as a basin scale model to assess the short- and long-term environmental impacts of the integrated VAF system.

This paper updates first-year progress of SWAT implementation in the selected test site of Indonesia’s watershed. The first step is to harmonize the available digital elevation model (DEM) with land-use categories. Under the Digital Terrain Elevation Data/High Resolution Terrain Information (DTED/HRTI) definition of the U.S. National Geospatial-Intelligence Agency (NGA), the existing DEM is categorized into Level 1, suitable only for 1:250,000 map scale. Because the target of this year is a first attempt to complete the SWAT processing chain, the approach has to be divided into two options: to continue processing with existing DEM by using medium resolution satellite image; and to prepare new DEM (Level 2 DTED/HRTI suitable for 1:50,000 map scale) appropriate for high resolution satellite imagery.

To avoid delay and reduce cost, three new medium resolution L-Band synthetic-aperture radar (SAR) imageries were acquired from ALOS/PALSAR through networking with JAXA (Japan). The Level 1.5 PALSAR image (ALPSRP083667050-H1.5GUA of 2007/08/20) is used to derive land use for the first option. The other two images are Level 1.1 PALSAR single look complex interferometric repeat pass pairs (ALPSRP050117050-H1.1_A of 2007/01/02 and ALPSRP056827050-H1.1_A of 2007/02/17) to derive new DEM (DTED/HRTI Level 2) by using SAR Interferometry (InSAR) for the future second option. This paper reports the progress of the first option of SWAT process to the level of hydrological response unit (HRU) derivation.