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The Applicability of Noaa Avhrr Data for Assessing Agricultural Land Use

Anwar Iqbal
PSO (Soils)
Bangladesh Agricultural Research Council, Dhaka, Bangladesh.

J. U. Shoaib
SSO
Soil Resources Development Institute, Faridpur, Bangladesh.

Abstract/ Executive Summary:

In Bangladesh, nearly 74 per cent of the land area is under agriculture, of which more than 80 per cent is under rice. The dominance of rice mono cropping, coupled with intensive land use, traditional farming and minimal or zero recycling of biomass, has resulted in a decline, or at best a stagnation, in the yield of major crops. To sustain agricultural productivity, manage key natural resources and maintain a sound environment, agricultural cropping needs to be diversified and reoriented. This calls for rapid and reliable monitoring/assessment of agricultural land use. By using NOAA AVHRR remotely sensed data and through real-time/near real-time random ground truthing, fragmentation of land and thus heterogeneity in cropping can effectively be isolated. The results of case studies revealed that remote sensing can be applied successfully for this purpose and can be a powerful tool for both macro and micro level agricultural land-use planning.

Keywords: NOAA AVHRR, Agricultural land use, Crop loss estimation.

Location: Bangladesh Agricultural Research Council

Start Date:

End Date:

Program Area: Knowledge Management

Non-commodity: Resource inventory

Objectives:

To examine the applicability of NOAA AVHRR Data for Assessing Agricultural Land Use in Bangladesh.

Methodology:

During the field investigations, the following materials were used to verify the NVI colour-coded imagery: topographic maps (1:50,000), soil association maps (1: 125,000), land-use maps (1: 150,000), district/region land record maps (1 cm = 0.64 km), local agricultural extension workers' records and interviews with farmers. The study was conducted in November after the flood waters receded because clear satellite pictures could be obtained during that time. Ground truthing was conducted and field data were collected from 38 randomly selected spots covering the entire Rangpur-Gaibandha region; from 32 spots in the Brahmanbaria region; and from 70 spots in the Tangail region. The observation sites in the studied regions were selected in such a manner that they represented the entire area under investigation; had a single, extensive, uniform colour tone in the NVI colour-coded imagery; and were easily accessible. The preselected observation sites were visited and then located in the NVI imagery. During the field visits, land cover, crops and growing stages, plant population/m², land types, soil moisture conditions and the corresponding colours in the NVI imagery were recorded. At the same time, local extension records were checked and farmers were interviewed. The ground truth areas were located in the imagery by overlaying topographic maps, by recognizing the features in the field using the vegetation indices and by measuring their position in reference to sites recognized earlier. As it was very important to locate the ground truth sites on the imagery, all possible errors were avoided by multiple checking and by discussion among the study team members. To eliminate errors and misinterpretation, ground information was generally taken over those areas in the image showing uniform colour over at least four pixels (aprox.4 to 5 km²). A single channel of NOAA AVHRR data is insufficient to explain diverse vegetation characteristics. For example, green vegetation is highly absorptive in channel 1 (in the visible range) but highly reflective in the near infra-red (NIR) range of channel 2. Thus, techniques have been developed to combine channels 1 and 2 for defining vegetation characteristics.

Source of Information: Asian-pacific remote sensing journal, Vol-6, N0-2, Page:121-125, Jan:1994

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

From the study it could be established that,there exists an intricate relationship between ground features and the colour of NVI imagery. This strongly suggests that NOAA A VHRR data can be effectively used for monitoring and assessing agricultural land use in situations like that of Bangladesh. Through scientific interpretation of the data with supporting field validation, reliable assessments of existing land uses can be made.

Knowledge Management: Journal