Spatiotemporal reconstruction of agricultural land cover in Nepal from 1970 to 2010

Abstract

Agricultural land cover and changes in its extent are directly related to human activities. The rapidly growing population in Nepal has resulted in an increasing trend of agricultural land expansion, and can be used to determine the long-term status of agricultural land cover via reconstruction. This decadal study considered spatially explicit agricultural area, statistical records, population density, soil types, and climate and topography datasets. We collected available datasets and revised them on the basis of a spatiotemporal reconstruction of agricultural land cover. The different datasets were based on 30 × 30 m grid cells used for agricultural land suitability and allocation models. This historical agricultural land reconstruction revealed an increasing trend in agricultural area from 37.03 to 43.88 (103 km2), between 1970 and 2010. In this period, the agricultural land expanded and agriculture became more intensified, especially in the southern and middle parts of the country. A slightly decreasing trend was found in areas surrounding big cities. The evaluation of the results of our reconstruction and a comparison with satellite-based data in 2010 confirmed that this study established an effective methodology. The results of the study were in agreement with the FAO, History Database of the Global Environment 3.1 and 3.2, and the range of differences was found closer. These reconstruction datasets were suitable for use in climatic impact assessments of agricultural land change, as well as carbon cycle and climate modeling studies.