Spatial distribution of soil moisture index across Nepal: a step towards sharing climatic information for agricultural sector

The agro-climatic zoning provides valuable information for crop suitability mapping in order to optimize the yield. Despite its huge importance, such studies are extremely lacking in Nepal. This study attempts to classify the agro-climates of Nepal using a climate data of recent 30 years (1986–2015) period from a large number of meteorological stations distributed across the country (75 stations for the first time). Climate data at station location is interpolated in high spatial resolution considering elevation as one of the dominant factors controlling the spatial variability of climate fields in mountains. The agro-climatic classification includes modified Thornthwaite's approach based on soil moisture index (SMI). The negative SMI values represent dry and arid whereas positive values represent the wet and humid environment. SMI > 100% represents perhumid agro-climate. Our results show the largely similar distribution of annual and monsoonal SMI, suggesting the dominance of monsoon SMI on annual. Based on the annual SMI indices, around 60% of areal coverage of the country falls under humid environment. The presented seasonal and spatial distribution maps of SMI can be helpful to assess the needs of the irrigational facility, choice of crops, and their rotations, and finally to design cropping calendar. The practitioners, researchers, and decision/policymakers can benefit from these tools.