Abstract: Whole hillslope is a basic unit for multi-scale measurement and conversion of water and soil loss, which lies between traditional slope and watershed scales. Based on the analysis of the basic unit of water and soil loss, we define the scope of whole hillslope surface as a complete geomorphic unit located between the watershed and from the top to the foot of the slope. Spatial heterogeneity, such as slope length, slope gradient, slope position, and land use distribution pattern, is a crucial factor that differentiates the whole slope from traditional slope research and affects the spatial differentiation of water and soil loss. Runoff, sediment, carbon, nitrogen, phosphorus, and other flux materials of water and soil loss are key elements for studying the erosion law of the whole hillslope. The migration and transformation of key elements of the whole hillslope is a complex physical and chemical process, while current measurement techniques are insufficiently efficient to identify, extract, and quantitatively analyze each element, thus requiring the establishment of a measurement technology system for the whole hillslope. The study of spatio-temporal variation of and measurement techniques for soil and water loss on the whole hillslope can provide an essential reference and basis for constructing multi-scale nested measurement system and simulating and predicting erosion, runoff, and sediment processes at different scales.

Key words: soil and water loss, key elements of soil and water, spatio-temporal variation, measurement techniques, whole hillslope