A dataset of soil water measurements at multiple scales and depths on China's Loess Plateau

Soil water content (SWC) is a key state variable in land-surface hydrologic processes and the primary water source for vegetation, particularly in arid and semi-arid regions. However, long-term, multi-scale in-situ measurements of deep SWC remain insufficient on the Loess Plateau of China (LPC)—the world’s largest and deepest loess deposit area. To fill this gap, Loess-Obs—the first operational SWC observatory on the LPC—was established in 2004 to provide representative coverage of diverse land uses and spatial scales. Loess-Obs covers five spatial scales: (1) plot scale: four plots with distinct land uses (with measurements taken weekly to monthly spanning 2004–2019); (2) hillslope scale: two 300-m hillslopes (2004–2016); (3) landscape transect: a 1340-m transect (2012–2013); (4) south-north transect: an 860-km transect (2012–2014); and (5) regional scale: a regional survey of 243 sampling points (2019). Using non-destructive neutron probe technology, Loess-Obs enables repeated deep volumetric SWC measurements (0–5 m) across different spatial scales. Here, we present the long-term (2004–2019) Loess-Obs dataset, including SWC measurements, soil properties and associated environmental datasets (e.g. land use, topography and meteorology), to support extended applications. This dataset is valuable for validating SWC products, developing upscaling methods, and understanding deep soil hydrological responses to land use and climate change.