The soil water retention curve (SWRC) is an essential soil property that relates soil water content and matric potential. It plays a crucial role in soil water dynamics and the understanding of various hydrological phenomena at the land surface, including infiltration, runoff, evaporation, and energy exchange processes. In recent years, proximal sensing methods have shown great potential for retrieving this challenging-to-measure property from spectral reflectance. However, a physically-based approach is still lacking as current methods rely on empirical data-driven algorithms. Here we propose a novel physics-based laboratory method that, for the first time, enables direct estimation of the entire SWRC from saturated to dry using soil water content/reflectance data pairs within the shortwave infrared domain. The main hypothesis underlying the new method is that soil optical properties not only vary with soil water content but also with the pore scale distribution of capillary and adsorbed soil water. For evaluation, retrieved soil water retention curves of 21 soils that vastly differ in physical and hydraulic properties were compared to direct measurements. The results suggest that the new method is a rapid and efficient alternative to established laboratory measurement methods.
", "keywords": ["Soil water retention curve", "Laboratory method", "Shortwave infrared reflectance", "Optical proximal sensing", "0401 agriculture", " forestry", " and fisheries", "04 agricultural and veterinary sciences", "15. Life on land", "Soil hydraulic properties", "01 natural sciences", "6. Clean water", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.jhydrol.2023.130284"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Hydrology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.jhydrol.2023.130284", "name": "item", "description": "10.1016/j.jhydrol.2023.130284", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.jhydrol.2023.130284"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-11-01T00:00:00Z"}}, {"id": "10.1029/2020wr028624", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:17:12Z", "type": "Journal Article", "created": "2021-06-21", "title": "Hydraulic and Physical Properties of Managed and Intact Peatlands: Application of the Van Genuchten\u2010Mualem Models to Peat Soils", "description": "AbstractUndisturbed peatlands are effective carbon sinks and provide a variety of ecosystem services. However, anthropogenic disturbances, especially land drainage, strongly alter peat soil properties and jeopardize the benefits of peatlands. The effects of disturbances should therefore be assessed and predicted. To support accurate modeling, this study determined the physical and hydraulic properties of intact and disturbed peat samples collected from 59 sites (in total 3,073 samples) in Finland and Norway. The bulk density (BD), porosity, and specific yield (Sy) values obtained indicated that the top layer (0\uffe2\uff80\uff9330\uffc2\uffa0cm depth) at agricultural and peat extraction sites was most affected by land use change. The BD in the top layer at agricultural, peat extraction, and forestry sites was 441%, 140%, and 92% higher, respectively, than that of intact peatlands. Porosity decreased with increased BD, but not linearly. Agricultural and peat extraction sites had the lowest saturated hydraulic conductivity, Sy, and porosity, and the highest BD of the land use options studied. The van Genuchten\uffe2\uff80\uff90Mualem (vGM) soil water retention curve (SWRC) and hydraulic conductivity (K) models proved to be applicable for the peat soils tested, providing values of SWRC, K, and vGM\uffe2\uff80\uff90parameters (\uffce\uffb1 and n) for peat layers (top, middle and bottom) under different land uses. A decrease in peat soil water content of \uffe2\uff89\uffa510% reduced the unsaturated K values by two orders of magnitude. This unique data set can be used to improve hydrological modeling in peat\uffe2\uff80\uff90dominated catchments and for fuller integration of peat soils into large\uffe2\uff80\uff90scale hydrological models.Undisturbed peatlands are effective carbon sinks and provide a variety of ecosystem services. However, anthropogenic disturbances, especially land drainage, strongly alter peat soil properties and jeopardize the benefits of peatlands. The effects of disturbances should therefore be assessed and predicted. To support accurate modeling, this study determined the physical and hydraulic properties of intact and disturbed peat samples collected from 59 sites (in total 3,073 samples) in Finland and Norway. The bulk density (BD), porosity, and specific yield (Sy) values obtained indicated that the top layer (0\uffe2\uff80\uff9330\uffc2\uffa0cm depth) at agricultural and peat extraction sites was most affected by land use change. The BD in the top layer at agricultural, peat extraction, and forestry sites was 441%, 140%, and 92% higher, respectively, than that of intact peatlands. Porosity decreased with increased BD, but not linearly. Agricultural and peat extraction sites had the lowest saturated hydraulic conductivity, Sy, and porosity, and the highest BD of the land use options studied. The van Genuchten\uffe2\uff80\uff90Mualem (vGM) soil water retention curve (SWRC) and hydraulic conductivity (K) models proved to be applicable for the peat soils tested, providing values of SWRC, K, and vGM\uffe2\uff80\uff90parameters (\uffce\uffb1 and n) for peat layers (top, middle and bottom) under different land uses. A decrease in peat soil water content of \uffe2\uff89\uffa510% reduced the unsaturated K values by two orders of magnitude. This unique data set can be used to improve hydrological modeling in peat\uffe2\uff80\uff90dominated catchments and for fuller integration of peat soils into large\uffe2\uff80\uff90scale hydrological models.