Glossary#

POM#: Particulate Organic Matter. A form of organic matter that derives from the decomposition and fragmentation of litter and other necromass. Generally, these particulates are still in a state where the tissue they originated from can be determined. This chemical complexity makes this a form of protected carbon, however this is generally only a significant store of protected carbon in heavily waterlogged soils.
MAOM#: Mineral Associated Organic Matter. This is organic matter which has formed a strong association with soil minerals. This association impedes breakdown, making this a form of protected carbon and typically accounts for for a large proportion of total carbon stock in the soil.
LMWC#: Low Molecular Weight Carbon. These are organic molecules that are simple and soluble, i.e. molecules that do not require further transformation to be transportable across cell membranes. Thus, the availability of this type of organic matter strongly determines microbial growth rates.
soil moisture#: The amount of water held in the soil, typically expressed as volumetric water content (m3/m3 or %) or as depth of water per unit area (mm).
soil moisture capacity#: The maximum amount of water a soil can retain against gravity, often referring to water content at field capacity. Expressed in m3/m3, %, or mm.
soil moisture residual#: The water content remaining in the soil after it has drained beyond the point of plant availability. Expressed in m3/m3, %, or mm.
soil moisture at field capacity#: The amount of water the soil retains after excess water has drained and gravitational flow slows. This is the upper limit of plant-available water. Expressed in m3/m3, %, or mm.
effective soil moisture#: The portion of soil water available for plant uptake, typically the range between residual moisture and field capacity. Expressed in m3/m3, %, or mm.
effective saturation#: Rescaled soil water saturation so that it takes a value of zero at the physical minimum (soil moisture residual) and a value of one at the physical maximum (soil moisture saturation). This can also be referred to as the normalised water content.
relative soil moisture#: A ratio expressing the amount of water in soil, as a percentage, compared to the total water-holding capacity between the wilting point (very dry) and saturation (very wet) for a given soil type. Expressed as a unitless ratio (0–1) or %.
specific soil moisture#: Commonly refers to volumetric soil moisture content—the volume of water per volume of soil (%). In some contexts, it may also describe soil moisture at a specific location or layer, or (less commonly) the derivative of the water retention curve (specific moisture capacity). Alternative meaning (specific moisture capacity): 1/m or unitless per unit suction (if used in hydrological modeling).
permanent wilting point#: The water content at which plants can no longer extract moisture, leading to wilting and potential plant death. Water is still present in the soil, but it is tightly bound and unavailable to plants. This is lower limit of plant-available water. Expressed in m3/m3, %, or mm.
available water capacity#: Amount of water that a soil can store and make available to plants, defined as the difference between field capacity and the permanent wilting point. Expressed in m3/m3, %, or mm.
soil moisture saturation#: Maximum amount of water a soil can hold when all its pores are completely filled with water — that is, the soil is fully saturated and contains no air in the pore spaces. Expressed in m3/m3, %, or mm.
soil matric potential#: The potential energy of water in soil due to the adhesive forces between water molecules and soil particles, affecting how water is retained and moves through the soil. It is typically negative and measured in units of pressure, such as kilopascals (kPa), or as an equivalent water column height (cm or m).
gravitational head#: The potential energy of water in soil or an aquifer due to its elevation relative to a reference level, influencing the direction and rate of water movement. It is typically measured in units of length, such as meters (m), representing the height of a water column.
local runoff generation#: The water generated within a grid cell during a timestep. Includes both surface runoff (overland flow) and subsurface runoff (lateral soil flow and baseflow).
surface runoff#: The portion of local runoff that flows over the land surface into streams and rivers. In this model, this is purely precipitation-derived.
sub-surface runoff#: The portion of local runoff that moves laterally through soil and groundwater pathways before reaching the stream.
total runoff#: the depth of water produced from a drainage area during a particular time interval, including surface and subsurface runoff (mm).
inflow#: Water entering a cell from all upstream cells during the same timestep. Can be divided into surface inflow (overland) and subsurface inflow (through soils/groundwater).
river discharge rate#: The total volume of water moving through a river channel in a cell per unit time, combining both surface and subsurface flows. The model returns this variable a rate in cubic meters per second.