LTLS simulates past and future flows of water and macronutrients (carbon, nitrogen and phosphorus) between land, freshwaters, sea and atmosphere. It is used by researchers to: (1) simulate terrestrial and freshwater fluxes of C,N,P at national scales over decades and centuries; (2) predict the impacts of future changes in climate and landscape; and (3) understand macronutrient processes and effects.
LTLS comprises computer code and configurations (spatial datasets) to run the model on Linux workstations or supercomputers. It includes modules to account for the effects of hydrology (lakes and rivers), geology, vegetation and soils (both semi-natural and agricultural) on stores and fluxes of macronutrients. It can currently simulate UK (5km grid) or regional (1km grid) scales, and timeframes such as the past 200 years, a recent year, or the next 100 years. LTLS links to other models and frameworks: it incoprorates the UKCEH vegetation and soil model N14CP (see separate entry); it is now being incorporated in the UniFHy community hydrological modelling system as the water quality component.
LTLS was originally developed under the NERC Macronutrient Cycles programme (2014-2017) to understand changes to terrestrial and freshwater pools and fluxes of macronutrients over the last two centuries, and to develop a validated model able to forecast future changes. It is now applied more widely to look at the impacts of land-use and climate change on freshwater quality (UKRI-NERC National Capability programmes: ASSIST, LOCATE, UK-SCAPE, AgZero+). LTLS capability is now being included in Hydro-JULES UNIFHI system (under development).
LTLS operates at larger scales (national) and over longer periods (centuries) than other UKCEH models with similar functionality (eg Cascade).
The original LTLS model suite was developed by a consortium of UK research institutions including UKCEH, Rothamsted Research, British Gelogical Survey (BGS) and University of Lancaster. LTLS code is now part of the ASSIST modelling framework used by UKCEH and Rothamsted Research used to understand the impacts of agricultural intensification on the UK's food and natural environment; LTLS code and approach is now being incorporated in the Hydro-JULES community hydrological model.
Access to LTLS was initially restricted to UKCEH but will be become open access: available to other researchers at no cost via inclusion in the Hydro-JULES model (under development: see separate entry).
Development of LTLS was funded by: NERC Macronutrient Cycles programme (LTLS project); NERC National Capability programmes (LOCATE, ASSIST, Hydro-JULES); and Scottish Government.
LTLS, including the freshwater modelling component, is used by researchers at UKCEH and Rothamsted Research.