The need to get rapid estimates of the water resources available in a catchment is an issue facing environmental managers across the world. The LowFlows software system was developed to enable river flows to be estimated for ungauged catchments in the UK.
The hydrological estimation techniques used in the software are derived from the Low Flows 2000 software system developed jointly by CEH, the EA, SEPA and NIEA. These hydrological models have been further developed by WHS using the latest hydrometric data and output from WHS Research and Development projects.
LowFlows represents a common platform for both regulatory and commercial users with equivalent natural flow estimation routines. The EA, SEPA, NRW and NIEA have all adopted LowFlows Enterprise as a standard method for predicting flows in ungauged catchments.
The functionalities of the system include:
- National coverage with hydrological models for England and Wales, Scotland and Northern Ireland.
- Spatial orientation by hydrometric area
- Automated catchment definition routines to define catchments from the 1:50 000 river network.
- Estimation of natural flow duration curves (FDCs) including the impacts of significant natural water-bodies (lakes and lochs).
- The ability to explicitly incorporate local data gauges (LDG) to improve the estimation of natural flow statistics.
- Simulation of the seasonal effects of artificial influences (abstractions, discharges and impoundments) on natural river flows.
- Incorporation of complex artificial influences licence structures (licence, site and purpose).
- Analysis of influences in a specific catchment to identify the dominant features and hence focus data verification.
- Modification of existing influences and add new influenced via the graphical user interface (GUI).
- Flow estimates / variables returned for an ungauged catchment include:
- Annual mean flow (m3/s);
- Annual runoff (mm/yr);
- Base Flow Index (BFI);
- Annual and monthly flow duration statistics (including Q95) for the natural flow regime;
- Influenced annual and monthly flow duration statistics, based on the artificial influences loaded into the software.
- Inclusion of hydrometric features (gauging stations and spot gauges) to improve flow estimation and to assist in the analysis of results.
- Naturalisation routines to derive natural flow statistics from observed flow records and configurations of artificial influences.
- Automated assignment of flow percentiles to spot gaugings based on the use of similar analogue (gauged) catchments.
- Residual flow diagram generation to assess the relative impacts of influences along a river reach.