ZOODRM (Mansour and Hughes, 2004) is an object-oriented model developed by BGS as part of the ZOOM suite of models. It is a distributed recharge model that simulates runoff and recharge processes. The model provides its output in a gridded form that can be used with groundwater flow models or on a catchment basis for water balance purposes. It has been applied in the UK both nationally and regionally, as well as overseas (for example, West Bank and China).
The model incorporates the Food and Agricultural Organization of the United Nations (FAO) soil moisture balance method and a simplified version of this algorithm, in addition to other methods that calculate recharge in specific environments such as semi-arid and urban. The model includes:
- runoff routing
- overland flow routing and storage
- interaction with lakes and reservoirs
- rainfall interception
Estimation of spatially distributed potential recharge
British mainland
The GB-wide recharge model was built using BGS’s code ZOODRM. Potential recharge is calculated on a grid with 2 × 2 km2 cells over the area (National Grid Reference):
- bottom left: (40000, -10000)
- top right: (680000, 1010000)
The model has been run for the period 1 January 1962 to 31 December 2010 and calibrated against the runoff component of river gauged flow. It calculates recharge on a daily basis and aggregates the recharge to a monthly value.
The calculation method used is the modified FAO as proposed by Griffiths et al. (2006). It uses the distribution of soil parameters and crop parameters obtained from the HOST soil data map, which includes 33 classes of soil types (Boorman et al., 1995), and the land cover map Land Cover Map 2000, which includes nine land-use classes (Natural Environmental Research Council, 2000). The values of these parameters are obtained from the literature.
The model calculates potential recharge, which is the amount of water calculated to leave the bottom of the soil zone. It does not, therefore, take into account any modification of recharge resulting from the unsaturated zone and other, minor aquifers that may lie above the water table.
Further reading
Boorman, D B, Hollist, J M, and Lilly, A. 1995. Hydrology of soil types: a hydrologically based classification of the soils of the United Kingdom. Institute of Hydrology Report No. 126. (Wallingford, UK: Institute of Hydrology.) Available: https://nora.nerc.ac.uk/id/eprint/7369/
Griffiths, J, Keller, V, Morris, D, and Young, A R. 2006. Continuous Estimation of River Flows (CERF) — Technical Report: Task 1.3: Model scheme for representing rainfall interception and soil moisture. Environment Agency R & D Project W6-101. (Wallingford, UK: Centre for Ecology and Hydrology.)
Mansour, M M, and Hughes, A G. 2004. User’s manual for the distributed recharge model ZOODRM. British Geological Survey Internal Report IR/04/150. (Nottingham, UK: British Geological Survey.) Available: http://nora.nerc.ac.uk/id/eprint/12633/
Natural Environment Research Council. 2000. Countryside Survey 2000 Module 7. Land Cover Map 2000 Final Report. (Wallingford, UK: Centre for Ecology and Hydrology.) Available: https://nora.nerc.ac.uk/id/eprint/4380/
Contact
Please contact Dr Christopher Jackson for further information.