ABSTRACT
This chapter focuses on the methods to estimate recharge, concentrating on natural processes rather than the human-influenced sources of water. There are many published methods of estimation for specific types of recharge, but they can be grouped according to the underlying philosophy, rather than source of water. Such a categorisation is shown on one axis, which shows the ‘space’ in which any studies of recharge must be carried out. The water table is generally well below the ground, depending on topography, with an unsaturated zone up to 50 m thick. Rivers can be expected to be regional discharge points for groundwater, may be 10 km apart, and will only be perched above the water table if large boreholes are located nearby. However, bedrock is usually only of local importance as an aquifer. The important aquifers are glacial or fluvial sediments, including moraines, river valley alluvium and infills in bedrock topography.
