Apart from net precipitation, groundwater recharge is dependent on the geological composition of the upper layers and on the degree of interaction between groundwater and surface water. Nonetheless, groundwater recharge is also affected by the abstraction of water from the given aquifer: the higher the pumping rate, the greater the groundwater recharge. A sensitivity analysis was carried out based on the variation in WR corresponding to between 78 and 118% of the originalWR value used in the original Level 1 assessment of HOFOR