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AbstractOn the Channel Island of Jersey, a third of the total water requirements are obtained from groundwater sources. A reliable estimate of recharge is necessary for sustainable groundwater management. Past resource management has been limited, partly because the rate of recharge is uncertain.This paper describes the application of three independent methods of estimating recharge: (a) chloride balance, (b) stream baseflow analysis, and (c) rainfall‐recharge‐runoff simulation. All three methods produce reasonably consistent results, indicating that long‐term recharge is 16–19% of average annual rainfall, and results of modelling indicate that groundwater abstraction may have exceeded recharge in 5 out of 28 years. These findings have important implications for the management of the island's water resources.

ABSTRACTA simple model is used to assess the effect of flood‐plain storage on flood flows, with a view to developing methods for general use in flood‐frequency estimation. Recent floods on the River Severn at Montford are 'unrouted' in order to determine the shape and magnitude of the hydrographs, provided that there had been no overtopping and all flows had been contained within the banks. The model used to unroute the hydrographs has, at its core, a relationship between water depth and flooded area derived from a coarse (50 m) digital terrain model developed from Ordnance Survey 1:50 000 maps. The implications for flood‐frequency curves at sites downstream from significant flood‐plain storage are discussed.

AbstractThis paper suggests that the relative salt (sodium chloride) dilution method should be more widely used for the routine measurement of stream discharge, and has been written to increase awareness of the technique among flow‐gauging practitioners. Recent improvements in instrumentation have increased accuracy and simplified practical application, making the method better suited (in many circumstances) than the more widely used alternatives. The paper (a) reports on a field study to evaluate the performance of a portable dilution‐gauging flowmeter, and (b) considers the environmental issues which are associated with the method. The review reveals that the use of salt (in the quantities typically required) is unlikely to have any significant ecological impact, and argues that environmental concerns are founded upon little scientific basis.

AbstractAbandoned mines create pollution problems in rivers as minewater levels rise and discharges of metal‐rich acidic waters occur. Mines adjacent to rivers can cause serious pollution problems, reducing fish stocks and preventing restocking. A computer model has been used to simulate the impact of these discharges and to devise an optimal treatment strategy to meet river quality objectives. The use of this model, through application to two case studies, is described.