Comparison of Selected Methods for Estimating Groundwater Recharge In Humid Regions

Method:	Category:	Spatial Scale:	Temporal Scale:	Quantity Estimated:	Ease of Use:	Data Needs:	Cost:
Streamflow Gain/Loss Measurements	Streamflow	Local	Instantaneous	Potential Recharge	Easy	Low	Low
Measurements of streamflow losses along a reach provide an estimate of potential recharge that could arrive at the water table. The method involves measurement of streamflow at upstream and downstream locations in the channel and measurement of all inflows, outflows, and change in storage of water between those locations. The method is generally easy to apply and inexpensive. Accuracy of the method depends on the magnitude of streamflow and significance of evaporation and bank-storage terms, which can be difficult to estimate.