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HYDRAULIC ANALYSIS OF BASEFLOW AND BANK STORAGE IN ALLUVIAL STREAMS
Citation:
Hantush*, M M., M. HARADA, AND M. MARINO. HYDRAULIC ANALYSIS OF BASEFLOW AND BANK STORAGE IN ALLUVIAL STREAMS. Presented at Wetlands Engineering and River Restoration Conference, Reno, NV, August 27 - 31, 2001.
Description:
This paper presents analytical solutions, which describe the effect of time-variable net recharge (net accretion to water table) and bank storage in alluvial aquifers on the sustenance of stream flows during storm and inter-storm events. The solutions relate the stream discharge, stream-bank sediments water flux and volumes exchange, to the stream inflow hydrograph and groundwater recharge (negative in the case of net abstraction) events, via convolution integrals in terms of the impulse response and unit-step response functions. Discrete kernels can be derived from the continuous-time convolution integrals to predict the stream-aquifer interactions, stream outflow discharges, and cumulative discharge volumes in response to complex discrete-time inflow and groundwater recharge hydrographs. Application to a hypothetical stream-aquifer system shows that the response of the stream discharge to groundwater recharge is a long-term process when compared to increased stream inflows with and without bank storage. The time scale for a steady state stream discharge due to a sustained groundwater recharge is much longer than that due to bank storage releases only, as the unit step response function indicates. Simulations also illustrate the impact of sustained recharge on baseflow and the modification of the stream-aquifer flux exchange and bank storage of surface water.