W. Brutsaert et Jp. Lopez, BASIN-SCALE GEOHYDROLOGIC DROUGHT FLOW FEATURES OF RIPARIAN AQUIFERS IN THE SOUTHERN GREAT-PLAINS, Water resources research, 34(2), 1998, pp. 233-240
Low-streamflow hydrographs from 22 subbasins in the U.S. Department of
Agriculture-Agricultural Research Service (USDA-ARS) Washita River Ex
perimental Watershed complex in central Oklahoma were subjected to rec
ession slope analysis; this method, after that of Brutsaert and Nieber
[1977], was derived from a Dupuit-Boussinesq formulation for the grou
ndwater outflows from the adjoining phreatic aquifers. The longtime aq
uifer response characteristics were generally found to be close to lin
ear, and the short-time response characteristics were consistent with
Boltzmann similarity. Representative values of the resulting basin-sca
le effective groundwater parameters were (35 days)(-1) for the low-flo
w extinction coefficient (i.e., a storage half-life of 25 days); 0.021
m(2) s(-1) for the hydraulic diffusivity, D-h; 0.0035 m(2)s(-1/2) for
the hydraulic desorptivity, De(h); 8 x 10(-4) ms(-1) for the hydrauli
c conductivity k; and 0.018 for the drainable porosity (or specific yi
eld), f. The variabilities of D-h, De(h), and k from basin to basin co
uld be better represented by the log-normal than by the normal distrib
ution; f could be described nearly equally well by both. The storage h
alf-life is moderately and positively correlated with basin size; in t
he case of k the correlation is negative but weaker. Any scale depende
nce of D-h, De(h), and f appears to be negligible.