Abstract. In situ measurement of soil hydraulic properties may be achieved by analyzing the unconfined effiux from disc tension infiltrometers, once consistent infiltration equations can be derived. In this paper an analytical, three-dimensional infiltration equation is developed, based on the use of parameters with sound physical meaning and adjustable for varying initial and boundary conditions. The equation is valid over the entire time range. For practical purposes, a simplified solution is also derived. The full and simplified equations give excellent agreement with published experimental results and are particularly useful for determining soil hydraulic properties through application of inverse procedures.

Abstract. This paper presents a theoretical model of flow and chemical transport processes in subterranean estuaries (unconfined brackish groundwater aquifers at the ocean-land interface). The model shows that groundwater circulation and oscillating flow, caused by wave setup and tide, may constitute up to 96% of submarine groundwater discharge (SGWD) compared with 4% due to the net groundwater discharge. While these local flow processes do not change the total amount of land-derived chemical input to the ocean over a long period (e.g., yearly), they induce fluctuations of the chemical transfer rate as the aquifer undergoes saltwater intrusion. This may result in a substantial increase in chemical fluxes to the ocean over a short period (e.g., monthly and by a factor of 20 above the averaged level), imposing a possible threat to the marine environment. These results are essentially consistent with the experimental findings of Moore [1996] and have important implications for coastal resources management. Although these discharge components have been studied previously, the above conceptual model of SGWD is proposed for the first time.Dn can be estimated using aquifer recharge data. It is normally small compared with the discharge due to river flows into the ocean, Dr; the estimate of D n as a percentage of D r ranges from 0.1 to 10 [Younger, 1996]. Note that we are considering these discharges over a large coastal area (e.g., a few hundred kilometers in the alongshore direction) and a long period (e.g., seasonal). Although they contribute greatly to D sowr>, the magnitudes of D w and D t have not been described in previous studies nor measured independently in the field.

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