Field experiments were conducted in Lake Balaton, a large (surface area, 600 km2) but shallow (mean depth, 3.2 m) lake in Hungary, to quantify the resuspension and deposition of bottom sediment due to episodic storm events. Measurements were made of windspeed and direction, surface waves, mean water velocity, and suspended sediment concentration.During significant wind events, the computed bottom stress due to surface waves dominated that due to the mean current, and therefore surface waves were assumed to be the major cause of sediment resuspension. A simple model for the depth-averaged suspended sediment concentration based on surface wave height was calibrated with about 10 h of data collected during one storm event and verified against 15 d of data collected at the same site. The success of the suspended sediment model, which assumes that the bottom sediment was noncohesive, is surprising since the bottom material was composed predominantly of sediment in the clay and fine-silt size ranges. This fit may indicate the presence of a thin surface layer of loosely bound sediment that is continuously involved in resuspension. The suspended sediment model could easily be integrated into a water quality model (e.g. to predict light attenuation), provided that lateral transport is negligible, or it could be used to provide the bottom boundary condition for a more general suspended sediment transport model in which advective transport is included.Due to their small fall velocities, finegrained particles (i.e. those in the silt and clay size ranges) are transported easily by flows. An understanding of the dynamic behavior of these particles is particularly important in shallow lakes and estuaries since there they may repeatedly settle to the bot-

Coefficients of longitudinal and lateral dispersion were measured for steady uniform laminar flow through an isotropic porous medium. A unique experimental method for measuring lateral dispersion is described. It is found that the ratio of the coefficient of longitudinal dispersion D1 to the coefficient of lateral dispersion D2 is given by $\frac {D_1}{D_2} = \lambda \Re ^n$ where λ and n are dimensionless coefficients dependent upon the pore-system geometry, and [real ] is the Reynolds number based on the seepage velocity, the average grain diameter, and the kinematic viscosity.

The recharge and disposal of treated and untreated waste waters in groundwater aquifers results in a mixing of these waters with the natural groundwater. The distribution and boundaries of the ensuing mixture are determined by the combined mechanisms of convection, dispersion, diffusion, and sorption. In this study, the mass conservation equation for a dissolved substance in two‐dimensional groundwater flow is developed. An analytical solution and a numerical solution of this equation are obtained for the radial and temporal distribution of a conservative, dissolved substance, which is injected into a homogeneous isotropic confined aquifer by a single recharging well. Experimental measurements of the concentration distributions of a dilute salt water tracer support the theoretical solutions. It is found that, for homogeneous media, the dispersed or mixed region may be less than 1% of the volume of fluid recharged at distances of only 30–60 meters from the well. Finally, from the experimental results it is shown that the dispersion coefficient along the streamlines is the same for both uniform and nonuniform flows at the same velocity.

Data from eight evaporation pans containing brines of different salinity and ionic composition were analyzed to quantify the effect of salinity on evaporation. The common procedure of correcting fresh water evaporation by an empirical ratio (00 of salt water to fresh water evaporation rates is shown to only approximate. A more accurate approach based on the effect of salinity on saturation vapor pressure is described. The activity coefficient of water (•) was computed based on the pan evaporation data. Various analytical methods to compute the effect of salinity on saturation vapor pressure based on ionic composition of the solution are described and applied with Dead Sea data. These approaches can be applied in many engineering applications including water balance calculations for saline lakes, salt production ponds, and evaporatio n ponds used for disposal of saline effluents.