Field data, theoretical analyses, and numerical simulations were used to investigate the effects of lake basin bathymetry and spatial and temporal structures of the wind field on the basin‐scale internal wave spectrum in Lake Iseo. This deep Italian basin is characterized by the presence of a large island, imparting attributes of an annulus to the lake. During the summer of 2010, the internal wave activity was dominated by a basin‐scale internal wave of vertical and horizontal modes 1 (V1H1), superimposed on which were occasional higher vertical modes (V2H1) and higher horizontal modes (V1H5) trapped by the main island. The occurrence of these motions was interpreted as forcing by the wind components with similar horizontal structures and with energies at frequencies near the natural oscillations of the excited modes. The modifications of the wind field by the topography, in particular, controlled the excitation of an anticyclonic wave trapped around the island, whose features were investigated on the basis of an extension of the circular model to the case of an annular basin of constant depth.

Several large rivers enter Winam Gulf, a large shallow semi-enclosed embayment of Lake Victoria. Given the vast spatial scale of this embayment (1400 km 2 ), horizontal transport of waterborne material plays a major role in determining its biochemical properties. To identify the dominant hydrodynamic characteristics of this horizontal transport, a combination of field data and three-dimensional numerical modeling were employed to investigate effects due to variable wind forcing, riverine inflows, and interactions with the rest of Lake Victoria including astronomical tides and a complex bathymetry. Currents in the Gulf were oscillatory due to periodic wind and tidal forcing leading to surface seiching, with a residual circulation component. In the western region of the Gulf near the connection with Lake Victoria, substantial vertical and horizontal shear in the currents resulted in efficient horizontal dispersion with rates of up to 160 m 2 s 21 simulated using numerical tracers. In the eastern region, however, rates of horizontal dispersion were reduced to around 12 m 2 s 21 . This spatial variability in hydrodynamic conditions underpins regional differences in ecological properties of Winam Gulf.

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