The southern Piedmont has undergone extensive cropland reversion during the twentieth century with row crops being replaced by forest and pasture. Ten continguous river basins with a total area of 54,020 km 2 had 10 to 28% of their respective areas reforested during the period 1919-1967. During the same period, water yield decreased 3 to 10 cm according to both regression and double-mass analysis. These reductions in water yield constituted a 4 to 21% decrease in annual stream discharge and were statistically significant for a majority of the basins. The reduction of water yields by forests tends to be greater for dry years than for wet years. There was little or no relation between the degree of reforestation and reductions of water yield at the scale of this study, but when our data are included with the universe of data, the variance of our data from the overall model is much less than in the universal set. The inclusion of our results extends the range and predictive power of the universal model, giving it greater utility for water yield planning.

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Land-cover classifications in mountainous terrain are often hampered by the topographic effect. Several strategies can be pursued to correct for this. A traditional approach is to use training areas for the same land-cover class for different topographic positions and later merge those into one class. Other solutions involve topographic corrections, such as a Minnaert correction. In this study the classification result of the traditional training-area approach was compared with the classification result of a Minnaert-corrected image. In order to derive the Minnaert constants, a SPOT XS scene of the Santa Monica Mountains, USA, was divided into three visually relatively homogeneous regions. Eighty per cent of the pixels were assigned the same land cover in both classifications. Differences in classification were mainly in the section of the image that had more diverse land cover than in the more homogeneous chaparral-covered eastern section. This supports previous findings that the Minnaert constant needs to be derived for individual land-cover classes. The findings also suggest that after the Minnaert correction the resulting classification is comparable to the classification obtained using a more traditional approach.

As part of an overall study of sedimentation processes in a proglacial lake an effort was made to compare field results with some of the general equations for density flows. The results suggest that in relatively small glacial lakes the occurrence of underflows with lower sediment loads involves a complex interplay between thermal and sediment effects which is extremely sensitive to varying hydrologic and climatic conditions. In terms of actual transport mechanics the results: (i) indicate that a higher α value of 0·6 or 0·7 gives a closer agreement between the measured velocity values and the established equations on moderately shallow slopes; (ii) provide field support for the experimentally derived relationship of Britter & Linden (1980) for the velocity of underflows and suggest the equation may be applicable in situations below 5° slopes; and (iii) support the relationship between velocity of the front and body of a continuous underflow for moderate slope situations suggested by Middleton (1966b). Finally the velocity values measured by electromagnetic current meters stationed in the lake, the grain‐size data obtained from mapping core data, and the application of other criteria support the concept that in this environment the underflows are capable of erosion.

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