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The procedure describes a simple and functional method of using a commercial spreadsheet (Lotus 1-2-3) to calculate water and sediment yields from measured or given data sets. Suspended sediment concentrations are located on a storm hydrograph and concentrations for unsampled points on the hydrograph are estimated using the principle that thechange in concentration between two sampled points will be proportional to the change in discharge between the same two points. The relationships are then solved by a cross-correlation equation using simpleformulae in the form of triangle-square equations to calculate waterand sediment yields between each sample time. The technique is applied to a 51 month data set from a long-term monitoring programme assessing the impacts of commercial logging operations in Sabah, East Malaysia. Yields for the monitoring period derived by the spreadsheet technique are compared with results from the application of more traditional discharge-sediment rating techniques. In the undisturbed catchment, yields derived from some rating equations compare favourably withthe spreadsheet technique. However, in the disturbed catchment, rating techniques proved less applicable because of the continuously changing nature of the catchment in relation to vegetation recovery, exacerbating variation and scatter in the data set. The application of the spreadsheet technique provides detailed information at an individual storm level; however, working with the method on long-term discharge records requires a significant commitment of time as compared to the straightforward application of rating equations. [ABSTRACT FROM AUTHOR]

The inclined line separation technique of Hewlett and Hibbert has been widely adopted to separate delayed flow from the total stream storm runoff. Presented here is the application of the technique to highly responsive storm hydrographs using a personal computer method basedon a Lotus 1-2-3 spreadsheet. Using discharge measurements (in m3 s-1), catchment area (in km2) and time(in Julian days), the separation slope is adjusted on the monitor screen until the precise time at which the end of quickflow as storm runoff gives way to delayed flow may be established. The application ofthe inclined line method is compared with other separation techniques applied to the same dataset. The annual stream quickflow runoff forthe study catchment was calculated by the four different separating lines - (i) best-fit curve, (ii) N-day after peak, (iii) inclined line and (iv) horizontal line - was 250, 312, 368, and 588 mm, amounting to 33, 31, 51 and 78 per cent respectively of the annual total stream runoff. Separation of flow by computer spreadsheet methods may be consistently applied throughout a dataset and therefore have a comparative advantage over more arbitrary techniques. [ABSTRACT FROM AUTHOR]