A review is made of the use of stereophotogrammetry to measure the movements of civil engineering works. An improvement to the false parallax technique of stereophotogrammetry, and a method of using a type of stereoplotter common in South Africa, the Wild B8, for this technique, are presented.
'n Oorsig van die gebruik van stereofotogrammetrie om die bewegings van siviele ingenieursbouwerke te meet is gemaak. 'n Verbetering aan die valse parallakstegniek van stereofotogrammetrie, en 'n metode vir die gebruik van 'n stereostipmasjiene in algemene gebruik in Suid-Afrika, die Wild B8, vir hierdie tegniek word aangebied.
Several dams in South Africa were overtopped by the unprecedented floods of 1981, now well documented. Stage at the dam wall was, in every case amplified due to surges, waves and their reflections, leading to overestimation of the actual flood peaks. The dams did not fail although stressed beyond their design values. Even an earth dam, although twice severely overtopped, survived - probably because of the short-time duration of the amplified peak loading. Such surges can lead to overstress. The observed flood peaks at several dams were greater than those estimated by slope-area methods from down-river flood marks. These increased discharges ascribable to surge agree with calculated values. The results of theoretical analysis of unsteady-state flood routing and a hydraulic model simulation are presented in the paper.