Monitoring the Dam Deformation over Letsibogo Dam, Botswana Using GPS Measurement

The present study reports about the first deformation monitoring framework of Letsibogo dam in Botswana using Global positioning Systems (GPS) which is capable of detecting structural movement in three dimensions. Every civil engineering structure has the potential to deteriorate over time once it is built. A variety of reasons, including stress, unstable slopes, inadequate foundation shearing strength, settlement, expansion from temperature changes, and aging, can cause the deterioration of dams, bridges, tunnels, and high-rise buildings. As a results of these effects, long and short term deformation monitoring of these structures is very important to validate the construction specifications and safety measures. Long term deformation monitoring is mainly based on measurements of horizontal and vertical movement of the entire structure to ensure that every part of the structure is stable. In this work we present the first deformation monitoring of Letsibogo dam in Botswana by establishing baseline points using Global positioning Systems (GPS) which is capable of detecting structural movement in three dimensions. The results obtained shows that the established reference and monitoring points measured by using GPS are reliable with standard deviations of 0.004m and 0.007m in x and y respectively and horizontal displacement of 1cm. In addition, the correlation coefficient for the observations was \(\hat{\rho}\) = 0 which confirms that the GPS measurements of reference and monitoring points are correlated. The position accuracy obtained is suitable for dam deformation monitoring for the first epoch which is expected to take place in 2020. Based on the results obtained, height component determined using GPS is weak and must be supplemented by precise levelling before being used for deformation monitoring in the first epoch.