Özet:

This study was conducted to analyze vertical and horizontal spatial variability of penetration resistance (PR) in recently deposited sediments at Borçka Dam reservoir. Ninety-one grids with 50 m by 10 m were located and PR was measured to a depth 80 cm by 10 cm increment (8 layers) within each grid. Spatial variation of PR was assessed by geostatistical techniques in all 8 layers. Semivariograms of PR were constructed for all the layers and corresponding kriging maps were built. The PR values were greater in surface layer (0-10 cm) and gradually decreased by depth. Mean PR was greatest (0.747 MPa) in surface layer and lowest (0.413 MPa) in 61-70 cm (layer 7). Results from exploratory statistics and geostatistical analyses showed that the PR values were more variable in surface layer compared to those in deeper layers due to that the surface layer was drier at the sampling and that affected by environmental factors in a greater extent. All the studied layers exhibited differences in spatial variation of PR as sill, nugget, and range values of corresponding semivariograms and kriging-predicted surface maps showed. The shortest geostatistical range (40.8 m) occurred of surface layer while the longest (173.3 m) occurred for second layer (11-20 cm). The nugget effect was greatest (44%) in third layer (21-30 cm) while lowest (13%) in the surface layer. The same study may be repeated with more variables to understand the mechanisms behind development and extent of spatial variation in these newly deposited sediments.