Abstract:
Sequential aerial photography is used to determine changes in the extent of the "Zostera" beds on the flood delta, this being indicative of changes in the substrate sediments. Four cores have been taken from the flood delta, and standard grainsize analysis techniques employed to establish the composition and characteristics of the sediments. Together with survey work and other information, these two techniques enable description of the sedimentation changes and the present sediment dynamics on the flood tide delta. Virgin catchment runoff has been simulated using two models. Simulated and actual runoff are qualitatively compared. This, together with an examination of temporal increases in the total volume of water impounded in the catchment, enables the impact of dams on the hydrology of the river to be determined. It has been found that there has been a virtually complete annihilation of the "Zostera" beds, a concomitant loss of the mudflat areas, and that the sediments presently occurring on the flood delta are almost wholly of marine origin. It is concluded that there has been an increase in marine sedimentation and that this sedimentation is directly related to and consequent upon changes in the hydrology of the river as a result of impounding catchment runoff.
