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Six divergent genotypes of sesame (Sesamum indicum L.) were crossed using a half diallel mating design according to Griffing (1956) excluding reciprocal crosses, to estimate stability for studied traits under three sowing dates in the experimental farm at Agricultural Research Station in Ismailia Governorate during summer season 2018. The 15 hybrids and their 6 parents were grown in field experiments in two geographical locations (Ismailia and El-Sharkia Governorates) and two seasons (2019 and 2020) under three sowing dates (April 1st and 2nd (SD1), May 1st and 2nd (SD2) and June 1st and 2nd (SD3) in Ismailia and Sharkia, respectively. A split plot design was used in randomized complete blocks with four replications, the main plots included planting dates while the 21 genotypes were in sub-plots. Combined analysis of variance over locations and seasons gave highly significant differences. Most of the interactions between the studied factors showed high significance for most of the traits under study. Additive Main effects and Multiplicative Interaction (AMMI) analysis for seed yield for 12 environments (two locations, two seasons and three sowing dates) showed significant effect of environments, genotypes and their interactions. The E2, E3, E8 and E9 had high mean seed yield above the grand mean environments values and are considered suitable and favorable for sesame seed production due to its low interactive effects. Sesame genotypes 7, 18, 10, 19, 12, 13, 15 were nearly close to the origin and thus the most stable and less responsive to the GEI (Genotype-by-Environment Interaction). In contrast, genotypes 1, 20, 8, 11 and 2 were far from the origin, sensitive to environmental changes and their yields are unstable. Keywords: Sesame, half diallel, sowing dates, AMMI, biplot

Six divergent genotypes of sesame (Sesamum indicum L.) were crossed using a half diallel mating design according to Griffing (1956) excluding reciprocal crosses, to estimate stability for studied traits under three sowing dates in the experimental farm at Agricultural Research Station in Ismailia Governorate during summer season 2018. The 15 hybrids and their 6 parents were grown in field experiments in two geographical locations (Ismailia and El-Sharkia Governorates) and two seasons (2019 and 2020) under three sowing dates (April 1st and 2nd (SD1), May 1st and 2nd (SD2) and June 1st and 2nd (SD3) in Ismailia and Sharkia, respectively. A split plot design was used in randomized complete blocks with four replications, the main plots included planting dates while the 21 genotypes were in sub-plots. Combined analysis of variance over locations and seasons gave highly significant differences. Most of the interactions between the studied factors showed high significance for most of the traits under study. Additive Main effects and Multiplicative Interaction (AMMI) analysis for seed yield for 12 environments (two locations, two seasons and three sowing dates) showed significant effect of environments, genotypes and their interactions. The E2, E3, E8 and E9 had high mean seed yield above the grand mean environments values and are considered suitable and favorable for sesame seed production due to its low interactive effects. Sesame genotypes 7, 18, 10, 19, 12, 13, 15 were nearly close to the origin and thus the most stable and less responsive to the GEI (Genotype-by-Environment Interaction). In contrast, genotypes 1, 20, 8, 11 and 2 were far from the origin, sensitive to environmental changes and their yields are unstable. Keywords: Sesame, half diallel, sowing dates, AMMI, biplot

Bridge scour is the leading cause of bridge failure all around the world, affecting significantly on the total construction and maintenance costs. Therefore, scouring around piers and abutments has been extensively studied in the past, focusing on point measurements of scour depth in front of a circular pier in alluvial sand beds. A literature review showed, that there is still a lack of studies on the effects of main scour parameters on the scour hole geometry, and on the mechanism of local scour around piers of different shape and alignment in gravel beds. This thesis attempts to fulfill this gap by experimentally investigating the development of scour holes around piers of different shape and alignment in gravel and sand beds. New non-intrusive, high resolution topography measurements of complete developing and equilibrium scour holes were performed during the experiments with an experimental installation using a laser distance sensor (LDS) and positioning systems. Additionally, the turbulent flow field around a square pier in gravel bed is measured with the acoustic doppler velocimeter (ADV) providing an insight into the complex flow field. The spatio-temporal variations of the geometric characteristics of developing scour holes are analyzed including the scour hole topography, time-dependent and equilibrium scour depth, scour extent, scour slopes and scoured volume. Firstly, the general observations made for each experiment are presented. All the obtained data are then analyzed in comparisons, as a function of the pier shape, angle of attack and sediment sizes. Empirical equations for the prediction of scour depth, scour radius and scoured volume as well as new pier shape and angle of attack adjustment factors were also obtained. Further, numerous prediction equations of time-dependent and equilibrium scour depths are evaluated. Effect of the pre-estimated experiment time on measuring and predicting the scour depth is also discussed.

Bridge scour is the leading cause of bridge failure all around the world, affecting significantly on the total construction and maintenance costs. Therefore, scouring around piers and abutments has been extensively studied in the past, focusing on point measurements of scour depth in front of a circular pier in alluvial sand beds. A literature review showed, that there is still a lack of studies on the effects of main scour parameters on the scour hole geometry, and on the mechanism of local scour around piers of different shape and alignment in gravel beds. This thesis attempts to fulfill this gap by experimentally investigating the development of scour holes around piers of different shape and alignment in gravel and sand beds. New non-intrusive, high resolution topography measurements of complete developing and equilibrium scour holes were performed during the experiments with an experimental installation using a laser distance sensor (LDS) and positioning systems. Additionally, the turbulent flow field around a square pier in gravel bed is measured with the acoustic doppler velocimeter (ADV) providing an insight into the complex flow field. The spatio-temporal variations of the geometric characteristics of developing scour holes are analyzed including the scour hole topography, time-dependent and equilibrium scour depth, scour extent, scour slopes and scoured volume. Firstly, the general observations made for each experiment are presented. All the obtained data are then analyzed in comparisons, as a function of the pier shape, angle of attack and sediment sizes. Empirical equations for the prediction of scour depth, scour radius and scoured volume as well as new pier shape and angle of attack adjustment factors were also obtained. Further, numerous prediction equations of time-dependent and equilibrium scour depths are evaluated. Effect of the pre-estimated experiment time on measuring and predicting the scour depth is also discussed.

Bridge scour is the leading cause of bridge failure all around the world, affecting significantly on the total construction and maintenance costs. Therefore, scouring around piers and abutments has been extensively studied in the past, focusing on point measurements of scour depth in front of a circular pier in alluvial sand beds. A literature review showed, that there is still a lack of studies on the effects of main scour parameters on the scour hole geometry, and on the mechanism of local scour around piers of different shape and alignment in gravel beds. This thesis attempts to fulfill this gap by experimentally investigating the development of scour holes around piers of different shape and alignment in gravel and sand beds. New non-intrusive, high resolution topography measurements of complete developing and equilibrium scour holes were performed during the experiments with an experimental installation using a laser distance sensor (LDS) and positioning systems. Additionally, the turbulent flow field around a square pier in gravel bed is measured with the acoustic doppler velocimeter (ADV) providing an insight into the complex flow field. The spatio-temporal variations of the geometric characteristics of developing scour holes are analyzed including the scour hole topography, time-dependent and equilibrium scour depth, scour extent, scour slopes and scoured volume. Firstly, the general observations made for each experiment are presented. All the obtained data are then analyzed in comparisons, as a function of the pier shape, angle of attack and sediment sizes. Empirical equations for the prediction of scour depth, scour radius and scoured volume as well as new pier shape and angle of attack adjustment factors were also obtained. Further, numerous prediction equations of time-dependent and equilibrium scour depths are evaluated. Effect of the pre-estimated experiment time on measuring and predicting the scour depth is also discussed.

Bridge scour is the leading cause of bridge failure all around the world, affecting significantly on the total construction and maintenance costs. Therefore, scouring around piers and abutments has been extensively studied in the past, focusing on point measurements of scour depth in front of a circular pier in alluvial sand beds. A literature review showed, that there is still a lack of studies on the effects of main scour parameters on the scour hole geometry, and on the mechanism of local scour around piers of different shape and alignment in gravel beds. This thesis attempts to fulfill this gap by experimentally investigating the development of scour holes around piers of different shape and alignment in gravel and sand beds. New non-intrusive, high resolution topography measurements of complete developing and equilibrium scour holes were performed during the experiments with an experimental installation using a laser distance sensor (LDS) and positioning systems. Additionally, the turbulent flow field around a square pier in gravel bed is measured with the acoustic doppler velocimeter (ADV) providing an insight into the complex flow field. The spatio-temporal variations of the geometric characteristics of developing scour holes are analyzed including the scour hole topography, time-dependent and equilibrium scour depth, scour extent, scour slopes and scoured volume. Firstly, the general observations made for each experiment are presented. All the obtained data are then analyzed in comparisons, as a function of the pier shape, angle of attack and sediment sizes. Empirical equations for the prediction of scour depth, scour radius and scoured volume as well as new pier shape and angle of attack adjustment factors were also obtained. Further, numerous prediction equations of time-dependent and equilibrium scour depths are evaluated. Effect of the pre-estimated experiment time on measuring and predicting the scour depth is also discussed.