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Figure 2. Photograph showing the steel rods were installed cross section with spacing 1 meter at Desart beach For beach profile measurements, as suggested similar field method by Jensen et al. (2010), several steel rods were placed in a cross-shore transect along the beach with a space of 1 m. In order to estimate the net accretion or erosion across the beach face for this monitoring, volumetric change were recorded with the assumption that changes in elevation at each rod represents the average bed level changes within half meter square. The rods were measured daily using a total station during low tides under the spring tidal range condition based on standard surveying techniques.

Figure 2 Photograph showing the steel rods were installed cross section with spacing 1 meter at Desart beach For beach profile measurements, as suggested similar field method by Jensen et al. (2010), several steel rods were placed in a cross-shore transect along the beach with a space of 1 m. In order to estimate the net accretion or erosion across the beach face for this monitoring, volumetric change were recorded with the assumption that changes in elevation at each rod represents the average bed level changes within half meter square. The rods were measured daily using a total station during low tides under the spring tidal range condition based on standard surveying techniques.

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Figure 1. Location map of the study area at Desaru beach, Johor, Peninsular Malaysia
Figure 1. Location map of the study area at Desaru beach, Johor, Peninsular Malaysia
Vata OD SWast Waler depths were Obtained OY USINg wWiree pressure WaNsaucers (Fis), WHICn were deployed during t (x = 40 m), midd about 5 meter. For this experiment, only one Acoustic swash velocities during uprush and backwash at the installed as close synchronized at a his monitoring near to the Mean Hig e (x = 35 m) and upper (x = 30 m) to the bed as possible, about 1 cm h Water Spring (MHWS) shoreline at the lower part of the beach area at a separation distance Current Meter (ACM) was deployed to record beach middle point (Figure 3). The ACM was above the bed. Both the PTs and ACM were same sampling time at 1 Hz or every | sec per data and operated continuously throughout the experiment. For this paper, only the data from the middle point (x = 35 m) will be discussed. From this monitoring station, the data for swash water depths and velocities were analyzed and separated for the selected period of uprush and backwash activities during spring tidal condition. All these experiments were also recorded by a video camera as a backup for a data analysis processes. The separation processes for every single uprush or backwash activities were analyzed by the direction of fluid velocities and also rechecked by using recorded video for every experiment. The position of sampling based on the beachface point (x = 35 m) and the tidal elevation (MHWS at 1.56 m LSD) at the field work were selected at approximately as the same high tide condition during the dry and wet periods. This situation setup is very important for this experiment in order to get a clear view about beach morphological changes at the same sampling point but under difference periods of seasonal variations in Malaysia. For the effects of Malaysia’s seasonal variations, one rain gauge station was installed close to the study area to record rainfall depth data for every 10 minutes during the observation period. This rainfall depth data is very important for this study in order to relate the contribution of the rainfall characteristics during the dry and wet seasons to the beach morphological changes due to the different patterns of swash zone sediment movement. This station was monitored monthly by a researcher in order to make sure this rain gauge operated successfully and the data from this station was downloaded at the same time by using a laptop (Figure 4). This data also was double-checked with a data taken from the nearest rainfall station from Malaysia’s local agency, Department of Irrigation and Drainage (DID) at Bandar Penawar rainfall station, which is about 10 km from the study area.
Vata OD SWast Waler depths were Obtained OY USINg wWiree pressure WaNsaucers (Fis), WHICn were deployed during t (x = 40 m), midd about 5 meter. For this experiment, only one Acoustic swash velocities during uprush and backwash at the installed as close synchronized at a his monitoring near to the Mean Hig e (x = 35 m) and upper (x = 30 m) to the bed as possible, about 1 cm h Water Spring (MHWS) shoreline at the lower part of the beach area at a separation distance Current Meter (ACM) was deployed to record beach middle point (Figure 3). The ACM was above the bed. Both the PTs and ACM were same sampling time at 1 Hz or every | sec per data and operated continuously throughout the experiment. For this paper, only the data from the middle point (x = 35 m) will be discussed. From this monitoring station, the data for swash water depths and velocities were analyzed and separated for the selected period of uprush and backwash activities during spring tidal condition. All these experiments were also recorded by a video camera as a backup for a data analysis processes. The separation processes for every single uprush or backwash activities were analyzed by the direction of fluid velocities and also rechecked by using recorded video for every experiment. The position of sampling based on the beachface point (x = 35 m) and the tidal elevation (MHWS at 1.56 m LSD) at the field work were selected at approximately as the same high tide condition during the dry and wet periods. This situation setup is very important for this experiment in order to get a clear view about beach morphological changes at the same sampling point but under difference periods of seasonal variations in Malaysia. For the effects of Malaysia’s seasonal variations, one rain gauge station was installed close to the study area to record rainfall depth data for every 10 minutes during the observation period. This rainfall depth data is very important for this study in order to relate the contribution of the rainfall characteristics during the dry and wet seasons to the beach morphological changes due to the different patterns of swash zone sediment movement. This station was monitored monthly by a researcher in order to make sure this rain gauge operated successfully and the data from this station was downloaded at the same time by using a laptop (Figure 4). This data also was double-checked with a data taken from the nearest rainfall station from Malaysia’s local agency, Department of Irrigation and Drainage (DID) at Bandar Penawar rainfall station, which is about 10 km from the study area.
Figure 4. Photograph showing the (left) monitoring well with water level indicator and (right) rain gauge station
Figure 4. Photograph showing the (left) monitoring well with water level indicator and (right) rain gauge station
Figure 5. Relationship between monthly rainfall data and beach groundwater table elevation
Figure 5. Relationship between monthly rainfall data and beach groundwater table elevation
Figure 6. Beach profiles and mean groundwater level for 3 different days of monitoring significantly increased the beach groundwater level and enhanced the offshore transport due to higher saturated beach face. The beach groundwater level also increased higher with about 0.6 m in well no. | and 0.8 m for well no. 2.
Figure 6. Beach profiles and mean groundwater level for 3 different days of monitoring significantly increased the beach groundwater level and enhanced the offshore transport due to higher saturated beach face. The beach groundwater level also increased higher with about 0.6 m in well no. | and 0.8 m for well no. 2.
Figure 7. Profiles of swash water depth and velocity during wet season During the wet period in Figure 7, the average depth was 7.14 cm with the maximum and minimum values were 27.0 cm and 0 cm respectively. For the velocity data, the highest values of uprush and backwash were recorded at 3.76 m/s and 2.13 m/s respectively. The sampling point for data profiles during the wet period, when the uprush flow came, there was always a maximum instantaneous acceleration in uprush velocity and followed by more steadily decrease until zero velocity at the end of the uprush flow. During this moment, it clearly showed that the maximum water depth always occured when zero velocity reading at the end of uprush flow. In contrast, when the backwash flow took the action in the swash zone, the velocity increased gradually until it reached its maximum value. After that, the backwash flow depth and velocity decreased to zero until the new uprush flow came. This observation was consistent with other field study work by Hughes (1997).
Figure 7. Profiles of swash water depth and velocity during wet season During the wet period in Figure 7, the average depth was 7.14 cm with the maximum and minimum values were 27.0 cm and 0 cm respectively. For the velocity data, the highest values of uprush and backwash were recorded at 3.76 m/s and 2.13 m/s respectively. The sampling point for data profiles during the wet period, when the uprush flow came, there was always a maximum instantaneous acceleration in uprush velocity and followed by more steadily decrease until zero velocity at the end of the uprush flow. During this moment, it clearly showed that the maximum water depth always occured when zero velocity reading at the end of uprush flow. In contrast, when the backwash flow took the action in the swash zone, the velocity increased gradually until it reached its maximum value. After that, the backwash flow depth and velocity decreased to zero until the new uprush flow came. This observation was consistent with other field study work by Hughes (1997).
Figure 8. Profiles of swash water depth and velocity during dry season decreasing of swash energy happened during this period with an average depth was 2.05 cm with th maximum and minimum values were 12.3 cm and 0 cm respectively. This an important condition ca explain why the developed berm in Figure 7 during the wet season before did not change due to wav attack with the limitation of observed uprush length occurred as far as at point x = 17 m, which » shorter 10 m if compared with the furthest uprush length during the wet season (x = 7 m). For th velocity data during this period, the highest values of uprush and backwash were detected at 2.85 m and 1.58 m/s respectively. It clearly found that the swash velocity was decreasing for the uprush an backwash flow but the backwash velocity was significantly reduced by greater infiltration effect due t high value of unsaturated beach surface. This unique condition has played a major role in accretio processes in the swash zone due to high infiltration effect. In this condition, the sediment or san carried by swash water during the uprush and backwash flow has settled down easily on the beachfac due to high infiltration process and this situation put the beach in the accretion mode.
Figure 8. Profiles of swash water depth and velocity during dry season decreasing of swash energy happened during this period with an average depth was 2.05 cm with th maximum and minimum values were 12.3 cm and 0 cm respectively. This an important condition ca explain why the developed berm in Figure 7 during the wet season before did not change due to wav attack with the limitation of observed uprush length occurred as far as at point x = 17 m, which » shorter 10 m if compared with the furthest uprush length during the wet season (x = 7 m). For th velocity data during this period, the highest values of uprush and backwash were detected at 2.85 m and 1.58 m/s respectively. It clearly found that the swash velocity was decreasing for the uprush an backwash flow but the backwash velocity was significantly reduced by greater infiltration effect due t high value of unsaturated beach surface. This unique condition has played a major role in accretio processes in the swash zone due to high infiltration effect. In this condition, the sediment or san carried by swash water during the uprush and backwash flow has settled down easily on the beachfac due to high infiltration process and this situation put the beach in the accretion mode.
Figure 6. Groundwater table in well no. 2 and tidal elevation
Figure 6. Groundwater table in well no. 2 and tidal elevation
Related topics:
GeologyCoastal EngineeringCoastal GeomorphologyHydraulic and HydrologyCoastal HydrogeologySwash Zone
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