Impact of Shelf Valleys on the Spread of Surface Trapped River Plumes

This study focuses on mechanisms of shelf valley bathymetry affecting the spread of riverine freshwater in the nearshore region. In the context of Changjiang River, a numerical model is used with different no-tide idealized configurations to simulate development of unforced river plumes over a sloping bottom, with and without a shelf valley off the estuary mouth. All simulated freshwater plumes are surface-trapped with continuously growing bulges near the estuary mouth and narrow coastal currents downstream. The simulations indicate that a shelf valley tends to compress the bulge along the direction of the valley long axis and modify the incident angle of the bulge flow impinging toward the coast, which then affects the strength of the coastal current. The bulge compression results from geostrophic adjustment and isobath-following tendency of the depth-averaged flow in the bulge region. Generally, the resulting change in the direction of the bulge impinging flow enhances down-shelf momentum advection and freshwater delivery into the coastal current. Sensitivity simulations with altered river discharges (Q), Coriolis parameter, shelf bottom slope, valley geometry, and ambient stratification show that enhancement of down-shelf freshwater transport in the coastal current, ΔQc, increases with increasing valley depth within the bulge region and decreasing slope Burger number of the ambient shelf. Assuming potential vorticity conservation, a scaling formula of ΔQc?Q is developed, and it agrees well with results of the sensitivity simulations. Mechanisms of valley influences on unforced river plumes revealed here will help future studies of topographic influence on river plumes under more realistic conditions.

Track Deflection of Typhoon Maria (2018) during a Westbound Passage Offshore of Northern Taiwan: Topographic Influence

This study applies a global model (FV3GFS) with stretched resolution of approximately 7 km for simulating Typhoon Maria (2018), which exhibited a sudden northward track deflection when approaching about 150 km northeast of Taiwan. As Maria approached land, the outer cyclonic flow at the western flank of the typhoon is split around the northern part of the Central Mountain Range (CMR) in Taiwan to converge east of Taiwan with the recirculating southerly flow around the southern corner of the CMR. Such strong convergence leads to northward deflection of the west-northwestward-moving typhoon with the stronger wind mainly east of the vortex center. The radial inflow at low levels is intensified south of the vortex center and transports larger angular momentum (AM) inward with the enhanced upward motions and vertical mean AM advection to increase the azimuthal mean tangential wind in the lower-tropospheric eyewall. A vorticity budget of wavenumber-1 decomposition indicates that the track deflection is dominated by horizontal vorticity advection in response to the intensifying flow. Numerical experiments with idealized WRF also support such northward track deflection as westward tropical cyclones approach a mountain range within an offshore meridional distance of about 200 km. The northward track deflection is only slightly amplified as the terrain height is considerably increased, consistent with the real-case simulation. However, the northward track deflection is not increased as the approaching vortex is initialized closer to the northern end of the mountain range, due to the enhanced east–west symmetry of wind structure in the inner vortex.

Topographic influence on landslides characteristics and implication for risk management in upper Manafwa catchment, Mt Elgon Uganda

This study aimed to characterize the topographic effect on landslides attributes and explore the implications on risk management in a tropical mountainous environment. A database was constructed based on landslide inventory from field surveys supplemented by desk research. The topographic parameters were derived from STRM DEM of a 30 m resolution for the study area. The analysis of the data was conducted in Arc GIS 10.5 environment. The relationship between landslides and topographic conditioning factors was analysed using the Frequency Ratio model. Results revealed that most landslides were distributed within the altitudinal range of 1500 to 1800 m a.s.l. on moderately steep slopes (15 o-20o) in concave curvatures (hollows). Shallow slides mainly debris flows and debris slides were predominant. Most slope failures were initiated on mid to upper slope positions in either new or old scars. Some runout depositions of large slides ended in streams thus undermining water quality. The findings on topographic parameters have implications and yet landslide risk management by the local population was generally inadequate. Any efforts toward effective landslide risk management should prioritise greening the sensitive topographic hollows and old scars particularly on mid to upper slope positions.

Topographic Influence On Landslides Characteristics And Implication For Risk Management In Upper Manafwa Catchment, Mt Elgon Uganda

This study aimed to characterize the topographic effect on landslides attributes and explore the implications on risk management in a tropical mountainous environment. A database was constructed based on landslide inventory from field surveys supplemented by desk research. The topographic parameters were derived from STRM DEM of a 30 m resolution for the study area. The analysis of the data was conducted in Arc GIS 10.5 environment. The relationship between landslides and topographic conditioning factors was analysed using the Frequency Ratio model. Results revealed that most landslides were distributed within the altitudinal range of 1500 to 1800m a.s.l. on moderately steep slopes (15 o -20 o ) in concave curvatures (hollows). Shallow slides mainly debris flows and debris slides were predominant. Most slope failures were initiated on mid to upper slope positions in either new or old scars. Some runout depositions of large slides ended in streams thus undermining water quality. The findings on topographic parameters have implications and yet landslide risk management by the local population was generally inadequate. Any efforts toward effective landslide risk management should prioritise greening the sensitive topographic hollows and old scars particularly on mid to upper slope positions.

Study of Calculation of Terrain Correction Using square pattern and sloped triangle Method in Karangsambung Area

Conventional assessments of terrain correction are carried out by laying out transparent paper containing the Hammer chart on topographic maps, then estimating the elevation for each compartment. But this procedure has disadvantages, the number of compartments are too small for area with many topographic variations, and there is a subjectivity from the observer in estimating the compartments height. This research aim to overcome these problems and get more accurate terrain correction value. In this research, estimation of terrain correction carried out using square pattern and sloped triangle method. This method divides the area around the measurement point into a zone containing a square-shaped and triangle compartment. The research start with testing the program by using synthetic data to see the effect of rock bodies on terrain correction value. Then the program was applied to Karangsambung to see the topographic influence around Karangsambung on terrain correction. The program is then applied to gravity data, and the results are compared with calculations using the Hammer chart. Based on the synthetic data test, it was found that the value of terrain correction from a rock body measuring 10 x 10 km with a height difference of 1000 m from the station no longer significantly affects at the distance of 20 km. The topography around Karangsambung in the form of South Seraju Ranges with altitude of 1000 m at distance of 20 30 km gives effect of 0.05 mGal on terrain correction, while the Quaternary Volcano with an altitude of 3000 m at distance of 30 40 km gives effect of 0.1 mGal. The results of applying program at the gravity data show that the use of the square pattern method is able to correct errors from Hammer chart up to 3 mGal. The difference between the calculation of the two methods is getting bigger in the station located at slope area. It happens because estimation of the height difference in slope area is more difficult to do.

Pengaruh Topografi dan Umur Ayam yang Berbeda terhadap Ketebalan Kerabang dan Ph Telur Ayam Ras Petelur

This study aims to determine the effect of topography and age of different breeds of chickens on egg weight and haugh unit. The study was conducted in August 2018, data collection was taken from Amparita Village, Tellu Limpoe District, Sidenreng Rappang Regency, Mario Village Kulo District, Sidenreng Rappang District and Kaluppang Village, Maiwa District, Enrekang District. The study used 135 eggs as eggs. The study used a Factorial Randomized Block Design with three stages of treatment and three repetitions, namely Factor A (Age of chicken 30 weeks, age of chicken 50 weeks, and age of chicken 70 weeks) then Factor B (Topography of lowland, medium and high). The treatment of topographic influence and age of laying chicken showed that the age of different chickens had no significant effect (P> 0.05) on eggshell thickness while the topography greatly affected eggshell thickness (P <0.01). Different age of race chicken has significant effect (P <0.05) on egg pH, and different topography has very significant effect (P <0.01) on egg ph.Keywords: Laying Chicken, Topography, Chicken Age, Shell Thickness and Egg pH

Pengaruh Topografi dan Umur Ayam yang Berbeda terhadap Berat Telur dan Haugh Unit Ayam Ras Petelur

This study aims to determine the effect of topography and age of different breeds of chickens on egg weight and haugh unit. The study was conducted in August 2018, data collection was taken from Keluragan Amparita, Telulimpoe District, Sidenreng Rappang Regency, Mario Village Kulo District, Sidenreng Rappang Regency and Kaluppang Village, Maiwa District, Enrekang District. The study used 135 eggs as eggs. The study used a Factorial Randomized Block Design with three stages of treatment and three repetitions, namely Factor A (Age of chicken 30 weeks, age of chicken 50 weeks, and age of chicken 70 weeks) then Factor B (Topography of lowland, medium and high). The treatment of topographic influence and age of laying chicken showed that the effect of topography had a very significant effect (P <0.01) on egg weight while chicken age did not significantly affect egg weight (P> 0.05). Topography has a very significant effect on Haugh Unit (P <0.01), and chicken age has a significant effect (P <0.05) on Haugh units.Keywords: Laying Chicken, Topography, Egg Weight, Haugh Unit, and Chicken Age