Scour Depth Estimation on Abutment With HEC RAS and Some Empirical Equation

Toe Scour around abutment will be very dangerous and cause loss of stability on the bridge. The case of structure failure on Batang Kalu bridge in Korong Pasa Usang Nagari Kayu Tanam, Padang Pariaman Regency on Monday (10 December 2018) is a clear example of toe scouring. A case study of toe scour was on the Batang Kalu River bridge structure has been carried out. Rainfall data closest to the study location, Kandang Empat Station was used to minimize the errors in the calculation of flood discharge design. Numerical modeling with HEC RAS and scouring estimation with some empiric equation was conducted to predicting scour depth on abutment. Simulation results show scour depth results to an average of 2.731 m and close to the scour depth that occurred in the field (2.83 m). Results showed that the local scouring in the Batang Kalu River bridge structure can be suspected as the influence of the increasing river steepness. Discharge that is triggered by heavy rain with a long duration and increased river flow velocity due to steepness has the potential to create a very intense scouring. Increasing of steepness may have been caused by sand mining activities in the upper reaches. Further studies are needed to see the potential slope changes due to exploitation in the Batang Kalu River upper reache

Pemanfaatan Bahan Limbah Pembangkit Listrik Tenaga Uap Pada Campuran Beton K-225

Fly Ash is a waste material from coal burning at thermal power plant. Power Plant Sijantang produces ± 600 tons per day and it is an environmental problem in the area. In this study, the waste fly ash substituted into concrete K-225 or fc'=19.04 MPa amounted to 0%, 5%, 10%, 15%, 20%, 25% and 30%. Results optimum compressive strength at 5% substitution. After that the additive is added Sikamen NN 0.3%, 1.3% and 2.3%.The addition of 2.3% additive produces compressive strength of 298.59 kg / cm2 very much required at 225 kg / cm2. On the addition of additive 0.3% age 28 day compressive strength of 279.19 kg / cm2, the larger the required amount of 225 kg / cm2. Without the addition of additive, compressive strength of 218.35 kg / cm2, less than the required amount of 225 kg / cm2. So for concrete K-225, mix with the substitution of 5% and 0.3% addition of additives can be used as a standardmixture

Analisis Kapasitas Penampang Sungai Batang Mahat Terhadap Besaran Debit Banjir Menggunakan Pendekatan Model Matematik

Batang Mahat watershed has a total area of 772.87 km2 with a total length of the main rivers around 44.06 km. With the topographic condition on the upstream side was a mountainous terrain and steep slope relatively into downstream. The problem was can be classified as river siltation, narrowing of the river, and riverbank erosion that has caused flood and threaten a public facilities. Numerical simulations using the application of the HEC RAS model were conducted to determine the capability of the river storage capacity into various discharge values. The results of the analysis show that with the discharge condition Q2 there has been flood caused by the high surface elevation of water that was overtopping of the left and right embankments elevation at the upstream and midstream areas. The water surface elevation will increase with the increasing of flood discharge. River normalization efforts with additional depth and widening of river channel were recommended

THE UTILIZATION OF THE DRONE AND SONAR FOR FLOOD DESIGN IN CONSTRUCTION ERA 4.0.

Climate change caused by global warming has become an interesting study in recent years which is indicated by an increase in seawater temperature, sea-level rise and flooding. In the research area at Jabon District Sidoarjo was affected by sea flood in December 2017 within material loss about 5 billion rupiahs. This research aims to utilise the recent technology in construction era 4.0 with photogrammetric techniques using Unmanned Aerial Vehicles and sonar tools to analyse flooding events by making bathymetry maps with low and affordable costs in watersheds, including the effects of tides was also carried out. The method in this research was carried out the right photogrammetric technique and processed to provide a 3-dimensional appearance. Also, sonar tools use as benchmarks with high accuracy in the bathymetry mapping and river sedimentation occurrence. The outcome of this study proves that the watershed at the study site was a tidal influence on the condition of the highest high water level, which caused seawater to pass through the river bank as high as 10 centimetres. Fur further to overcome this problem, it recommends to do dredging of the riverbed, and the appropriate construction of river banks/embankments are higher and more durable

The Investigation of 1997 and 2015 El Nino Events in West Sumatera, Indonesia

The 1997, 2010, and 2015 El Nino events have been recognized worldwide as a primary factor of decreasing biomass productivity. Its effects occur at farm as well as regional scale. Yet some still think that the effect is only perceived by farmers directly. We proposed a simple method to describe that its effect at catchment scale is not negligible. For this purpose, we analysed an upstream catchment in West Sumatera that normally receives high rainfall up to 5000 mm per year. This catchment is in pristine condition due to its status as national park. We used satellite and ground monitoring systems i.e. rainfall and stream water level. Satellite data such as DEM (Digital Elevation Model) used to trace river networks is acquired from ASTER GDEM in 30 m resolution. To monitor vegetation health, we used NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index) on board MODIS (MODerate resolution Imaging Spectroradiometer) Terra (daytime) MOD13Q1 (250 m resolution). Catchment delineation was performed using local land use map. Time series of EVI and NDVI was processes for year 2015, comprising 23 datasets. Rainfall data from year 1980 to 2012 from 9 stations and water level at the main river were analysed. We found the trace of 1997 El Nino very clearly through rainfall anomalies at all stations. As for the 2010 event, the pattern was not consistent across all rainfall stations. The 2015 event was not imminent until late October 2015. Throughout the year, NDVI remains above 0.8. In late October, maximum NDVI dropped below 0.4. This coincides with very low water level in the stream. The same pattern was also found in two neighbouring catchments with similar land use, Kuranji and Air Dingin, and Tampo catchment. This proves that the 2015 El Nino did not only threatens farmers, but also other aspects that depend on vegetation health and stream flow. Both methods are proven to be robust and may be used as an alternative way to monitor vegetation health and the impact of global climate change for ecology and water management such as domestic water use, irrigation and flood control

Kajian Terhadap Unjuk Kerja Bangunan Pengaman Pantai Dengan Penerapan Simulasi Numerik One Line Model

With the position on the west coast region of Sumatra, Padang beach facing directly to Indian Ocean that have potentially threat by the ocean waves that relatively give effect to changes in the coastline. This study was conducted to evaluating the performance of existing coastal protection structure to restrain the rate of erosion as a result of the influence of hydrodynamics process. Condition that reviewed was in form of distance shoreline as simulation results to initial reference line before. One Line Model was conducted to get shoreline change in each time step calculation. Model consists of two conditions, with the absence of coastal structures and with structure respectively. The simulation result show that potential erosion occurs at Batang Arau river mouth with no protection structure. Large erosion predicted around 59.04 meters from the shoreline position early. With coastal protection, model result obtained sedimentation of 7.33 meters coastline from its initial position. This occurs at a distance of 475 meters from the boundary domain. Modeling results also showed erosion is 18.39 meters at a distance of 250 m from the boundary domain. This is likely due to the limited modeling conditions that without reviewing of littoral transport direction that occurred in perpendicular to the coast. Result study show that the presence of a groyne in Padang coasts looks already quite effective in defense of the shoreline of the littoral transport direction, however the installation of groins seemingly did not give significant meaning in the addition of the coastlin

Model Numerik 1D Penggerusan Endapan di Mulut Muara dengan Metode Beda Hingga

Sedimentation at estuary river have potency to cause floods because the narrowing of estuary as outlet. Sedimentation process can be caused by the so small river discharge at dry season so that cannot to flushing the sediment that happened at estuary mouth. When the rains arrive, river discharge which starting to big shall no long castaway to sea freely, so that causes floods in headwaters. Numerical simulation by using finite different method with Preissmann implicit scheme conducted to see ability of river discharge in early the rains to flushing the sediment in estuary mouth. Simulation was done at river with sediment elevation at + 4.00 m in estuary mouth. Boundary condition in the form of discharge hydrograph in early the rains at upstream boundary and also critical water surface elevation in sediment top and sea level at downstream boundary applied at model to see behavior of sediment transport and change of profile at bottom channel that happened. Simulation result show with 24 hours floods charge in early the rains, sediment volume of flushed equal to 20,52 %, with elevation reside at + 3,179 m. Sediment will fully under sea-water face after 9 days simulation. Change of upriver discharge and tidal elevation at downstream will influence to speed of stream that happened. By the end of simulation, the bottom profile of channel influenced of tide

Pemanfaatan Bahan Limbah Pembangkit Listrik Tenaga Uap Pada Campuran Beton K-225

Fly Ash is a waste material from coal burning at thermal power plant. Power Plant Sijantang produces ± 600 tons per day and it is an environmental problem in the area. In this study, the waste fly ash substituted into concrete K-225 or fc’=19.04 MPa amounted to 0%, 5%, 10%, 15%, 20%, 25% and 30%. Results optimum compressive strength at 5% substitution. After that the additive is added Sikamen NN 0.3%, 1.3% and 2.3%.The addition of 2.3% additive produces compressive strength of 298.59 kg / cm2 very much required at 225 kg / cm2. On the addition of additive 0.3% age 28 day compressive strength of 279.19 kg / cm2, the larger the required amount of 225 kg / cm2. Without the addition of additive, compressive strength of 218.35 kg / cm2, less than the required amount of 225 kg / cm2. So for concrete K-225, mix with the substitution of 5% and 0.3% addition of additives can be used as a standardmixture

Studi Sedimentasi di Sungai Batang Lampasi Sedimentation Study at Batang Lampasi River

BatangLampasi River was located in Talawi village, Nagari Koto Nan GadangPayakumbuh, about 30 km from Bukittinggi, with 48.19 km river length and around 226 km2 Cathment Area. The river flow carries a lot of sediment material, causing siltation on the riverbed which causes the river to overflow in the surrounding area. Sediment transport was triggered by Lampasi watershed erosion, that especially in the upstream section and settling on the riverbed. Prediction of depth decrease caused by sedimentation was conducted. Theoretical flood discharge determined used Nakayasu method. Sediment yield caused by land erosion determined by USLE equation and will compared with total sediment transport that calculated for 5 years return period with Yang's, Engelund Hansen, Ackers and White's methods. HEC-RASS 4.0 was used to find the high of flood water level and also as input hydraulics term to calculating transport sediment. The equivalent value approaching sediment yield was Yang's method where the sediment transport value is 21294,763 tons / year with sediment thickness of 27.24 cm / year. With these deposits thickness we can see from HEC-RASS 4.0 modeling the elevation of high flood water during normal conditions and the presence of thick sediment deposits