Biochar is a known potential for nutrient removal in wastewater. This study focuses on the adsorption of rice-husk biochar to remove nutrients in the form of nitrate, ammonium, and phosphate in the wastewater. Two types of biochar production were used: laboratory-made biochar with variations of...

Flood disasters often occur in Padang City due to rainfalls with high intensity and frequency, and are exacerbated by the city located on a flatter coast up to the steep Bukit Barisan. The mountain of Bukit Barisan is parallel to the Padang shoreline, and the distance between them is relatively close, it’s just about 20 km. The present research focuses on the determination of the significant factors in the assessments of both hazard and vulnerability in flood mitigation in Padang City. The hazard assessment in the present study uses indicators of hydro-meteorological, elevation, slope, land use, and flood-frequency data. Whereas the vulnerability assessment uses indicators of Population density, Settlement density, sex ratio and age group ratio data. The results of the present study show that the most significant factors in flood-hazard assessment in Padang City are the land elevation factor from the sea level and the slope factor especially in the upper reaches of the river. Meanwhile, the factors of density levels of both the settlement and population are crucial in the assessment of flood vulnerability in Padang City.

This research is about numerical simulation to determine the effectiveness of groynes and breakwaters as protective structures for Gandoriah Beach in Pariaman City (West Sumatra - Indonesia) using an existing program. The effectiveness of the protective structure can be seen based on the bathymetry that is formed as a result of this structure performance. In the simulation of the present research, the direction of the incoming waves at the offshore boundary condition is the dominant direction, namely the west direction, with two wave conditions, namely during normal and stormy times. Simulations of morphological changes are carried out in six scenarios. The first three scenarios are for wave simulations under normal conditions with no shore protective structures (scenario 1), with groynes (scenario 2) and with breakwaters (scenario 3). Meanwhile, the second three scenarios are for wave simulation in storm conditions with no shore protective structures (scenario 4), with groynes (scenario 5) and with breakwaters (scenario 6). The simulation results for the 20 days state show that in normal wave conditions, the breakwaters have a fairly good performance for the formation of sedimentation behind the structures so that it is estimated that the formation formed is tembolo. Meanwhile, groyne is only effective to restrain the sedimentation rate along the structures. In the wave simulation during stormy time, there is a dominant current along the nearshore. In this case the performance of the groynes is better than the breakwaters because the groynes can inhibit the rate of erosion along the shore. Due to the use of breakwaters there is erosion behind the structures. Based on the simulation results without shore protective structures, both in normal and storm waves, abrasion and erosion processes occur, so that Gandoriah Beach needs handling.

Batang Anai is a river that crosses through four administrative regions in the West Sumatra Province with a catchment area of about 498 km2. The upstream is a steep topography because it is located in west part of the Marapi mount. While the middle and lower reaches are mild since in the lowlands. The flow empties into the Indian Ocean. These conditions make this river meandering in the middle and lower reaches. The river mouth is influenced by the tide in which resists sedimentation toward the ocean. As a result, the capacity of the river cross-section decreases which eventually causes flooding. In 2013, the lower reach was dredged. In 2015, however, the river mouth was covered back by sedimentation by two-meter height in some points. Bathymetry was measured before and after dredging. This study is conducted to determine a design flood-discharge that caused sedimentation based on the 2015 bathymetry data by simulation using the SMS software, i.e. the RMA2 module for modelling hydrodynamics and the SED2D module for modelling sedimentation. The attention is paid to see both flow patterns and sedimentation profiles. The model scenarios consider by either including or excluding the Batang Kandis flow. Batang Kandis is a tributary of Batang Anai which empties into near its river mouth. The design flood-discharges for simulation are varied according to the return periods of 2, 5, 10, 25 and 50 years. The bathymetry data used for simulation are the 2013 one after dredging. All the simulation results are then compared to the 2015 bathymetry data. The hydrodynamic model in which the Batang Kandis flow included gives velocities close to those from the field for all return periods. The results of the sediment model using the flood flow with a 5-year return period, that’s Batang Anai is 1060 m3/s and Batang Kandis is 268.5 m3/s, show that the sedimentation profiles are closed to the 2015 bathymetric measurement data.

Overcoming Flood in Batang-Takung Downstream Using Numerical Simulations

Lake Diatas is one of the largest lakes in West Sumatra with a variety of uses that are vulnerable to contamination that could endanger lake organisms. Therefore, the objective of the present study is to describe the vertical distributions of both temperature and dissolved oxygen (DO) in Lake Diatas as an indication of lake quality. The samples of lake water were taken at five points, namely in the middle of the lake, Teluk Kinari, Muara Danau, Gurun Datar and in Tanduk Kecil. Frequency of taking was once a month in October, November and December 2019. Variation in depth for temperature and DO observations was based on the methods of surface-water sampling (SNI 6989.57: 2008). The present study results show that the temperature range at various points with respect to lake depth variation was 20.1 to 25.9 °C with a standard deviation of 1.15 °C, while DO was in the range of 6.2 to 7.9 mg/l. These conditions still met the quality standards of lake water (Governor Regulation No. 24 Year 2010 Class II) where the temperature deviation must be less than 3 °C, and the minimum DO is 4 mg/l. By using statistical method of the two-way ANOVA, it is found that the temperature was significantly different from the time of sampling with a P-value <0.05, but the temperature did not differ significantly based on depth. The sampling time and depth of collection differed significantly for DO at 2 points close to the agricultural land. It can be concluded that the temperature and DO in Lake Diatas were still good because the oxygen content was still sufficient to ensure the survival of lake organisms. In addition, there was no indication of thermal stratification in the lake.