No abstract

The efficacy of a water quality management strategy highly depends on the analysis of water quality data, which must be intensively analyzed from both spatial and temporal perspectives. This study aims to analyze spatial and temporal trends in water quality in Code River in Indonesia and correlate these with land use and land cover changes over a particular period. Water quality data consisting of 15 parameters and Landsat image data taken from 2011 to 2017 were collected and analyzed. We found that the concentrations of total dissolved solid, nitrite, nitrate, and zinc had increasing trends from upstream to downstream over time, whereas concentrations of parameter biological oxygen demand, cuprum, and fecal coliform consistently undermined water quality standards. This study also found that the proportion of natural vegetation land cover had a positive correlation with the quality of Code River’s water, whereas agricultural land and built-up areas were the most sensitive to water pollution in the river. Moreover, the principal component analysis of water quality data suggested that organic matter, metals, and domestic wastewater were the most important factors for explaining the total variability of water quality in Code River. This study demonstrates the application of a GIS-based multivariate analysis to the interpretation of water quality monitoring data, which could aid watershed stakeholders in developing data-driven intervention strategies for improving the water quality in rivers and streams.

Landslide is one of the most dangerous hazards worldwide. It could be caused by several factors and could have a massive destructive impact on the environment. A landslide event occurred in one of the urban cities in Indonesia. In the middle of 2002, a landslide disaster due to rainfall occurred in the Ciliwung River's floodplain, precisely in the South Jakarta area. The landslide profoundly affected large areas of the region and seriously injured many people. Several circumstances that could trigger landslide occurrences are the building load in the settlement area around the river, increase in the rainfall intensity, slope, and soil characteristics in the Ciliwung River area. This research proposes a combination of nonstructural and structural disaster mitigation methods for water-related landslide by investigating the safety factor (SF) of the river bank's slope in one of the impacted sites, i.e., the area under the main bridge of Grand Depok City regency. This site is located in the boundary area between Depok City and South Jakarta. The authors simulate analytical and numerical modeling to estimate the SF of the slopes. This research concludes that the minimum SF in the analyzed location is recognized as a safety criterion for society. The condition becomes less secure when an earthquake occurs. Furthermore, high rainfall intensity could become the worst scenario that generates considerable damage. The proposed structural mitigation for river bank with anchor or snail increases the SF. However, this reinforcement program is not recommended because of its high cost and ineffectiveness in solving problems. Hence, green infrastructure (GI) is highly suggested for nature-based mitigation to prevent rainfall-triggered landslides in the Ciliwung River area. The authors conduct the preliminary design of the study and recommend further analysis of GI or soil bioengineering to ensure its effectiveness and applicability in the research area.

No abstract

This research uses Resource Modelling Associate (RMA) program to conduct a two-dimension model of Agathis Lake to analyse velocity and sediment transport distribution. The main programs are RMA-10 for velocity distribution and RMA-11 for the pollutant distribution. The sediment transport focuses on total suspended solids (TSS) pollutant. The research aims to construct total suspended solid model. Firstly, RMA Generation produces mesh of Agathis Lake. Next, RMA-10 and RMA-11 would perform both velocity and TSS simulation model to represent the actual condition. This research still gives temporary result due to limited sampling data. Calibration analysis of the model is needed to make the result of the program more accurate and more representative to the real condition.

There have been attempts to simulate meander dynamics (Langbein and Leopold 1966, Oodgard 1989, Campoerale et. al 2007, da Silva and El-Tahawy 2008, Duan and Julien 2010, Blanckaert and de Vriend 2010, Esfahani and Keshavarzi 2011). Meandering geometry is complex phenomena (Chanson 2004, Wu 2008), this would include the dynamics of flow properties and of morphology. Simulating meander flow dynamics is mostly popular using either Finite Element Method (FEM) or Finite Volume Method (FVM) where are based on Eulerian description, and based on stationer grid-based methods (Wormleaton and Ewunetu 2006, Wu 2008, Duan and Julien 2010, Gomez-Gesteira et. al 2010). As such this model is lack of capability in simulating the dynamics of meander morphology; much effort is put through to overcome this issue with such as Smoothed Particle Hydrodynamics (SPH), Boundary Element Methods, Arbitrary Lagrangian Eulerian, etc. This paper has two objectives; to identify meander flow characteristics and sediment transport distribution patterns, and to simulate meander flow characteristics and sediment transport distribution patterns using FEM. This study has identified that the key of dynamics of flow characteristics are helical flow and coherent structures, and the key of dynamics of transport characteristics are erosion-deposition zone patterns. The finite element model using in this study, RMA has shown its capability to simulate the meander key characteristics above, for small deflection angles (30°) location of maximum erosion-deposition zones near the crossover of the sinuosity, for intermediate deflection angles (70°) location of maximum erosion-deposition zones between the crossover and apex of the sinuosity, and for large deflection angles (110°) location of maximum erosion-deposition zones near the apex of the sinuosity, these are agreed with experiments of Odgaard 1989, da Silva 2006, da Silva et. al 2006, and Esfahani and Keshavarzi (2012). These results can be used as a reference to develop a method to model meander morpho-dynamics.

Abstract-Lakes in Universitas Indonesia

The several things to fulfil human needs are water resources, like household, laundry, industry and agriculture, the activities that reduce the availability of ground water and produce waste which makes the quality of river water decrease. This research was conducted in a catchment area outside University of Indonesia which is included in the Ciliwung watershed area which aims to increase the carrying capacity of water resources by carrying out a Water Governance approach by considering 3 aspects Place, People and Policy. The Place aspect or technical recommendations was an approach using the concept of WSUD (Water Sensitive Urban Drainage), the green infrastructure used are bioretention and constructed wetland by using ArcGIS, GitBola and SWMM for simulations of improving air quality and volume of runoff water reduction. The People aspect or stakeholders are conducted in-depth interviews or snow ball interview with stakeholders and residents in the catchment to find out responses to green technology recommendations and stakeholder responses. The policy aspect makes appropriate policy recommendations that regulate the management of liquid and solid waste so as not to pollute water bodies, to improve the condition of catchments around University of Indonesia, making policy recommendations based on the technical aspects of green technology proposals, community or stakeholder responses and also based on existing policies or regulations from the central to the regional level.