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Jagakarsa is one of the districts in South Jakarta that has a rainwater catchment area. Problems arise as a result of the high rate of population growth, which has an impact on changes in land use and increased surface runoff, causing flooding. On the other hand, the absence of clean water provision facilities from the government means that people use groundwater-drilled wells to meet their daily clean water needs. Sustainable groundwater consumption has an impact on land subsidence and vulnerability to groundwater availability. Therefore, it is necessary to carry out research. This research seeks to assess the potential for rainwater harvesting based on field observations. The research was carried out by analyzing rainfall data, field surveys, research program socialization, and community socio-economic analysis. Rainfall is high, with an annual average of 2809.7 m. 98% of respondents use drilled groundwater wells with a wells depth in the deep aquifer layer, and public interest in rainwater harvesting (RWH) technology is high. These show the potential for implementing RWH in the study location. This research is an initial study; for the integrated implementation of RWH, further research is needed after this study.

Modernising irrigation is a top priority in Indonesia, with managing irrigation water supply services effectively and efficiently, particularly in providing value to farmers. Sediment traps are an essential component of the head structure in irrigation. Vortex Settling Desilting Basins (VSDB) have inherent advantages over other types of sediment-removal desilting basins. The experiments were conducted under three different discharge scenarios, and three-dimensional flow velocities were measured. The streamlines and velocity vectors in the horizontal superimposed sections were drawn and analysed then for the incipient motion of sediment. This study presents the results of experimental research that was accomplished in a VSDB to observe the slope orifice chamber with 1:10, 1:5 and 1:2. The method used numerical methods with CFD simulations by Ansys R.21 2020 (student version) to approach geometric shapes then laboratory experiments with a model scale 1:40 prototype to an undistorted 3-D physical model. Comparing the magnitude of the velocity and streamlined path in horizontal sections with the occurrence of secondary in radial sections revealed that the flow in the vortex direction plays a higher role in the removal efficiency of the desilting basin. As a result, by comparing the performance of rectangular shapes with the same hydraulic parameters, the slope orifice chamber of 1:5 is more effective in case of deposition and removal than another slope chamber. Eleven times running, it settled 84.90% of the sediment fraction and left a sediment fraction of 12.10%, higher than the effectiveness of the performance of sediment traps with a rectangular shape. [ABSTRACT FROM AUTHOR]

Modern irrigation schemes are increasingly demand-based, which means that the crop water requirements determine the water flow in a canal. The sediment transport aspect is a significant factor in irrigation development as it determines to a large extent the sustainability of an irrigation scheme, particularly in the case of unlined canals in alluvial soils, and as a trigger in reducing the wet capacity of the irrigation canal. The conventional sediment traps with a rectangular shape, rapidly advancing development, are challenging to construct because they require adequate space. The Vortex Settling Desilting Basin (VSDB) has proposed to replace the rectangular shape with more effectiveness considering the more concise area, deposition rate and removal efficiency, and minimum human resources as an operator. The method uses numerical methods with Computational Fluid Dynamic (CFD) simulations by Ansys R.21 2020 Student to acquire a geometric shape approach, then laboratory experiments with a model scale 1:40 prototype to an undistorted 3D physical model. This study aims to develop a two-dimensional numerical model and the optimal regression equations for determining settling basin dimension and then simulate and compare the efficiency of the selected settling basins. The VSDB shape is slimmer at 42% than the rectangular shape by optimizing the slope orifice chamber. As a result, by comparing the performance of rectangular sediment traps with the appleto- apple hydraulic parameters and sediment variables, the results obtained based on deposition performance increased from 69.12% to 84.90% and flushing performance by leaving the minimum sediment fraction increased from 53.33% to 87.90%. [ABSTRACT FROM AUTHOR]

This study proposes hybrid models to solve the Colebrook–White equation by combining explicit equations available in the literature to solve the Colebrook–White equation with an error function. The hybrid model is in the form of f H = f o − e A.   f H   is the friction factor value f predicted by the hybrid model, f o is the value of f calculated using several explicit formulas for the Colebrook–White equation, and e A is the error function determined using the neural network procedures. The hybrid equation consists of a series of hyperbolic tangent functions whose number corresponds to the number of neurons in the hidden layer. The simulation results showed that the hybrid models using five hyperbolic tangent functions could produce reasonable predictions of friction factors, with the maximum absolute relative error (MAXRE) around one tenth, or ten times lower than that produced by the corresponding existing formula. The simplified hybrid models are also given using four and three tangent hyperbolic functions. These simplified models still provide accurate results with MAXRE of less than 0.1%. [ABSTRACT FROM AUTHOR]

This study proposes seven equations to predict the settling velocity of sediment particles with variations in grain size (d), particle shape factor (SF), and water temperature (T) based on the artificial neural network procedure. The data used to develop the equations were obtained from digitizing charts provided by the U.S. Interagency Committee on Water Resources (U.S-ICWR) and compiled from the measurement data of settling velocity from several sources. The equations are compared to three existing equations available in the literature and then analyzed using graphical and statistical analysis. The simulation results show the proposed equations produce satisfactory results. The proposed equations can predict the settling velocity of natural particle sediments, with diameters ranging between 0.05 mm and 10 mm in water with temperatures between 0 °C and 40 °C, and shape factor SF ranging between 0.5 and 0.95. [ABSTRACT FROM AUTHOR]

The Upper Citarum River Basin is the main catchment area of the Saguling Dam, the most upstream of three cascade dams in the Citarum River Basin. During the last 30 years, rapid economic development has led to an increase of water extraction and land conversion from green area to developed area. Also, evidence of climate change can clearly be seen from the climatological records of a number of climatology stations in this basin over the last few decades. In this study, the effect of anthropogenic and climate change in the Upper Citarum River Basin river discharge was simulated using the Sacramento Catchment Model. Historical river discharge, rainfall, climatology, and land cover from 1995 to 2009 were used for model calibration and verification. The multi-model mean monthly rainfall and the temperature projection taken from Coupled Model Intercomparison Project 5 (CMIP5) for the RCP6 and RCP8.5 climate change scenarios were statistically downscaled and used as input for a simulation of future river discharge from 2030 to 2050. The result showed that the combination of anthropogenic and climate change may result in a significant decrease of low flow in the Upper Citarum River Basin. This study underlines the importance of land cover and climate change factors for future infrastructure planning and management in the Upper Citarum River Basin. [ABSTRACT FROM AUTHOR]