EVALUATION OF DIVERSION ALGORITHM FOR SPATIAL DISTRIBUTION OF RUN-OF-RIVER WATER ENERGY POTENTIAL (Case Study: CITARUM HULU WATERSHED)

• Main Author: Putri Purnama, Olivia
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43793
• Institution: Institut Teknologi Bandung

Indonesia is an archipelago that has mountainous relief and very high rainfall of more than 3 meters/year, so it generally has abundant natural resource potential with the largest hydropower energy potential, but still has some areas that have not yet been electrified. Therefore, PLTM is one of the solutions for the supply of electrical energy in the area. To develop a hydropower plant, potential studies are needed first in a series of Pre-Feasibility Study activities. Potential studies require rainfall data to analyze river discharge and topographic data to analyze heads. However, the available observation data is very limited and not spatially distributed. Therefore, this study will utilize global topographic data and hydrological models to create algorithms that are able to predict the distribution of locations that have hydroelectric potential with maximum head potential and reliable flow, so as to simplify most of the stages of the technical feasibility study in the field of hydrology and civil. In a previous study (Arya, D.K., 2017), the Soil and Water Assessment Tool (SWAT) model was used to predict the discharge in a watershed using the Global Forecast System Re-analysis (CFSR) global data input. While the head at a location can be traced from the Digital Elevation Model (DEM) data using a headrace tracking algorithm that minimizes head loss. By evaluating each grid of the carrier channel plan, the optimal carrier channel length that produces the maximum head can be obtained. The great potential on each grid is the product of discharge, head, water density, and gravitational constant. Determination of the most potential points is done by resample which ranks the largest potential to the smallest, then the river grid between the intake and tailrace is the first potential eliminated so that there is no other potential to stem the flow or throw water from or to this eliminated river, and so on. From 35 points of hydropower potential (TPH) that have been predicted from research (Arya, D.K., 2017), 5 points were chosen that can be developed into a PLTM, based on river width, location accessibility, DEM data consistency, energy gradient, and land use. Locations in residential areas and rice fields are considered to be less feasible due to technical obstacles and higher water use priority for irrigated rice fields compared to hydropower. Then the 5 TPHs were analyzed by field investigations when the mainstay discharge probability was exceeded 50% (design discharge) and 90% (firm flow). From the results of the investigation, it was found that the actual and model power comparison values were more influenced by the discharge value, but the improvement that would be done was the head value, because the head algorithm had a more significant influence in predicting the number of TPH, whereas the discharge was only significant at the quantity of power yield from each TPH. Mapping point map of hydropower potential modified algorithm and resample headrace with design debit input 50% chance of occurrence from CFSR Before Correction obtained 274 points with a total power of 562,645 kW, whereas with design input discharge 50% chance of occurrence of CFSR After Correction obtained 101 points with total power146,326 kW spread over the Cikapundung, Ciwidey, Cisangkuy, and Citarum Hulu rivers, and almost coincides with 5 existing hydropower sites and 5 TPH locations in the field of research investigations (Arya, DK, 2017). From the results of the analysis of models modified with existing hydropower, there are 5 points that have an actual and model power ratio that is influenced by the discharge value from SWAT and the other 5 points have a comparison value of the actual power and model that is affected by the head value of the head algorithm. Improvement / modification of algorithm and headline resample that has been done with the Python programming language in this study is only sufficient to provide a preliminary description and identify / spotting the number of potential locations to be developed into hydropower, but because there are still several different head, discharge, and installed power values with the existing location, field measurements must be made, because there are several locations that have interbasin conditions. Interbasin conditions where there is water supletion from other watersheds, as happened in the PLengan, Lamajan and Cikalong hydropower cascade systems, are not discussed in this study, so that of course it will produce a discharge and quantity of power potential that is different from the existing ones. However, what can be compared from the results of algorithm modification in this study with existing hydropower is the quantity of the head value.