ANALYSIS OF NITROGEN DYNAMICS IN JATILUHUR RESERVOIR BASED ON HORIZONTAL SEGMENTATION MODELING

• Main Author: ASHURI , AMALLIA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25440
• Institution: Institut Teknologi Bandung

<p align="justify">Nitrogen dynamics in the reservoir occur due to nitrogen transformation as well as the inclusion of nitrate loads from surface runoff from the catchment area and fish cages in reservoir. High nitrogen concentration in water bodies can cause health problems and it also become one of the factors that can trigger eutrophication in reservoir. An effort that possibly done to overcome these problem was by using a computer model. There were two computer models that used in this study which is surface runoff model and reservoir water quality model. The implementation of the water quality model was approached by horizontal segmentation of the reservoir. In this study, nitrogen species that will be observe was nitrate as the most stable species among other nitrogen species. Runoff simulation results show that nitrate concentration in the surface runoff had a strong correlation with the catchment area land use. Furthermore, reservoir water quality simulation results show that temporally nitrate concentration in the reservoir is influenced by climatic factors. While, spatially it was influenced by the number of fish cages compared to nitrate inputs that come from the catchment area. In addition, simulation of improvement scenario, such as fish cage reduction, fish cage relocation, and the combination of reduction and relocation of fish cages, was conducted. The improvement scenario simulation results show that reduction of nitrate concentration was equivalent to fish cages reduction. Whereas, fish cages relocation lead to the increasing of nitrate loads up to 97 times from the initial value at the target location of the fish cage relocation but the nitrogen loads decline up to 82% at the fish cage initial location. In addition to the three improvement scenarios, the scenario of hypolimnion withdrawal technique with three variations of hollow jet discharge was also done. Hypolimnion withdrawal scenario simulation results show that the increasing of hollow jet discharge by 14% has led to increasing nitrate concentration by 8.9% at the last segment of the reservoir, while the increasing of hollow jet discharge <br /> <br /> by 28% has led to increasing nitrate concentration by 20% at the last segment. From the simulation results it could be concluded that the first-order equation does not represent the behavior of nitrate in the water. The other conclusion was fish cages provide a greater contribution to the nitrate load input compared with <br /> <br /> the catchment area. In addition, hollow jet discharge affect nitrate concentration in the reservoir downstream. <p align="justify">