Modelling reservoir dynamics in a data scarce semi-arid region

In order to evaluate measures to increase water availability in and around reservoirs it is necessary to have reliable reservoir water storage models. For that reason, it is necessary to assess the validity of these models. The aim of this research is to do this assessment of two models in data scarce semi- arid regions. The Nakamb ́e catchment is used as a case study. The study covers important aspects of hydrological modelling, such as model input (data) selection, hydrological model choice, calibration, model performance testing, parameter sensitivity, and reservoir water storage simulation.For the selection of the optimal model forcing data diverse precipitation products are reviewed: CHIRPS, ERA5, and local measurements. Among the evaluated datasets, CHIRPS emerges as the superior choice validated against the local measurements. With respect to the potential evaporation, the combination of ERA5 and local measurements results in the most suitable potential evaporation data, leveraging the temporal and spatial aspects of ERA5 and the absolute values of the local measurements.Comparing a lumped hydrological model (HBV) with a distributed model (SBM Wflow) in simulating river discharge reveals that the HBV model outperforms its counterpart in simulating discharge. This contrast in performance is attributed to potential overparameterization in the Wflow model, coupled with the complexities of parameter estimation in data-scarce areas. The HBV model, while bearing simplifications, benefits from a more comprehensive calibration process. The model performance is strongly influenced by the calibration efficiency, where the significantly shorter simulation time of the HBV model facilitates an extensive Monte Carlo sampling-based calibration, in contrast to Wflow’s time consuming manual parameter adjustment.Additionally, the sensitivity analysis showed that in the HBV model, the parameters affecting actual evaporation are the most sensitive one. This emphasizes the importance of accurately simulating this component for the proper model performance. The Wflow model exhibits strong equifinality due to the many parameters within the model. The complexity of this model made it impossible to test all parameters and therefore only some parameters are tested.Both reservoir water storage models studied, the HBV Reservoir Water Storage Model (HBV RWSM) and the Wflow reservoir module, can effectively simulate reservoir water storage fluctuations, although they differ in how the components are calculated. Due to data limitations, it is impossible to determine which, if any, of the models is correct. However, based on the downstream discharge the HBV RWSM displays a more promising performance.In conclusion, the HBV model outperformed the SBM Wflow model in simulating discharge due to its simplicity and ease of calibration. Sensitivity analyses highlighted the significance of accurately representing actual evaporation. Both water balance models, the HBV RWSM and the Wflow reservoir module, performed similarly concerning the NSE values. The fluxes contributing to the water balance in the two reservoir water storage models differ significantly. The lack of data on these fluxes makes it impossible to determine which models performs best. Data limitations remain a significant hurdle in model evaluation, emphasizing the need for additional data collection, particularly upstream and downstream of the reservoir, to enhance reliability and reduce uncertainties.Water Managemen

Pantai Project

For the past years large quantities of plastic waste have been accumulating on the beaches in Southwest Bali. This has economical, environmental and health implications in this area. This event mainly occurs between December to March. The objective of this report is to map the plastic waste problem in Southwest Bali and look for efficient solutions to mitigate plastic washing ashore at its beaches. To reach this objective the main drivers for the plastic waste accumulation are investigated. Furthermore, research on the distribution and composition is provided. The local waste management system and its shortcomings are assessed. Personal waste treatment is analyzed using a survey. Background information on the problem was gathered with the use of a literature study and area analysis. A conceptual model is introduced to reach the research objective. This conceptual model is a schematization, in order to better understand the research area and the behavior of the plastic in the case area. In order to quantify the model further research is required. This consist of four research disciplines. Namely, ocean, boundaries and bottom; river measurements; beach measurements and waste management & social studies. Via literature studies and interviews, research on the ocean, boundaries and bottom is performed. Three rivers where measured over the course of 2 months. Research was done to determine river parameters. Plastics were caught by a manta trawl and visual waste counting was performed to understand the plastic flux in rivers. Research on the beaches was done on the composition and quantity of various plastic sources namely oceanic, terrestrial and river inputs. Via interviews with local stakeholders the waste management system the case area is mapped. With the use of a survey, personal awareness and motivation among plastic pollution is analyzed. The plastic accumulation is largely dependent on the climate and local waste treatment. As waste management facilities are lacking and local awareness and motivation is limited, large quantities of plastic enter local rivers. Together with increased rain conditions large quantities of plastic end up in the ocean. Wind then transports plastic waste towards the beaches. This debris is mainly 'pushed' towards the beaches in Southwest Bali due to the coastal shape. During the research single use plastics are found to be the most common plastic type. Four solutions are proposed to reduce the plastic accumulation in the beaches of Southwest Bali. Intercepting plastics in rivers prevents further dispersion into the ocean and thus limits plastics accumulating on the beaches. Improved waste management could tackle the source of plastics pollution and reduce the amount of plastics entering our nature. Increased education on plastic pollution can result in improved personal waste management, especially in remote areas. As a lot of stakeholders are involved in the problem an improved communication network is desired in order to achieve a combined goal and work more efficiently.Pantai Project | Multidisciplinary ProjectCivil Engineering | Hydraulic Engineerin