Hydrological & hydrodynamic modelling of the Baliem River in Highland Papua, Indonesia

Abstract

The hydrology of the Baliem River in Highland Papua, Indonesia, has never been previously studied, despite its importance to the local populace. In this study, we addressed this by modelling the river at two locations (also known as pour points) near Wamena and Ilunggume in Highland Papua. We first delineated the watersheds for these pour points in ArcMap to characterise their attributes. Thereafter, we generated simulated river discharges at these pour points with meteorological data in the Génie Rural à 4 paramètres Journalier (GR4J) rainfall-runoff hydrological model. Lastly, we used these simulated discharges to conduct coupled 1-dimension-2-dimension (1D-2D) hydrodynamic modelling in the Hydrologic Engineering Centre-River Analysis System (HEC-RAS) software.

This study saw varying degrees of success for the different aspects. Watershed delineation successfully provided us with valuable information on the watersheds’ attributes, such as their areal coverages, total stream lengths, and drainage densities. However, the GR4J hydrological model was only partially successful. While this model simulated discharges at the pour points as intended, these values could not be calibrated due to the lack of observed ground discharge data, resulting in high degrees of uncertainty. This uncertainty was further propagated into the hydrodynamic models in HEC-RAS, which ultimately generated less-than-satisfactory results that failed to accurately model the river’s behaviour.

Although this study saw limited success, it has established the foundations for further hydrology-related work along the Baliem River. Should better meteorological and ground data be accessible, there is great potential for enhancing our understanding, and appreciation, of the region’s hydrology.