SALTWATER INTRUSION STUDY AT KAPUAS BESAR ESTUARY, WEST KALIMANTAN USING 1-DIMENSIONAL ANALYTICAL METHODS

• Main Author: Aziz, Danke
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/74102
• Institution: Institut Teknologi Bandung

The Kapuas Besar Estuary in West Kalimantan plays a pivotal role in ecological and economic functions for the local community. One of the challenges faced in the Kapuas Besar Estuary is the saltwater intrusion (SWI). SWI has a negative impact on the river ecosystem and the people who rely on the river, especially for clean water and irrigation needs. This study aims to determine the SWI distance variation that occurs in the Kapuas Besar Estuary and watershed using a one-dimensional (1D) analytical model. The data used are estuary geometry, tides, salinity and river discharge data for the period December 2011 to April 2015. The simulation results show that the 1D analytical model is able to predict the SWI distance based on the Root Mean Square Error (RMSE), Percent Bias (PBIAS), and Nash-Sutcliffe Efficiency (NSE) values between the analytical model results and observed data ranging from 0.82-1.70 psu, 1.64-2.85%, and 0.96-0.99 respectively. The model proves applicable during the May-October period, subject to the condition that the river discharge remains below 3,200 m3/s. During November-April, the model underestimates actual distance. Simulations show SWI distance increasing from December to June by 49 km, then decreasing from July to November by 38 km. The minimum SWI is in May (1 km from estuary mouth) with a discharge of 8,853.82 m3/s. The maximum SWI is in June (71 km from estuary mouth) with a discharge of 1,034.55 m3/s (near Kapuas Kecil bifurcation point).