Suitability of Water from Tropical Epikarst Spring for Irrigation in the Gunungsewu Karst Area, Indonesia

Abstract

Epikarst springs which are dominated by diffuse flows with undeveloped conduits commonly have hydrogeochemical characteristics that are strongly influenced by water-rock interactions. Gedong Spring is an epikarst spring in the Gunungsewu Karst Area, Java Island, Indonesia, which functions as the main source of irrigation water for the surrounding paddy fields. This research was conducted due to the importance to analyze further investigations to determine whether the hydrogeochemical characteristics of the Gedong Epikarst Springs were suitable for agricultural purposes. Therefore, this study aims to determine the quality of water from the epikarst spring temporally which is used for agricultural irrigation, especially rice fields. The study was carried out for one year with sampling intervals of every two weeks. Analysis of water suitability for irrigation purposes was performed using Sodium Adsorption Ratio (SAR), Sodium Percentage (Na%), USSL Diagram, Wilcox Diagram, Residual Sodium Carbonate (RSC), Magnesium Hazard (MH), Permeability Index (PI), Kelly's ratio (KR), and Hardness (CaCO3). Based on the results obtained from nine different methods, it can be concluded that the water from the Gedong Spring has good potential for year-round agricultural irrigation.