| Abstrak/Abstract |
Residents of the food estate area of Central Sumba Regency have depended on groundwater as their primary water source. Groundwater is mainly used for domestic and agricultural needs, and irrigation is crucial in sustaining agricultural productivity. Groundwater sources in the research area include dug wells, bore wells, and springs. Food estate in the Central Sumba Regency is one of Indonesia’s National Strategic Projects aimed at increasing Indonesia’s food supply, but the surface water is limited. Therefore, groundwater can be used as an alternative irrigation source to meet the needs of the food estate project. The food estate area geologically is in the Waikabubak formation, mainly composed of limestone, forming a karst landscape. Because of the uneven network of caves, conduits, fissures, and pores with varied connections, karst aquifers are typically characterized by a high heterogeneity level, making karst groundwater especially vulnerable to contamination. Hence, understanding karst groundwater quality for irrigation is essential to water management for long- term productivity. The objective of the research is to assess groundwater quality for irrigation purposes. Groundwater samples were collected from various locations representing the research area’s actual conditions. The groundwater samples were collected from 32 locations and analyzed in the laboratory for the concentration of Ca2+, Mg2+, Na+, K+, Cl−, NO3−, SO42-, and HCO4− using Metro Ohm 850 Professional IC (Ion Chromatography). The groundwater quality index for irrigation, such as soluble sodium percentage (Na%), sodium adsorption ratio (SAR), and residual sodium carbonate (RSC), can be estimated from the laboratory result and then compared to The Food and Agriculture Organization (FAO) for irrigation water quality standards. Laboratory results compared to the FAO standard show that all groundwater samples have good quality. The soluble sodium percentage (Na%) calculation of groundwater is mostly classified as excellent, the sodium adsorption ratio (SAR) value of all groundwater samples is classified as excellent, and the residual sodium carbonate (RSC) calculation of groundwater samples is classified as safe. It can be concluded that all the groundwater samples are suitable to use as irrigation water. |
