| Penulis/Author |
ESTHER E. TANTAMA (1) ; Dr.rer.nat Ir. Doni Prakasa Eka Putra, S.T., M.T., IPM. (2); Ir. Gayatri Indah Marliyani, S.T., M.Sc., Ph.D., IPM (3) |
| Abstrak/Abstract |
The community living in the Randublatung Basin and its surroundings (Grobogan, Blora, and Bojonegoro
Regencies) uses groundwater for daily needs and agriculture activities. Groundwater is extracted from dug wells as existing shallow groundwater resources. Therefore, it is crucial to identify the origin of shallow groundwater in the Randublatung basin and its surroundings to understand its sustainability. This research aims to analyze the origin of shallow groundwater based on stable isotopes (18O and 2H). The method to analyze the stable isotopes (18O and 2H) uses the Liquid-Water Stable Isotope Analyzer LGR (Los Gatos Research) DLT-100. The water samples representing groundwater, surface water, and rainwater are taken from Randublatung Basin and its surroundings. There are five samples from dug wells, six rainfall samples, and two samples of Bengawan Solo River collected in the research area. The result shows that the composition of stable isotopes in shallow groundwater is between -6.92‰ to -3.83‰ of δ18O and δ2H is between -41.30‰ to -24.00‰. Meanwhile, the rainwater isotopes are between -5.89‰ to -5.13‰ of δ18O and -38.00‰ to -30.60‰ of δ2H. While in the Bengawan Solo River, samples are between -6.23‰ to -6.27‰ of δ18O and -43.20‰ to -43.00‰ of δ2H. The equation of Local Meteoric Water Line (LMWL) is δ2H = 7.93δ18O + 10.19. Through the LMWL, it indicates that shallow groundwater originates from rainwater but also deeper groundwater systems. Therefore, the shallow groundwater in the Randublatung Basin and its surroundings will remain available during the rainy and dry seasons. |
