Evaluation of Groundwater Availability for Rice during Period 2018-2022 in Tuban Regency, East Java

Research has been conducted on the deficit, surplus, percentage of groundwater availability, and classification of Oldeman climate type in Tuban Regency, East Java in 2018-2022 to increase rice crop productivity in Tuban Regency, East Java. This process begins with the collection of data, namely rainfall, air temperature, coordinates and height of rain posts, and soil physical data which is then calculated ETC (Plant Evapotranspiration) rice, deficit, surplus, and ATS using the Thornthwaite and Mather methods. The results of data analysis obtained the smallest deficit value of 0.1 mm which occurred in Medalem in June and the largest deficit occurred in Ngimbang in November of 279.6 mm. The smallest surplus of 0.9 mm occurred in Sumurgung in April and the largest surplus of 313 mm occurred in Jenu in January, with 100% groundwater availability which generally occurs in November-April and 0% ATS which occurs in June-September and Oldeman Climate type in Tuban Regency consecutively C3, D3, D4, and E3.