Evaluation of water balance in the Jaro Irrigation area, Tabalong Regency, South Kalimantan Province

In the Tabalong Regency, South Kalimantan Province, many irrigation networks have not worked optimally. The Jaro Irrigation Area is one of these irrigation networks, the majority of available fields are planted with Paddy. Evaluation of irrigation water to irrigate paddy fields is very important for optimal growth and development of paddy. The objective of this research is to evaluate the water balance, the potential area for paddy field area development can be obtained by applying the optimal crop pattern. Analysis of the rainfall data used in this study with statistical analysis in the form of validation and correction of rainfall data. Rainfall data was obtained from the Tropical Rainfall Measurement Mission (TRMM) and the Meteorology, Climatology, and Geophysics Agency (BMKG) Jaro Station in the period 2013-2019, the data using statistical analysis obtained a correlation coefficient and regression equation. The regression equation is used to obtain the corrected rainfall value which will be used in the hydrological analysis. Water requirement analysis with several cropping pattern scenarios. Calculation of evapotranspiration using the Modified Penman method. The F.J Mock method is used to develop the discharge value. Dependable discharge, 80%, is used to estimate water availability. Furthermore, an evaluation of the water balance is carried out for each scenario, and the result of information on surplus or deficit conditions can be obtained each month. Analysis of water demand discharge based on planting scenarios is divided into three. First Scenario with a high-yield paddy - a high-yield paddy according to the existing conditions at the research location. The second scenario is with a high-yield paddy - high-yield paddy - beans and the third scenario is with a high-yield paddy - paddy. According to the results of the water balance evaluation for the three scenarios, the potential area can be reached up to 900 ha from 850 ha with the chosen crop pattern in scenario number 2.