Implementation of Hydrological Model for the Malino Catchment Area in South Sulawesi Province, Indonesia

In South Sulawesi, the development of irrigation may be hindered by the continuing limitations and inadequacies of hydrological data. It is well known that the rainfall monitoring station is more extensive than the river flow monitoring station. Therefore, the Malino Catchment Area was selected to illustrate the theory of four tank components. The 1st tank (tank A) has two horizontal outlets ( Q a 1 and Q a 2 ) and one vertical outlet ( I a ); the 2nd tank (tank B) has one horizontal outlet ( Q b ) and one vertical outlet ( I b ); the 3rd tank (tank C) has the same conceptual structure as tanks A and B; and the 4th tank (tank D) has only one horizontal outlet ( Q d ). To ensure that the tank model represents vertical and horizontal flows in a watershed region, the flows ( Q a 1 , Q a 2 , Q b , Q c , and Q d ) are predicted to accumulate in one flow, more or less, and must equal the measured discharge ( Q o ) at the specified time. Rainfall and evapotranspiration data are required to calculate this model. The 264.55 km 2 (25902 ha) research area has an elevation range of 400–2400 masl. The findings for land use are dominated by plantations (41.01%), forests (40.79%), rice fields (15.44%), and residential areas (0.96%). In the calibration of the tank model, R 2 is evaluated at 0.560% (good) and Nash–Sutcliffe efficiency is evaluated at 0.526% (good) to ensure that the model can represent the distribution of water flow components. Additionally, the measurements for the total water flow ( Q total ) were 13702 m 3 /y with a total rainfall of 3996 mm/y. Furthermore, surface flow accounts for 77.26% of the total runoff water, while intermediate flow accounts for 20.25%.