Analisis Kondisi Hidrologi Daerah Aliran Sungai (DAS) Way Besay dengan menggunakan model Flow Persistence

Hydrological function can be used as tools to assess the hydrology condition of watershed. Hydrological assessment with a simple approach is expected to be a bridge to overcome the problems related with error because the number of suspected input in hydrological models. Flow Persistence Model (FlowPer) which is based on autocorrelation between today and the next day discharge will be able to answer these problems. This model calculates a value that can indicate the behavior of the river flow and provide information about watershed condition. Way Besay watershed (415 km2), Lampung is used to test the FlowPer model ability by comparing three scenarios of land cover change; actual (the real condition), deforestation (describe degraded condition) and reforestation (describe improved condition). There are two main steps in this study: (1) discharge simulation based on three conditions using GenRiver model and (2) Calculation of FP value based on simulation discharge using FlowPer model. The average of the FP value over 31 years of simulation (1976-2006) showed the same value between the actual and the deforestation condition, 0.85. However, the changes of FP value in deforestation condi tion have a tendency to decline over 31 years. Otherwise, the changes of FP value in actual condition has a table tendency. The reforestation condition showed a higher value than actual and deforestation condition, 0.88. This means that the value of FP can be used as assessment tools to assess the hydrology condition of watershed.