Land use change effect on river discharge of the way Pengubuan watershed, Sumatra_Indonesia.

The Way Pengubuan Watershed is a tributary of the Way Seputih watershed which is administratively located in Central Lampung Regency, Lampung Province, Indonesia. Land cover changes are closely related to the hydrological characteristics of the Way Pengubuan Sub-watershed area. This study aims to determine the impact of land cover change on surface runoff coefficient and water discharge in the Way Pengubuan sub-watershed area, Indonesia. Data was collected in the form of rainfall data, river discharge data, and water level data. Land cover data were identified through the interpretation of Landsat 5.7 and 8 imagery in 2014-2017, and its contribution to surface flow coefficient was analyzed using multiple linear regression models. The results also show that the total rainfall [RAIN] has decreased from 2,921 mm/year to 2,525 mm/year. Likewise, the river discharge [DISC] which in 2014 amounted to 262.29 m3/s to 238.70 m3/s in 2017. However, it is proportional to the surface flow coefficient value which has increased from 0.031 to 0.032. For land cover in the Way Pengubuan Sub-watershed area, it is still dominated by agricultural areas which have an area of over 50% each year, compared to forest area [FRST] which are only <1% of the total area of the Way Pengubuan Sub-watershed throughout the year. By employing series data of annually rain fall, % forest cover, % shrub, and % plantation, therefore, the annual river discharge can be express : [DISC]= 75.0+0.062 [RAIN]+0.0713 [FRST] – 0.00203 [SHRB]+0.000725 [PLTN] with R.Sq (adj)= 92.5%. [ABSTRACT FROM AUTHOR]