Hydrological responses of micro-catchments under different farming practices in Banjarnegara, Indonesia

Abstract

Effects of two different farming practices namely mixed-cropping (i.e. agroforestry) and mono-cropping systems on hydrological responses were investigated based on a paired catchment method. Two catchments namely Tamansari catchment (16.4 Ha) and Penanggungan catchment (3.6 Ha), both are located in Banjarnegara district, Central Java, Indonesia, were studied. Based on drone mapping, the dominant land use of the Tamansari catchment was agroforestry where trees were combined with seasonal crops like cabbage, potatoes and carrots on the same unit of land, whereas the dominant land use of the Penanggungan was seasonal crops without any trees. For both catchments, meteorological data and discharge data were available from May 2017 to March 2018, so that made it possible to compare each other. Furthermore, the hydrological responses of the two catchments were compared for their water balance and the annual, seasonal and monthly Flow Duration Curves (FDC). The results showed that both catchments had their lowest rainfall in August and their highest rainfall in February. Based on the FDC, the Tamansari generally had a steadier flow and the range of discharge values was smaller than the Penanggungan, especially on February, the wettest month of the year. In the drier periods, the two catchments behave similarly, but in general, the Tamansari produced more discharge than the Penanggungan. Finally, based on the observation, it can generally conclude that a micro catchment mostly occupied with seasonal crops like in the Penanggungan catchment reacted more extreme to rainfall than a micro catchment mostly occupied with combined trees and seasonal crops in form of agroforestry like in the Tamansari catchment.