How land use/land cover changes can affect water, flooding and sedimentation in a tropical watershed: a case study using distributed modeling in the Upper Citarum watershed, Indonesia

[EN] Human activity has produced severe LULC changes within the Upper Citarum watershed and these changes are predicted to continue in the future. With an increase in population parallel to a 141% increment in urban areas, a reduction of rice fields and the replacement of forests with cultivations have been found in the past. Accordingly, LCM model was used to forecast the LULC in 2029. A distributed model called TETIS was implemented in the Upper Citarum watershed to assess the impact of the different historical and future LULC scenarios on its water and sediment cycles. This model was calibrated and validated with different LULCs. For the implementation of the sediment sub-model, it was crucial to use the bathymetric information of the reservoir located at the catchment's outlet. Deforestation and urbanization have been shown to be the most influential factors affecting the alteration of the hydrological and sedimentological processes in the Upper Citarum watershed. The change of LULC decreases evapotranspiration and as a direct consequence, the water yield increased by 15% and 40% during the periods 1994-2014 and 2014-2029, respectively. These increments are caused by the rise of three components in the runoff: overland flow, interflow and base flow. Apart from that, these changes in LULC increased the area of non-tolerable erosion from 412 km(2) in 1994 to 499 km(2) in 2029. The mean sediment yield increased from 3.1 Mton -yr(-1) in the 1994 LULC scenario to 6.7 Mton-yr(-1) in the 2029 LULC scenario. An increment of this magnitude will be catastrophic for the operation of the Saguling Dam.This study was partially funded by the Spanish Ministry of Economy and Competitiveness through the research projects TETISMED (CGL2014-58,127-C3-3-R) and TETISCHANGE (RTI2018-093717-B-I00). The authors are also thankful to the Directorate General of Higher Education of Indonesia (DIKTI) for the Ph.D. funding of the first author.Siswanto, SY.; Francés, F. (2019). How land use/land cover changes can affect water, flooding and sedimentation in a tropical watershed: a case study using distributed modeling in the Upper Citarum watershed, Indonesia. Environmental Earth Sciences. 78(17):1-15. https://doi.org/10.1007/s12665-019-8561-0S115781

Penanganan Lahan Kritis dengan Metode Konservasi Lahan di Citarum Hulu

LAND CRITICALY HANDLING USING CONSERVATION METHODS ON UPPER CITARUM. The annual loss of erosion in Java is Rp. 5.9 trillion (Kompas, 21 October 2020). This illustrates, we are so weak in the aspects of planning, development, and supervision. One of the problems experienced in the upper of Citarum river is the level of erosion reach 120 tons/ha/ year (Risdiyanto, 2009). According to Hardjowigeno (1986), the erosion limit that can be tolerated is generally around 20 tonnes /ha/year. Seeing this condition, the problem of erosion is an important thing for community assistance. Community service aims to conduct training, mentoring, and field trials to reduce the rate of erosion. This service is carried out to farmer groups at Cimenyan District. The result of this service activity is the formation of awareness for agricultural business actors. Second, the allocation of proceeds from efforts to prevent erosion and sedimentation. Third, erosion can be maximally reduced, characterized by existing demonstration plots

Pengenalan Erosi untuk Petani di Desa Cibeureum dan Kampung Nyomplong, Bandung

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