At the GRDC (http://www.bafg.de/GRDC) catalogue from September last year (this is the version I have downloaded), this river is not included. But I saw this resource: http://flood.dpri.kyoto-u.ac.jp/ihp_rsc/riverCatalogue/Vol_05/3_Indonesia-11.pdf - Maybe you can contact the authors or find something in the references?
look at http://flood.dpri.kyoto-u.ac.jp/ihp_rsc/riverCatalogue/Vol_05/preface.pdf - there are the editors listed. I suggest to google the persons and write an email to them where you can get the data used for the diagrams. Or contact UNESCO-IHP (at the bottom of http://flood.dpri.kyoto-u.ac.jp/ihp_rsc/riverCatalogue/Vol_05/).