Fig. 1

a The Bislak River, like many rivers in the country, serves multiple purposes in Philippine communities, including: b agriculture on floodplains; c aquaculture/fish pens in channels; and, d the provision of construction materials from gravel mining on riverbeds and bars. Semi-permanent/permanent structures such as bridges, embankments, dikes, and gabions (e–g) are commonly constructed along Philippine rivers. Examples shown are from the Bislak Catchment; locations are indicated by the corresponding labels (a–g)