Water authorities are required to have a survey of large woody debris (LWD) in river channels and to manage this aspect of the stream habitat, making decisions on removing, positioning or leaving LWD in a natural state. The main objective of this study is to develop a new methodology that assists in decision making for sustainable management of river channels by using generated low-cost, geomatic products to detect LWD. The use of low-cost photogrammetry based on the use of economical, conventional, non-metric digital cameras mounted on low-cost aircrafts, together with the use of the latest computational vision techniques and open-source geomatic tools, provides useful geomatic products. The proposed methodology, compared with conventional photogrammetry or other traditional methods, led to a cost savings of up to 45%. This work presents several contributions for the area of free and open source software related to Geographic Information System (FOSSGIS) applications to LWD management in streams, while developing a QGIS  plugin that characterizes the risk from the automatic calculation of geometrical parameters.
Ortega-Terol, D., Moreno, M. A., Hernández-López, D., & Rodríguez-Gonzálvez, P. (2014). Survey and classification of large woody debris (LWD) in streams using generated low-cost geomatic products. Remote Sensing, 6(12), 11770–11790. https://doi.org/10.3390/rs61211770