I have been editing rivers and stream within the Marikina-Pasig river basin for the past few weeks. Typhoon Ondoy/Ketsana which caused the most catastrophic floods in the country [1] have dramatically altered many river channels.

My personal goal for updating river data is to support research initiatives on flood monitoring [2] and effective basin management.

Thanks again to Bing, new imagery is available in the whole basin/watershed. Icing in the cake are the imagery dates which are between October 2009 to Feb 2010. All of which are post-Ondoy/Ketsana.

Over the course of my edits, I have observed general geographic phenomena that is happening in this area:

1. The floods have dramatically altered many river channels. Previous courses where diverted due to landslides and other obstructions.

2. Many river and stream channels are now gone. This is not primarily due to the floods but of the rapid urbanization in the area. Most of rice paddies are now converted to subdivisions. As a result many of the natural irrigation channels, intermittent creeks and streams are either completely filled up, diverted or the stream banks are constricted thereby limiting natural flow. [3]

3. Within the headwaters of one major river (Boso-boso River) is a big industrial pig farm. I noticed that some canals coming from their waste ponds drains towards the river. [4] I'm interested to know whether they have a pig s*%t processing before dumping water to the river.

[1]
http://wiki.openstreetmap.org/wiki/Humanitarian_OSM_Team/philippines_ondoy
[2]
http://epsg4253.wordpress.com/2009/10/13/free-our-data-rainfall-and-water-level-monitoring/
[3] http://osm.org/go/4zhcDayW--
[4] http://osm.org/go/4zhavWmD