Flooding in Chiang Mai: the river, the history and the maps
Chiang Mai’s flood history is tied to the Ping River and the broad valley around it. The city’s markets, neighbourhoods and roads sit within a landscape shaped by water. To understand a particular location, start with its position on that landscape and the recorded extent of previous floods. This tool puts those maps together around the point you choose.
The Ping River and the 2005 flood
Heavy rain upstream can become a city flood downstream. A study of the September 2005 flood traced the event to the tropical depression associated with Typhoon Damrey, which brought intense rainfall to the mountains of northern Thailand. Water spread into parts of Chiang Mai and across the surrounding floodplain, reaching places away from the main river channel. The researchers also documented the sediment left behind as the water receded. Read the published study of the 2005 Ping River flood.
That history explains why distance from the river is only one part of the picture. Floodwater follows connected ground and waterways. In the 2005 study, tributary openings and water crossing river defences helped explain how water reached the floodplain. A map of the actual flooded area adds information that a simple distance-to-river measurement leaves out.
The October 2024 flood
In October 2024, another major flood affected Chiang Mai and Lamphun. The United Nations Satellite Centre, UNOSAT, assembled observations from multiple satellites covering 5–10 October. Its regional assessment mapped water across affected land, including agricultural areas and developed parts of the valley. The satellite layer in this tool comes directly from that product. View the original UNOSAT assessment.
Satellite mapping gives us a geographic record of that event. When you choose a point, the tool checks the point against the mapped water boundary and shows the surrounding area. The result also includes the distance to nearby mapped flooding, so a point just beyond an edge is easy to distinguish from one farther away.
How Chiang Mai’s five flood zones work
Chiang Mai University’s Water Center maps five river-level scenarios using the P.1 gauge at Nawarat Bridge. Those levels are 4.30, 4.50, 4.70, 5.00 and 5.30 metres. The figures describe the gauge reading at the river. Each layer shows the corresponding mapped zone around the city and valley. Our lookup checks all five layers and displays the matching levels beside your selected point.
CMU’s current flood information system incorporates the 2024 event and also retains a previous map based on the 2011 flood. It combines river monitoring, local flood records and geographic information. This page uses the five-zone geometry for its CMU map and keeps it separate from the satellite record. Read CMU’s explanation of the system.
Reading a street, a neighbourhood or a housing estate
A neighbourhood name can cover a large area. Start with the actual building or street you want to check, then open the evidence and compare the surrounding roads. Both maps use the same point and move together. You can click another street, check an entrance, or compare a second part of a housing estate without starting your search again.
Google place suggestions, GPS coordinates and Google Maps links all lead to the same calculation: a point checked against the downloaded geographic layers. Nearby distances are measured to the mapped areas. The report is generated from those calculations, with the original sources linked below the maps.
The original flood maps
Explore CMU’s five-zone flood map for its original river-level layers, or open UNOSAT’s Thailand flood application to browse the wider satellite mapping. This tool brings their geographic data into a single location search, with a matching pin and side-by-side evidence.