Decision Support Tools

Surface Water Mapping Tool

Surface water distribution changes over space and time and these patterns can provide insight into ecological structure and function, patterns of flooding and flood risk, and the impacts of infrastructure and climate change on landscapes and hydrological systems. However, such patterns have been difficult to track and measure over large areas and longer time spans. With increased access to large volumes of remotely sensed data and innovative techniques for optimizing the processing and interpretation of those data, these measurements are now more accessible than ever before.

Surface Water Mapping Tool

Surface water distribution changes over space and time and these patterns can provide insight into ecological structure and function, patterns of flooding and flood risk, and the impacts of infrastructure and climate change on landscapes and hydrological systems. However, such patterns have been difficult to track and measure over large areas and longer time spans. With increased access to large volumes of remotely sensed data and innovative techniques for optimizing the processing and interpretation of those data, these measurements are now more accessible than ever before. The Surface Water Mapping tool leverages the extensive archive of Landsat data in the Google Earth Engine archive and Google’s cloud processing power to quickly calculate past patterns of surface water extent from multiple layers of Landsat imagery. The tool consists of a Google Earth Engine application and a user friendly web interface which allows the user to specify the period evaluated and other calculation parameters that are then executed in a cloud service. Results are displayed on screen and can be downloaded for specified areas.

Application Purpose

The Surface Water Mapping Tool was initially developed to document the historical dynamics of seasonal flooding cycles on the Mekong River in order to better understand some of the likely impacts of completed and proposed dams. Other uses include flood risk assessment for disaster preparedness, identifying areas of permanent water (valuable in the context of severe drought response), and numerous water resources management applications.

Application Uses

Specific uses include assessing the variable flood risk in areas susceptible to flooding, identifying areas of significant seasonal inundation (to identify and maintain key ecological processes), and tracking changes in river courses to anticipate land erosion and accretion for planning and risk assessment.

Geographic Region
Lower Mekong
Developer(s)
Deltares, Technical University Delft, SERVIR-Mekong, eartH2Observe, Google, ADPC, Stockholm Environment Institute (SEI), Spatial Informatics Group (SIG)
Contributors/Partners

Climate-Resilient Mekong Project

Users
  • Natural Heritage Institute
  • Vietnam: Institute of Meteorology, Hydrology and Environment
  • Cambodia: Ministry of Water Resources and Meteorology 
  • Lao PDR : Ministry of Natural Resources and Environment; Ministry of Energy and Mines
  • Thailand: Department of Water Resources
  • WWF Greater Mekong Freshwater Program
Earth Observations and NASA Products Used
  • Landsat 7 and 8 data
  • Google Earth Engine
  • OpenStreetMap
  • SRTM Plus (30 m Digital Elevation Model)
  • Hydrosheds hydrological data
  • EnviSat ASAR (historical)
  • Moderate Resolution Imaging Spectroradiometer (MODIS) (historical)