About Reservoir Assessment Tool (RAT) 3.0 - Mekong

The Reservoir Assessment Tool (RAT) uses satellite remote sensing data to monitor water surface area and water level changes in artificial reservoirs. It uses this information, along with topographical information (either derived from satellite data, or in-situ topo maps) to estimate the Storage Change (∆S) in the reservoirs. Additionally, RAT models the Inflow (I) and the Evaporation (E) of each reservoir. Finally, RAT uses the modeled I, and E, and estimated ∆S, to estimate the Outflow (O) from reservoirs.

RAT 3.0 makes numerous improvements to the code structure, performance optimizations, added configurations, ability to run RAT for multiple basins, among some introduced features. It also introduces packaging of RAT as a conda package, allowing for quick and easy installation.

It was originally developed by Biswas et al. (2021) at SASWE, University of Washington. The RAT framework developed by Biswas et al. (2021) was a first-of-its-kind open-source reservoir monitoring tool, it is reffered to as the version 1 of RAT, or RAT 1.0. It currently runs for 3 regions - (1) South and South East Asia, (2) Africa, and (3) South America, and can be accessed at http://depts.washington.edu/saswe/rat_beta/.

The Reservoir Assessment Tool (RAT) 2.0 was introduced with numerous improvements over the RAT 1.0. Such as weekly satellite observations (every 1-5 days) using a combination of multiple satellites (Sentinel-2, landsat-8, landsat-9 and Sentinel-1), usage of VIC hydrological model (VIC 5, Hamman et al. (2018)) and MetSim in parallel computation mode, data storage using NetCDF format and explicit representation of Evaporation using the Penman Combination method. RAT 2.0 - Mekong is designed to help stakeholders, such as the Mekong River Commission (MRC), address limitations faced by the Lower Mekong nations of limited access to measurement data and upstream opaque transboundary reservoir policies.

Major improvements introduced in RAT 2.0 over RAT -

  1. Daily inflow estimates are obtained using VIC 5.0 in a high performance workstation and updated daily.
  2. Reservoirs are mapped at a 1-5 day temporal frequency, in contrast to the 1-month temporal frequency of RAT using a multi-tiered multi-sensor surface area estimation algorithm called "Tiered Multi-Sensor - Optical/SAR (TMS-OS)". Landsat-8 (Optical), Sentinel-2 (Optical), and Sentinel-1 (SAR) sensors are used in conjunction to estimate the surface area.
  3. Outflow and ∆S estimates are also obtained at a 1-5 day temporal frequency.
  4. Wherever available, altimetry estimates using the Jason-3 are also provided.
  5. Evaporation is explicitly modeled using the Penman-Monteith Combination method.