Knowledge Base

1
What is the global distribution of freshwater
storage and river discharge and what are its
societal impacts?
Global measurements of river discharge and
inundation extent, and freshwater storage in
lakes, reservoirs, wetlands, and river channels
Global Surface Water Mission
UAV or Airborne Technology Demonstration
ESE Goals Answered Measure, model, and predict
variability in the storage and movement of
freshwater on the land surface globally Develop
global flood forecast capability for large rivers
(stage as well as inundation extent) Measure and
predict drought globally Define the role of river
dynamics in the contribution of wetlands to
global carbon fluxes

• Expected Results Technology testing and
  evaluation of higher resolution altimeters,
  surface velocity estimates, concurrent stage and
  inundation extent (hence channel storage)
  estimates

Radar and Lidar Altimeters

• Technology Development Altimetry measures
  geoidally correct elevations in profile form, but
  present technology is limited by along-track
  spatial resolution (radar) or by cloud cover
  (lidar). Existing sensors do not provide surface
  velocity estimates
• Expected Results New altimeters capable of high
  spatial along- and across-track resolution
  measurements (hence applicability to smaller
  rivers) and doppler measurements of surface
  velocity

Virtual Mission Assimilation of Existing Sensor
Observations
Knowledge Base

• Model Assimilate measurements of inundation
  extent (from SARs), water elevations (radar and
  lidar altimeters), and large area volumetric
  storage (GRACE) from existing sensors
• Expected Results Continental and sub-continental
  estimates of surface water storage change and
  fluxes evaluation of spatial and temporal
  resolutions required in dedicated mission that
  would address water cycle and carbon questions

Interferometric SAR, GRACE

• Data First Volumetric measurement of
  continental-scale water storage
• Results local measurement of Amazon Basin
  floodplain storage, Demonstrated importance of
  storage change

Topex/POSEIDON, ICESat, Jason-1

• Data Profiles of water surface elevations in
  channels (but not inundation extent)
• Results Amazon Basin rivers, some African, some
  Lakes Demonstrated feasibility of radar
  altimetry, limited by overpass and horizontal
  resolution

ERS 1/2, JERS-1, TM, Passive Active Microwave

• Data Imagery of inundated areas including
  sub-canopy
• Results global map of wetlands areas but poor
  spatial and temporal resolutions
• Exploratory local studies demonstrate feasibility
  of high spatial and temporal resolutions for
  hydrology

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