Mobile version

High-resolution hydrology: hydrology is changing dimension with Swot

Even though the first altimetry missions were designed for ocean, quite early on they were also used to look at rivers and lakes. Several projects offer today a database of river/lake level time series over some water bodies. However nadir altimetry can measure only just beneath the satellite, so an important number of water bodies are not, or not regularly sampled, because never overflown (e.g. Dead Sea, or Hourtin lake in France). Swot, by providing with an image everywhere thus enables to know where is the water, its slope and thus compute its discharge at least every 21 days. Comparisons between two successive measurements also provide with variations of those quantities.

Water cycle & Water storage changes

Floodplains and wetlands have an important impact on flood and ecosystem management. Moreover, lakes and reservoirs are of major importance including for issues related to water conflicts between nations. However, currently, there are huge uncertainties on their distribution. Swot, with its swath, should detect a large nomber of the water bodies. It should measure 65% of total annual lakes/reservoirs changes.
A global assessment of water resources, including transboundary rivers, lake and reservoir storage and river dynamics is of major importance to understand the global water cycle. This should also enable to define future Water Policy Strategies, based on the science of global water cycle and the evolution of freshwater resources.

Swot can refine, validate or change existing understanding based on its observational capability and may point to newer science-based strategies. It is able to improve and even provide first estimates (where unavailable) of human impact (e.g. dam building). Simultaneous availability of water height and width/extent from Swot should significantly improves physical models (hydrodynamic, land surface hydrology, climate).
 

Rivers and discharge

One of the major question in hydrology is the running waters. Today, very few rivers are observed and even fewer monitored. Swot will bring not only height measurements, but also slope and width of the rivers, and observe a lot more rivers than any combination of altimeter which has ever flown. Rivers over 100 m wide (goal: 50 m) should be measured with an accuracy of 10 cm over a 1 km2 area, 25 cm for a 250m*1 km area with a 1.7 cm/km slope (10 mrad) on an average length of 10 km .

By providing with those quantities regularly Swot enables to compute the rivers' discharge, and also help in modelizing rivers (and floods). Some studies are ongoing, in particular for complex cases like multi-braided rivers.

Estuaries

Estuaries serve as a meeting point between land and sea. Estuarine hydrodynamics are very complex because there are interactions between different water bodies: the sea with the same phenomena as the coast ocean (tides, waves, surges, sea level rise) but also the river, its tributaries, and groundwater. Numerical models have been increasingly used to predict river and estuarine flow, water quality and sediment and contaminant transport processes. However, to better define these models, and also to assimilate data into those models, one needs data, but only a few estuaries in the world have enough in situ gauges to allow this. The interest of using satellite height data for estuaries is to provide information on the hydrodynamic spatial variability. Until now, within estuaries, the contribution of satellites has mainly focused on the monitoring of water color and its relation to suspended sediment and chlorophyll. However, e.g. turbidity distribution varies considerably with tidal and river flow conditions, fluctuating on a variety of timescales, and are heavily influenced by bottom topography. In order to validate these models,  we need the high resolution, 2D satellite altimetry data which Swot is bringing.

EnglishFrançais
Rss feedsContactPartnersFAQLexiconLegal noticePersonal Data Protection PolicyMobile
You must enable cookies in your browser preferences to save the modifications
You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

Customize the home page

View all widgets
Reduce display
Public profile
User profile

Select/Deselect widgets

Discover AVISO+

Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

Customizable homepage

This home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Reading tools

Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

Products search guide

The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

AVISO+ Multimedia

The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!