Welcome to the SDG6.worldwaterquality.com portal, a free online visualiser for global satellite-based water quality products. It supports monitoring and reporting of the Sustainable Development Goal No. 6 set by the UN by contributing with data needed for several global indicators, for instance Target Indicator (TI) 6.3 on Water quality and wastewater or TI 6.4 on Water use and scarcity.
For instance, by providing valuable assessment proxies for areas lacking traditional, ground-based water quality data, the online available data sets can be used for monitoring of target indicator 6.3.2 on Proportion of bodies of water with good ambient water quality (see SDG6 Indicator 6.3.2).
The portal is co-funded by the Thematic Exploitation Platform for Hydrology (Hydrology TEP by European Space Agency (ESA).
Current available data sets included a merged global set of water quality parameters in 90m resolution for all inland water bodies and coastal areas. You can also access time series products in 30m sampling resolution, for selected regions in each continent and several additional time series for three use cases in Africa, ranging from 10m to 300m spatial resolution. For these African use cases, also temporal aggregates, i.e. monthly and seasonal means, are available and spatially aggregated water body means are calculated.
In addition, water storage products will be made available for the African use cases.
The application allows you to interactively browse the water products. Use the features on the right hand side to select your region of interest, select various water parameters, set any desired virtual sampling stations, gather values and time series information. A quick information guide gives a summary of how to use this portal, see also below.
To download an information booklet on the water quality products, click Information Booklet Water Quality Monitoring.
To download a training handbook covering main practical questions of using satellite based information products, click Training handbook.
The blue function bar includes the following:
Chlorophyll-a: Chlorophyll-a is an essential pigment included in phytoplankton cells and therefore a measure of phytoplankton. The displayed Chlorophyll-a CHL is calculated from total scattering and total organic absorption of water constituents. Unit is [µg/l]
HAB Indicator: Harmful Algae Blooms (HAB) indicator shows possible areas affected by harmful algae blooms formed by cyanobacteria containing phycocyanin.
Secchi Disk depth: Secchi Disc Depth or visibility in (m) is a measure of transparency in the water column. The EOMAP SDD product is calculated from the attenuation coefficient Kd after Lee et al. 2005 and 2015. In situ measure of Secchi Depth with a so called Secchi disk is a common parameter in water quality analysis and is related to the euphotic zone in the water.
Surface Temperature: Surface Water Temperature in degree Celsius is calculated from thermal infrared channels recorded by optical satellites. It measures the top skin temperature of the water body, which might represents also epilimnic temperature.
Total Absorption:Total Absorption is retrieved from the absorption of light by particulate and dissolved organic and inorganic matter. The relative contribution of inorganic absorptions varies for changing specific inherent optical properties (SIOPs), which are monitored within the retrieval algorithms. The Unit is absorption at 440nmin 1/m. The total absorption product includes the absorption of organic and inorganic components, which are not shown separately at this portal.
Total Suspended Matter: Total Suspended Matter or Total Suspended Solids (TSS) is essentially related to the total scattering of organic and inorganic particles in the water column and is therefore linearly related to turbidity at low to moderate values. High concentrations of particles affect for example the light penetration, influences habitat quality for fishes or other aquatic life and can provide attachment possibilities for pollutants such as bacteria or heavy metals. The measurement unit of Total Suspended Matter is mg/l or g/m³. The linear relation between turbidity and suspended matter/solids in low to moderate concentrations is in most cases regional constant, but can vary with particle size distribution. A regional calibration may further assure the accuracy for high concentrations.
Trophic State: Trophic State Index provides a classification of biological productivity following the proposed scale from Carlson (1977), calculated from the Chlorophyll-a concentrations. The Trophic State Index ranges from 0 to 100, while values of below 40 indicate an oligotrophic state, values above 70 represent a hypereutrophic state.
Turbidity: measures the degree to which light is being backscattered by particles in the water. Tracking changes in turbidity is useful when monitoring sediment plumes from dredging and dumping activities. The measurement unit is Earth Observation Turbidity Unit (ETU) and directly related to backscattering of particles, very similar in magnitude to Nephelometric and Formazine Turbidity Units (NTU and FTU). It is linearly related to Total Suspended Matter (TSM) at low to moderate turbidity values.
Please read the information booklet for further information on the water quality products and to learn more about the validity range of the products. Products are generated independent on any form of ground truth data, and inter-comparable over the various resolutions provided. The Chlorophyll and HAB indicator may have site-specific limitations e.g. for extremely humid, calcareous, or ferruginous waters, and can be improved with local adaptations. General restrictions are caused by clouds, optical shallow waters, or undetected artefacts from e.g. cloud shadows.
Q: How can I learn more about these satellite-derived map and data water quality products, uncertainties and methodological differences between satellite based and in-situ or laboratory measurements
A: For a first overview, please download our information booklet. For further details on WQ monitoring…please refer to links provided in the booklet. Information Booklet Water Quality Monitoring Validation Examples Water Quality
Q: I have technical problems using the portal, or wish to access water quality data for other dates or resolutions. Who can help me?
A: Please contact the support team at firstname.lastname@example.org, or the support team of EOMAP at email@example.com.
Q: I am interested in a location outside the polygon areas that you feature here. How can I view water quality maps for my location?
A: In the blue function bar on the right hand side, you can select the full world mosaic layer. As soon as you have set a virtual station, you can see the date of the data record for that point. Or you can select in the same tab other available demo regions with time series data of 2016 in 30m resolution.
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One of the largest freshwater high-altitude lakes of Eurasia, Lake Sevan in Armenia at 1900m above sea level, the recently completed Semkir Reservoir in the Caucasus region of Azerbaijan and the associated river systems including the Kur river are covered in this focus region. The waterbodies in this region have been intensively used for irrigation in the past century, resulting in severe ecological impacts for Lake Sevan.
The Caucasus region around the Semkir reservoir is characterized by semiarid subtropical steppe climate, mild winters, hot summers and an annual precipitation of 250nm. At Lake Sevan the winters are very cold due to the high-altitude semiarid continental climate, with an slightly higher annual precipitation of 300nm.
Located right at the border of Paraguay and Brazil, the Itaipú dam impounds the Paraná river over a distance of more than 170 km. Until the construction of the Chinese Three Groges Dam, it was the world’s biggest power plant, and in terms of annual energy produced, it still is. Its construction took eight years and did not only have direct impacts on the economy, but also on the ecology and geography of the area. Forest had to be cut down to make room for the gigantic project, thousands of indigene people were moved and vast areas of rainforest, together with their adjacent waterfalls, were flooded. One of them had been the world’s largest waterfall by volume and had separated the areas above and below him into different ecoregions.After the building of the dam, species, formerly restricted to of these ecoregions, were able to enter the other and caused the typical problems that come with such invasions. On the other hand, the dam produces 75% of Paraguay’s and nearly 20% of Brazil’s energy and is also considered one of the seven modern Wonders of the World. Due to its size, political and economic value and its location within an ecologically precious region, monitoring the state of the river and lake is crucial.
More than 2000 small and few larger lakes cover the MecklenburgischeSeenplatte in Northern Germany. The lakes have formed from a pro-glacial lake during last glacial period.In this target area, a large variety of meso- and eutrophic lakes is included, which are under anthropogenic pressures such as fertilizers from agriculture. An increasing number of Cyanobacteria blooms is of public interest, and currently investigated as possible side effect of global warning. The regular assessment of the ecological status as requested by the European Union’s Water Framework Directive WFDis a challenging task for environmental agencies in states like Mecklenburg-Vorpommern with avery high number of distributed lakes larger than 10ha. Remote Sensing can therefore efficiently support planning and fundamental monitoring tasks - also for smaller lakes which are not covered under the WFD. The climate in Northern Germany is characterized by moderate warm summers and mild cloudy winters, with an annual mean temperature of 10 degrees Celsius and 600mm annual precipitation.
The region is well suited as a reference area for extended validation exercises of satellite-derived water quality products, due to the high activity level of several leading environmental research institutions, universities and the water agencies themselves.
Lake Nasser in Egypt and its southern end Lake Nubia as called by the Sudanese was created as result of the construction of the Aswan High Dam in Egypt, and fed by the Nile, the world’s longest river. Lake Nasser is one of the largest men-made reservoirs and was constructed to control flooding, provide increased water storage for irrigation, and generate hydroelectricity . It improves the extremely vulnerable food and water security situation in Egypt. Still, the Nile River has a major impact on the interstate politics of the region, as it is the only reliable source for renewable water supplies in the area. As other dams, sediment trapping is causing changes in downstream water quality, with significant impacts on coastal erosion in the Nile delta , which reversed from growth to a shrinking process since the closing of the dam.For this study, we selected the inflow area of Lake Nasser between Sudan and Egypt, covering the highest sedimentation levels and water quality gradients in the reservoir.
The climate conditions are subtropical at the borderline to a tropical arid climate, with extremely dry and hot summers and an annual precipitation of almost 0 mm. The Nile highwater season is in August/September, following the rainfall season in the upstream area in Ethiopia.
The Volta River Basin is one of the largest river systems in Africa, drained by four sub-basins: the Black and White Voltas (from Burkina Faso), Oti River (Benin), the Lower Volta (Ghana), and emptying into the Gulf of Guinea. The Volta Lake in the Lower Volta is one of the largest man-made reservoirs in the world. It emerged from the construction of the Akosombo dam in 1965 and the surface area today covers over 8,500 square kilometres by an average depth of 18.8m. The climate in the region is ranging from semi-arid and sub-humid and is largely influenced by the West African Monsoon with a dry and rainy season, lasting e.g. from April to October in Northern Ghana. In general, the surface water quality in the basin is indicated of having a good water quality with low average nutrient levels, especially in the Volta Lake. Nevertheless, densely populated cities in the north with associated limited sanitation infrastructure as well as high nutrient loads from agricultural sources – e.g. from sugar cane production and oil palm plantations - are affecting and deteriorating the water quality in this region. Together with deforestation, land degradation and high population growth, the effects of climate change will increase the pressure on water resources in the basin. The monitoring of the water quality is more than ever important to enable fast reactions on deteriorating conditions by effective water management procedures.
The Mekong delta represents by far Vietnams highest productive aqua- and agriculture environment, and is home for a population of around 17 million people. It is highly vulnerable to several climate change impacts, such as saltwater intrusion caused by sea level rise . Also massive human made disturbances to the river ecosystem from large dams create major threads to the fish and agriculture production, both to Cambodia and Vietnam. Half of the sediments are trapped in a cascade of upstream dams and water diversion schemes, resulting in a significant nutrient reduction and consequent halving of productivity . Satellite based water quality measurements can contribute with independent measurements of turbidity , sediment flows, assessments of the organic components. A sediment analysis for the entire delta and the cascade of upstream dams can quantify not only actual impacts, but also historic changes using satellite data up to 30 years back in time.
The Mekong delta has a tropical wet and dry climate within the drainage basin (monsoonal), a high annual precipitation of approx. 1500mm especially during the summer months from May to October, and a relative dry season from November to April.
Lake Victoria is the second largest freshwater lake in the world and the largest in Africa with a surface area of approximately 68,870 square kilometres, drained by the Nile river in the North. The former natural lake has been extended by the building of the Owen-Falls Dam, completed in 1954. Along the Ugandan and Tanzanian shorelines, the eutrophic lake is characterized by increased oxygen consumption and primary production due to atmospheric deposition of ash and high nutrient loads from contributing catchments.
Lake Victoria represents the most important base of the regional and African wide fishery, but with the introduction of new invasive fish species like the Nile perch the extinction of endemic species has been accelerated, one of the main ecological problems. In addition, due to high nutrient levels originated by industrial and agricultural runoff, massive water hyacinth growth lead to anoxic conditions in the lake, influencing plant, fish and human lives.
The water quality in the lake is further affected by the change of main phytoplankton compositions from diatom flora to one dominated by cyanobacteria, an general increase of algae biomass, fish kills and more prevalent deep-water anoxia.
Located near the eastern shore of central Florida, this area is covered by numerous lakes, from small to vast, with a wide spectrum of characteristics. The climate can be classified as humid subtropical, with an annual precipitation of approx. 1200mm, resulting in warm winters and hot, humid summers. Therefore, the waterbodies and their water quality parameters are highly dynamic and might differ within small areas. While some lakes are very clear, others can become very turbid, sometimes even with high amounts of phytoplankton. Their classification ranges from eutrophic to hyper-eutrophic, with some lakes showing regular and significant blooms of cyanobacteria. Partly, the lakes can be covered by water lilies and surrounded by cattail plants or swamp cypresses. Due to these differences and dynamics, the area is specifically interesting to put water quality algorithms to a test. Additionally, there are large amounts of validation data available, especially from the Lake County Water Authority and the United States Environmental Protection Agency (EPA). Those institutions provide long-term in-situ measurements for a large number of lakes in this region, which makes them well suited for extended validation exercises of satellite-derived water quality products.
The Cape town region is the most populated coastal area in South Africa, with a population of about 4 Million inhabitants. The entire urban region including Cape Town, Stellenbosch and further cities along the western coast of the Western Cape region are supplied by surface water from six big reservoirs and highly dependent on the annual winter precipitation from April to September. At the beginning of 2018, the region was faced with an extreme drought, making the authorities thinking of alternative water resources to be used, including desalination, water reuse and groundwater extractions. Here, the surface reservoirs play an important role as storage and infrastructure facility for the extracted groundwater resources, which enables the exploration also in hard-to reach and ecological vulnerable mountain terrains like the Table Mountain Group Aquifer. An operational satellite-based water quality monitoring can support the management of these large dams and reservoirs.
Lake Kariba is one of the largest reservoirs worldwide, providing electricity to much of Zambia and Zimbabwe. Lake Kariba is fed by the Zambesi River. The selected area covers the eastern part of Lake Kariba and the Middle Zambesi river between the Lower Zambesi National park and the Mana Pools National park. As other dams, sediment trapping in the Lake Kariba and the subsequent Cahora Bassa dam is causing significant impacts on coastal erosion in the Sambesi delta, which nowadays is only half of its original size.
Lake Kariba and the Middle Zambesi river is located in a tropical semiarid climate with an annual precipitation of approx. 800mm, where the significant contributions are during the summer months from November to March. April to October is very dry.