## 4 Towards Enhanced Global-Scale Local-Relevant Monitoring and Forecasting
### Anthropogenic Surface Modifications
#### Changing Water Bodies and Irrigated Areas  
Inland waters have been dramatically modified by humans in the last decades. Recent satellite observations demonstrate that the world's surface water bodies are far from static [307; 308]. In particular, by analysing more than 3 million satellite images between 1984 and 2015 by the USGS/NASA Landsat satellite programme, new global maps of surface water occurrence and change have been produced with 30-m resolution [307]. These global maps demonstrate that, over the past 30 years, 90,000 square kilometres of what was thought to be permanent surface water has disappeared from the Earth's surface, linked with climatic variability and human influence (e.g., river diversions or damming and unregulated withdrawal). Elsewhere, 184,000 square kilometres of new permanent bodies of surface water have appeared, some man-made (e.g., reservoirs) and others as a result of climate change (e.g., melting of glaciers). Satellite observations provide a means for defining spatially varying lakes in NWP, but this concept has not yet been realised fully. Future studies should investigate how NWP can benefit from the real-time monitoring of inland surface water bodies. A more dynamic representation of lakes should be a future ambition of forecast centres. One of the recent possibilities to observe changes in ecosystems and take them into account in NWP is to use the 30 m (1\({}^{\prime\prime}\)) horizontal resolution Global Water Surface Dataset (GWSD) created by Joint Research Centre (JRC). JRC used Landsat 5, 7 and 8 individual images over the past 32 years to map the spatial and temporal variability of global surface water and its long-term changes.  
Figure 25 shows different places on the globe and their evolution in recent years. Upper plots show Aral Sea area. After massive diversion of water for cotton and rice cultivation in the 1960s shrinking of water surface area accelerated and in 1998 became 28,990 sq.km (less than a half of its initial size) [309]. Due to major recovery program launched in 2001 by Kazakhstan President Nursultan Nazarbayev and supported by the World Bank, Aral Sea water surface area started to stabilise and in 2014 became 7660 sq.km (almost 10 times less of its initial size) [309].  
Lower plots show emergence of the new, largest in Western Europe, man-made Alqueva reservoir (Figure 25). It was built in 2002, and reached its present water surface area of 210 sq.km in 2006. Newly built reservoirs can be found all over the globe. Influence of inland water bodies on local climate is over 1 \({}^{\circ}\)K in temperature [225; 230]. Local weather influence can be more pronounced--correct lake surface state (ice/no ice) in winter conditions can lead up to 10 \({}^{\circ}\)K [310] difference in 2 m temperature. At the moment, there are several satellite products that have lake ice cover variables.  
Irrigated areas have also been considered in preliminary tests, following the approach by [311; 312]. Ref. [313] have demonstrated the relevance of including irrigation in a 20 th century reanalysis. Figure 26 illustrates the fractional cover of irrigation and urban areas as dominant surface anthropogenic land use modifications, that are yet neglected in most global NWP models.  
Figure 26: Urban areas and irrigated areas.  
Figure 25: Aral sea (Kazakhstan/Uzbekistan, **top panels, a and b**), and Alqueva reservoir (Portugal, lower panels, c and d**): water distribution in 2015 (**left, a and c**) and 1998 (**right, b and d**).