# Ten Years of Experience with Scientific TerraSAR-X Data Utilization
## 3 Results
### Proposal Analysis Overview
#### 3.1.1 Anthroposphere  
The focus of 17 percent of all TerraSAR-X proposals is the environment created by humans (see also Figure 4). Today, more than half of the world's population live in cities and the trend of migration into urban areas is still increasing. Urban sprawl, expanding, and increasing exposure to hazards are only some of the associated challenges. High-resolution TerraSAR-X data are utilized for mapping the urban extent [28; 29; 30] and its temporal evolution [31]. Especially the StripMap mode's ground resolution of approximately three meters enables an automated derivation of built-up areas on a global scale [32]. Furthermore, TerraSAR-X StripMap time series are employed for investigating the impact of urban growth and associated anthropogenic activities like tunnel excavation, or ground water pumping [33].  
The very high-resolution Spotlight modes are utilized on a local scale. Here, the reconstruction of individual buildings and the observation of settlements are of interest [34; 35]. Not only buildings but also infrastructure like expressways [36], railway tracks [37], bridges [38], and dams [39] are investigated. Very high-resolution data are even employed to measure thermal expansion of buildings and infrastructure [40; 41]. Mostly, interferometric techniques are applied.  
Figure 4: Thematic fields of anthroposphere-related TerraSAR-X proposals sorted by frequency, addressing the built-up area in general, individual buildings and infrastructure (e.g., dams, bridges, roads, railway tracks), the impact of natural disasters (in particular flooding), archaeology and manmade activities like mining.  
Figure 3: Histogram of TerraSAR-X related fields of research, expressed in percent based on the analysis of 1636 proposals.  
All TerraSAR-X modes are employed for investigating flooding events [42; 43; 44] and identifying areas with a higher risk of being flooded [45]. Damage assessment [46] as well as the monitoring of reconstruction activities are research fields utilizing high-resolution SAR data [47]. A new application field arises with the use of remote sensing data for archaeological purposes. This includes the investigation of historical sites and their surrounding areas [48; 49; 50] as well as the monitoring of historical sites endangered by natural or human-made hazards or under pressure from settlement expansion [51; 52]. Moreover, looting activities are observed in areas which are not accessible due to armed conflicts [53]. Most of the archaeological applications benefit from the high spatial resolution of TerraSAR-X.  
SAR interferometric techniques are applied to monitor mining activities [54; 55]. This includes active mining but also the effects of already sealed underground mines on above-ground settlements. Furthermore, the impact of geothermal drilling is investigated [56].  
More than 50 percent of all proposals in the anthroposphere domain address SAR interferometry in general or a particular interferometric measurement technique. Due to the high spatial resolution, more scatterers with a stable backscattering behavior over time can be identified, enabling for example the persistent scatterer technique. Further, SAR tomography employs SAR data acquired from different incidence angles. It allows not only the reconstruction of the three-dimensional position of stable scatterers along a building facade but also their spatial dynamics over time when time series are available. Notably, SAR polarimetry is not a driver when SAR data are used for mapping and monitoring of urban areas.