# Remote Sensing and Machine Learning Tools to Support
## 3 Results and Discussion
### Study Focus and Applications  
Knowledge of the status and extent of wetlands is essential to a series of research questions and applications. Thus far, many studies have characterized wetlands and monitored, mapped, and assessed them over time using a variety of satellite datasets with different spatial and temporal resolutions [47; 48]. Satellite imagery, such as the Landsat series, Sentinel, SPOT, and MODIS, provide long-term spatial data archives to assess, monitor, and manage ecological environments. These data collections have been widely  
Figure 8: Country and continent-based overview of first author affiliations. Among the continents, Asia (with 42%), America (with 40%), and Europe (with 13%) hold the largest shares, and among countries, China (with 35%), the USA (with 21%), and Canada (with 17%) hold the largest shares.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Rank** & **Ref.** & **First Author** & \begin{tabular}{c} **Total** \\ **Citations** \\ \end{tabular} & \
\begin{tabular}{c} **Average** \\ **Citation** \\ \end{tabular} &
\begin{tabular}{c} **Publication** \\ **Year** \\ \end{tabular} \\ \hline
1 & [37] & [PERSON] & 260 & 37.14 & 2015 \\ \hline
2 & [38] & [PERSON] & 176 & 16 & 2011 \\ \hline
3 & [39] & [PERSON] & 169 & 14.08 & 2010 \\ \hline
4 & [40] & [PERSON] & 168 & 10.5 & 2006 \\ \hline
5 & [41] & [PERSON] & 155 & 31 & 2017 \\ \hline
6 & [42] & [PERSON] & 147 & 21 & 2015 \\ \hline
7 & [43] & [PERSON] & 142 & 17.75 & 2014 \\ \hline
8 & [44] & [PERSON] & 138 & 34.5 & 2018 \\ \hline
9 & [45] & [PERSON] JM & 130 & 14.44 & 2013 \\ \hline
10 & [46] & [PERSON] & 114 & 38 & 2019 \\ \hline \hline \end{tabular}
\end{table}
Table 3: List of highly cited papers in the database, ranked by the total number of citations (as of 30 June 2022).  
utilized in environmental studies, for instance, in LULC change analysis, wetland status monitoring and extent mapping, biomass estimation, soil moisture retrieval, inundation mapping, and water level monitoring [7; 49; 50; 51; 52], amongst others[PERSON]  
As depicted in Figure 9, satellite imagery is mainly applied in seven major application domains for wetland studies: (1) the generation of landscape-type thematic maps for wetland types; (2) the dynamic change analysis of wetlands; (3) wetland vegetation mapping; (4) the survey and recognition of wetland extent; (5) the evaluation and estimation of biomass in wetland areas; (6) wetland hydrological characterization and surface water hydroperiod; and (7) soil and carbon estimation. The share of each of these applications within the reviewed literature is also presented in Figure 9. Of all reviewed publications, 51% investigate wetlands from the perspective of the classification of wetland classes[PERSON] Following the classification, 14% of the publications analyzed wetlands' changes[PERSON] Wetland vegetation mapping and wetland extent recognition are in third and fourth places, with a share of 12% and 7% among all reviewed papers. Since the classification and CD frameworks have the most significant shares, a brief discussion of these applications is presented below.