This article applies a multi-method approach to develop a better measurement of urbanization dynamics using remote and human sensing based on a GIS platform. The results demonstrate the benefits of bringing human and remote sensing sources together in a framework of hot spot analysis for a megacity such as Mexico City. Furthermore, our analysis suggests that human and remote sensing work well together in detecting the expansion of illegal urban settlements. Looking at the driving factors of illegal settlements, the existence of strong association between the expansion of illegal urban settlements and socioeconomic factors such as unemployment, provides some answers and reveals new questions. Illegal urban growth often leads to the loss of ecological areas in the urban frontiers, especially in areas where the urbanization potential is high. As a consequence, there are conflicts with legal settlers who dislike the illegal expansion. This approach can be extended to and replicated in new urbanizing areas, in particular in Africa and Asia

The fast and broad adoption of mechanization and chemical inputs in Mediterranean terraced agriculture, combined with warming climate trends, has led to the progressive degradation of environmental and social conditions. These factors have concurred with the increasing abandonment of smallholder agriculture. We aimed to detect and quantify the progression of cultivated and abandoned terraced fields in the Ricote Valley between 2016 and 2019 while also exploring reasons for land abandonment over the past decades. To quantify cultivated and abandoned agricultural terraces, we conducted (1) a terrace detection based on Lidar and cadaster data, (2) a land use classification based on Sentinel imagery, and (3) an investigation of the reasons for land abandonment based on participant observation and an expert survey. Our results show high rates of abandonment compared to the total available agricultural terraced area in the Ricote Valley. In 2016, 56% of the detected terraced area was classified as not cultivated. In 2019, the percentage decreased to 40%. Small parcels are cultivated to a higher percentage than large or medium-sized parcels. We identified five main reasons underlying land abandonment: (1) low income of farmers; (2) land fragmentation resulting in higher transaction costs; (3) lack of interest in agricultural activities among young generations; (4) lack of modernization; and (5) emotional bonds preventing the sale of abandoned parcels. We stressed the importance of a place-based mixed method approach to gain a comprehensive understanding of the specificities of a given research area.

Due to the availability of Web 2.0 technologies, volunteered geographic information (VGI) is on the rise. This new type of data is available on many topics and on different scales. Thus, it has become interesting for research. This article deals with the collective potential of VGI and remote sensing to detect peri-urbanization in the conservation zone of Mexico City. On the one hand, remote sensing identifies horizontal urban expansion, and on the other hand, VGI of ecological complaints provides data about informal settlements. This enables the combination of top-down approaches (remote sensing) and bottom-up approaches (ecological complaints). Within the analysis, we identify areas of high urbanization as well as complaint densities and bring them together in a multi-scale analysis using Geographic Information Systems (GIS). Furthermore, we investigate the influence of settlement patterns and main roads on the peri-urbanization process in Mexico City using OpenStreetMap. Peri-urbanization is detected especially in the transition zone between the urban and rural (conservation) area and near main roads as well as settlements.

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