The Tucson metropolitan area, located in the Sonoran Desert of southeastern Arizona (USA), is affected by both massive population growth and rapid climate change, resulting in important land use and land cover (LULC) changes. As its fragile arid ecosystem and scarce resources are increasingly under pressure, there is a crucial need to monitor such landscape transformations. For such ends, we propose a method to compute yearly 30 m resolution LULC maps of the region from 1986 to 2020, using a combination of Landsat imagery, derived transformation and indices, texture analysis and other ancillary data fed to a Random Forest classifier. The entire process was hosted in the Google Earth Engine with tremendous computing capacities that allowed us to process a large amount of data and to achieve high overall classification accuracy for each year, ranging from 86.7 to 96.3%. Conservative post-processing techniques were also used to mitigate the persistent confusions between the numerous isolated houses in the region and their desert surroundings and to smooth year-specific LULC changes in order to identify general trends. We then show that policies to lessen urban sprawl in the area had little effects and we provide an automated tool to continue monitoring such dynamics in the future.

This paper analyzes whether national laws acknowledge indigenous peoples and other rural communities in 100 countries as owners of waters that arise within their lands. Results derive from information collected by LandMark to score the legal status of community land tenure. Findings are positive; half of all countries recognize communities as lawful possessors of water on their lands. Three quarters permit communities to manage the distribution and use of water on their lands. While 71 percent of countries declare water to be a public resource, this belies the substantial existence of privately owned water. In 29 percent of countries, private water is an identified legal category, and in many other countries obtainable rights to water are sufficiently substantial to imply lawful possession. Communities are beneficiaries mainly where customary rights are accorded status as property rights, or where ownership of public lands and water are devolved to rural collectives. However, opposite trends of nationalization and regulation of water suggest that while legal recognition of community land ownership may rise in the future, this will not necessarily include waters on the land. Irrespective of tenure, rural communities in 72 of 77 countries (93.5 percent) are legally assured access to water for domestic purposes. This is consistent with the rising definition of safe drinking water as a human right, although access does not necessarily come free of cost.