Planting waterscapes: Green infrastructures, landscape and hydrological modeling for the future of Santa Cruz de la Sierra, Bolivia

The expansion of cities is an emerging and critical issue for the future of the planet. Water is one of the most important resources provided by urban and peri-urban landscapes, as it is directly or indirectly connected with the quality of the environment and life. Santa Cruz de la Sierra is the leading city in Bolivia (and the second in Latin America) in regard to population growth and soil sealing. Water is available to the city mostly from the Piraí River basin, and is expected to be totally inadequate to support such powerful urban development. The project Aguacruz, which is financed by the Italian Agency for Cooperation and Development, aimed to (1) restructure and harmonize existing data on the landscape ecology, hydrological features, and functional aspects of the Piraí River; (2) build hydrological scenarios for the future of the basin by introducing a landscape ecology approach, and (3) involve stakeholders and local actors in decision-making processes oriented to increase the resilience of the urban-rural landscape of the Piraì River and the city of Santa Cruz. SWAT (Soil and Water Assessment Tools) tested five scenarios through simulating different landscape settings, from the current previsions for urban expansion to a sound implementation of green infrastructures, agroforestry, and regreening. The results indicate that integrated actions in rural-urban systems can lead to a substantial reversal of the trend toward a decline in water supply for the city. From a governance and planning perspective, the proposed actions have been configured as to induce (i) integrated waterscape ecological planning; and (ii) the preparation and approval of departmental regulations for the incorporation of green infrastructures in the municipalities.