Taking the spatio-temporal effects of climate change into account for Life Cycle Assessment of prospective scenarios to secure water supplies in agricultural areas.

To cope with climate change, agricultural territories are forced to implement adaptation strategies, including the implementation of irrigation infrastructures. These strategies are deployed over a long term, and their environmental performance may vary in time and space due to climate change. Environmental assessment methods that include spatio-temporal dynamics must be developed to identify long term "no-regret" scenarios. This study proposes an innovative approach based on the coupling between a crop model, i.e. AquaCrop, and the Territorial-Life Cycle Assessment (T-LCA) framework. Results are exemplified and discussed, with comparison of scenarios with or without irrigation, between 1981 and 2099, at six contrasting locations in terms of climate and soil conditions for the Shared Socioeconomic Pathways 5-8.5 scenario developed by the Intergovernmental Panel on Climate Change. The assessments report that climate change can affect the eco-efficiency of irrigated perimeters over time. Moreover, climate change may alter the conclusions of the comparison of scenarios with or without irrigation infrastructure at a given location. Additionally, a sensitivity analysis is performed on key parameters of the study highlighting the importance of the electricity mix. Finally, spatio-temporal dynamics need to be considered to assess the environmental performance of long-term land planning scenarios and account for environmental effects such as climate change.

Prospective Water Supply Mix for Life Cycle Assessment and Resource Policy Support-Assessment of Forecasting Scenarios Accounting for Future Changes in Water Demand and Availability.

Freshwater comes from different sources unevenly distributed over time and space around the world and plays a key role in the planning of all social and economic sectors on a regional scale. In this context, a consistent framework for modeling regional water supply mix (WSmix) at a worldwide scale has already been developed for use in life cycle assessment (LCA). However, changes in water sources, driven by climate and socio-economic changes, will occur, affecting WSmix. This study aims to assess the need for a Prospective WSmix (P-WSmix) for implementation in LCA and water footprint studies as well as regional water management strategies. Environmental and socio-economic factors affecting future water supply are defined. Projections of the three main components of the P-WSmix (i.e., water sources mix (P-WOmix), technology evolutions, and associated electricity mix) are proposed for two water users (public water and irrigation), under three scenarios and time horizons until mid-21st century. For implementation of the P-WSmix in LCA, a P-WOmix database is provided for 74 countries on all continents as well as a prospective technological matrix and prospective electricity mixes. An illustrative case study shows the importance of including P-WSmix in LCI databases for the LCA of infrastructures or products with a long life span and tangible water use during use or end-of-life phase, through the example of a toilet flushing system. P-WSmix has an important added value in supporting regional adaptation strategies for the future water supply management.

Diffuse and point sources of silica in the Seine River watershed.

Dissolved silica (DSi) is believed to enter aquatic ecosystems primarily through diffuse sources by weathering. Point sources have generally been considered negligible, although recent reports of DSi inputs from domestic and industrial sources suggest otherwise. In addition, particulate amorphous silica (ASi) inputs from terrestrial ecosystems during soil erosion and in vegetation can dissolve and also be a significant source of DSi. We quantify here both point and diffuse sources of DSi and particulate ASi to the Seine River watershed. The total per capita point source inputs of Si (DSi + ASi) were found to be 1.0 and 0.8 g Si inhabitant(-1) d(-1) in raw and treated waters of the Achères wastewater treatment plant, in agreement with calculations based on average food intake and silica-containing washing products consumption. A mass balance of Si inputs and outputs for the Seine drainage network was established for wet and dry hydrological conditions (2001 and 2003, respectively). Diffuse sources of Si are of 1775 kg Si km(-2) y(-1) in wet conditions and 762 kg Si km(-2) y(-1) in dry conditions, with the proportion of ASi around 6%. Point sources of Si from urban discharge can contribute to more than 8% of the total Si inputs at the basin scale in hydrologically dry years. An in-stream retention of 6% of total inputs in dry conditions and 12% in wet conditions is inferred from the budget.