Global and regionalized method for the assessment of agricultural water use impacts on biodiversity

Doctoral thesis of Francesca Verones

Doctoral thesis of Danielle Tendall

The world’s water resources are under great pressure, amongst others due to increasing populations, pollution and unsustainable and inefficient water management and water use infrastructures. One of the largest water users is the agricultural sector mainly due to irrigation water needs. If water levels drop this is not only impairing the health and quality of life of humans, but also of terrestrial and aquatic ecosystems. However, so far it is not possible to assess impacts of water use, such as dropping groundwater level but also reduced flows and levels in surface water bodies, on ecosystems. It is therefore the goal of this PhD to develop a spatially differentiated methodology which allows assessing the impacts of water use on terrestrial ecosystems and the vulnerabilities of groundwater-dependent terrestrial ecosystems in order to support more sustainable agricultural production. The focus is on countries ‘in the South’, i.e. developing and emerging countries, which are often semi-arid and arid countries. The foci for water use and biodiversity are mainly groundwater use and terrestrial flora.

The developed method is compatible with common life cycle impact assessment methods (LCIA). Two approaches were used: 1) a top-down approach, which will focus on larger world areas via globally available datasets, remote sensing and modeling in order to derive estimates of the impacts of (ground) water use on terrestrial biodiversity and 2) a bottom-up approach, consisting of more detailed modeling approaches in spatially limited areas and case studies for deriving impact factors for terrestrial biodiversity. The results of the bottom-up approach also helps to validate the results of the coarser top-down approach. Finally the implications of the outcomes for decision-making are discussed and future research options are proposed.