Multidimensional assessment of the spatial distribution of water resource vulnerability in the Columbia River basin, USA

Background/Question/Methods

With ongoing land development driven by population growth and expected climate change, many regions of the world are facing the issues of water scarcity and water pollution, which threaten the long-term sustainability of water resources.  While dams have, to some extent, achieved the goal of delivering a reliable water supply to downstream users, this management often comes at the expense of deteriorating ecological and biological integrity of freshwater ecosystems.  We investigated water resource vulnerability in the U.S. portion of the Columbia River basin using multiple indicators representing water supply, water demand, and water quality, asking the following research questions.  (1) What are the spatial patterns of water resource vulnerability in a large heterogeneous river basin?  (2) What are the major controls of spatial water resource vulnerability?  (3) What are the added values of studying water resource vulnerability using an integrated approach that encompasses water supply, demand, and quality?  At the county scale, spatial analyses were conducted using 21 biophysical and socioeconomic indicators that control water vulnerability.  In addition, multivariate analyses were used to identify major drivers of water resource variability.

Results/Conclusions

Water supply and water demand vulnerability exhibited a similar spatial clustering of significant hotspots in areas where agricultural lands and variability of precipitation were high, but dam storage capacity was low.  The hotspots of water quality vulnerability were clustered around the mainstem of the Columbia River where major population and agricultural centers were located.  The multidimensional analysis confirmed that different combinations of drivers were associated with different types of vulnerability in the distinct sub-basins of the Columbia River basin.  This result suggests that adaptive water resource planning drives much of the vulnerability within the study area.  Increased coordination of water management across multiple levels of governance is needed to reduce water resource vulnerability in the Columbia River basin in the face of future climate change and population growth.