Special colloquium on Hydrology: new demands on science and services

The theme of the 90th Annual Meeting is “Weather, climate, and society: new demands on science and services. In this session, four invited speakers will comment on challenges in hydrology related to the meeting's theme, ranging from challenges in hydrologic prediction in a changing climate, demands and potential for new observing systems, as well as global and domestic water policy in a changing environment. Global and continental scale hydrological models intended both for application in off-line and coupled modeling studies for prediction of the evolution of future biogeochemical cycles and resource assessment have evolved over the last two decades. However, as the complexity of these models has increased, they have become poorly constrained. The role of new modeling constructs, and new global and continental scale data both from in situ earth observation networks such as FLUXNET, and remote sensing data such as the Gravity Recovery and Climate Experiment (GRACE) will be discussed. In the case of water, the implications of advances at the modeling-observation nexus have motivations that go far beyond scientific understanding. They have also been motivated in part by increasing awareness of climate change among water managers and users, and give rise to new questions about appropriate adaptation responses and the most effective way of implementing those responses. Lessons from recent studies will be described and suggestions for climate/water policies presented. With respect to climate adaptation, the response of the water resources sector in the U.S. has been particularly problematic. Notwithstanding evidence of ongoing changes in the water cycle which will ripple into many water-related sectors including energy, human health, agriculture, and ecosystems, our current methods of integrating scientific knowledge and observations into water planning, management, and policy are still based on 20th century ideas. In addition to the scientific underpinnings of the interactions between climate, the land water cycle, and water use, this session will address actions needed in the next five years to reform the U.S. water sector so as to meet 21st century needs.