International Association of Hydrological Sciences Association Internationale des Sciences Hydrologique

ICCLAS, Coupled Land-Atmosphere Systems

ICCLAS Coupled Land-Atmosphere Systems


Eva Boegh



Chris White



Kaniska Mallick



Richard Petrone



Harald Kunstmann



Koray K. Yilmaz


International Commission of the Coupled Land Surface – Atmosphere System (ICCLAS)

ICCLAS is one of ten commissions of the International Association of Hydrological Sciences (IAHS).

Global climate variability and change impacts the quantity and quality of freshwater resources in many regions on Earth. The effect of natural climate variability and the additional threat of anthropogenic changes are particularly felt in less developed countries, which often have less monitoring and predictive capacities. These regions are also where hydrometeorological extremes like floods and droughts often result in substantial loss of life, infrastructure and livelihood. Due to the paucity of hydrometeorological observational networks, there is a critical need for reliable hydrological and meteorological information on water cycle variables (e.g., evapotranspiration, soil moisture, and rainfall) at different spatial and temporal scales as a prerequisite for flood and drought hazard mitigation and sustainable water resource management activities. It is by the consideration of the coupled land-atmosphere system that hydrological and meteorological prediction performance can be further improved.

ICCLAS assesses the limits and potentials of hydrometeorological science for helping decision makers to understand and cope with the impacts of climate variability and change on water resources. Further to advancing our capacity for the management of water resources globally, ICCLAS is also poised to improve our understanding and predictive capacity of climate change. At the heart of the coupled land – atmosphere system, hydrologically sensitive processes have important control on the atmospheric component of surface biogeochemical cycling, most significant being the exchange of greenhouse gases (H2O, CO2, CH4, N2O…) impacting the energy balance of the Earth system.

Objective of ICCLAS 
The objective of ICCLAS is to facilitate research, scientific exchange and knowledge transfer with respect to these issues through the organisation of symposia and workshops in collaboration with other IAHS commissions and international organizations, and through the publication of edited volumes that summarize the current state-of-the-art. ICCLAS is responsible for organizing scientific meetings addressing the coupled land-atmosphere system, particularly the role of weather, climate and land surface dynamics for the terrestrial hydrological and biogeochemical systems at multiple spatial and temporal scales. Central research themes for ICCLAS are:

-      Analysis and prediction of the joint atmosphere-terrestrial water balance and extreme hydrometeorological events, including improved modelling approaches and techniques, ensemble hydrological forecasting (e.g. sub-seasonal to seasonal), flood and drought prediction, and hydrometeorological observational networks

-      Climate and land cover change impacts on hydrometeorological observations, including water resource modelling and hydrologically driven feedbacks in the climate system

-      Land surface water and energy balances, evapotranspiration measurements and modelling, and the use of ecohydrological spatio-temporal signatures and biogeochemical fluxes/tracers to progress understanding and representation of soil-plant-climate interactions in hydrological modellin

-      Joint use of models and ground, airborne and satellite based Earth observation data to understand and up- and downscale hydrological processes

ICCLAS relations

Panta Rhei. ICCLAS is supporting the IAHS Panta Rhei research programme to gain an improved understanding and interpretation of the hydrological cycle through focusing on the changing dynamics of the inter-linked atmospheric and terrestrial hydrological compartments and processes.

UNESCO. ICCLAS contributed to the development of the strategic programme for UNESCO’s VIII International Hydrology Programme (IHP-VIII) “Water Security: Responses to Local, Regional and Global Challenges” (2014-2021), and aims to organize scientific meetings to support IHP-VIII, in particular in relation to the strategic themes addressing hydrological change, water scarcity, flood risks and the use of ecohydrological principles for sustainable water management in developing countries.

WMO, WCRP, GEWEX, IAMAS. ICCLAS supports the World Meteorological Organization and World Climate Research Programme (WCRP) through research development, discussions and communication to improve spatial hydrometeorological predictions for weather and climate modelling and water management at both regional and global scales. ICCLAS also organized several scientific meetings cosponsored by the Global Energy and Water Exchanges (GEWEX) and the International Association of Meteorology and Atmospheric Sciences (IAMAS).

Future Earth, IGBP, ILEAPS. ICCLAS’s research on water-land-atmosphere processes is strongly related to and supporting other international scientific research programmes and platforms, such as Future Earth, the International Geosphere-Biosphere Programme (IGBP) and the Integrated Land Ecosystem-Atmosphere Processes Study (ILEAPS).

If you have ideas for new workshops or symposia important to ICCLAS research area and/or supportive to affiliated scientific programmes and organisations, then please send your suggestions to ICCLAS Secretary Koray K. Yilmaz or ICCLAS President Eva Boegh.