About WATCH Outreach
WATCH was funded under the European Union’s Sixth Framework Programme and ran from
1st February 2007 to 31st July 2011
Climate models can deliver figures for rainfall across the Earth’s surface, but there is no simple formula to translate these into river flows. Every catchment is different and the proportion of rainfall that finds its way into rivers, and the delay in it doing so, is influenced by topography, soil type, land cover, geology, human activity, and other physical processes. To translate climate into river flow we need models that capture these influences. Numerous models exist, but they have been developed for a variety of purposes, many at the catchment scale, and often for areas as small as a few thousand square kilometres.
WATCH needed to establish whether it was possible to upscale these models and use them to produce meaningful results at a global scale.
The model inter-comparison project (Water MIP) was a relatively small component of the original WATCH plan. However, recognising its potential to improve models, to quantify uncertainty within them, and to provide a valuable framework for future global water-cycle work, it quickly became a major output of WATCH. Water MIP will benefit inter-governmental policy-making and large scale impact studies in the future.
Water MIP embraced two types of model: land-surface and hydrological . Both types take climate data – along with other variables – and are able to provide estimates of evaporation and river flows. However, the methods that they use to achieve this can be quite different. Land-surface models are concerned primarily with the physics of energy exchange at the land surface. Representation of hydrological features and processes within them tend to be simplified. Hydrological models tend to be more statistically based, and focus on hydrological features and processes. The physical processes within them, such as evaporation, are often simplified.
Seven models were included in the first phase of Water MIP. By the later phases, as global interest in the project grew, this number had increased to thirteen.
The science of climate change is now well-established. Yet, climate scientists continue to separate what is happening in the atmosphere from what is happening on the ground; particularly when water is involved. This is not realistic. WATCH was established to bridge the gap, and to resolve the water cycle at the global scale so that studies of climate and hydrology become inseparable.
Listen to Richard Harding, Co-leader of WATCH, as he introduces “from climate to river flows”.