Water Balance In North America

The hydrological cycle plays a central role in geobiological and near-surface geological processes and in the energy balance of the earth. It is of crucial importance to many vital practical problems relative to man and his environment. This is especially true in arctic and subarctic regions, where knowledge of hydrologic processes is particularly limited. The introductory section of this report discusses the global hydrologic cycle and summarizes current estimates of the quantities of water involved in various portions of it. Following this, the definitions and boundaries of the arctic and subarctic are reviewed; a map showing these boundaries and annotations of a number of publications dealing with this problem are also presented. The main part of the report gives several hundred annotations of reports that directly discuss elements of the water balance in arctic and subarctic regions. These annotations are grouped by geographic area: the Northern Hemisphere, Europe, the U.S.S.R., Alaska, Canada, and Greenland and Iceland. For each area, annotations are presented according to water-balance elements: precipitation, evapotranspiration, runoff, streamflow, groundwater contributions to runoff, and changes in glacial storage. (Modified author abstract).

Leonardo da Vinci, the eminent Renaissance scholar and philosopher said, "water is the driver of nature". Many may have considered it to be an overstatement in the past, but at the beginning of the third millennium, no sane individual would disagree with Leonardo's view. Water is becoming an increasingly scarce resource for most of the world's citizens. The current trends indicate that the overall situation is likely to deteriorate further, at least for the next two decades, unless the water profession eschews its existing "business as usual" practices, which can only allow incremental changes to occur. Somewhat surprisingly, the water profession as a whole neither realised nor appreciated the gravity of the global water situation as late as 1990, even though a few serious scholars have been pointing out the increasing criticality of the situation from around 1982. For example, the seriousness of the crisis was not a major issue, either at the International Conference on W ater and the Environment, which was organised by the UN system in Dublin and also at the UN Conference on Environment and Development at Rio de Janeiro. Held in 1992, both are considered to be important events for the water sector of the past decade. It is now being increasingly recognised that the Dublin Conference was poorly planned and organised, and thus not surprisingly it produced very little, if any, worthwhile and lasting results.