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Hydrologists should resist the temptation to extrapolate hydrologic understanding of temperate regions on cold regions. Snowfall undercatch is often overlooked in temperate regions, but is very significant in cold regions where snow makes up the majority of the precipitation. Evaporation is-often over-estimated in cold regions. The Arctic tundra is sometimes referred to as a desert because of the very low annual precipitation. However, the abundance of lakes proves that the area has a large excess of water resulting in relatively low evapotranspiration and high annual runoff coefficients. Snow accumulation can also be deceiving. Large bare areas in winter mask the storage of large quantities of snow in depressions and on the lee side of hills. The absence of runoff and stream flow during most of the year and the small size of streams are not indicative of minimal water yield since much of the flow occurs during melt conditions in spring. The lack of data and incomplete understanding of cold region hydrology suggest the need for an explicit technique to handle uncertainty.