Snow hydrology is a scientific study in the field of hydrology which focuses on the composition, dispersion, and movement of snow and ice. Studies of snow hydrology predate the Anno Domini era, although major breakthroughs were not made until the mid eighteenth century. Snowfall, accumulation and melt are important hydrological processes in watersheds at high altitudes or latitudes. In many western states in the United States, snow melt accounts for a large percentage of the spring runoff that serves as water supply to reservoirs, urban populations and agricultural activities. A large portion of snow hydrology groups are pursuing new methods for incorporating snow hydrology into distributed models over complex terrain through theoretical developments, model development and testing with field and remote sensing data sets. Snow hydrology is quite complex and involves both mass and energy balance calculations over a time-varying snow pack which is influenced by spatial location in the watershed, interaction with vegetation and redistribution by winds. Some researchers seek to accurately capture snow dynamics at a point and over a domain as the spatial pattern of snow cover area is readily observable from remote sensing.
Overview Snow and ice account for around 75% of Earth's entire freshwater volume but lacks the capability of reliable applications. In comparison, the water supplied from rivers and freshwater lakes carries a consistent annual source of water. These natural bodies of water are formed through springs, rainfall and mountainous snow runoff. According to estimates, snow represents about 5% of the precipitation that reaches the Earth's surface. Due to the large amount of water held within these sources, snow hydrology has been a growing study in the field of river tides and seasonal flow rates. Despite common belief, snow fall is not the main cause for the destruction of organic matter in cold climates. The most damaging aspect is cold temperature winds that exist above the snow pack surface. Studies have shown the insulating properties of snow defend the plants and small animals in the environment from these frigid winds. “The snow itself is the habitat for various micro-organisms like snow worms and algae.” Without consistent annual snowfall, many plants would be destroyed due to frost damage. Both ice worms (Mesenchytraeus Solifugus) and green algae are unique organisms that can live in glacial and snowy habitats.
History Though most of the knowledge in the field of snow hydrology has been discovered in the last two centuries, there is evidence that some understanding existed as early as 500-428BC in the Greek states.
Ancient Some of the earliest evidence that supports an ancient technical understanding of snow movement was produced by the Greeks. Anaxagoras, an ancient Greek notes:
"the water in the Nile comes from the snow in Ethiopia, which freezes in the winter and melts in the summer". The upper class Greeks in these city states were shown to have basic understanding of the cooling properties that snow exhibited. Upper class citizens would have hay lined pits dug beneath their homes and bring snow down from the mountains to fill them. Perishable food items could then be stored in these pits for months at a time. The Christian Bible contains numerous passages in its text that express a basic understanding of the hydrological cycle. Each of the following verses shows fundamental ideas behind the hydrological processes.
Modern
One of the earliest modern records of the snow hydrology practice, was introduced by the geologist, Antonio Vallisnieri around the time of the 17th century. His work Theorized, “That rivers arising from springs in the Italian Alps came from rain and snowmelt seeping into underground channels." The first American research labs were introduced during the 1940s in order to solve the many problems associated with snow movement in the World War II era. These three labs were:
Central sierra Snow Laboratory (CSSL) Upper Columbia Snow Laboratory (USCL) Willamette Basin Snow Laboratory (WBSL) Currently there are hundreds of snow hydrology labs and sensing devices placed throughout the world. As of 2004, every continent was under observation with the exception of Antarctica. Since then, several sensing devices have been established in the Arctic Circle, allowing for constant observation. Using these in part with satellite imaging systems has produced an accurate depiction of underlying landmass, which was unknown in the past.
Hydrologists Snow hydrologists focus specifically on movement and composition of snow and ice, within the field of hydrology. The knowledge gained from this career is most commonly used in weather forecasting and ecological/ agricultural jobs, which require knowledge about the effects of snow migration. They retrieve the information they need through depth, density, and composition readings, as well as various remote sensing techniques. Workers in this field can work for government agencies, research firms and public information services.
Equipment and testing
Terrestrial measurements The study of snow and glacial movement, though now largely dependent on remote sensing devices, still requires in field techniques to accurately determine the validity of the data. These tools and techniques range from simple, such as a depth spike, to complex, such as the core sampling machines used to check for variations in ice composition. Three common types of terrestrial measurements are:
Snow Depth-This is a measurement from the snow surface to the ground in meters. It is commonly does over a large time span using immobile graduated stakes. Snow Water Equivalency- A measuring tool which represents the vertical depth of water that would accumulate in an area, if all the snow and ice were melted in that given area. Snow Density- This is the value found by dividing the water equivalency measurement by the snow depth reading.
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