Archive for Article

Ice Cores and Ancient Climatic Conditions

In polar and alpine regions that are sufficiently cold, snowfall can persist from year to year and consequently can build up in layers. With time, the weight of the snow compresses the deeper snow layers to form solid ice, resulting in a sheet of ice and snow called a glacier.

Each layer of snow, which eventually becomes a layer of ice, carries with it some information about the environment and climate that existed when the snowfall occurred. By drilling down into glaciers and removing long cores of this layered ice and snow, scientists can better understand how Earth’s climate has changed over time. Read more

Security and Water

Complex relationships exist between water and the security of individuals, communities, nations, and the global community as a whole. The vital role of water in daily life and economic activity underscores its importance to a secure and stable world. Water resources and the provision of water services involve political decision-making, and extreme types of conflict can escalate into violence, terrorism, or war.

Gleick (2000) provides a timeline of water conflicts throughout history, categorizing them according to the basis of the conflict and the actors involved.

  • State and non-state parties fight over water supplies or access to water supplies (control dispute).
  • Nations use water resources or water systems as a weapon during a military action (military tool).
  • State and non-state parties use water resources or water systems for political goals (political tool).
  • Non-state parties use water resources or water systems as a target or tool for violence or coercion (terrorism).
  • Nations use water systems as a target for military action (military target).
  • State and non-state parties argue over water resources or water systems in the context of economic development (development dispute).

Military and terrorist actions are of particular concern to security experts and those who are responsible for managing water resources and water systems.  Read more

Desert Hydrology

Deserts are arid regions, generally receiving less than 25 centimeters (10 inches) of precipitation a year, or regions where the potential evaporation rate is significantly greater than the precipitation. In most cases, deserts possess a high average temperature with large differences between daytime and nighttime temperatures. Arid regions can also be defined as environments in which water is the limiting factor for biosystems . This means that survival

This desert in Valley of the Tsauchab, Namibia illustrates the vegetation, desert crust, and occasionally pooled water that characterize these arid regions. Annual rainfall in Namibia’s coastal desert is 50 millimeters (about 2 inches).
of life in these regions involves a constant struggle to obtain this limited commodity and to draw the maximum benefit from it. Read more


Human societies have long worked on changing nature’s waterways for their purposes. Canals are artificial waterways constructed for irrigation , drainage, river overflows, water supplies, communications, and navigation, or in connection with power generation from hydroelectric dams. The digging of canals for irrigation probably dates to the beginnings of agriculture, with traces of canals found within ancient Chinese, Egyptian, and Babylonian civilizations.

Written evidence shows that the Suez Canal, for instance, was excavated prior to 2000 B.C.E. It was documented to be navigable for small vessels by 600 B.C.E. and remained in operation for fourteen centuries as a convenient trade route between the Mediterranean and Red Seas. One of the world’s longest canals, the Grand Canal of China, was constructed primarily during the seventh and thirteenth centuries. The 1,900-kilometer (1,200-mile) canal connected the cities of Beijing and Hangzhou, and is often considered the most notable of the early canals. Read more

Agriculture and Water

Humans depend on water in many ways, well beyond the few liters needed daily for drinking. Water is also essential for the production of food. Various forms of agriculture, practiced on about half of Earth’s land surface, provide the vast majority of food that over 6 billion people eat. Agriculture also provides much of the fiber for cotton, wool, and linen clothing.

Rain-fed Agriculture

One of the primary ways in which humans use water is by planting important crops in places where they can capture natural rainfall as rain-fed agriculture. Some forms of agriculture, such as intensive rice and corn production, can be practiced only in rainy climates. Such agricultural forms are much more productive than others, such as cattle and sheep herding, which are usually relegated to semiarid climates.

One of the primary reasons rain-dependent forms of agriculture are more productive than dry-land forms is that they have sufficient water to allow plants to grow to their maximum potential. Therefore, the most agriculturally productive regions of the world are all regions where natural rainfall is sufficient to allow rain-fed agriculture to flourish:

for example, the Subsistence agriculture on small farm plots is practiced in the highly elevated Altiplano of Chile and Bolivia (South America). Farmers in the arid highlands must cope with the variable weather conditions and extreme climatic uncertainty.  Read more