Precipitation hydrologic variability

Lichtner (2001) developed the computer code FLOTRAN, with coupled thermal-hydrologic-chemical (THC) processes in variably saturated, nonisothermal, porous media in 1, 2, or 3 spatial dimensions. Chemical reactions included in FLOTRAN consist of homogeneous gaseous reactions, mineral precipitation/dissolution, ion exchange, and adsorption. Kinetic rate laws and redox... 

The interactions of the chemical kinetic and macroscopic transport processes depend to a variable extent on each of the nine couples given in Table 1. For example, transport of solutes by water runoff is a result of atmospheric precipitation, land exposure to water, chemical reactivity of solids in an aqueous solution, and flow of water over the continental surface. The net result of this process is controlled by coupling among the physical, hydrological and chemical entities in Table 1, as shown below ... 

For most of the earth s continental environments, the hydrologic cycle is probably more important to living things than is temperature. For example, the hydrologic cycle is the main determinant of whether cold )laces are tundra or ice sheets, and whether warm places are rain forests or deserts. 5 0 or 5D of water record such truly important variables as amount of precipitation. Given the complexity of the controls on 6 0 and 5D, widespread success in simulating them almost certainly demonstrates model skill. 

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