Surface Water Interaction Modelling Using Visual MODFLOW and GIS

PHYLARESIntroduction / ch.1__________________________________________________________________________________________1Chapter 1Introduction1.1 General OverviewWater covers two-thirds of the Earth’s surface and surrounds the planet in vapor form. Chemicaland density stratification during and immediately following accretionary heating of the Earth’sprimordial planetary body resulted in its present layered configuration. Internal heat andchemical reactions caused water, which was originally bound as oxygen and hydroxide inminerals, to diffuse from the Earth’s interior towards its surface. This degassing (still an ongoingprocess) of both water and other volatile species resulted in the accumulation and eventualcondensation of the fluid envelope of the Earth. Of course, water was also delivered to our planetby infalling comets and other H 2 O bearing planetesimals.The hydrologic cycle describes the complex system whereby water circulates among its variousreservoirs at and near the surface of the Earth. These reservoirs include the oceans, theatmosphere, underground water (including both soil water and groundwater), surface water(lakes, rivers and wetlands), glaciers and the polar ice caps. The Hydrologic cycle is directlycoupled to the Earth’s energy cycle, because solar radiation combines with gravity to drive theglobal circulation of water. This circulation, in turn, plays an important role in the heat balanceof the Earth’s surface. The hydrologic cycle is also closely linked to the geosphere and its rockcycle. Water erodes geologic materials, and the breakdown of these materials releases manychemical constituents that in turn define the chemical nature of the water. Water can also buildgeologic formations, through both chemical and mechanical depositional processes. Water isessential to all life forms in the planetary biosphere. (Mauricie, et.al, 2001).Only a small portion (3 %) of the water covering the earth’s surface is fresh. Of the fresh water77.5% is locked in ice fields and glaciers. Surface water and underground water are the utilizable______________________________________________________________________________________Groundwater – Surface water interaction modeling using visual MODFLOW and GIS