Laserfiche WebLink
<br />OO~I%~ <br /> <br />DATA REQUIREMENTS FOR MODELING HYDROLOGIC SYSTEMS <br /> <br />The data requirements for ground-water planning depend upon many <br />factors such as the hydrologic complexity of the area, types of water <br />problems, and size of area. Some planning studies would need sophis- <br />ticated large-scale model analyses while others would require only a <br />descriptive evaluation of existing hydrologic data. A summary of the <br />major steps in an intensive study of a ground-water basin are: <br /> <br />1. Collect and interpret data needed by the hydrologist to <br />describe geology, hydrology, and historical development of <br />water supp lies, <br /> <br />2. Develop a model, analog or digital, of the basin. <br /> <br />), Calibrate model. <br /> <br />4. Use model to evaluate water problems and predict future changes. <br /> <br />The first phase of a ground-water basin study consists of the <br />evaluation of existing hydrologic and hydrogeologic data to define the <br />physical character of the ground-water system. This evaluation is used <br />to develop a conceptual model of the system, to guide the data-collection <br />program, and to identify major water-supply deficiencies or problems. <br />The field data-collection program includes the collection of information <br />on the hydrogeologic character and operation of the aquifer, well <br />locations and withdrawals, surface-water diversions, precipitation, and <br />streamflow, Supplementary data might be obtained by test drilling, <br />installation of observation wells, geophysical logging, pumping tests, <br />installation of gaging stations, and water-quality analyses, These <br />field data are summarized and then interpreted to provide a description <br />of the water resources and an evaluation of the historical development <br />of the water supply, <br /> <br />If a more intensive study is indicated the next phase of the study <br />might be the development of a model (analog or digital) of the basin. <br />A model is essential for many projects because of the difficulty of <br />integrating and analyzing large quantities of hydrologic data. The <br />model should at first be used principally as a tool to synthesize the <br />data and to test hypotheses of how the hydrologic system functions, The <br />development and testing of the model for accuracy requires quantitative <br />hydrologic and geologic data to describe the operation of the ground- <br />water system and its interrelation with streams. The results of a model <br />analysis are no more reliable than the basic data used to construct the <br />model and to provide hydrologic input. For most model studies a team <br />approach is recommended because of the varied knowledge and experience <br />required for accuracy of model calibration and prediction analysis. The <br />team should normally consist of specialists in geohydrology and geo- <br />chemistry, and in some studies ot~er specialists in law, economics, <br />ecology, and soil science, <br /> <br />6 <br />