ANALYSIS OF GROUNDWATER FLOW TO DEEP WELLS IN AREAS WITH A NON-LINEAR FUNCTION FOR THE SUBSURFACE DRAINAGE

THE QUANTITATIVE ANALYSIS OF GROUNDWATER FLOW TO DEEP WELLS IN AREAS WHERE THE EXCESS PRECIPITATION IS DISCHARGED FOR A MAJOR PART BY SURFACE DRAINS, REQUIRES INFORMATION ABOUT THE SYSTEM OF THIS SURFACE DRAINAGE. THE NON-LINEAR RELATION BETWEEN THE DISCHARGE AND THE PHREATIC LEVEL (AREAL MEAN) CAN BE EXPLAINED MAINLY BY THE FACT THAT THE LENGTH OF THE DRAINS CONTAINING WATER AND GIVING DISCHARGE IS VARYING IN THE SAME SENSE AS THE DISCHARGE AND THE PHREATIC LEVEL. CHANGES IN EVAPORATION BY THE PLANTS ARE OF LESS IMPORTANCE IN THIS CONNECTION. AS THERE IS SOME EVIDENCE THAT THE AMPLITUDE OF THE SEASONAL FLUCTUATIONS OF THE PHREATIC SURFACE WILL NOT BE INFLUNECED VERY MUCH WHEN THERE IS A CONSTANT PUMPING OF WATER FROM DEEP WELLS, THE CHANGE IN THAT SURFACE EFFECTED BY PUMPING CAN BE PUT EQUAL TO THE DRAWDOWN DURING A STEADY STATE FLOW TO THE DEEP WELL. WHEN THE RELATION BETWEEN HYDRAULIC HEAD AND DISCHARGE BY DRAINS IS LINEARIZED, I. E. REPRESENTED IN A GRAPH AS A BROKEN STRAIGHT LINE WITH FOR EACH PART A SPECIFIC VALUE FOR THE EFFECTIVE DRAINAGE RESISTANCE THE BASIC DIFFERENTIAL EQUATION IS REDUCED TO A BESSEL EQUATION OF ZERO ORDER. THE STEADY STATE SOLUTION EITHER CONTAINS A COMBINATION OF MODIFIED BESSEL FUNCTIONS (FOR FINITE VALUES OF THE EFFECTIVE DRAINAGE RESISTANCE) OR A LOGARITHM (WHEN THE EFFECTIVE DRAINAGE RESISTANCE EQUALS INFINITY). THE DETERMINATION OF THE INTEGRATION CONSTANTS FOR SEVERAL ZONES AROUND THE WELL IS IN PRINCIPLE NOT DIFFICULT. IN THE PAPER AN EXPLICIT SOLUTION IS ONLY GIVEN FOR A RATHER SIMPLE CASE. /JH/

  • Supplemental Notes:
    • Vol 14, No 2, PP 158-180, 11 FIG, 23 REF
  • Authors:
    • Ernst, L F
  • Publication Date: 1971-11

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Filing Info

  • Accession Number: 00238031
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 24 1972 12:00AM