Estimating Recharge Rates Through Unsaturated Glacial Till by Tritium Tracing

摘要: A tritium profile obtained from a core located on the Tipton Till Plain near West Lafayette, Indiana, showed “tritium reversal” (corresponding to low-high-low activity of relative depth) at 7 m, indicating present position recharge water derived 1963/64 precipitation. The average rate calculated using data is 3.5 cm/yr for “mass-balance” method and 4.7 “transit-time” method. 4.1 in reasonable agreement with Arihood's (1982) estimate 5.1 tills, based numerical modeling water-budget study White River basin Indiana. Two other cores, nearby topographically lower slope, no definite reversal activity, probably because lateral flow components these locations. To be applied, technique should assess contribution summer winter precipitation activities tend peak spring Contrary usual assumptions that aquifers temperate zones northern hemisphere occurs between October April, stable isotopic well area indicate an appreciable amount annual (about 34%) actually April October.