Well Hydrograph Analysis for the Estimation of Hydraulic and Geometric Parameters of Karst and Connected Water Systems

Abstract

Well hydrographs contain crucial information about the hydraulic parameters and geometric characteristics of karst aquifers and connected water systems. This chapter provides quantitative tools for the estimation of hydraulic and geometric parameters by means of well hydrograph analysis. The analytical formulae provided in this chapter establish links between aquifer properties and hydrograph recession coefficients, and describe the spatial and temporal variations of the water table. A first set of equations describe the recession limb of hydrograph peaks, while another formula provides a quantitative characterization of the entire hydrograph peaks as a response to diffuse recharge. While existing spring hydrograph analytical techniques provide information on the overall characteristics of a karst catchment, well hydrograph analysis provides information on the hydraulic and geometric characteristics of individual matrix blocks. The combination of the spring and well hydrograph analytical techniques provides a powerful tool for the characterization of the structure and hydraulic behaviour of karst and connected water systems. A new approach to well hydrograph decomposition is presented, which makes the estimation of exact block geometry possible. In most cases, well hydrograph peaks can be decomposed into three exponential segments. These segments, however, do not represent different types of storage as suggested by previous studies. The asymmetric analytical solution presented in this study represents a powerful tool for parameter estimation in both karst and connected water systems. The symmetric and 1D solutions can be applied for order of magnitude parameter estimation. The proposed investigation method provides useful information for water resource assessment, flood prediction, vulnerability assessment, contamination risk assessment, geotechnical and speleological studies.