USGS

Model-Estimated Ground-Water Recharge and Hydrograph of Ground-Water Discharge to a Stream

U.S. Geological Survey Water Resources Investigations Report 97-4253

By A.T. Rutledge


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Abstract

The computer model PULSE, described in this report, can be used to construct a hydrograph of ground-water discharge to a stream. The model is applicable to a ground-water flow system that is driven by areally uniform recharge to the water table, and in which ground water discharges to a gaining stream. One of the two formulations used by the model allows for an instantaneous recharge pulse and subsequent ground-water discharge to the stream. The other formulation, which allows for a gradual hydrologic gain or loss term in addition to the instantaneous pulse, can be used to simulate the effects of gradual recharge to the water table, ground-water evapotranspiration, or downward leakage to a deeper aquifer.

Contents

Abstract

Introduction

Mathematical Model

Model Applicability

Ground-Water Discharge Resulting from a Pulse Recharge to the Aquifer

Ground-Water Discharge Resulting from a Pulse Recharge to the Aquifer and a Gradual Gain or Loss Applied Areally

Procedure for Estimation of Ground-Water Discharge for a Streamflow Hydrograph

Model Input Variables

Initial Ground-Water Discharge

The Recession Index

The Time of Surface Runoff

Estimation of Recharge and GWET

Example Applications

Time Scales for Reporting Results

Computer Implementation of the Model

Possible Future Analysis and Application of the Model

References Cited





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