San Diego Hydrogeology

Groundwater Flow Model

A groundwater flow model is a mathematical representation of groundwater flow through an aquifer, which is composed of saturated sediment and rock. In order to solve the equations that constitute the flow model, it is necessary to make simplified assumptions about the aquifer and the physical processes governing groundwater flow. The most important of these assumptions are embodied in the conceptual model of the aquifer. Although the groundwater flow model cannot be as detailed or as complex as the real system, the model is useful in at least four ways: (1) the model integrates and assures consistency among aquifer properties, recharge, discharge, and groundwater levels; (2) the model can be used to estimate flows and aquifer characteristics for which direct measurements are not available; (3) the model can be used to simulate response of the aquifer under hypothetical conditions; and (4) the model can identify sensitive areas where additional hydrologic information could improve understanding.

Reconnaissance-level model for the San Diego River basin

As part of a regional water-balance study for the San Diego area, a reconnaissance-level groundwater flow was developed for the San Diego River basin. The purpose of this model was to evaluate the distributed quantity of recharge calculated by the water-budget model, in particular to determine if this quantity could reasonably flow through the hard rock and coastal sediment. The flow model also included simulation of streamflow and its interaction with the groundwater system; inflow to the streams was derived input from the water-balance model. The flow model is documented in the following document, which focuses primarily on the regional water-budget model:

Flint, L. E., Flint, A. L., Stolp, B. J., and Danskin, W. R., 2012,
A basin-scale approach for assessing water resources in a semiarid environment: San Diego region, California and Mexico, Hydrol. Earth Syst. Sci., 16, 3817-3833, doi:10.5194/hess-16-3817-2012.

Project Chief: Wes Danskin
Phone: 619-225-6132

Welcome to the United States Geological Survey (USGS) San Diego Hydrogeology project website, which provides geologic and hydrologic information for the transboundary San Diego–Tijuana area, USA and Mexico. This website provides background information about the project; a variety of news items; a large amount of data, in particular for USGS multiple-depth, monitoring-well sites; geologic and hydrologic models; and additional resources including photos, illustrations, and references. Last updated: April 2016

Some additional data may be available from the USGS database National Water Information System (NWIS).

Questions about San Diego Hydrogeology? Please contact Wes Danskin (email: or send a letter). 619.225.6132