The Pearl River Delta (PRD), located in the coastal area of South China, contains a large confined Quaternary aquifer. This aquifer has been identified to have high concentrations of total dissolved solids–ranging from 1 g/l in the inland area to 26.8 g/l near the southeast shoreline. This work aims to investigate the origin of groundwater salinity and the major hydrogeochemical processes contr...

This uniquely designed study investigates a fundamental issue—the feasibility of predicting stream depletion rates using linear uniform two-dimensional models. Required input for these models includes the hydraulic parameter estimates of the aquifer and the stream–aquifer interface, which may be obtainable through pumping test data analysis. This study utilizes pumping test data collected near ...

[1] The method of recession analysis proposed by Brutsaert and Nieber (1977) remains one of the few analytical tools for estimating aquifer hydraulic parameters at the field scale and beyond. In the method, the recession hydrograph is examined as dQ/dt = f(Q), where Q is aquifer discharge and f is an arbitrary function. The observed function f is parameterized through analytical solutions to th...

Seepage-face boundaries are common features of unconfined ground water flow. These boundaries exist at the intersection of an unconfined aquifer and a surface water body such as a lake, river, or wetland. The existence of a seepage-face boundary is necessary to provide a physical transition between the internal water-table boundary and the external equipotential boundary when an unconfined aqui...

A polyphasic approach based on cultivation and direct recovery of 16S rRNA gene sequences was utilized for microbial characterization of an aquifer contaminated with chlorinated ethenes. This work was conducted in order to support the evaluation of natural attenuation of chlorinated ethenes in groundwater at Area 6 at Dover Air Force Base (Dover, DE). Results from these studies demonstrated the...

Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ ce...

The deep phreatic thermal explorer (DEPTHX) is an autonomous underwater vehicle designed to navigate an unexplored environment, generate high-resolution three-dimensional (3-D) maps, collect biological samples based on an autonomous sampling decision, and return to its origin. In the spring of 2007, DEPTHX was deployed in Zacatón, a deep (approximately 318 m), limestone, phreatic sinkhole (ceno...

Gisser and Sánchez (1980a) state the conditions under which welfare gains from policy intervention are negligible in aquifer management, when compared with non-regulation or “free market” outcomes. This is the so-called Gisser-Sánchez effect (GSE), which has been supported by the ensuing literature during recent decades. The GSE requires a number of assumptions, among which is the disregard for...

Head measurements at a single observation well during a cross-hole pumping test carry a great amount of information about aquifer heterogeneity other than the average property of the aquifer as implied in Theis analysis of aquifer test. In this commentary, we use simple examples and a probabilistic reasoning approach based on Darcy’s law to unravel this information, buried in the results of qua...