Basic Ground-Water Hydrology (USGS Water-Supply Paper 2220)
by Ralph C. Heath · U.S. Geological Survey
An 86-page illustrated USGS primer organised one topic per two-page spread: aquifers, porosity, hydraulic head, Darcy's law, well hydraulics, aquifer tests and water budgets. Readers gain the vocabulary and equations used in professional groundwater work.
More resources on Hydrology
HEC-HMS Technical Reference Manual
US Army Corps of Engineers documentation for the watershed modelling package used in American flood studies, explaining the equations behind loss, transform, baseflow, routing and reservoir methods and when each applies. Readers can choose and defend modelling methods. Practitioner Source Truth with real skin in the game: these method descriptions are what a flood study is defended on. Bridges the gap between the physics in Dingman and what a working hydrologist does.
Physical Hydrology, Third Edition
The standard university text on the physics of the hydrologic cycle: precipitation, snow, evapotranspiration, soil water, groundwater and streamflow, each developed from mass and energy balances. Readers can quantify individual fluxes and read the hydrologic literature.
Rainfall-Runoff Processes (Utah State / NWS COMET module and workbook)
Utah State module built for the National Weather Service COMET program, archived with its full workbook on runoff generation mechanisms, soil properties, infiltration models and model representation. Readers can compute infiltration and identify which runoff mechanism dominates a hillslope.
Ground Water and Surface Water: A Single Resource (USGS Circular 1139)
USGS synthesis of how streams, lakes, wetlands and estuaries exchange water with aquifers across different landscapes, including measurement methods and contamination pathways. Teaches the single most important mental model in the topic — that the two halves of hydrology are one system — using real landscape case studies rather than abstraction. Readers stop treating surface water and groundwater as separate systems when assessing a watershed.
Groundwater (Freeze & Cherry, 1979) — free online edition
The field-defining hydrogeology text, rights-reverted and republished free by the Groundwater Project. Covers physical and chemical principles, flow nets, regional flow systems, resource evaluation and contamination. Readers can construct flow nets and analyse aquifer behaviour quantitatively. This is the Source Truth of quantitative hydrogeology and it is now legally free, in full, in several languages, with no registration wall on the web edition.
Applied Hydrology
Standard graduate text covering the hydrologic cycle, unit hydrographs, flood routing, frequency analysis and design storms, with worked derivations. Readers can size hydraulic structures and estimate design flows from rainfall and streamflow records.