Key takeaways
- Covers hydrology and irrigation engineering together, as most syllabi do.
- Boxed formulas for the normal ratio method, Horton's equation, rational method, risk and well flow.
- Worked examples for rational method peak, flood risk, well discharge and duty and delta.
- Tables for rain gauges, mean rainfall methods, aquifer types and weir versus barrage.
- Original Uncodemy revision notes based on the common syllabus.
About these Hydrology and Water Resources notes
Hydrology and Water Resources covers the path of rain from the sky to the river, the aquifer and the canal. It has many named methods and empirical formulas. These notes list each method with what it is used for, so you can pick the right one in the exam.
These are original Uncodemy revision notes. They follow the topics common to most Indian B.Tech Civil syllabi for Hydrology and Water Resources, written in a neat handwritten style with formulas boxed and key numbers highlighted. They are short notes for revision, not a replacement for your textbook or class notes.
What's inside the notes: unit by unit
The PDF follows the water: rainfall and losses, runoff and floods, groundwater, then irrigation works.
Unit 1: Hydrologic cycle and precipitation
- Cycle and water budget: the water budget equation and the forms and types of precipitation.
- Rain gauges: recording and non-recording gauges and the optimum number of gauges.
- Rainfall data: normal ratio method, double mass curve and mean rainfall by arithmetic, Thiessen and isohyetal methods.
Unit 2: Abstractions
- Evaporation and evapotranspiration: factors, pan coefficient and potential ET.
- Infiltration: Horton's equation, φ-index, W-index and infiltrometers.
Unit 3: Runoff and hydrographs
- Hydrograph: its parts and base flow separation.
- Unit hydrograph: assumptions, S-curve, synthetic UH and IUH.
- Rational method: peak runoff from small catchments, with an example.
Unit 4: Floods and flood routing
- Flood estimation: Dickens, Ryves and Inglis formulas, return period and risk, with an example.
- Frequency analysis: Gumbel's method, SPF and PMF.
- Routing: reservoir routing by the Modified Puls method and channel routing by Muskingum.
Unit 5: Groundwater
- Aquifers: aquifer types, specific yield, storage coefficient and transmissivity.
- Well hydraulics: Thiem and Dupuit equations with an example, and well tests.
Unit 6: Irrigation water requirement
- Duty, delta and base period: the Δ = 8.64 B / D relation with an example, and crop seasons.
- Soil-water relations: field capacity, wilting point, available water and consumptive use.
- Irrigation methods and efficiencies: surface, sprinkler and drip irrigation.
Unit 7: Canals and diversion head works
- Canal design: canal alignment, Kennedy's and Lacey's theories, lining and water logging.
- Weirs and barrages: Bligh's creep theory, Lane's weighted creep and Khosla's exit gradient.
Unit 8: Dams, spillways and reservoirs
- Gravity dams: forces, modes of failure, the middle third rule and elementary profile.
- Earth dams and spillways: causes of failure, seepage line, spillway types and energy dissipation.
- Reservoir planning: storage zones, mass curve and trap efficiency.
How the PDF is laid out
Each section opens with short definitions in bullet form, followed by tables that compare types, tests or methods. Formulas are written in separate boxes so they stand out when you flip through the pages, and the values that examiners ask most often are highlighted. Short tip boxes point out exam favourites and common traps. Wherever a formula is used in exams, a short solved example shows the steps with real numbers. The last page lists 10 most asked practice questions so you can test yourself after revising.
How to revise Hydrology and Water Resources
- Make a method-and-purpose table. For each named method, write what it finds. Thiessen finds mean rainfall, Muskingum routes floods, Lacey designs canals.
- Practise the unit hydrograph by hand. Derive a UH of another duration using the S-curve at least twice.
- Keep units visible. Rational formula has two forms (km² and hectares); duty is in ha per cumec. Write units at each step.
- Draw the hydrograph and dam sections. Labelled sketches of a hydrograph, a gravity dam and an earth dam seepage line earn marks.
- Revise irrigation formulas together. Duty-delta, soil moisture depth and Lacey's set fit on one page.
Exam focus: high-weightage topics and numericals
Hydrology papers are numerical-heavy; irrigation papers mix theory and design. Common areas:
- Mean rainfall, missing data and consistency of records.
- Infiltration indices and the unit hydrograph.
- Flood estimation, return period and risk.
- Well hydraulics in confined and unconfined aquifers.
- Duty and delta, canal design by Lacey and forces on gravity dams.
Typical numericals to practise
- Find mean rainfall by the Thiessen method and missing data by the normal ratio method.
- Find φ-index and W-index from a storm hyetograph.
- Find a unit hydrograph of another duration using the S-curve.
- Find the risk of a design flood over the life of a structure.
- Find well discharge by Dupuit's equation, and delta from duty and base period.
A one-week plan with these notes
If your Hydrology and Water Resources exam is a week away, this plan covers the whole PDF once and leaves time for practice.
- Day 1: Hydrologic cycle and precipitation and Abstractions. Read the section, then close the PDF and write the key formulas and tables from memory.
- Day 2: Runoff and hydrographs and Floods and flood routing. Read the section, then close the PDF and write the key formulas and tables from memory.
- Day 3: Groundwater and Irrigation water requirement. Read the section, then close the PDF and write the key formulas and tables from memory.
- Day 4: Canals and diversion head works and Dams, spillways and reservoirs. Read the section, then close the PDF and write the key formulas and tables from memory.
- Day 5: redo every solved example in the notes without looking at the steps.
- Day 6: answer the 10 practice questions at the end of the PDF under a time limit.
- Day 7: solve one recent official paper from your university and revise the topics you got wrong.
Who these notes are for
- B.Tech semester exams: covers both the hydrology and the irrigation units of the semester paper.
- GATE CE basics: unit hydrograph, φ-index, risk, well equations, duty-delta and Lacey's equations are common GATE CE topics.
- Site work and interviews: engineers in irrigation, water resources and drainage projects get quick formula recall.
Check your own syllabus and the current IS codes
Universities split and order these topics differently, and some leave out units or add extra ones. Match the notes against your own university syllabus and recent official question papers before you plan your revision. Design practice for dams, canals and spillways in India follows IS codes and Central Water Commission guidelines. Codes are revised from time to time, so check the current edition and any amendments before you use a value in design work or quote it in an answer. Uncodemy keeps a list of previous year question paper sources if you want official papers to practise with.
Download Hydrology and Water Resources Handwritten Notes PDF
Hydrology and Water Resources Handwritten Notes PDF
The PDF carries the same content as this page in a clean, print-ready layout, so you can read it offline and keep it for revision.
7 pages · 275 KB · PDF · Updated 5 Nov 2026