---
title: "Stages of hydropower project study"
subject: "Hydro Power"
chapter: 3
key: "semester_6/hydro_power:hydropower-study-stages"
source: https://www.bctengineer.com/q/semester_6/hydro_power/hydropower-study-stages
site: BCT Engineering
---

# Stages of hydropower project study

Hydro Power · Chapter 3: Planning of Hydropower Projects

- Asked in: 2080 Chaitra, 8 marks; 2081 Asoj, 8 marks; 2071 Magh, 8 marks (asked 3 times)
- Video: [What are the Stage of Hydropower Development #water #energy #generated #powerhouse #dam #electricity](https://www.youtube.com/watch?v=QAR-x4D_0Gk) — Hydropower
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/hydro_power/hydropower-study-stages
- Whole chapter: https://www.bctengineer.com/md/semester_6/hydro_power/chapter-3

## Question

In what stages study of a hydropower project are completed? What parameters do you investigate in each stage? Discuss with hydropower development cycle.

## Short answer

Hydropower studies progress through desk study, reconnaissance, pre-feasibility, feasibility (with EIA), and detailed design. Each stage investigates hydrology, geology, layout, cost, environmental and socio-economic parameters with increasing accuracy to justify investment.

## Answer

A hydropower project is studied in stages of increasing detail, so that money is spent on detailed work only for projects that prove worthwhile. Together with construction and operation these form the **hydropower development cycle**.

```text
 Identification / desk study
            |
 Reconnaissance study
            |
 Pre-feasibility study
            |
 Feasibility study  (+ EIA, licences)
            |
 Detailed design & tender
            |
 Construction & commissioning
            |
 Operation & maintenance  --> rehabilitation
```

#### 1. Desk study / identification
Using maps (1:50 000 topo), existing hydrological records and reports, possible sites are identified and rough power potential $P = 9.81\,QH\eta$ is computed. Several alternatives are listed.

#### 2. Reconnaissance study
A short site visit and study to screen alternatives.
- Rough layout: headworks, waterway, powerhouse locations.
- Approximate head (altimeter/GPS) and spot flow measurement.
- General geology, access, land use, settlements.
- Rough cost and power; ranking of sites.

#### 3. Pre-feasibility study
Selects the best scheme and decides whether a full feasibility study is justified.
- Topographic survey at larger scale; hydrological analysis (flow duration curve, floods).
- Preliminary geology (surface mapping), sediment and seismic data.
- Comparison of layouts and capacities; preliminary design and cost estimate.
- Initial environmental examination, power market and economic indicators (B/C, IRR).

#### 4. Feasibility study
Detailed enough for financing and licensing decisions.
- Detailed topographic surveys; long-term hydrology, design flood, sediment study.
- Subsurface investigation: drilling, test pits, seismic refraction, lab tests of construction materials.
- Optimisation of installed capacity, firm/secondary energy; final layout.
- Design of main structures, construction schedule, detailed cost estimate.
- Full **EIA**, social and resettlement study; power market and transmission; financial and economic analysis (NPV, IRR, B/C, cost per kWh).
- In Nepal, the generation licence (DoED) and PPA with NEA are based on this stage.

#### 5. Detailed design and tender
Final engineering drawings, specifications, bill of quantities, tender documents; further investigation where needed.

#### 6. Construction and commissioning
Access roads, river diversion, civil works, electro-mechanical and transmission works; testing and commissioning.

#### 7. Operation and maintenance
Power generation, monitoring of sediment, structures and equipment; later upgrading or rehabilitation, which restarts the cycle.

| Stage | Main output | Accuracy of cost |
|---|---|---|
| Reconnaissance | Promising sites | ±40–50% |
| Pre-feasibility | Best alternative | ±25–30% |
| Feasibility | Go / no-go, financing | ±10–15% |
| Detailed design | Drawings, tender | ±5–10% |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why is a hydropower project studied in stages of increasing detail?
   A. To delay construction
   B. To spend money on detailed work only for projects that prove worthwhile
   C. Because law requires exactly seven reports
   D. To avoid hydrological data
   Answer: B. Early cheap screening removes poor options before costly detailed investigation. (Key point: Purpose of staged studies)

2. What is the correct order of studies?
   A. Feasibility, reconnaissance, pre-feasibility, desk study
   B. Reconnaissance, desk study, feasibility, pre-feasibility
   C. Desk study, reconnaissance, pre-feasibility, feasibility
   D. Pre-feasibility, desk study, feasibility, reconnaissance
   Answer: C. Identification/desk study, reconnaissance, pre-feasibility, feasibility, then detailed design and tender. (Key point: Order of stages)

3. Which is investigated at the feasibility stage but not in earlier stages?
   A. Full EIA, subsurface drilling and financial analysis for licensing
   B. Rough power from maps
   C. Spot flow measurement
   D. Ranking of sites
   Answer: A. Feasibility includes detailed surveys, drilling, full EIA and financial analysis (NPV, IRR) used for licence and PPA. (Key point: Feasibility parameters)

4. How does the accuracy of cost estimates change along the stages?
   A. It stays the same
   B. It gets worse
   C. It improves from about +/-40-50% at reconnaissance to +/-10-15% at feasibility
   D. It is best at reconnaissance
   Answer: C. More investigation reduces uncertainty, so accuracy improves with each stage. (Key point: Cost accuracy)

## Related in Hydro Power

- [Stage discharge curve and its application](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Astage-discharge-curve) — Hydro Power, chapter 2
- [Flow duration curve and planning parameters](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Afdc-planning-parameters) — Hydro Power, chapter 3
- [Parameters for powerhouse dimensions](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Apowerhouse-dimensions) — Hydro Power, chapter 5, asked 2×

## Related in other subjects

- [Stages of hydropower development cycle](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Adev-cycle-stages) — Hydropower Engineering, chapter 2
- [Study stages for 10 MW remote project](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Asmall-10mw-study-stages) — Hydropower Engineering, chapter 2
- [Project development life cycle phases](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Aproject-development-life-cycle) — ICT Project Management, chapter 1
- [Development cycle and detailed design studies](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Adev-cycle-detailed-design-studies) — Hydropower Engineering, chapter 2