--- title: "Power market, hydrology and geology in planning" subject: "Hydro Power" chapter: 3 key: "semester_6/hydro_power:power-market-hydrology-geology" source: https://www.bctengineer.com/q/semester_6/hydro_power/power-market-hydrology-geology site: BCT Engineering --- # Power market, hydrology and geology in planning Hydro Power · Chapter 3: Planning of Hydropower Projects - Asked in: 2077 Chaitra, 6 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/hydro_power/power-market-hydrology-geology - Whole chapter: https://www.bctengineer.com/md/semester_6/hydro_power/chapter-3 ## Question Explain Power market, Hydrology and Geology as a planning parameter for hydropower development. ## Short answer Power market defines demand, tariff, and grid access. Hydrology provides flow data for firm power, design flood, and sediment. Geology ensures safe foundation, tunnel stability, and construction materia availability, which are critical in Himalayan region. ## Answer Hydropower planning depends on several parameters. Three of the most important are the power market, hydrology and geology. #### Power market The power market is the demand for the energy and the price it can be sold at. - **Load demand and growth:** the plant size must match present and future demand; an oversized plant spills energy. - **Load pattern:** base-load demand suits run-of-river plants; peak demand needs peaking run-of-river (PROR) or storage plants. - **Seasonal mismatch:** in Nepal, run-of-river plants have surplus energy in the monsoon and a shortage in winter, so storage or export markets (India, Bangladesh) are important. - **Tariff and power purchase agreement (PPA):** the buying rate (e.g. NEA rates, different for wet and dry season) decides revenue and financial viability. - **Grid access:** distance to the grid and transmission capacity. #### Hydrology Hydrology tells how much water is available and when. - **Mean monthly flows and FDC:** fix firm flow, design discharge (e.g. Q40–Q65) and annual energy. - **Flood flows:** design flood (e.g. 1-in-1000 or 10,000-year) sizes the spillway, diversion works and cofferdams. - **Low flows:** decide firm power and environmental flow. - **Sediment load:** sizes the desander and estimates reservoir life. - **Glacial lakes (GLOF), snowmelt, climate change:** need special study in Himalayan basins. - Long, reliable records are needed; for ungauged rivers, regional methods (e.g. MIP, WECS/DHM methods) are used. #### Geology Geology decides whether the structures can be safely and economically built. - **Foundation:** dam and powerhouse need strong, watertight rock with low permeability. - **Tunnelling conditions:** rock class, faults, shear zones, squeezing and water ingress control tunnel cost and time. - **Slope stability:** landslides at the intake, headworks and penstock route. - **Seismicity:** Nepal is a high seismic zone; design must include earthquake loads. - **Construction materials:** sand, aggregate, clay for dams. - **Reservoir leakage and sedimentation** depend on geology of the catchment. Weak geology is the most common reason for cost and time overruns of Nepalese hydropower projects. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is Nepal's seasonal mismatch in the power market? A. Surplus in winter, shortage in monsoon B. Surplus in monsoon, shortage in winter for run-of-river plants C. No mismatch D. Demand is constant Answer: B. Run-of-river output peaks in monsoon, so storage or export is needed for winter. (Key point: Seasonal mismatch) 2. What do flood flows decide? A. Turbine type B. Tariff C. Spillway, diversion works and cofferdam design D. Load factor Answer: C. The design flood sizes the spillway, diversion works and cofferdams. (Key point: Hydrology role) 3. What does geology decide? A. Whether structures can be built safely and economically B. The tariff C. The load pattern D. The river flow Answer: A. Foundation, tunnelling, slope stability and seismicity are geological issues; weak geology often causes overruns. (Key point: Geology role) ## Related in Hydro Power - [Stages of hydropower project study](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-study-stages) — Hydro Power, chapter 3, asked 3× - [Flow duration curve and planning parameters](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Afdc-planning-parameters) — Hydro Power, chapter 3 - [Layout of hydropower scheme components](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-scheme-layout) — Hydro Power, chapter 5 - [Advantages and limitations of hydropower](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-advantages-limitations) — Hydro Power, chapter 3 - [Firm power and plant load factors](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Afirm-power-load-factors) — Hydro Power, chapter 3 - [Flow and power duration curves](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Aflow-power-duration-curves) — Hydro Power, chapter 3 ## Related in other subjects - [Transmission expansion planning in deregulated market](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atransmission-planning-deregulated) — Power Plant Design, chapter 2 - [Hydropower and holistic regional development](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ahydropower-holistic-development) — Power Plant Design, chapter 1 - [Hydropower Development Policy 2001 (2058 BS)](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Ahdp-2001-objectives-features) — Hydropower Engineering, chapter 1, asked 4× - [Importance of hydropower development in Nepal](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aimportance-hydropower-nepal) — Hydropower Engineering, chapter 1