---
title: "Define hydrology and its importance in water resources"
subject: "Engineering Hydrology"
chapter: 1
key: "semester_5/engineering_hydrology:hydrology-define-importance"
source: https://www.bctengineer.com/q/semester_5/engineering_hydrology/hydrology-define-importance
site: BCT Engineering
---

# Define hydrology and its importance in water resources

Engineering Hydrology · Chapter 1: Introduction

- Asked in: 2082 Baisakh, 1+3 marks
- Video: [Hydrology 101: Intro to Water Resources Engineering and Hydrology](https://www.youtube.com/watch?v=RhbU1pyXWFo) — Clear Creek Solutions
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/engineering_hydrology/hydrology-define-importance
- Whole chapter: https://www.bctengineer.com/md/semester_5/engineering_hydrology/chapter-1

## Question

Define hydrology. Why is hydrology considered important in case of water resources engineering?

## Short answer

Hydrology is the science of water's occurrence, circulation, distribution, movement, and properties on and below the earth's surface and in the atmosphere. In water resources engineering, it is crucial for determining water availability, design floods for structures, storage capacity of reservoirs, hydropower potential, drought flows, and safe operation of water systems.

## Answer

**Hydrology** is the science that deals with the occurrence, circulation, distribution and movement of water on and below the earth's surface and in the atmosphere, and its properties and relation to the environment and living things.

#### Importance in water resources engineering
1. **Quantity of water available:** Rainfall, runoff and groundwater data decide how much water a river or aquifer can supply for water supply, irrigation or hydropower.
2. **Design floods:** Spillways, dams, bridges, culverts and embankments are designed for flood discharge of a chosen return period.
3. **Storage planning:** Reservoir capacity is found from the mass curve of inflows and demands.
4. **Hydropower:** The flow duration curve gives firm power and installed capacity.
5. **Drought and low flow:** It gives the minimum flow for water supply and environmental needs.
6. **Drainage and flood control:** Runoff estimates size drains, sewers and flood protection works.
7. **Operation and forecasting:** Flood warning and reservoir operation use hydrologic models.
8. **Safety and economy:** Reliable hydrologic design avoids both failure and over-design.

## Check yourself

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

1. Spillways, bridges and embankments are designed for:
   A. Mean rainfall
   B. Flood discharge of a chosen return period
   C. Minimum flow
   D. Average temperature
   Answer: B. Return period sets the design flood. (Key point: Design floods)

2. Reservoir capacity is found from:
   A. Isohyetal map
   B. IDF curve
   C. Mass curve of inflows and demands
   D. Soil survey
   Answer: C. Rippl diagram. (Key point: Storage planning)

3. The flow duration curve gives:
   A. Flood level
   B. Pump size
   C. Rainfall depth
   D. Firm power and installed capacity
   Answer: D. Used in hydropower. (Key point: Hydropower)

4. Reliable hydrologic design avoids:
   A. Both failure and over-design
   B. Only failure
   C. Only construction
   D. Any survey
   Answer: A. Balance of safety and cost. (Key point: Safety and economy)

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