---
title: "Hydrological losses from precipitation"
subject: "Engineering Hydrology"
chapter: 3
key: "semester_5/engineering_hydrology:hydrological-losses"
source: https://www.bctengineer.com/q/semester_5/engineering_hydrology/hydrological-losses
site: BCT Engineering
---

# Hydrological losses from precipitation

Engineering Hydrology · Chapter 3: Hydrological Losses

- Asked in: 2068 Chaitra, 4 marks
- Video: [Exercise 1   Rainfall losses  Introduction](https://www.youtube.com/watch?v=QFGCWxWqfHU) — Open Water Network
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/engineering_hydrology/hydrological-losses
- Whole chapter: https://www.bctengineer.com/md/semester_5/engineering_hydrology/chapter-3

## Question

Discuss briefly the various hydrological losses from precipitation.

## Short answer

Hydrological losses include evaporation, transpiration, interception, depression storage, infiltration, and watershed leakage. Infiltration is the largest storm loss; evapotranspiration is the main long-term loss. Effective rainfall equals precipitation minus these losses.

## Answer

Hydrological losses are the parts of precipitation that do not become direct (surface) runoff. They are:

1. **Evaporation:** Water changes to vapour from open water, wet soil and wet surfaces. It depends on temperature, humidity, wind and radiation.
2. **Transpiration:** Water taken from the soil by plant roots and released through leaves. Together with evaporation it is called evapotranspiration, the largest loss from land.
3. **Interception:** Rain held on leaves and branches and evaporated later.
4. **Depression storage:** Water held in small depressions on the ground, lost by evaporation and infiltration.
5. **Infiltration:** Water entering the soil. It is the biggest loss in a storm; it recharges soil moisture and groundwater.
6. **Watershed leakage:** Water leaving the catchment through deep percolation or seepage to another basin.

The sum of interception, depression storage and early infiltration is called the **initial loss (abstraction)**. The remaining part of rain is **rainfall excess** (effective rainfall) that forms direct runoff:

$$
P_{eff} = P - \text{losses}
$$

Evaporation and transpiration continue in all periods (long-term losses), while the others occur mainly during storms.

## Check yourself

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

1. Hydrological losses are
   A. Peak flow
   B. Groundwater
   C. Runoff
   D. Parts of precipitation that do not become direct runoff
   Answer: D. Losses are removed before direct runoff. (Key point: Definition)

2. The largest loss during a storm is
   A. Transpiration
   B. Interception
   C. Leakage
   D. Infiltration
   Answer: D. Infiltration is the biggest storm loss. (Key point: Biggest storm loss)

3. Initial abstraction is the sum of
   A. Runoff and baseflow
   B. Interception, depression storage and early infiltration
   C. Leakage
   D. Evaporation and transpiration
   Answer: B. These early losses occur before runoff. (Key point: Initial loss)

4. Effective rainfall is
   A. Losses
   B. Runoff minus P
   C. P plus losses
   D. P minus losses
   Answer: D. Peff = P - losses. (Key point: Rainfall excess)

## Related in Engineering Hydrology

- [Hydrological losses statement, factors affecting evaporation](https://www.bctengineer.com/question.md?key=semester_5%2Fengineering_hydrology%3Alosses-not-actual-evap-factors) — Engineering Hydrology, chapter 3
- [Interception and depression storage losses](https://www.bctengineer.com/question.md?key=semester_5%2Fengineering_hydrology%3Ainterception-depression-storage) — Engineering Hydrology, chapter 3

## Related in other subjects

- [Hydrological cycle and mean precipitation methods](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydrological-cycle-mean-precipitation) — Hydro Power, chapter 2, asked 2×