science

Surface water

Surface water is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Surface water rather than just read about it. In short: Surface water is water located on top of land, forming terrestrial (surrounding by land on all sides) waterbodies. This may also be referred to as blue water, opposed to the seawater and waterbodies like the ocean.

Key takeaways

Surface water belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Surface water to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Surface water from memory before moving on to harder problems.

Reference excerpt

Surface water is water located on top of land, forming terrestrial (surrounding by land on all sides) waterbodies. This may also be referred to as blue water, opposed to the seawater and waterbodies like the ocean. The vast majority of surface water is produced by precipitation. As the climate warms in the spring, snowmelt runs off towards nearby streams and rivers contributing towards a large portion of human drinking water. Levels of surface water lessen as a result of evaporation as well as water moving into the ground becoming ground-water. Alongside being used for drinking water, surface water is also used for irrigation, wastewater treatment, livestock, industrial uses, hydropower, and recreation. For USGS water-use reports, surface water is considered freshwater when it contains less than 1,000 milligrams per liter (mg/L) of dissolved solids. There are three major types of surface water. Permanent (perennial) surface waters are present year round, and includes lakes, rivers and wetlands (marshes and swamps). Semi-permanent (ephemeral) surface water refers to bodies of water that are only present at certain times of the year including seasonally dry channels such as creeks, lagoons and waterholes. Human-made surface water is water that can be continued by infrastructures that humans have assembled. This would be dammed artificial lakes, canals and artificial ponds (e.g. garden ponds) or swamps. The surface water held by dams can be used for renewable energy in the form of hydropower. Hydropower is the forcing of surface water sourced from rivers and streams to produce energy.

Measurement

Surface water can be measured as annual runoff. This includes the amount of rain and snowmelt drainage left after the uptake of nature, evaporation from land, and transpiration from vegetation. In areas such as California, the California Water Science Center records the flow of surface water and annual runoff by utilizing a network of approximately 500 stream gages collecting real time data from all across the state. This then contributes to the 8,000 stream gage stations that are overseen by the USGS national stream gage record. This in turn has provided to date records and documents of water data over the years. Management teams that oversee the distribution of water are then able to make decisions of adequate water supply to sectors. These include municipal, industrial, agricultural, renewable energy (hydropower), and storage in reservoirs.

Impacts of climate change

Due to climate change, sea ice and glaciers are melting, contributing to the rise in sea levels. As a result, salt water from the ocean is beginning to infiltrate our freshwater aquifers contaminating water used for urban and agricultural services. It is also affecting surrounding ecosystems as it places stress on the wildlife inhabiting those areas. It was recorded by the NOAA in the years 2012 to 2016, ice sheets in Greenland and the Antarctic reduced by 247 billion tons per year. This number will continue to increase as global warming persists. Climate change has a direct connection with the water cycle. It has increased evaporation yet decreased precipitation, runoff, groundwater, and soil moisture. This has altered surface water levels. Climate change also enhances the existing challenges we face in water quality. The quality of surface water is based on the chemical inputs from the surrounding elements such as the air and the nearby landscape. When these elements are polluted due to human activity, it alters the chemistry of the water.

Conjunctive use of ground and surface water Surface and groundwater are two separate entities, so they must be regarded as such. However, there is an ever-increasing need for management of the two as they are part of an interrelated system that is paramount when the demand for water exceeds the available supply (Fetter 464). Depletion of surface and ground water sources for public consumption (including industrial, commercial, and residential) is caused by over-pumping. Aquifers near river systems that are over-pumped have been known to deplete surface water sources as well. Research supporting this has been found in numerous water budgets for a multitude of cities. Response times for an aquifer are long (Young & Bredehoeft 1972). However, a total ban on ground water usage during water recessions would allow surface water to retain better levels required for sustainable aquatic life. By reducing ground water pumping, the surface water supplies will be able to maintain their levels, as they recharge from direct precipitation, surface runoff, etc. It is recorded by the Environmental Protection Agency (EPA), that approximately 68 percent of water provided to communities in the United States comes from surface water.

Illustrations

Worked examples

Example 1 — a first encounter with Surface water

Start with the simplest possible case. Write down what Surface water claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Surface water before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Surface water ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Surface water

In research: Surface water appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Surface water in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Surface water is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydrology, Water, so understanding it makes those chapters shorter.
In everyday life: Look for Surface water outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Surface water in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Surface water means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Surface water out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Surface water in simple terms?

Why does Surface water matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Surface water?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Surface water.