science

Lilingyan

Lilingyan 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 Lilingyan rather than just read about it. In short: Lilingyan (Chinese: 戾陵堰; pinyin: lìlíngyàn) was an ancient irrigation system built in 250 AD during the Three Kingdoms period to irrigate the Beijing Plain around Jicheng (modern-day Beijing). The irrigation system consisted of Lilingyan, a dam across the Shishui (Yongding River) at the foot of Liangshan (Shijingshan), and the Chexiangqu, a diversion channel that carried the water west into the Beijing Plain.

Key takeaways

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

Reference excerpt

Lilingyan (Chinese: 戾陵堰; pinyin: lìlíngyàn) was an ancient irrigation system built in 250 AD during the Three Kingdoms period to irrigate the Beijing Plain around Jicheng (modern-day Beijing). The irrigation system consisted of Lilingyan, a dam across the Shishui (Yongding River) at the foot of Liangshan (Shijingshan), and the Chexiangqu, a diversion channel that carried the water west into the Beijing Plain. The diversion channel fed water to the fields north, east and southeast of Jicheng and emptied into the Gaoliang River, which flowed back into the Yongding River. The irrigation system was an important development in Beijing's early history and helped increase food production and population in and around the city. Lilingyan was named after Liling, the tomb of Liu Dan, Prince of Yan, who was buried in Liangshan after his death in 80 BC.

History Lilingyan was built in 250 AD by Liu Jing, a military commander of Youzhou, a prefecture in north China based in Jicheng. Liu Jing was the son of Liu Fu, who had built irrigation systems along the Huai River. As the commander of the local garrison, Liu Jing had to purchase grain from afar due to limited food production locally. To improve local agricultural output, Liu Jing diverted the waters of the Yongding River, which flowed south of Jicheng to irrigate the plains to the north of the Yongding River. He deployed soldiers to dam the Yongding in the hills west of Ji and channeled the water eastward along the Chexiangqu into the Beijing Plain. The dam was 2.4 meters high and piled from woven baskets of stone. To withstand the flash flood of theYongding as the river flows out of the Western Hills, the dam was 72 meters thick and gently sloped so that flood water can flow over the dam. The Chexiangqu made use of the old river bed of the Yongding, which used to flow north of Jicheng before it changed course and flowed south of the city. In 262, a sluice gate was added to control the flow of water into the diversion channel. The irrigation system greatly improved agricultural output of the region and helped increase the population of Ji. In 295, Liu Jing's son, Liu Hong, repaired and expanded the irrigation system by extending the aqueduct further east to modern-day Tongzhou. During the Northern Qi dynasty, the irrigation system was repaired in 519 and further expanded in 565 by connecting channels to the Sha River further north. The system was again repaired in 650-655 during the Tang dynasty, and later became part of subsequent irrigation systems of Beijing. Much of the land irrigated by the Lilingyan is now under urban Beijing, after the city shifted northward from Jicheng to Dadu in the 13th century.

See also History of Beijing Dujiangyan Geography of Beijing

References

Worked examples

Example 1 — a first encounter with Lilingyan

Start with the simplest possible case. Write down what Lilingyan 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 Lilingyan 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 Lilingyan 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 Lilingyan

In research: Lilingyan 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 Lilingyan 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: Lilingyan is common in secondary-school and first-year university syllabi. It links to neighbouring topics Canals in China, History of Beijing, History of agriculture in China, so understanding it makes those chapters shorter.
In everyday life: Look for Lilingyan 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 Lilingyan in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lilingyan 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 Lilingyan out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lilingyan in simple terms?

Why does Lilingyan 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 Lilingyan?

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 Lilingyan.