engineering

Rainwater management

Rainwater management is a engineering 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 Rainwater management rather than just read about it. In short: Rainwater management is a series of countermeasures to reduce runoff volume and improve water quality by replicating the natural hydrology and water balance of a site, with consideration of rainwater harvesting, urban flood management and rainwater runoff pollution control. The continuous growth of human populations and the consequent growing need for drinking water is a global problem.

Key takeaways

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

Reference excerpt

Rainwater management is a series of countermeasures to reduce runoff volume and improve water quality by replicating the natural hydrology and water balance of a site, with consideration of rainwater harvesting, urban flood management and rainwater runoff pollution control. The continuous growth of human populations and the consequent growing need for drinking water is a global problem. Rainwater is an important source of drinking water, and as a free source of water, considerable quantities can be collected from roof catchments and other surface areas for various uses. Due to water shortages, rainfall events and flooding, attention has been given to rainwater management. Rainwater management re-conceptualizes urban rainwater, transforming it from a community risk to a resource for urban development, and good rainwater management is important for the design of sanitation systems and the environment, nowadays different methods of rainwater management have been developed, including reduction of impervious surfaces, separation of rainwater and sanitary sewers, collection and reuse of rainwater, and Low-impact development (LID). Global Rainwater Management Program (GRMP).

Components

Rainwater harvesting and use Rainwater harvesting (RWH) is the process of collecting and storing rainwater rather than letting it run off. Rainwater harvesting systems are increasingly becoming an integral part of the sustainable rainwater management "toolkit" and are widely used in homes, home-scale projects, schools and hospitals for a variety of purposes including watering gardens, livestock, irrigation, home use with proper treatment and home heating. For households it is effective in reducing electricity and greenhouse gas emissions and providing domestic water; for urban agriculture, it is effective in reducing rainwater runoff and related issues; and for industry, it provides sustainability of facilities and low financial resource utilization.

Rainwater harvested from roof structures or other compact surfaces is discharged through drains into storage tank, processed by treatment systems and then deployed in use facilities to complete the beneficial use of rainwater. Rainwater so treated is mainly used for irrigation, washing, laundry, and in some countries it is also considered as drinking water after the necessary purification.

Urban flood management

Urban flood management has now become one of the highest priorities in urban development, Urban flooding has a major impact on both public transportation systems and supply chains and is an important topic in rainwater management

Gray-green infrastructure The use of combined sewer systems to treat excess rainwater runoff is common in older urban areas. The Combined Sewer System (CSS) collects rainwater runoff, domestic sewage and industrial wastewater into a single pipe. Combined sewer overflows (CSOs) occur when untreated wastewater is discharged to surface water beyond its hydraulic capacity, when this occurs, untreated rainwater and wastewater are discharged directly into nearby streams, rivers and other water bodies. Combined sewer overflows (CSOs) contain untreated or partially treated human and industrial waste, toxic materials and debris, and rainwater. a problem that is currently a key challenge for rainwater management and can lead to public health incidents. Gray-green infrastructure is the key technology to solve this problem and is the core technology of the currently introduced "sponge city". The implementation of gray infrastructure, such as upgrading drainage networks, storage facilities or pumping stations with large diameter pipes, is critical to drain rainwater from urban catchments, while most green infrastructure handles the storage and infiltration of rainwater and drainage of gray infrastructure

Constructed wetlands Constructed wetlands for sewer overflows treatment are currently an effective and less costly option to prevent untreated wastewater from overflowing from polluted natural water bodies, and constructed wetlands that act as retention ponds during the rainy season can collect and treat rainwater due to their natural purification function, and produce high quality water for reuse after treatment by constructed wetlands with aeration system and soils infiltration system.

Separate sewer systems The conversion of Combined Sewer System (CSS) to separate sewer systems with retention ponds will not only increase rainwater drainage and reduce the potential for urban flooding, but their own retention ponds will also retain pollutants, thereby reducing or preventing unnecessary pollution of a single receiving waters.

Land use The ratio of pervious to impervious surfaces is important in flood management. Building vegetated spaces, such as parks integrated with urban facilities, can increase the amount of pervious area. For new and redevelopment projects, reduce the amount of impervious surfaces, such as buildings, roads, parking lots, and other structures.

Low-impact development (LID)

Low-impact development (LID) refers to systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat. Low-impact development (LID) practices provide more sustainable solutions than traditional piping and storm ponds in rainwater management. The sustainability of LID practices is achieved primarily through the use of porous pavement, bioretention, green roofs, rainwater harvesting, and other rainwater management strategies. Bioretention can effectively retain large amounts of runoff, porous pavement can effectively infiltrate rainwater runoff, and green roofs can retain rainwater under a variety of climatic conditions. These methods create and restore green space and reduce the impact of built-up areas at the site and regional scales, promoting the natural flow of water within an ecosystem or watershed. Applied over a wide range of scales, LID can maintain or restore the hydrologic and ecological functions of a watershed.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Rainwater management

Start with the simplest possible case. Write down what Rainwater management claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, 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 Rainwater management 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 Rainwater management 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 Rainwater management

In research: Rainwater management appears in engineering 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 Rainwater management 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: Rainwater management is common in secondary-school and first-year university syllabi. It links to neighbouring topics Civil engineering, Rainwater harvesting, Water management, so understanding it makes those chapters shorter.
In everyday life: Look for Rainwater management 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 Rainwater management in 20 minutes

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

Frequently asked questions

What is Rainwater management in simple terms?

Why does Rainwater management matter?

Because it connects several engineering 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 Rainwater management?

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 Rainwater management.