25.3.1 - Empirical Values
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Introduction to Empirical Values
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Today, we’ll discuss the empirical values pertaining to depression storage based on different land uses. Can anyone share what they believe depression storage refers to?
Isn't it about how much rainfall water collects in depressions before it runs off?
Exactly! Now, let's dive into the empirical values. Can anyone guess which land use type has the highest depression storage?
I think it might be forests, right?
Correct! Forests can retain between 2 to 5 mm of water. Let's explore some other land uses.
Land Use Types and Their Values
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We have different values depending on land type. For cultivated land, what values do you think we might have?
Maybe 1 to 3 mm?
Correct! It ranges from 1 to 3 mm. And what about grasslands?
I’d guess around the same, like 1 to 2 mm.
Right again! Grasslands have 1 to 2 mm of storage. Now, can anyone tell me why urban areas have close to zero mm?
Because they are made of impervious surfaces, so the water can't be stored there?
Exactly! This knowledge is essential for anyone involved with hydrology. Let’s summarize the key values: forests have 2-5 mm, cultivated land 1-3 mm, grasslands 1-2 mm, and urban surfaces about 0 mm.
Introduction & Overview
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Quick Overview
Standard
This section presents empirical values for depression storage based on various land uses, emphasizing the significance of these values in hydrology. Forests retain more stormwater than urban areas, which have negligible storage, influencing effective precipitation calculations and watershed management strategies.
Detailed
Summary of Empirical Values in Depression Storage
Depression storage refers to the temporary storage of water in surface depressions before runoff occurs. This section highlights the empirical values derived from field experiments for depression storage across various land cover types. The values are crucial for hydrologists and watershed managers when assessing potential runoff and flood control strategies.
Key Empirical Values by Land Use Type
- Forest: 2 to 5 mm of depression storage, making it the most effective in retaining water.
- Cultivated Land: 1 to 3 mm, showing moderate retention capabilities.
- Grassland: 1 to 2 mm, which allows for some water retention but less than forests.
- Urban Surfaces: Approximately 0 mm, as these areas are typically impervious, resulting in minimal depression storage.
Understanding these empirical values is vital for accurately modeling hydrological responses and planning effective water resource management strategies.
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Empirical Values of Depression Storage Across Land Uses
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Chapter Content
Different land uses have typical empirical values of depression storage derived from field experiments:
- Forest: 2 – 5 mm
- Cultivated Land: 1 – 3 mm
- Grassland: 1 – 2 mm
- Urban Surfaces: ~0 mm
Detailed Explanation
This chunk provides numerical data on how much water can be stored in surface depressions across different types of land use. For forests, the empirical values indicate that between 2 to 5 millimeters of rainwater can be temporarily retained in depressions. In cultivated lands, the figure is lower, ranging from 1 to 3 mm, while grasslands can hold about 1 to 2 mm. In contrast, urban surfaces typically offer negligible storage, around 0 mm, due to their impervious nature which does not allow water to accumulate effectively. This information is crucial for understanding how different landscapes manage rainfall and can inform effective land and water resource management.
Examples & Analogies
Think of different types of containers used to store water. A forest with its natural depressions can hold a decent amount of water, just like a large bucket. In contrast, a cultivated field is like a medium-sized bowl, which can hold some water but not as much. Grasslands might resemble smaller bowls that can hold even less. An urban area, with its flat and hard surfaces, is comparable to a plate that just spills water rather than holds it. This visualization helps highlight how the landscape affects the ability to capture and retain rainfall.
Key Concepts
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Depression Storage: The amount of water temporarily held in surface depressions before contributing to runoff.
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Empirical Values: Specific measurements of depression storage associated with different types of land use.
Examples & Applications
In a forested area, depression storage can range from 2 to 5 mm during a rainfall event.
Urban surfaces typically exhibit negligible depression storage, around 0 mm due to their impervious nature.
Memory Aids
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Rhymes
Forests store well, two to five; Cultivated lands, just one to three, they thrive. Grasslands too, one to two and be; Urban areas barely hold, water flows free.
Stories
In a lush forest, the trees stand tall, gathering rainwater in their small, deep halls. The farmer’s field, with furrows shaped well, catches some too, but not like the forest can tell. The grasslands await, ready to collect, while cities paved smooth, have nothing to protect.
Memory Tools
To remember depression storage values: 'F-C-G-U', where 'F' is forest (2-5 mm), 'C' is cultivated land (1-3 mm), 'G' is grassland (1-2 mm), and 'U' is urban (0 mm).
Acronyms
Use the acronym 'F-C-G-U' to remember the order of values
Forest (F)
Cultivated (C)
Grassland (G)
Urban (U) and their respective depression storage.
Flash Cards
Glossary
- Empirical Values
Quantitative measurements obtained from field experiments used to describe characteristics of depression storage in different land use types.
- Depression Storage
The quantity of water that is temporarily retained in surface depressions before evaporating or contributing to runoff.
- Initial Abstraction
The total losses from precipitation before runoff occurs, including depression storage, interception, and infiltration.
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