science

Spatial variability

Spatial variability 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 Spatial variability rather than just read about it. In short: Spatial variability occurs when a quantity that is measured at different spatial locations exhibits values that differ across the locations. Spatial variability can be assessed using spatial descriptive statistics such as the range.

Key takeaways

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

Reference excerpt

Spatial variability occurs when a quantity that is measured at different spatial locations exhibits values that differ across the locations. Spatial variability can be assessed using spatial descriptive statistics such as the range. Let us suppose that the Rev' z(x) is perfectly known at any point x within the field under study. Then the uncertainty about z(x) is reduced to zero, whereas its spatial variability still exists. Uncertainty is closely related to the amount of spatial variability, but it is also strongly dependent upon sampling. Geostatistical analyses have been strictly performed to study the spatial variability of pesticide sorption and degradation in the field. Webster and Oliver provided a description of geostatistical techniques. Describing uncertainty using geostatistics is not an activity exempt from uncertainty itself as variogram uncertainty may be large and spatial interpolation may be undertaken using different techniques.

References

Literature

Isaaks, E.H., Srivastava R.M.: Applied Geostatistics. 1989 Fortin, Marie-Josee, Dale, Mark.: Spatial Analysis A Guide for Ecologists. 2005. Cambridge University Press, 365 pp. Kristensen, Terje; Ohlson, Mikael; Bolstad, Paul; Nagy, Zoltan (2015-07-24). "Spatial variability of organic layer thickness and carbon stocks in mature boreal forest stands—implications and suggestions for sampling designs". Environmental Monitoring and Assessment. 187 (8). Springer Science and Business Media LLC: 521. Bibcode:2015EMnAs.187..521K. doi:10.1007/s10661-015-4741-x. ISSN 0167-6369. PMID 26205281. S2CID 6396005. Delhomme, J. P. (1979). "Spatial variability and uncertainty in groundwater flow parameters: A geostatistical approach". Water Resources Research. 15 (2). American Geophysical Union (AGU): 269–280. Bibcode:1979WRR....15..269D. doi:10.1029/wr015i002p00269. ISSN 0043-1397.* Cambardella, C. A.; Moorman, T. B.; Novak, J. M.; Parkin, T. B.; Karlen, D. L.; Turco, R. F.; Konopka, A. E. (1994). "Field-Scale Variability of Soil Properties in Central Iowa Soils". Soil Science Society of America Journal. 58 (5). Wiley: 1501–1511. Bibcode:1994SSASJ..58.1501C. doi:10.2136/sssaj1994.03615995005800050033x. ISSN 0361-5995.* Novak, J. M.; Moorman, T. B.; Cambardella, C. A. (1997). "Atrazine Sorption at the Field Scale in Relation to Soils and Landscape Position". Journal of Environmental Quality. 26 (5). Wiley: 1271–1277. Bibcode:1997JEnvQ..26.1271N. doi:10.2134/jeq1997.00472425002600050011x. ISSN 0047-2425.* Jacques, D; Mouvet, C; Mohanty, B; Vereecken, H; Feyen, J (1999). "Spatial variability of atrazine sorption parameters and other soil properties in a podzoluvisol" (PDF). J Contam Hydrol. 36 (1): 31–52. Bibcode:1999JCHyd..36...31J. doi:10.1016/S0169-7722(98)00141-7. Price, OR; Walker, A; Wood, M; Oliver, MA (2001). "Using geostatistics to evaluate spatial variation in pesticideysoil interactions". In Walker A. (ed.). Pesticide behaviour in soils and water. BCPC Symposium Proceedings No. 78. Farnham, UK. pp. 233–238.{{cite book}}: CS1 maint: location missing publisher (link) Webster, R (2007). Geostatistics for environmental scientists. Chichester Hoboken, NJ: Wiley. ISBN 978-0-470-02858-2. OCLC 212122100. Jansen, Michiel J.W. (1998). "Prediction error through modelling concepts and uncertainty from basic data". Nutrient Cycling in Agroecosystems. 50 (1/3). Springer Science and Business Media LLC: 247–253. Bibcode:1998NCyAg..50..247J. doi:10.1023/a:1009748529970. ISSN 1385-1314. S2CID 38278687. Dubus, Igor G; Brown, Colin D; Beulke, Sabine (2003). "Sources of uncertainty in pesticide fate modelling". Science of the Total Environment. 317 (1–3). Elsevier BV: 53–72. Bibcode:2003ScTEn.317...53D. CiteSeerX 10.1.1.472.35. doi:10.1016/s0048-9697(03)00362-0. ISSN 0048-9697. PMID 14630412. {{cite journal}}: Cite uses deprecated parameter |citeseerx= (help)

External links "EPA Regional Vulnerability Assessment (ReVA) Environmental Decision Toolkit". amethyst.epa.gov. 2006-10-01. Archived from the original on 2006-10-01. Retrieved 2021-04-12. http://gis.esri.com/library/userconf/proc05/papers/pap1184.pdf https://web.archive.org/web/20100110102738/http://willingtoncropservices.co.uk/case_study_GPS-soil-sampling-nutrient-mapping.htm Willington Crop Services shows spatial variability in action with Case Study on GPS soil sampling, GPS nutrient mapping and nutrient management.

Worked examples

Example 1 — a first encounter with Spatial variability

Start with the simplest possible case. Write down what Spatial variability 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 Spatial variability 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 Spatial variability 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 Spatial variability

In research: Spatial variability 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 Spatial variability 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: Spatial variability is common in secondary-school and first-year university syllabi. It links to neighbouring topics Spatial analysis, so understanding it makes those chapters shorter.
In everyday life: Look for Spatial variability 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 Spatial variability in 20 minutes

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

Frequently asked questions

What is Spatial variability in simple terms?

Why does Spatial variability 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 Spatial variability?

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 Spatial variability.