The variability of winter drainage in England and Wales
| العنوان: | The variability of winter drainage in England and Wales |
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| المؤلفون: | D.A. Rose |
| المصدر: | Soil Use and Management. 7:115-121 |
| بيانات النشر: | Wiley, 1991. |
| سنة النشر: | 1991 |
| مصطلحات موضوعية: | Return period, Animal science, Meteorology, Coefficient of variation, Soil Science, Drainage, Cockle, Extreme value theory, Soil type, Pollution, Agronomy and Crop Science, Mathematics |
| الوصف: | Estimates of winter drainage, D, are available for 82 locations in England and Wales for each winter during the 35-year period, 1940/1 to 1974/5. At each location, D is approximately normally distributed. The variability, expressed as a coefficient of variation, is approximately inversely proportional to the average drainage; it is large, ranging from 20–30% in Wales and the uplands of northern and western England to 60–70% in eastern England. Assuming a normal distribution, the probability of exceeding a given amount of drainage is easily found. The proportion, f of solute initially in the soil that is leached each winter can be calculated using these estimates of D in a simple layer model. However, f is not normally distributed, but can be fitted by the Type-1 extreme-value distribution. If there are n years of data, and m is the rank of a value in order of decreasing size, the estimation of the probability, P, of exceeding the mth largest value, fm, is P(ffm) =m/(n+1), and the return period, t, is 1/P years. Using the transform, W= In[—In P], graphs of/against W yield families of lines that, for a given location and depth in the soil, depend only on soil type, and from which extreme values likely to be encountered in a given return period can be forecast. Results are discussed for Mildenhall, Suffolk (= 99 ± 68 mm), Cockle Park, Northumberland (±= 275 ± 125 mm), Welshpool, Powis (±= 373 ± 121 mm), Carmarthen, Dyfed (±= 764 ± 196 mm) and Ambleside, Cumbria (±= 1280 ± 276 mm). |
| تدمد: | 1475-2743 0266-0032 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_________::2f3d4b1259215af41555e32fab645e0eTest https://doi.org/10.1111/j.1475-2743.1991.tb00859.xTest |
| حقوق: | CLOSED |
| رقم الانضمام: | edsair.doi...........2f3d4b1259215af41555e32fab645e0e |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14752743 02660032 |
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