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Adaption to Droughts
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
Arranging monthly precipitation data into deciles is another drought-monitoring technique. It was developed by Gibbs and Maher [10] to avoid some of the weaknesses within the “percent of normal” approach. The technique developed divided the distribution of occurrences over a long-term precipitation record into tenths of the distribution. Gibbs and Maher called each of these categories a decile. The first decile is the rainfall amount not exceeded by the lowest 10% of the precipitation occurrences. The second decile is the precipitation amount not exceeded by the lowest 20% of the occurrences. These deciles continue until the rainfall amount identified by the 10th decile is the largest precipitation amount within the long-term record. By definition, the fifth decile is the median, and it is the precipitation amount not exceeded by 50% of the occurrences over the period of record. The deciles are classified into five groups. The classification is given in Table 4.6.
Hydrological Drought: Water Surface and Duration Curve Indices
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
Manish Kumar Goyal, Vivek Gupta, Saeid Eslamian
Larsen [20] analyzed the twentieth-century rainfall and streamflow data to characterize the drought in Puerto Rico Island, located about 1700 km south-east of Miami, Florida. Monthly and annual rainfall, mean daily streamflow, and daily reservoir pool elevation data were considered in this study. Streamflow data from four river streams, among which three were draining into La Plata and Loiza reservoirs during the period of low rainfall of 1993–1998, were collected. Rainfall data from 12 rain gauge stations were collected for 100 years (1900–2000) and were averaged to calculate the mean rainfall for the island. Stations were also paired to observe regional differences. The severity of the meteorological drought was calculated by an index defined by Morris and Vazquez (1990). Monthly rainfall was also analyzed using deciles. Commonly used deciles are lowest 20%, next lowest 20%, middle 20%, next highest 20%, and highest 20%.
Environmental Evaluation: Lessons Learned from Case Studies
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
The decile index developed by Gibbs and Maher [19] groups monthly precipitation occurrences into deciles. The index provides an accurate statistical measurement of precipitation with long-term climatic data required for accurate determination of the index. The strength of this index is that pitfalls within the percent of normal approach are avoided and the distribution of occurrences over a long-term precipitation record is divided into tenths of the distribution. Each of these categories is called a decile. Thus, the first decile is the rainfall amount not exceeded by the lowest 10% of the precipitation occurrences. The second decile is the precipitation amount not exceeded by the lowest 20% of the occurrences. These deciles continue until the rainfall amount identified by the 10th decile is the largest precipitation amount within the long-term record. By definition, the fifth decile is the median, and it is the precipitation amount not exceeded by 50% of the occurrences over the period of record. The deciles are grouped into five categories, and the description is shown in Table 33.4.
Examining the mathematics education values of diverse groups of students
Published in International Journal of Mathematical Education in Science and Technology, 2023
Five schools throughout New Zealand were invited by email to participate in the study. In New Zealand, there is a strong intersection between ethnicity and socio-economic background particularly for Pāsifikā and Māori communities (Stats NZ, 2018). New Zealand schools use a decile ranking system to indicate socio-economic status. Decile one indicates that the school is within the lowest socio-economic area while decile ten indicates that the school is in the highest socio-economic area. Overall, students from Pāsifikā and Māori backgrounds are more likely to attend low decile (and socio-economic) schools, whilst European Pakeha and Asian students tend to attend higher decile (and socio-economic) schools. Given a key focus in this study was on the values of culturally diverse students, all of the schools invited to participate were middle to low decile. The schools were also selected to cover a range of geographic locations and to include both urban and rural areas. All five schools consented to take part which included 566 middle school students (Years 7 and 8). Student demographics variables are summarized in Table 1. Three low decile and two medium decile schools are included here. The clustering of ethnicities by school decile is reflected in our study with most Pāsifikā and Māori students attending the low decile schools and European and Asian students attending the medium decile schools.
Use of meteorological data for identification of drought
Published in ISH Journal of Hydraulic Engineering, 2021
Ravi Kiran Karinki, Sanat Nalini Sahoo
The technique for decile estimation depends on dividing the distribution of monthly record precipitation into 10 parts (Gibbs and Maher 1967). The total monthly precipitation values from a long-term record are arranged in a descending order and ranking has been given from top to bottom to construct a cumulative frequency distribution. The obtained distribution is then split into 10 parts (tenths of distribution or deciles). The first decile is the precipitation value not exceeded by the lowest 10% of all precipitation values in a record. The second decile is between the lowest 10% and 20% etc. The severity of drought can be assessed by comparing the amount of precipitation in a month (or during a period of several months) with the long-term cumulative distribution of precipitation amounts in that period (Morid et al. 2006). The deciles are grouped into five classes, two deciles per class (as shown in Table 3). If precipitation falls into the lowest 20% (deciles 1 and 2), it is classified as much below normal. Deciles 3 and 4 (20–40%) indicate below normal precipitation, deciles 5 and 6 (40–60%) indicate near normal precipitation, 7 and 8 (60–80%) indicate above normal precipitation and 9 and 10 (80–100%) indicate much above normal precipitation. In the current study, deciles 1–2 and 3–4 are considered to be drought condition and all other categories come under non-drought condition.
A material footprint model for green information systems – using statistical learning to identify the predictors of natural resource use
Published in Cogent Engineering, 2019
Johannes Buhl, Christa Liedtke, Jens Teubler, Sebastian Schuster, Katrin Bienge
In the first step, the Material Footprint according to its partial footprints, ranging from housing to holiday making is predicted. Figure 2 shows the partial footprints by decile. Decile 1 represents 10% of users with the smallest overall Material Footprint. Decile 10 represents 10% of the users with the biggest overall Material Footprint. Mobility, housing and nutrition constitute the largest footprints across all deciles. While the Material Footprints for housing and nutrition do not differ relevantly between deciles, the Material Footprint for mobility significantly increases with each increasing decile. The Material Footprint for mobility seems to better differentiate users than housing or nutrition.