Presentation on theme: "The Start of the rains at Moorings. Contents The data Annual values Examples of years Defining the start of the season Results omitting dry spells Adding."— Presentation transcript:
Start of the season Following discussion with Amina: Use the following criteria: Planting from mid-November Plant when more than 20mm in a 3-day period Replanting needed –if more than 12 days dry in 30 days –for farmers practicing simple water-harvesting Replanting needed –if more than 9 days dry in 30 days –for other farmers
Summary of results Graph shows no indication of trend No obvious evidence of climate change With this definition: Plant within a week in 40% of years Could an earlier start be considered? Plant by end November in 52 out of 82 years About 2/3 of years Plant by mid-December in all by 5 years About 19 years out of 20
Summary of initial results With 10-day dry spell replanting in 15 years About 1 year in 6 If 12 days OK (rainwater harvesting) then only replant in 7 years About 1 year in 12 A second definition – suppose you need 20mm in November, but relax to 15mm from 1 st December, Does this make a difference?
Both starts Difference in 9 years – late starts are prevented Now plant by 15 December except in one year
Conclusions and further work Definition of start seems reasonable Water harvesting is useful – halves the risk Some farmers claim to always plant by mid- December What definition would correspond to this? Possibly relax amount to 15mm from 1 December. This seems to work! If earlier planting is considered Before 15 th November Then what is the conditional risk of a long dry spell?