The impact of rainfall variability and crop production on vertisols in the central highlands of Ethiopia

Environmental Systems Research

Table 5 Probability (%) of receiving rainfall at different threshold levels in a week

Rainfall (mm)	Probability (50%) and above in a week			Length of the growing season
Rainfall (mm)	P(W)	P(W/W)	P(W/D)	Total no. of weeks	No. of days
> 10	13–40	21–38	21–38	27	189
> 20	22–38	20–37	22–37	17	119
> 30	25–37	21–36	26–36	15	105
> 40	26–35	22–34	26–33	12	84
> 50	29–34	28–34	28–30	7	49

^aLength of the growing period based on > 20 mm threshold level P(W/W)
*P(W)-wet week, P(W/W)-wet week preceded by by wet week, (P(W/D)- dry week preceded by wet week.