While working on prediction of drought and flood years we are always making judgements and decisions on the basis of incomplete information, but this is preferable to decisions based on no information at all. In this light, we do statistical predictions of future rainfall. Predictions of future amount of rainfall can be made at least for three reasons: to test hypothesis, for planning purposes and to attempt to avert catastrophes. While analysing future annual excess and deficit runs, there are concerns with the first and possibly with the second of these objectives. Through this analysis occurrence of drought and flood years can be predicted.
Using such run lengths it might be possible to predict below or above the average rainfall when data indicate high probability of occurrence of certain length of run. For example, if a deficit run of length one has got a very high probability of occurrence, then it can be predicted with confidence that an excess rainfall is followed with high frequency by a deficit rainfall and vice -versa.
- Panda, S.; Datta. D. K. and Das, M. N. (1996). Prediction of drought and flood years in Eastern India using lengths of runs of annual rainfall, J. Soil & Water Conserv., 40 (3 & 4): 184 – 191.