Disaggregation Techniques for Estimating Rainfall of an Urban Area: A Case Study

Abstract

Disaggregation of rainfall is a very important technique to reduce values from the regional scale to local scale. It is done mainly to study the hydrological changes more effectively over a smaller area at a finer level. In the present study, spatial disaggregation has been carried out for the district of Ahmedabad. The monthly and annual point rainfall values for four stations: Bavla, Nal Lake, Sanand, Warna, have been disaggregated from the mean areal level.
For this purpose, the frequency analysis technique and the disaggregation technique based on Valencia- Schaake Model have been used. In the frequency analysis, it was observed that the R2 values between the generated and the historical data were as high as 0.98. This indicates the high applicability of the model.
The VS model was used to estimate parameters and generate the point rainfall values for the next 11 years. The results are promising and can be used to estimate more values with approximately 10-15% error.