SENSITIVITY ANALYSIS OF RAINFALL RECHARGE MODEL FOR A NOISY DATA

M. K. Nagaraj, Harish Kumar .S

Abstract: Groundwater resource estimation with particular focus on the estimation of annual replenishable recharge is an important task. For the accurate assessment of groundwater resource, the recharge from rainfall is to be estimated correctly. In the present study, a rainfall recharge model is presented considering both instantaneous recharge and delayed recharge contribution to the groundwater. The model estimates these parameters at zonal level on a regional scale considering three different antecedent moisture conditions. The parameter estimation model is developed using output error criterion. The model uses Gauss-Newton algorithm for minimization; where the objective is to minimize the least square error between observed and computed recharge or water level change. The model is applied on one hypothetical system and on one real field problem. Sensitivity analysis of the parameters are also studied using parameter perturbation method. The results indicate that the proposed rainfall recharge model can be conveniently used for estimation of rainfall recharge. This is highly useful in hard rock areas where the major contribution to groundwater is from rainfall during only in monsoon season.

Keywords: Sensitivity analysis, noisy data, parameter perturbation method, annual replenishable recharge, hypothetical system

DOI: https://doi.org/10.15623/ijret.2015.0423009