Key Station Network Method

One of the most rational methods for determination of key station is as suggested by Hall (1972). In this method, at first, the correlation coefficient between the average of storm rainfall and the individual station rainfall are found. The stations are then arranged in the order of their decreasing correlation coefficients and the station exhibiting highest correlation coefficient is called the first key station and its data is removed for determination of next key station. The procedure is repeated by considering the average rainfall of the remaining stations. The station showing the highest correlation coefficient after removing the data of first key station is called the second key station. Similarly third and successive key stations are determined after removing the data of already selected key stations. Now the sum of the squares of deviations of the estimated values of average rainfall from the actual rainfall in respect of 1st, 2nd, 3rd key station etc. is determined and a graph is plotted between the sum of the square of deviation and corresponding number of stations in combinations. It will be seen that a stage comes when the improvement in the sum of squares of deviation is very little with the addition of more stations. The corresponding number of stations at that stage is taken to be representative and key stations for the network in the catchment/ basin.