Kshipra Sub Basin - Asian Development Bank

Support to the National Water Mission NAPCC
Appendix 3 Kshipra Sub Basin 16
A very high positive value of S is an indicator of an increasing trend, and a very low negative value
indicates a decreasing trend. However, it is necessary to compute the probability associated with S and
the sample size, n, to statistically quantify the significance of the trend.
2. Data Quality
18. A large number of missing values were found in the IMD records of both stations. Each station had
almost three complete years of missing data, and several years in which 10-20% of data were missing.
This would be a concern for many types of analysis. In the long term GHCBN record there were only two
missing records at Indore, but 1107 missing records at Ujjain.
3. Test Results
19. The results of the Mann-Kendall trend analysis at Indore and Ujjain, using the composite records
from 1901 are summarised in Table 2, Table 3 and Table 4. Generally in the evaluation of these tests, a
significance level of less than 0.05 would indicate the existence of trend, or there would be 95%
confidence in the existence of trend.
20. There is evidence of a slight trend of increasing annual rainfall at Indore, that has a significance
level of 0.06. The trend is most evident in southwest monsoon rainfall, for which the significance level is
0.03. The increase in monsoon rainfall amounts to 194 mm over a 102 year period (22%). The time
series southwest monsoon rainfall at Indore is shown in Figure 21. There is a mild decreasing trend in
northeast monsoon rainfall.
21. At Ujjain, where it will be noted there more missing records, there is no statistically significant trend
in annual or seasonal rainfall, although the regressions fitted to the data are similar to those at Indore.
The time series for southwest monsoon rainfall at Ujjain is shown in Figure 22..
Table 2: Annual rainfall trends
Stations Basin Linear equations Mann-Kendall test Significance level
Indore Kshipra y = 2.0019x + 868.19
statistics (Calculated z)
1.88 >0.05
Ujjain Kshipra y = 2.0107x + 802.12 1.45 >0.10
Table 3: Seasonal rainfall trends, southeast monsoon (June-September)
Stations Basin Linear equations Mann-Kendall test Significance level
Indore Kshipra y = 1.9x + 783.82
statistics (Calculated z)
2.19 0.10
Table 4: Seasonal rainfall trends, northeast monsoon (October-December)
Rainfall Basin Linear equations Mann-Kendall test Significance
Stations
statistics (Calculated z) level
Indore Kshipra y = -0.0013x + 17.541 1.88 >0.05
Ujjain Kshipra y = 0.0083x + 15.591 1.45 > 0.10