Wavelet analysis was also applied to the series of two sub-divisions – Odisha and Nagaland, Manipur, Mizoram, and Tripura (NMMT) – both at the annual level and for monsoon season and the results are presented in Table 7. It is noted from this table that Sen's slope for all the components is very high for the NMMT sub-division and the declining trends in all components are statistically significant. For Odisha also, the trends are declining but not statistically significant. The approximate and detailed components for these two sub-divisions for annual and monsoon data series are presented in Figures 9–12. A notable feature here is that the approximate (a3) component of various series shows smooth variation over most duration while the d1 component has rapid fluctuations; the variations in the d2 component are in between. The Mood test brought out change points in the variance of some components, as summarized in Table 8. The presence of change points in some components indicates that the properties of rainfall-generating mechanisms at the related scale are changing at different times.

Table 8

Region and component series . | Sen's slope . | MK test: p- and Z-value. | |
---|---|---|---|

p-value
. | Z-value
. | ||

Odisha – Annual | |||

A3 | −2.858 | 0.180 | −1.340 |

A3 + D1 | −2.001 | 0.534 | −0.623 |

A3 + D1 + D2 | −2.289 | 0.572 | −0.565 |

Odisha – JJAS | |||

A3 | −1.232 | 0.507 | −0.663 |

A3 + D1 | −1.800 | 0.514 | −0.653 |

A3 + D1 + D2 | −2.357 | 0.496 | −0.680 |

NMMT – Annual | |||

A3 | −18.363 | 1.13 × 10^{−13} | −7.424 |

A3 + D1 | −19.644 | 7.69 × 10^{−6} | −4.474 |

A3 + D1 + D2 | −18.902 | 0.119 × 10^{−3} | −3.848 |

NMMT – JJAS | |||

A3 | −15.399 | 2.2 × 10^{−16} | −9.201 |

A3 + D1 | −16.753 | 1.53 × 10^{−9} | −6.041 |

A3 + D1 + D2 | −16.192 | 1.81e × 10^{−7} | −5.218 |

Region and component series . | Sen's slope . | MK test: p- and Z-value. | |
---|---|---|---|

p-value
. | Z-value
. | ||

Odisha – Annual | |||

A3 | −2.858 | 0.180 | −1.340 |

A3 + D1 | −2.001 | 0.534 | −0.623 |

A3 + D1 + D2 | −2.289 | 0.572 | −0.565 |

Odisha – JJAS | |||

A3 | −1.232 | 0.507 | −0.663 |

A3 + D1 | −1.800 | 0.514 | −0.653 |

A3 + D1 + D2 | −2.357 | 0.496 | −0.680 |

NMMT – Annual | |||

A3 | −18.363 | 1.13 × 10^{−13} | −7.424 |

A3 + D1 | −19.644 | 7.69 × 10^{−6} | −4.474 |

A3 + D1 + D2 | −18.902 | 0.119 × 10^{−3} | −3.848 |

NMMT – JJAS | |||

A3 | −15.399 | 2.2 × 10^{−16} | −9.201 |

A3 + D1 | −16.753 | 1.53 × 10^{−9} | −6.041 |

A3 + D1 + D2 | −16.192 | 1.81e × 10^{−7} | −5.218 |

*Note:* All component series had a falling trend.

Figure 9

Figure 10

Figure 11

Figure 12

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