Study: Greenhouse effect key reason for wet spells

There has been an increase in the number of wet spells and heavy rainfall events in the state over the last 18 years attributed to a variety of environmental factors, according to the latest report by the Telangana State Development Planning Society.

According to the study, the primary causes of wet spells and heavy rainfall were Ghg-induced warming, regional anthropogenic forcing such as aerosols and changes in land use due to urbanisation, which enhanced local convection in conjunction with favourable synoptic conditions.

Wet spells increased from 2004 to 2021, with Mulugu having the most (30 wet spells), Bhadradri Kothagudem having 25, and Adilabad district having 24. Further, the (TSDPS) investigated the rainfall pattern and variability for the state using rainfall data from 1989 to 2022, indicating an increase in the annual normal rainfall from 906.3 mm to 919.4 mm, with an increase of 17.8 mm during the southwest monsoon season, and 13.1 mm in the annual rainfall for the state from 1989 to 2004 to 1989-2022.

The underlying reason for the increase in the normal and annual rainfall from 1989-200 to 1989-2022 is that the southwest monsoon is presently passing through a neutral multidecadal epochal variability of dry and wet epochs of the state rainfall, and it will enter the wet epoch from 2021-30.

The report also suggested a possible shift in the alternating 30-year epochal pattern with fewer dry spells, as 19912000 had six dry years, 2000-2010 had three, and the last decade of 20112020 had only one. From 2004 to 2021, Adilabad had the most dry spells (17), followed by 15 in Mancherial and Nalgonda districts, and 14 in Nirmal, Nizamabad, Yadadri Bhuvanagiri, and Suryapet.

During the southwest monsoon season (19892022), the highest rainfall in the GHMC area was in the range of 107 to 118 mm, observed over the Northwest area of Patancheru, Ramachandrapuram, and the Northeast area of Alwal, Malkajgiri, Uppal, Balanagar, Qutubullapur, Trimulgherry, Secunderabad, and Musheerabad.

Although the state’s receding rains indicated the withdrawal of the southwest monsoon for 2022, the growing greenhouse emission effect is certain to impact monsoon patterns in the coming decades, with the possibility of more wet spells in the future.

THE PRIMARY causes of wet spells and heavy rainfall were Ghginduced warming, regional anthropogenic forcing such as aerosols and changes in land use.