3-Influence of morphological factors on meteorological drought characteristics

Abstract

Drought characteristics over different climatic regions in India have been related with the ratio of mean annual potential evapotranspiration to mean annual precipitation (EP/Pa), distance from mountains and sea coast. The study revealed that the average drought frequency can be described using Ep/Pa ratio. It was found that the frequency duration and intensity of meteorological droughts have significantly relationship with the

E

P/Pa ratio. Average drought frequency (i.e. yr-1) decreases exponentially with increase

in wetness. The probability of occurrence of a severe or extreme intensity drought increases gradually from wet to dry regions, the case is however reverse for moderate intensity droughts. Study revealed that the areas located in arid and semiarid climatic regions are prone to suffer from relatively more. intense meteorological droughts than areas in the sub-humid climatic region. Study further substantiated that the occurrences of severe & extreme droughts events are much rare in the regions with EP/Pa ratio less than 1.2. Study indicates that the drought duration varies between 1 and 5 years in different climatic regions. Persistent drought events have more chances to occ_ir in arid and semi-arid climatic regions. Presence of mountains and ocean in close vicinity influence the drought characteristics in the regions with Pa EP. The study revealed that the stations which are located at relatively shorter distance from sea and have P;Ep rarely face persistent droughts of 2 or more consecutive years. Regions with Ep/Pa<1.2, ds<100 km, and dh<100 km hardly ever faced persistent droughts or the drought events of severe and extreme intensity. The stations which are within 100 to 150 km from ocean (100<ds<150) and have close distance (dh< 100 km) from mountain/major hill hardly faced the drought events of severe and extreme intensity, and also the occurrence of persistent droughts events had been very rare. The results were compared with drought experiences in other countries and were found to be in conformity with them.