EFFECT OF TROPICAL DRY AND WET FOREST ON CONVECTIVE PRECIPITATION – A CASE STUDY OF RANCHI REGION, JHARKHAND, INDIAAmit Kumar Jha, Ajai Singh and Pratibha Warwade
Tropical deforestation on many scales influences local, regional, and even global climate. Equatorial climate has characteristics of local convective rainfall event. In the recent past, convective rainfall pattern in Ranchi region of Jharkhand, India is observed to be changed. Tropical storm intensity and numbers of dry days are probably more sensitive to the degree of forest cover than annual precipitation. In the present research work, an attempt has been made to determine the extent of contribution of local forest in local cumulonimbus cloud formation and convective precipitation. Transpiration is an important characteristic of ecosystem. Transpiration rate of some important tree species found locally in Ranchi plateau forest was measured by using CI 340 hand held photosynthesis measuring equipment. The forest cover map of the Ranchi district was prepared for the year of 2018 for pre monsoonal season using Arc-GIS. The total dense forest cover area was estimated at 1508.819 km2 which were 30.165% of the total study area, which is slightly more than the data (28.42%) available on the Forest, Environment and Climate Change Department of Jharkhand. Average transpiration rate from the local vegetation was obtained around 800 mL/m2 of vegetation area for 5 hour duration of the day. Total approximate transpiration per day helpful in convective cumulonimbus cloud formation from the whole dense forest cover of study area was obtained around 1210 million of liter. Study shows that local green cover have significant role in local convective rainfall. Study also shows that the local green cover of Ranchi district may contribute maximum up to 27.48% in the pre-monsoonal local convective precipitation.