Assessment of Runoff in the High Humid Foot-hill Areas of Arunachal Himalayas Using Thornthwaite Equation

Abstract

Present study examines daily runoff trend in Dikrong river catchment which is located in the lower foot-hills of Arunachal Himalaya. The river catchment is characterized by the monsoon dominated hydrologic regime. For the purpose daily statistics of temperature, rainfall and discharge were collected from the various sources of state Government of Assam, Guwahati and Government of Arunachal Pradesh, Itanagar and used for testing the validity of Thornthwaite-Mather [T-M] method in Dikrong river catchment of high humid areas of Arunachal Himalayas. It is found that this method is not suitable for the correct assessment of daily Potential Evapotranspiration [PET] as well as daily runoff [RO]. The fluctuation in predicted RO are found more than the observed RO with an over estimation during high rainfall intensity and under estimation in the period of low rainfall regime