Nature Environment and Pollution Technology | 2021
Statistical Downscaling of Rainfall Under Climate Change in Krishna River Sub-basin of Andhra Pradesh, India Using Artificial Neural Network (ANN)
Abstract
Due to the very coarse spatial resolution of the different global circulation model (GCM), we cannot use them in their natural form to study the various impacts of climate change. For matching this spatial inequality between the GCMs output (predictor) and historical precipitation data (predictands), we need to establish a relation between them which is known as downscaling. In the present study, we tried to examine the efficiency of the Artificial Neural Network (ANN) with Principal Component Analysis (PCA) for downscaling the rainfall for 3 districts of Andhra Pradesh of India. Firstly, for all the regions, the downscaling was performed by using ANN. Then seasonal and annual analysis was performed based on the R and RMSE. The results show that the ANN worked adequately based on the statistical parameters. The study uses the Canadian Earth System Model (CanESM2) of the IPCC Fifth Assessment Report, re-analysis from the National Centre for Environmental Prediction (NCEP) as GCM model, and observed rainfall data as the observed rainfall. The analysis was performed for the three RCPs scenario, RCP 2.6, 4.5 and 8.5. Finally, the ANN model is applied to downscale the precipitation. INTRODUCTION Krishna River is one of the important rivers in AP and Telangana. Krishna basin is the second-largest eastward draining interstate river in peninsular India. It starts its journey near Jor village (near Mahabaleswar) in the Western Ghats at an elevation of about 1337 m above MSL and ends its journey into the Bay of Bengal near Hamsala Deevi near Vijayawada. The Krishna basin covers an area of nearly 8% of the total geographical area of the country. The Krishna river basin is located in the south part of Andhra Pradesh and Telangana. The basin spreads over parts of administrative limits of Mahabubnagar, Kurnool, Krishna, Nalgonda, Guntur, and Prakasam districts. It flows for a distance of 305 km in Maharashtra, 483 km in Karnataka and 612 km in Andhra Pradesh and Telangana combined before finally out falling into the Bay of Bengal. The present study area (Fig. 1) is from Nagarjuna Sagar dam to Hamsala Deevi passing through Krishna, Guntur, and parts of Prakasam districts. The climate of the river basin varies from humid to sub-humid and arid conditions. Most precipitation occurs in the southwest monsoon season (June to September). In other seasons all tributaries and master 2021 pp. 805-818 Vol. 20 p-ISSN: 0972-6268 (Print copies up to 2016) No. 2 Nature Environment and Pollution Technology An International Quarterly Scientific Journal Original Research Paper e-ISSN: 2395-3454 Open Access Journal Nat. Env. & Poll. Tech. Website: www.neptjournal.com Received: 22-04-2020 Revised: 03-06-2020 Accepted: 26-06-2020