Temporal Analysis of Evaporation Trends and their Magnitude in Ambedkar Nagar District, India

Abstract

This research explores the estimation of pan evaporation in five selected locations—Tanda, Jalalpur, Allapur, Bhete, and Akbarpur—from 1999 to 2022, utilizing meteorological data from NASA Prediction of Worldwide Energy Resources (POWER). Key environmental variables including as temperature, relative humidity, and wind speed were acquired using the Inverse Distance Weighting (IDW) by leveraging nearby stations in Paraspur, Sarai Meer, Kaptanganj, and Pratapgarh. Dalton's equation was used to calculate Pan evaporation rates using these parameters, resulting in an estimate of evaporation rates across the study sites. Subsequently, the study further investigates long-term trends in the derived evaporation rates and meteorological variables using non-parametric Mann-Kendall trend tests, which allow for the assessment of statistically significant changes over time. Additionally, Sen's slope estimator is used to quantify the magnitude of these trends, providing a reliable assessment of the rate of change in evaporation and climatic variables across the research period. Decreasing evaporation trend (1999–2022) was observed in August to December across all five regions: Tanda, Jalalpur, Allapur, Bhete, and Akbarpur, with statistical significance at the 95% confidence level. Akbarpur is the only region showing a significant increasing trend in June, indicating a localized seasonal shift in evaporation patterns.