Developing empirical monthly groundwater recharge equations based on modeling and remote sensing data – Modeling future groundwater recharge to predict potential climate change impacts

• Published in: Journal of hydrology (Amsterdam) 2017-03, Vol.546, p.1-13
• Main Authors: Gemitzi, Alexandra, Ajami, Hoori, Richnow, Hans-Hermann
• Format: Article
• Language: English
• Subjects: Climate change effects on recharge; Groundwater recharge; MODIS evapotranspiration data; SWAT model
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2017.01.005

[Display omitted] •A simple monthly recharge estimation formula for a Mediterranean basin is developed.•MODIS monthly evapotranspiration data were used for past recharge estimation.•The developed formula provided similar results to those of numerical modeling.•Future recharge up to 2100 was estimated using an ensemble of 5GCMs.•Results showed an annual recharge increase while a summer decrease is expected. Groundwater recharge is one of main components of the water budget that is difficult to quantify due to complexity of recharge processes and limited observations. In the present work a simple regression equation for monthly groundwater recharge estimation is developed by relating simulated recharge from a calibrated Soil and Water Assessment tool (SWAT) model to effective precipitation. Monthly groundwater recharge and actual evapotranspiration (AET) were computed by applying a calibrated (SWAT) model for a ten year period (2005–2015) in Vosvozis river basin in NE Greece. SWAT actual evapotranspiration (AET) results were compared to remotely sensed AET values from the MODerate Resolution Imaging Spectroradiometer (MODIS), indicating the integrity of the modeling process. Water isotopes of 2H and 18O, originally presented herein, were used to infer recharge resources in the basin and provided additional evidence of the applicability of the developed formula. Results showed that the developed recharge estimation method can be effectively applied using MODIS evapotranspiration data, without having to adhere to numerical modeling which is many times constrained by the lack of available data especially in poorly gauged basins. Future trends of groundwater recharge up to 2100 using an ensemble of five downscaled climate change projections indicated that annual recharge will increase up to the middle of the present century and gradually decrease thereafter. However, the predicted magnitude is highly variable depending on the Global Climate Model (GCM) used. While winter recharge will likely increase in the future, summer recharge is expected to decrease as a result of temperature rise in the future.