Estimating the Groundwater Recharge of the Chindwin and Irrawaddy Basin in Myanmar Using Remote Sensing Based Water Accounting (WA+)

Abstract

Sustainable land and water management in Myanmar are desired since the country is rapidly changing. An analysis of the discharge data and an estimation on the groundwater recharge are desired to obtain this. In this paper, the discharge data of seven gauge stations in the Irrawaddy river are analyzed. Also, a method is described to estimate the groundwater recharge based on the Water Accounting + framework (WA+). This is done for the Irrawaddy basin in Myanmar upstream Pyay, and the Chindwin basin, which is part of the Irrawaddy basin. The groundwater recharge estimation is made with the use of remote sensing data, no ground measurements were needed for this. The method is based on the water balance and uses precipitation data (CHIRPS), actual evaporation data (ETensv1.0.) and output from the PCRaster Global Water Balance model. On a yearly basis, it is assumed that the change in storage is zero. Therefore, the annual discharge for the Chindwin basin and at Pyay could be used to validate the remote sensing precipitation minus evaporation. For the period 2005-2010 the 6-year average groundwater recharge is estimated to be 430-500 mm/year (20-23% of the rainfall) in the Chindwin basin and 340-400 mm/year (19-22% of the rainfall) for the Irrawaddy basin upstream Pyay. Most groundwater recharge takes place in the Northern part of Myanmar, as expected considering the high rainfall there. Some simplifications were made in the groundwater recharge estimation and the calculations were made on a cell basis. This is taken into account when determining the range. The method provided in this paper can be applied everywhere with remote sensing data. However, ground truth is recommended to validate the results.