Field work in the Kanali Floodplain

By Mayuri Phukan, January 2023

Mayuri Phukan is a PhD candidate at Utrecht University. Her research will establish the hydrogeology of the Himalayan megafan and interactions between surface water and groundwater systems, and its impact on grasslands of Bardia National Park. Due to the nature of the research and the less studied area, data collection from field is of utmost importance for my project. Hence her work started with a 3 month fieldwork campaign during November ’22 to January ’23, in Bardia. With the help of local workers, they set up 19 groundwater monitoring wells around the study area. Most of these wells have been drilled manually, by the process of impact drilling while a few have been mechanically dug, depending on the nature of the substrate and the local practice. She has also sampled soil from the locations which is being tested for textural classification, as well as collected well logs from the drillers.

While it is fairly early into the project to present any major results, few observations have been noted from the fieldwork activities. It has been noted that the groundwater level is shallow around Karnali floodplain (central region) with primarily sandy soil layers while in the foothills of Shiwalik hills in north and in the south, groundwater levels are deeper, with predominantly silty to clayey soil layers. Erosion from Shiwalik hills as well as depositional process by the Karnali river system could be a reason behind these features. Further, two type of water bearing layers have been encountered: sand with pebble/boulder layers and finer sand with clayey layers. That could also mean that the aquifer system in the study area could be disconnected at places due to clay pockets. And local precipitation and subsurface flow may be major recharge mechanisms. It is expected that, with progress in the data collection and analysis process, these mechanisms will be more explicit.

Fig. 1: Styudy area in the Karnali floodplain