A scientist shares his insight into how technology empowers research, and discusses the tools of the trade that are used to study Gangetic river dolphins.
On a warm winter afternoon as I unpacked my equipment onto a small wooden boat, one of my curious assistants approached me asking what was the red torch that I was holding. «It’s not a torch,» I said hastily, checking if my survey sheet was in place. «It is a depth meter… umm… Depth dekhar jonno… (to look at the depth).» Perhaps overwhelmed by my sense of urgency he moved back and let me continue my work. Soon, I jumped onto the boat, and was on my first survey of the River Ganga, at Farakka in West Bengal. Farakka, a small town in central Bengal, sits besides NH34, bustling with heavy movement of traffic and people all day long. It is perhaps the last place a layman would imagine a wildlife researcher to be in. Yet there I was, on a motored wooden boat in the middle of the vast Ganga, constantly dipping my depth meter in the water, recording its reading and looking for Ganges river dolphins at the same time. ‘What are you writing?’ asked the curious guy again as our boat – barely big enough for five people – rocked on crashing waves. “Depth. Goirahi.” I told him. “Hmm… goirahi ki kore deikhen?” he asked and immediately I had realised the subtleties of speaking a non-native language. He wanted to know how I was ‘looking’ at the depth. I slowly explained to him that it is not light that the device uses, but sound. Sound – too high in frequency for us to hear – is emitted by one end of the depth meter and its reflection from the bottom of the river is received by an acoustic sensor on the same end. Since the speed of sound in water is known, the time elapsed between emitting this sound and sensing its reflection is translated into the distance travelled or depth – goirahi. A Hawkeye handheld depth meter used to measure the water levelPhoto Credit: Imran Samad He looked confused by the details, but refrained from asking any following questions.
