 In order to manage water resources, we got to know how much we have. So there is a lot of water, there is a lot of water in the sea, there is a lot of water in the rain and rivers. But the water that is fresh water, it looks like a lot in the rain and rivers when it creates problems for us. But it is still a very minuscule proportion of the total fresh water that is available to us. And most of that is below the ground. And that water is difficult to see, is difficult to measure and therefore difficult to manage. Isotopes tell us very quickly, relatively cheaply and give us a record over a long period of time of where that water comes from. And this allows us to then manage the water, how much we should withdraw, who should use the water. Is the water quality good enough to be used for drinking purposes or is it slightly poor to be used for some other purposes? So whatever allocation of water we want to make, it should all be based upon information. Most of the measurements that occur for isotopes are using some kind of a mass spectrometer where you take a little sample of water or a gas and you put it into a system which goes through magnets and separates the ions based upon the mass. Now more recently there are techniques based upon the absorption of laser light to separate isotopes. So if you have a gaseous sample in a laser spectroscopy instrument, the amount of laser that is absorbed will depend upon the amount of different isotopes that we have and therefore we can calibrate and calculate the amount of isotope, different isotopes in a sample. So we use different techniques. In terms of sustainable development, water is a key to sustainable development. We cannot survive without water and if you go back in history of the human civilization, civilization has always occurred next to water in rivers or in mountainous areas by the springs and that's because easy availability of water is a key to human survival.