Isotope hydrology in New Zealand and the Pacific

Isotopes of water provide a window into otherwise invisible aspects of the water cycle including sub-surface hydrological pathways and sources of water to trees. In the first part of this talk, Dr. Bruce Dudley describes application of isotope mixing models to map impacts of invasive trees on water and nutrient cycles. Secondly, he illustrates how dual-isotope techniques can be used to examine water sources for shrubs and how simultaneous measurement of sapflow can add support to inferences made using isotopes. In the final part of the talk, he discusses the use of stable isotopes in national-scale hydrology. To begin, this work has required us to set up networks of precipitation and river water isotope collections across New Zealand. One important part of this discussion is the development of national isotope maps (isoscapes) using a range of methods. As a conclusion, he will briefly discuss future applications of this work.