stream is an indicator the proportion of the streamflow comes from overland flow and what portion comes from subsurface flow. Stable isotopes in the water molecule are also useful in tracing the sources (or proportion of sources) of water that plants use. Current use The isotope hydrology program at the International Atomic Energy Agency works to aid developing states to create a detailed portrait of Earth's water resources. In Ethiopia, Libya, Chad, Egypt and Sudan, the International Atomic Energy Agency used radioisotope techniques to help local water policy identify and conserve fossil water. The International Atomic Energy Agency maintains a publicly accessible global network and isotopic database for Earth's rainfall and rivers. See also Baseflow Hydrograph Water chemistry analysis References External links Isotope Hydrology at the IAEA Environmental isotopes in the hydrological cycle: Principles and applications Water Hydrology Hydraulic engineering