MODELING LOCAL WATER CYCLE DYNAMICS BY INTEGRATING STABLE ISOTOPES OF PRECIPITATION AND CLIMATE PARAMETERS

The stable isotopes of water carry distinct information on climate, hydrological and ecological processes. Here we report stable isotope data (δ¹⁸O and δD) of individual precipitation events collected from November 2012 to February 2016 in Carbondale, Illinois. The isotope data were integrated with climate parameters and HYSPLIT modeling, which was

Our results show that precipitation isotopic and deuterium excess (d-excess) values exhibit clear seasonality. Deuterium excess parameter can be taken as a measure of locally recycled water to precipitation. Factors affecting the isotopic values were the sources of moisture, local distillation and evaporation processes, and temperature. Overall, the two major moisture sources to Carbondale precipitation events were the Gulf of Mexico and the local recycled water through evapotranspiration. Moisture originating from local recycled water was a key component to most precipitation events while moisture originating from the Gulf of Mexico was the dominant component typically during the months of April and May. The other four mentioned advective sources contributed moisture to precipitation events mostly during the cold fall and winter months. Precipitation events with major moisture contribution from the Gulf of Mexico represented ~44% of total events and had distinct ranges for δ¹⁸O (0 to 10‰) and d-excess (5 to 25‰) as compared to those that incorporated other moisture sources which had δ¹⁸O ranging from 0 to 20‰ and d-excess from -5 to 15‰.

Since most of the surface water in Southern Illinois is stored in soil and vegetation, changes in the amount as well as transfer rates among different water reservoirs can have a significant impact on the regional land-atmosphere water fluxes with direct implications on ecosystems and regional economic activities.