Research
This project will try to understand the synergies and trade-offs between, and hydrologic functions related to mitigation of extreme rain events, that is, infiltration, flow pathways, delayed flow, evapotranspiration; and soil carbon storage dynamics of natural and semi-natural ecosystems, which is critical to evaluating the effectiveness of reforestation programmes.
There are three components to this project: hydrology, carbon flux measurement and meteorology and spatio-temporal dimensions.
Hydrology
We have installed 26 rain gauges, 8 water level recorders (WLR) for stream monitoring and 2 for groundwater monitoring and 26 temperature-humidity sensors (hygrochrons) in the Aghnashini basin (Uttar Karnataka). Likewise, we have installed 26 rain gauges, 9 water level loggers and
26 hygrochrons in the Nilgiris. Flumes have been installed for getting direct discharge data during low flows, and current meters are being employed for measuring stream velocity. An automatic weather station has been installed in both the sites. The data is downloaded weekly. Water samples are being collected from both the sites using depth integrated and grab sampler. The samples are being analyzed for nitrates, phosphates and sediment loads and forother physico-chemical parameters. The method of salt dilution (slug and constant rate) is being applied for discharge measurements during very low and heavy flows at both the sites.
Carbon fluxes
The team has established an intensive 1 ha forest plots for monitoring carbon dynamics at Sirsi, (Uttar Karnataka) and the establishment of a second plot is in progress. Within the plot, all trees >10cm dbh have been measured, tagged, spatially mapped and fitted with dendrobands to quantify growth and carbon accumulation patterns. Seedlings have been mapped and measured, and are being monitored in smaller subplots. Further, 50 stem respiration collars and 25 soil respiration collars have been set-up in plots to quantify CO2 fluxes from tree stems and soil, respectively. Collars are now being monitored at two- week intervals to determine background CO2 respiration rates.
In the Nilgiris, established respiration collars in grassland, shola, wattle and pine plantations have been set up to investigate links between land-use type, rainfall and soil CO2 efflux patterns in
this ecosystem.
Meteorology and spatio-temporal dimensions
This team deals with the first objective of the project, that is, to understand the spatial and temporal dimensions of extreme rain events in the Western Ghats in relation to spatial patterns of land-cover and land-use. The team has collected baseline meteorological data from the Indian Meteorological Department, which form a basis for the identification of different rainfall-producing systems (using classification procedures) across both the synoptic scale and mesoscale.
Using TRMM 3B42 (Version 7), the diurnal rainfall occurrence at three-hourly intervals (0.25 ̊ x 0.25 ̊) over the Western Ghats for the period 1998-2012 has been analyzed across four meteorological systems to identify likely areas of flood-producing rains and place the experimental basins in the context of such diurnal rain occurrence. This work was supported by the use of 6-hourly surface winds reanalysis data from NCEP and NCAR at a spatial resolution of 2.5 ̊ x 2.5 ̊.
