The full title of the project is "Hydrologic and Carbon Services in the Western Ghats: Response of Forests and Agro-ecosystems to Extreme Rainfall Events".
Although the impact of deforestation on enhancing flood risk is well known (van Dijk et al, 2009), the effects of forest degradation and reforestation on floods and the hydrological cycles in the humid tropics are less well established, especially under scenarios of climate change. Certain combinations of land-cover, soil types and agro-ecosystems in the Western Ghats are already vulnerable to increased surface flows under current rainfall regimes, but the responses of these and other land-cover and soil types to future changes in rainfall regimes is less well understood.
There is presently only a sparse raingauge network over the higher topography of the Western Ghats and a lack of detailed understanding of spatial–temporal variability in rainfall intensities (at fine temporal resolutions) by event linked with atmospheric dynamics of rain-producing systems. Until now studies on floods emanating from Extreme Rainfall Events (ERE) in the Western Ghats have relied on daily or coarser time resolution rainfall data. At present, there is considerable uncertainty in linking finer resolutions of rain intensities to daily totals and the spatial and temporal dimensions of ERE in regions such as the Western Ghats. Moreover, the coupling of synoptic meteorology–rainfall characteristics with storm runoff generation (i.e., hillslope hydrology) in this work will address a global weakness in the humid tropics. Another over-arching issue while studying ERE is that of scales at which the impacts of land cover change (LCC) are overridden by the characteristics of rain–producing systems in terms being the primary source of flood runoff. Blöschl et al. (2007) proposed the concept of a variable “threshold scale”. The latter separates the two dominant controls (LCC and rain-producing systems) across different ecosystems (the spatial dimension) and within an ecosystem (the temporal dimension) depending on antecedent hydrological conditions. However such a concept remains to be proven and is the focus of this study in the context of inter-relating the impacts of ERE with the suite of complex land covers in the Western Ghats.
This is an inter-disciplinary project with four objectives:
The UK contribution (University of Dundee and Lancaster University) will focus on Objective 1 with our Indian partners taking the lead on the other objectives.
The NERC team will work with the MoES Indian partners in developing close working links with the Indian Meteorological Department and other Government agencies as part of the identification and analyses of atmospheric and satellite information linked with different rain – producing systems across scales. Data will also be compiled from the existing (but sparse) network of rain gauges and river flow from State and water resource agencies. In addition, new data will be generated by the establishment of a dense rain gauge network in four (4) research basins (~100km2) (sampling both the SW and NE monsoon) as part of the analysis of the temporal and spatial characteristics of rainfall for specific events across scales. These basins will also be instrumented with a nested network of runoff gauging stations.
Principal Investigator: Michael Bonell, University of Dundee
Nick Chappell, Lancaster Environment Centre, Lancaster University
Wlodek (Włodzimierz) Tych, Lancaster Environment Centre, Lancaster University
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Chappell, N.A., Tych, W., Chotai, A., Bidin, K. Sinun, W., Thang H.C. 2006. BARUMODEL: Combined Data Based Mechanistic models of runoff response in a managed rainforest catchment. Forest Ecology and Management 224: 58-80.
Chappell, N.A., Discenza, A.R., Tych, W., Whittaker, J., Bidin, K. 2009. Simulating hourly rainfall occurrence within an equatorial rainforest, Borneo Island. Hydrological Sciences Journal 54(3), 571-581.
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