CWC Western Ghats
Hydrologic and Carbon Services in the Western Ghats: Response of Forests and Agro-ecosystems to Extreme Rainfall Events (NERC)
Dec 2012 to 30 Aug 2016 extended (outputs continuing)
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. Bloschl 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.
Objectives:
- To couple the synoptic and mesoscale meteorology with the spatial and temporal dimensions of Extreme Rainfall Events (ERE) in the Western Ghats (Karnataka and Kerala States) and in turn, the hydrologic responses linked with the spatial patterns of land-cover and land-use
- To determine the hydrologic and carbon dynamics consequences of existing land-cover and land-use including large scale forestation in the Western Ghats and adjacent Deccan plateau
- To assess the hydrologic and carbon vulnerability of ecosystems, natural, semi-natural and agro-ecosystems, to ERE at various spatial scales
- To prioritise sites in the Western Ghats and adjacent Deccan plateau for restoration under the Green India Mission (India is one of the global leaders in forestation of degraded land) and contribute towards water resources management and climate change mitigation policy
SMART watersheds network: Western Ghats SMART basins
Funding sources
NERC (EAA7198 and EAA7725)
Investigators
Michael Bonell (Original PI), John Rowan (Overall PI), Jagdish Krishnaswamy (PI, India), Nick A Chappell (Lancaster PI), Wlodek Tych, Shrinivas Badiger, Mahesh Sankaran, R.S. Bhalla, Naresh Vissa, Trevor Page, Tim Jones and Ciaran Broderick.
Cited Publications
Bloschl, G., Ardoin-Bardin, S., Bonell, M., Dorninger, M., Goodrich, D., Gutknecht, D., Matamoros, D., Merz, B., Shand, P., Szolgay, J. 2007. At what scales do climate variability and land cover change impact on flooding and low flows? Hydrol. Process. 21:1241-1247
van Dijk, A.I.J.M., van Noordwijk, M., Calder, I.R., Bruijnzeel, L.A., Schellekens. J., Chappell, N.A. 2009. Forest-flood relation still tenuous - comment on Global evidence that deforestation amplifies flood risk and severity in the developing world by C. J. A. Bradshaw, N. S. Sodi, K. S.-H. Peh and B. W. Brook. Glob. Change Biol. 15:110-115. doi:10.1111/j.1365-2486.2008.01708.x
Project Publications (ongoing)
Ramakant Nayak, R.R., Krishnaswamy, J., Vaidyanathan, S., Chappell, N.A., and Singh Bhalla, R. 2023. Invasion of natural grasslands by exotic trees increases flood risks in mountainous landscapes in South India. Journal of Hydrology, 617 (Part A): 128944. view online.
Chappell, N.A., Jones, T.D., and Tych, W. 2017. Sampling frequency for water quality variables in streams: systems analysis to quantify minimum monitoring rates. Water Research, 123, 49-57. DOI: 10.1016/j.watres.2017.06.047 view online or view paper (pdf).
Chappell, N.A., Jones, T.D., Tych, W. and Krishnaswamy, J. 2017. Role of rainstorm intensity underestimated by data-derived flood models: emerging global evidence from subsurface-dominated watersheds. Environmental Modelling and Software, 88: 1-9. DOI: 10.1016/j.envsoft.2016.10.009 view online or view paper (pdf).
Krishnaswamy, J., Chappell, N.A., Bhalla, R.S., Sankaran, M., Vaidyanathan, S., Badiger, S. and Varghese, S. (eds) 2017. Hydrologic and Carbon Services in the Western Ghats: Response of Forest and Agro-ecosystems to Extreme Rainfall Events. Technical Report submitted to Ministry of Earth Sciences, Government of India. 67pp.
Krishnaswamy J., V. Srinivas, R. Balaji, M. Bonell, M. Sankaran, R. S. Bhalla, S. Badiger. 2014. Non-stationary and non-linear influence of ENSO and Indian Ocean Dipole on the variability of Indian monsoon rainfall and extreme rain events. Climate Dynamics (August 23): 1-10. doi:10.1007/s00382-014-2288-0
Bhalla, R. S., K. V. Devi Prasad and Neil W. Pelkey. 2014. Impact of India's watershed development programs on biomass productivity. Water Resources Research 49 (3): 1568-1580. doi:10.1002/wrcr.20133
Krishnaswamy. J., M. Bonell, B. Venkatesh, B. K. Purandara, K. N. Rakesh, S. Lele, M. C. Kiran, V. Reddy and S. Badiger. 2013. The groundwater recharge response and hydrologic services of tropical humid forest ecosystems to use and reforestation: support for the "infiltration-evapotranspiration trade-off hypothesis. Journal of Hydrology 498 (August 19): 191-209. doi:10.1016/j.jhydrol.2013.06.034
Krishnaswamy, J., M. Bonell, B. Venkatesh, B. K. Purandara, S. Lele, M. C. Kiran, V. Reddy, S. Badiger, and K. N. Rakesh. 2012. The rain-runoff response of tropical humid forest ecosystems to use and reforestation in the Western Ghats of India. Journal of Hydrology 472-473 (November 23): 216-237. doi:10.1016/j.jhydrol.2012.09.016
Selected conference presentations
Chappell, N.A., and Mindham, D. 2024. High frequency measurement of phosphate, nitrate, DOC and turbidity for NbS evaluation. Presentation at the 5th International Workshop on High Temporal Resolution Water Quality Monitoring and Analysis at the James Hutton Institute, Aberdeen, Scotland, 17-19 June 2024. view presentation (pdf)
Chappell, N.A., Tych, W., Page, T., 2017. Hydrologic and carbon services in the Western Ghats: Response of forests and agro-ecosystems to extreme rainfall events. Banner presentation at Changing Water Cycle Finale Event, Church House, Westminster, London 28 March 2017.
Bonell, M., Krishnaswamy, J., Bhalla, R.S., Badiger, S., Ball, B., Chappell, N.A., Tych, W., Vaidyanathan, S., Sankaran, M., Varghese, S., Vissa, V., Page, T., Jones, T., & Broderick, C., 2016. Hydrologic & carbon services in the Western Ghats: Response of forests & agro-ecosystems to extreme rainfall events. Presentation at India-UK Water Security Exchange Initiative, CEH Wallingford 18 Feb 2016. view presentation or blog
Chappell, N.A., Jones, T., Young, P., and Krishnaswamy, J. 2015. Demonstrating value of fine-resolution optical data for minimising aliasing impacts on biogeochemical models of surface waters. Presentation in session B14D of the American Geophysical Union meeting AGU Fall Meeting 2015 in San Francisco 14-18 December 2015.
Jones, T., Chappell, N.A., Tych, W., and Bhalla, R.S., 2015. Importance of high-frequency chemistry for resolving hot moments in headwaters: a combined optical sensor and time-series modelling approach. Presentation in session B53H of the American Geophysical Union meeting AGU Fall Meeting 2015 in San Francisco 14-18 December 2015.
Krishnaswamy, J. and Vaidyanathan, S. 2015. La Nina and Indian Ocean Dipole influence on distribution of daily rain intensities in India. Poster presentation in session A13A of the American Geophysical Union meeting AGU Fall Meeting 2015 in San Francisco 14-18 December 2015.
Bhalla, R.S., Kumaran K., Vaidyanathan, S., Krishnaswamy, J., Chappell, N.A., and Jones, T. 2015. Estimating evapotranspiration demands of different land covers using diurnal signals in dry season stream discharge. Poster presentation in session H13D of the American Geophysical Union meeting AGU Fall Meeting 2015 in San Francisco 14-18 December 2015.
Vissa, N., Bonell, M., Chappell, N.A., Tych, W., Krishnaswamy, J., Bhalla, R.S., Badiger, S. and Srinivas, v. 2014. Effect of extreme rainfall characteristics within differing monsoon synoptic systems on flood response in headwaters. Presentation to the British Hydrological Society meeting BHS2014 Challenging hydrological theory and practice at Birmingham University 2-4th Sept 2014.
Impact and outreach
Training and outreach activites of the WGhats / HyCASE project in India are summarised on the outreach website
Chappell, N.A., Krishnaswamy, J. and Bhalla, R.S. 2015. MoES-NERC CWC-WGhats project: Emerging Policy Recommendations. Policy brief. Lancaster University, Lancaster 10/8/2015.