Community resources management implications of HKH hydrological response to climate variability

Transcription

1 Community resources management implications of HKH hydrological response to climate variability -- presented by N. Forsythe on behalf of: H.J. Fowler, C.G. Kilsby, S. Blenkinsop, G.M. O Donnell (Newcastle University) N. Rutter, B.W. Brock (Northumbria University) D. Archer (JBA Consulting Engineers and Scientists)

2 Presentation outline: 1. Resource dependency of HKH communities to climate-driven hydrological variability 2. Dominant climate variables and their influence as expressed through hydrological regimes 3. Comparison and contrasts of hydrological response, and consequent impacts, along the Himalayan mountain arc

3 Resource dependency of HKH communities on climate-driven hydrological variability

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5 [1] Thermal (temperature) and radiative (sunshine) conditions constrain both crop development and water demands (PET). [2] Crop water demands can be supplied either through rainfall ( green water ), irrigation ( blue water ) or a combination of the two. nb: figure purloined from Rockström & Falkenmark hydro-climatological impacts at the parcel/terrace scale: crop imperatives

6 Timing & variability of annual melt-runoff cycle glacial & nival regimes: similar seasonality and variability despite differing dominant climate controls [1] [3] glacial catchment nival catchment

7 Dramatic spatial profiles & annual climate cycles sources = SRTM90, PMD & MODIS

8 Dominant climate variables and their influence as a expressed through hydrological regimes

9 see Forsythe et al, 2012a. Climate inputs to nival & glacial regimes mass represented by SCA energy represented by CMA nival catchment nival catchment glacial catchment glacial catchment

10 MODIS degree days with areal weighting When area-weighted (by catchment fraction), differentiated relationships between glaciated and unglaciated vertical profiles by hydrological regime. For the nival (seasonal snowpack) regime, glaciated degree-days are smaller with a higher centroid and narrower vertical range than snowpack degree-days. For the glacial regime, glaciated surface annual total degree-days match quite closely with non-glaciated degree-days. Vertical relative positions of the area-weighted glaciated and non-glaciated degree-days reverses the configuration of absolute values (previous slide).

11 Comparison and contrasts of hydrological response, and consequent impacts, along the Himalayan mountain arc

12 Differentiated climate regimes along the Himalayan mountain arc Example of climate classification based principal components analysis (PCA) and k-means clustering: NASA MERRA reanalysis, 12 zones. from Forsythe et al, in: ESD(D) Special Issue 2014

13 Different climate regimes result in different hydrological (mass & energy) inputs from Forsythe et al, in: ESD(D) Special Issue 2014 mass input: precipitation ç energy inputs è air temperature solar radiation

14 Thank you for your time. Your questions and comments are most welcome!

15 Spatial focus: primary gauged catchments in the larger context of the Himalayan Arc / South Asia

16 Snow Cover Duration Annual Totals In Hunza catchment MODIS snow cover detection over glaciated areas is substantially greater at lower elevations (<5000m asl) than for non-glaciated areas. In Astore catchment there is less distinction in estimated snow cover duration between glaciated and non-glaciated surfaces. Much small surface area above 5000m asl also introduces noise from individual pixel biases

17 July LST profiles & lapse rates

18 Observed degree days from MODIS annual totals, unweighted Similar vertical profiles for glaciated and non-glaciated surfaces in terms of absolute values by elevation band. Higher annual degree day values for glaciated surfaces at lower elevations (<5000m asl) where seasonal snowpack zones are mass limited. nb: Degree-days represent /quantify energy inputs to the surface in the presence of cryospheric mass (snow or glacial ice). They do not quantify hydrological yield (rates), i.e. mm of runoff (per degree-day).

19 References : Forsythe, N., Fowler, H.J., Kilsby, C.G., Archer, D.R. (2012a) Opportunities from remote sensing for supporting water resources management in village/ valley scale catchments in the Upper Indus Basin. Water Resources Management 26 (4) Forsythe, N., Kilsby, C.G., Fowler, H.J., Archer, D.R. (2012b) Assessment of Runoff Sensitivity in the Upper Indus Basin to Interannual Climate Variability and Potential Change Using MODIS Satellite Data Products. Mountain Research and Development, 32(1): MRD-JOURNAL-D