Testing the process-based Hydrograph model under non-stationary conditions in small fire-affected watersheds in France and Russia Lebedeva L.1,2, Semenova O.2,4, Volkova N.3 1Nansen Environmental and Remote Sensing Centre 2Gidrotehproekt Ltd 3State Hydrological Institute 4St. Petersburg State University St. Petersburg, Russia The study is partially supported by Russian-German Otto Schmidt Laboratory for Polar and Marine research

Goal and objectives to develop method to cope with non-stationary post-fire conditions using process-based Hydrograph model: case study of small watershed in France and middle-scale watershed in Russia Objectives: to detect and compare fire impact on flow regime in diverse scales and landscapes by statistical and modelling approaches to establish datasets of landscape characteristics in pre- and post- fire periods accounting for vegetation succession to estimate the hydrological model parameters in a dynamic mode, according to the landscape succession in post fire period. to simulate runoff generation both for pre- and post-fire periods

Methodology Detection of fire impact on hydrological regime by data analysis Detection of fire-induced landscape changes based on literature review Runoff formation process-based modelling with fixed parameters Development of dynamic set of model parameters for post-fire period Runoff formation process-based modelling simulated hydrographs and variable states for pre- and post-fire periods comparison of catchment responses to fire in France and Russia approach to assess and to project possible hydrological changes after fire

Study area: the Ruisseau du Rimbaud at Collobrieres, France Area 1.46 km2; elevation 470 - 620 m; daily data available for 1968-2004 Mediterranean climate with intense autumn rains and summer drought Precipitation - 1200 mm/year, flow - 700 mm/year, PE - 900 mm Shrubby maquis and a degraded forest of cork oak, chestnut and maritime pines Thin, sandy soils of the ranker type August 1990 fire destroyed 85 % of the watershed Vine P., Puech C., Clement B., Bouguerzaz F. 1996. Remote sensing and vegetation recovery mapping after a forest fire. EARSel Advances in remote sensing. Vol.4, No 4 - XI Fourcade B. , Coudrain-ribstein A. , Martin C. 2002 What can be deduced from chemical measurement in an open-field raingauge? An example in the Maures Massif, southeastern France. Hydrological Sciences Journal  Vol. 47, Iss. 3

Study area: Vitimkan and Vitim river basins, Russia Area 969 and 18200 km2; elevation 1000 – 2500 m Severe continental climate with snowmelt high-water period in spring and summer floods Precipitation – 350-600 mm/year; runoff – 140-300 mm/year Bare rocks, tundra, sparse larch forest, taiga; continuous permafrost Daily data available for 1958-2004 May and June 2003 fire destroyed 78 % and 49 % of the watersheds

Wildfire impact on hydrology: Rimbaud watershed Relationship throughout the autumn-winter period (September, October, November and December) between instantaneous peak flood discharge and precipitation within 24 hours. Period after the fire: September 1990 - November 1994 (Cosandey et al. 2005) Cosandey C, Andréassian V, Martin C, Didon-Lescot JF, Lavabre J, Folton N, Mathys N, Richard D. 2004. The hydrological impact of the Mediterranean forest: A review of French research. Journal of Hydrology 301:1–15

Wildfire impact on hydrology: Rimbaud watershed Relationship throughout the autumn-winter period (September, October, November and December) between daily peak flood discharge and daily precipitation (period after the fire: September 1990 - November 1994). 27.09.1992 09.12.1990

Wildfire impact on hydrology: Rimbaud watershed Instantaneous flood peaks for 24-hour rainfall events >20 mm for pre- and post-fire periods (Shakesby, 2011) Shakesby RA (2011) Post-wildfire soil erosion in the Mediterranean: Review and future research directions Earth Science Reviews 105, 71-100. 

Wildfire impact on hydrology: Rimbaud watershed Daily flood peaks for daily rainfall >20 mm for pre- and post-fire periods 1990-1994: Prec = 38 mm Runoff = 0.18 m3/s 1968-1990: Prec = 43 mm Runoff = 0.31 m3/s 1990-2004: Prec = 41 mm Runoff = 0.26 m3/s Fire Fire impact is evident on fine time resolution only?

Wildfire impact on hydrology: Vitim and Vitimkan river basins Annual daily peak floods, 1958-2004 2003 2003 annual peak flood in Vitimkan river basin is heightened 20-50 % comparative to Vitim river basin Vitim river basin – 49 % burnt area; Vitimkan river basin – 78 % burnt area

Wildfire impact on hydrology: Vitim and Vitimkan river basins July and August monthly depth, 1958-2004 2003 July and August monthly runoff depth in Vitimkan river basin is heightened 20 – 300 % comparative to Vitim river basin Vitim river basin – 49 % burnt area; Vitimkan river basin – 78 % burnt area

Wildfire impact on hydrology: Vitim and Vitimkan river basins Spring flood depth, 1958-2004 2003 and 2004 spring flood depth in Vitimkan basin is lower 40-150 % comparative to Vitim river basin Vitim river basin – 49 % burnt area; Vitimkan river basin – 78 % burnt area

Process-based hydrological modelling It can use dynamic set of parameters which are changing in time Minimum calibration (parameters can be obtained apriori) Common input daily data (air temperature and moisture, precipitation) Free of scale problem (from soil column to large basin) initially developed by Prof. Yury Vinogradov www.hydrograph-model.ru

Results of the Hydrograph model application to Rimbaud watershed The average year: P = 1216 mm; Qobs = 722 mm; Qsim = 623 mm; NS = 0.82 The wettest year: P = 1822 mm; Qobs = 1314 mm; Qsim = 1224 mm; NS = 0.91 The driest year: P = 596 mm; Qobs = 129 mm; Qsim = 164 mm; NS = -4.5 The year after the fire: P = 1099 mm; Qobs = 591 mm; Qsim = 541 mm; NS = 0.70 Fire Simulated hydrographs have satisfactory agreement with observed ones in both pre- and post-fire period. Modelling results doesn’t detect any significant changes after the fire.

Results of the Hydrograph model application to Rimbaud watershed Modelling results doesn’t detect any significant changes after the fire.

Results of the Hydrograph model application to Rimbaud watershed Relationship between observed and simulated peak monthly discharges On average mean and low peak discharges are slightly overestimated by simulations High peak discharges are slightly underestimated by simulations Agreement between observed and simulated monthly peak floods doesn’t noticeably change in post-fire period (using daily data) correlation coefficient = 0.89 Forest fire doesn’t lead to non-stationary catchment behavior detectable on daily temporal resolution

Hydrograph model application to Vitimkan river watershed The only meteorological station located outside of the basin in 150 km from the border. Precipitation inadequacy could be clearly seen in comparison observed vs simulated hydrographs:

Results of Hydrograph model application to Vitimkan river watershed – fixed parameters average year: NS = 0.79 dry year: NS = 0.55 wet year: NS = 0.59 NS = 0.13 Fire Change detection modelling indicates 2003 peak flow increase in 6-15 times in Vitimkan river basin (78 % burnt area)

Development of dynamic set of model parameters: first estimate Talik Hinzman, L., M. Fukuda, D. V. Sandberg, F. S. Chapin III, and D. Dash, FROSTFIRE: An experimental approach to predicting the climate feedbacks from the changing boreal fire regime, J. Geophys. Res., 108(D1), 8153, doi:10.1029/2001JD000415, 2003.

Development of dynamic set of model parameters: first estimate based on literature review of field studies in cold regions and modelling experience. Vegetation properties: - shadiness - interception capacity - evaporation coefficient - albedo (Anilova, 2012; Beskorovainaya et al., 2005) Soil properties: - density (Sabaeva, 2006; Tarasov et al., 2008) - porosity (Tarasov et al., 2008) - water holding capacity (Beskorovainaya et al., 2005) - heat properties (Bolton, 2006; Beskorovainaya et al., 2005) - infiltration coefficient (Beskorovainaya et al., 2005)

First run of the model with dynamic set of parameters

Conclusion Forest fire effect on flow in Rimbaud watershed is negligible on daily temporal resolution. The reason is quick response and relatively simple watershed functioning. Finer data are needed. Forest fire have pronounced effect on peak floods, monthly and seasonal flow in Vitimkan river basin. Results of the Hydrograph model application are reasonable for both pre- and post-fire period for Rimbaud watershed and for pre-fire period for Vitimkan river basin. Model efficiency is higher in wet years than in dry in Rimbaud watershed. First results of the Hydrograph model application with dynamic set of parameters couldn’t be considered successful but promising for further work.

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