This study aims to understand the influence of vegetation cover on the hydrological response of the Hana forest watershed. Using the GR2M hydrological model, hydroclimatic data over the 2000-2018 period were simulated to obtain real evapotranspiration (ETR), infiltration (I), and runoff (R). These different water balance terms were then correlated with a time series of NDVI extracted from MODIS-Terra (MOD13Q1) images over the period 2000-2018. The calibration of the hydrological model over the periods 1984-1989 and 2000-2018, respectively gave good Nash values of 74.1% and 64.6%. The validation, on the whole, gives satisfactory Nash values, except for the 1990-1999 one which is 56.4%. Cusum and t-student tests confirmed a significant break at α=5% in 2009 in the NDVI time series. Statistical analysis around this break date reveals a good correlation between NDVI and rainfall on the one hand and between NDVI and real evapotranspiration on the other hand, with respective correlation coefficients of 0.68, 0.66 for the sub-period 2000-2009. The relationship between NDVI and runoff is relatively weak there with a value of 0.38. Very high correlation coefficient values were obtained over the period 2010-2018 between NDVI and rainfall (0.78), between NDVI and real evapotranspiration (0.72) and between NDVI and runoff (0.68). However, low correlation coefficients of the order of 0.53 and - 0.07 were recorded between the NDVI and infiltration respectively before and after 2009.

This study is a preliminary reflection on monitoring of waters physicochemical quality and contaminants transfer within fissured aquifers of Como