Changes in the flooded surface, groundwater levels and rainfall data have been analysed in eight ponds of DNP from 1994 to 2015. In addition, a Hydrological Function Index (HFI), that relates morphological and climatic variables, was calculated for the ponds and subsequently compared.
Results showed that precipitation was 10% lower during the second half of the study period (2006 - 2015). We used precipitation as a proxy of water inputs to the ponds (via both direct rainfall and groundwater discharge). A consequent and proportional reduction in the average flooded surface (i.e. a reduction of 10% or less) was detected in 3 out of 8 ponds studied. On the rest of the ponds, reductions of the flooded surface ranging from 35% to 97% were measured. The average depth of the water level was also found to be of 4.5% lower in the second period. Finally, HFI exhibited remarkable differences in some of the studied ponds between the two periods. Two factors were found to have a major influence on the reduction of the flooded surface of the ponds: altitude and distance to pumping facilities. The size and the maximum depth of the pond were also relevant to soften the disturbances in the natural hydrological regime.