Developing hydrological indices in semi-arid playa-lakes by analyzing their main morphometric, climatic and hydrochemical characteristics

We analyzed the main morphometric, climatic and hydrochemical characteristics of 48 ponds and playa-lakes of the semi-arid Guadalquivir River basin (southern Spain). Based on a simple conceptual model we were able to develop a Hydrological Function Index (HFI) that relates the effective rainfall in each playa-lake to its watershed (WS). We verified that the average flooded surfaces (AFSs) adjust to their respective WSs in the systems that are not altered by human activities with few exceptions. Thus, the HFI allowed us to discriminate water bodies that adjust to the proposed model from the rest of the ponds studied. On the other hand, we observed that the morphology of a playa-lake basin (maximum depth) is the main factor related to the temporality in these temporal ecosystems, so we developed a temporality index (TI) relating such a characteristic with the average annual potential evapotranspiration (ET0) calculated for each location. The results adjust reasonably with the scarce and scattered information available about the evolution of the water level in these systems. Finally, we analyzed the data using well-known multivariate statistical techniques and classified the studied playa-lakes. The information presented in this study could be useful in guiding restoration plans in altered ecosystems.