Mediterranean intermittent rivers and ephemeral streams: temperature and
water level responses to precipitation events
Abstract
Despite continued interest in flow regime variability and its influence
on stream dynamics in intermittent rivers and ephemeral streams, the
link between different precipitation events and its control on water
presence in hydrologically transient catchments with varying land cover
and biophysical characteristics, has rarely been studied. This paper
presents the results from high-resolution (30-min) precipitation data
and streambed temperatures collected from a fifteen-month period from
six different Mediterranean intermittent and ephemeral catchments. The
monitoring timeframe proved to be one of the driest periods in the
studied areas in the last 50 years and most recorded rain events were
small, the majority of which not exceeding 0.4mm of rainfall in a single
event. The results demonstrate the larger studied catchments had longer
water level response lag times to precipitation episodes. In addition,
reduced water level responses to autumn rain events in rural areas
indicated that the soil water retention capacity due to the limited soil
moisture content during the summer period and the empty water-retention
infrastructure, play an important role in governing flow presence. The
smaller and predominantly urban catchment, resulted with the second most
rapid water presence response times and the highest average streambed
temperature peaks following precipitation events. Conversely, rural
catchments that have groundwater springs contributing to stream flows,
showed more stable temperature variations. This research highlights the
need for the improved understanding of the intrinsic landscape and basin
properties that control the spatio-temporal patterns of transient flows
and thermal responses to varying rain events, especially in a changing
climate.