Stream flow and yield
Periodic base flow measurements obtained during the monitoring program together with previous data revealed contrasting seasonal and multiannual trends across different streams in El Morro catchment (Figure 8). During the three years of frequent measurements, a clear seasonal pattern with higher flow in the dry (and cold) season and lower flow in the rainy (and warm) season was evident at all sites  (-31 to -50% in summer compared to the rest of the year, Table 1) except Site 2. Matching the seasonal patterns of water table depths (Figure 5), these fluctuations illustrate the dominant effect of groundwater uptake rather than precipitation inputs controlling stream base flow. Noticeably, the only site with no seasonal fluctuation corresponded to a segment of the Río Nuevo with deep incisions down to the gaging point (riparian consumption less likely), whereas most intense fluctuation were seen at site 3 and 5 (running dry in February 2020), which had shallow incisions and a large fractions of their trajectory surrounded by wetlands (Table 1). Older base flow data obtained before and shortly after the last erosion episode show how sites 1, 2,  and 3 gained flow while site 7, which was flanked by the first two, got completely dried out after being a high-yielding stream before (Figure 8, Table 1). Matching water table observation at site B, this switch in stream dominance suggests competition of neighboring incisions capturing groundwater as they deepen. While showing no seasonal trends, the deeply incised segment of Río Nuevo gaged at site 2 showed a slight but significant decline in its base flow with time between (-23 l s-1 per year between November 2016 and August 2020, r2=0.60, p<0.01).
Base flow water yield estimates were obtained considering a topographic (larger) and geometric (smaller) definition of the feeding catchment area for each site (Table 1). These two criteria suggested specific yields ranging from 4 to 56 and 8 to 159 mm y-1, respectively, with the highest values corresponding to the upper Río Nuevo sub catchment (Site 2) and the lowest to the Quebrachal sub catchment (Site 1).  Along the Río Nuevo catchment, water yields appear to be highest in the higher belt (Sites 2 and 3), declining but maintaining a positive contribution in the intermediate belt (site 4 and “site 4 - (sites 2 + 3)” in Table 1). In the final segment where the merged  La Guardia and Río Nuevo streams enter the terminal plain, negative yields were consistently observed (site 6 and “site 6 - (sites  4 + 5)” in Table 1). At this closure point, the total specific yield of the catchment was 19/29 mm  y-1(topographic/geometric area definition)(Table 1). While not accurately measured, a high-end estimate of peak flow contributions achieved at this site suggested that it would add less than 11% to the total yield of the catchment (Supplementary material).