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Creators/Authors contains: "Kimsal, Charles"

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  1. Abstract

    Hydrologic connectivity refers to the processes and thresholds leading to water transport across a landscape. In dryland ecosystems, runoff production is mediated by the arrangement of vegetation and bare soil patches on hillslopes and the properties of ephemeral channels. In this study, we used runoff measurements at multiple scales in a small (4.67 ha) mixed shrubland catchment of the Chihuahuan Desert to identify controls on and thresholds of hillslope‐channel connectivity. By relating short‐ and long‐term hydrologic records, we also addressed whether observed changes in outlet discharge since 1977 were linked to modifications in hydrologic connectivity. Hillslope runoff production was controlled by the maximum rainfall intensity occurring in a 30‐min interval (I30), with small‐to‐negligible effects of antecedent surface soil moisture, vegetation cover, or slope aspect. AnI30threshold of nearly 10 mm/h activated runoff propagation from the shrubland hillslopes and through the main ephemeral channel, whereas anI30threshold of about 16 mm/h was required for discharge from the catchment outlet. Since storms rarely exceedI30, full hillslope‐channel connectivity occurs infrequently in the mixed shrubland, leading to <2% of the annual precipitation being converted into outlet discharge. Progressive decreases in outlet discharge since 1977 could not be explained by variations in precipitation metrics, includingI30, or the process of woody plant encroachment. Instead, channel modifications from the buildup of sediment behind measurement flumes may have increased transmission losses and reduced outlet discharge. Thus, alterations in channel properties can play an important role in the long‐term (45‐year) variations of rainfall–runoff dynamics of small desert catchments.

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    Free, publicly-accessible full text available November 27, 2024
  2. This dataset contains water level data collected at 18 playas starting in June 2016 for a long-term study of playa inundation at the Jornada Basin LTER site in southern New Mexico, U.S.A. Playas are located throughout the Jornada Basin and are instrumented with dataloggers and attached pressure transducers located at the lowest point of each playa. Instantaneous measurements of surface water level are made every 15 minutes. Data are processed to flag errors and identify periods of playa inundation (floods). This is an ongoing study and the dataset will be updated yearly. 
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