Rainfall-runoff relationships at the Arroyo de los Piños, Socorro, New Mexico
Abstract
Small ephemeral streams are not studied as often as perennial streams because of their erratic nature and the fact that they are usually located in hard to access, remote deserts where flash floods are common. The Arroyo de los Piños is currently one of very few study sites collecting data during flash floods. The main study site is located close to the confluence with the Rio Grande, yet data on the contributing watershed are lacking. Gaining a clearer picture of stream connectivity and rainfall-runoff relationships in this channel will be useful for quantifying flow generation as well as aquifer recharge and transmission loss through the stream bed. Rainfall-runoff relationships have been studied in other semi-arid regions such as Walnut Gulch, but the Piños watershed is distinct because flow is generated over a variety of different lithologies with contrasting infiltration characteristics.
Eighteen Hobo U20 absolute pressure transducers and several barometric transducers have been installed in the Arroyo de los Piños watershed monitoring at 2 min intervals. One cellular-transmitting vented pressure transducer midway up the basin sends alerts when runoff is generated. The placement of the loggers aims to capture geologic heterogeneities within the watershed, which includes limestone (Grey Mesa Fm.), sandstone (Atrasado Fm.) and mudstone (Abo Fm.). Six tipping-bucket gauges provide rainfall data. Through rain gauge, radar backscatter and pressure transducer data we can infer storm pathway, and the relative contributions of runoff from lithologic units. We converted stage hydrographs to discharge hydrographs using one of several roughness equations. The lowest cross section is a typical southwest-US multi-thread channel; as it is easily accessible, it will be manually gauged to determine the variation of roughness with water depth. Knowing the discharge at several locations allows estimation of transmission losses through each lithologic unit. Only part of the basin experienced flow during two moderate floods in October 2018, while all rain gauges measured rainfall. We have limited rainfall and runoff data from 2018, but now that the full instrumentation network has been installed our coverage for the 2019 monsoon season will allow us to describe rainfall-runoff relationships in this semiarid environment.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP53F2223R
- Keywords:
-
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1826 Geomorphology: hillslope;
- HYDROLOGY