DOI: 10.5061/dryad.kh18932b8
title: Arid Hydrology Research Area (AHRA) rainfall simulator data

description: Much of the arid and semiarid western United States is affected by flash
 flooding associated with infrequent extreme rain events. Floods have large
 social and economic consequences for communities and individuals. Thus,
 flood hazard assessment is important to reduce flood-related risks and
 support sustainable development. Flood prediction relies heavily on
 hydrologic models, which are plagued by substantial uncertainties. To
 improve model performance, the Southern Sandoval County Arroyo Flood
 Control Authority (SSCAFCA) established an outdoor laboratory called the
 Arid Hydrology Research Area (AHRA) in 2022. AHRA is situated on a 1.5-ha
 parcel of land in Rio Rancho, New Mexico. The site is used to conduct
 runoff experiments using a rainfall simulator, a device that can reproduce
 intense precipitation events often observed during the summer Monsoon.
 This dataset contains runoff and infiltration time series for test plots
 covering a range of soil textures ranging from sand to silty clay.
 Experiments were designed to assess the impact of soil texture, antecedent
 moisture conditions, and physical soil crusts on the plot-scale runoff
 response. 
description: Runoff and infiltration time series were measured using a
 portable rainfall simulator. The simulator contains three nozzles
 suspended 3 m above the ground. Nozzles can be used individually or in
 combination to generate different rainfall rates and spray water onto a
 test plot below. Eight test plots, each covering an area of approximately
 2.6 m<sup>2</sup>, were prepared by first excavating native
 soil to a depth of 50 cm. A plastic sheet was then fitted to the bottom of
 each plot. On top of the plastic, a slotted polyvinyl chloride (PVC) pipe
 wrapped in permeable landscape fabric and covered with 5 cm of coarse sand
 was installed to divert any subsurface flow into a graduated container.
 Plots were then backfilled with air-dried soil in 10 cm lifts and
 compacted with a 20 cm x 20 cm hand tamper. All soils used to establish
 test plots were sourced locally and selected to cover a wide range of
 textures. At the surface, a sheet metal or plastic barrier inserted into
 the ground to a depth of 5 cm provides the boundary for the plot and
 directs runoff to a 75 L container via a PVC pipe. Weight of the container
 was recorded in 30-second increments using a weighing scale. Rainfall
 simulator tests were conducted using a constant rainfall intensity of 48
 mm h<sup>-1</sup> for a 60-min duration.  The only exception
 was plot B (sand), where this rate resulted in no runoff. We therefore
 started each test run for plot B using a rate of 107 mm
 h<sup>-1</sup> and switched to 48 mm
 h<sup>-1</sup> after the onset of runoff. Tests were then
 continued until a cumulative precipitation value of 48 mm was reached.
 After the conclusion of each test run, sediment accumulated in the surface
 runoff container was collected, dried, and weighed. Suspended sediment
 concentration was estimated from a 1-L sample collected during the test.
 Sediment weight was subtracted from incremental runoff measurements to
 obtain the weight of water alone. Assuming a water density of 1000 kg
 m<sup>-3</sup>, incremental runoff depth (mm) was calculated
 by dividing incremental runoff volume by the plot area. Plot-average
 incremental infiltration rate was estimated by subtracting the runoff rate
 from the precipitation rate.