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Arid Hydrology Research Area (AHRA) rainfall simulator data


Schoener, Gerhard; Rassa, Sara (2023), Arid Hydrology Research Area (AHRA) rainfall simulator data, Dryad, Dataset,


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. 


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 m2, 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-1 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-1 and switched to 48 mm h-1 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-3, 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.