@article {JRN54905,
	title = {On the sensitivity of hillslope runoff and channel transmission losses in arid piedmont slopes},
	journal = {Water Resources Research},
	volume = {54},
	year = {2018},
	pages = {4498-4518},
	abstract = {<p class="rtejustify">Channel transmission losses alter the streamflow response of arid and semiarid watersheds and promote focused groundwater recharge. This process has been primarily studied in dryland channels draining large areas that are displaced away from hillslope runoff generation. In contrast, small watersheds on arid piedmont slopes allow the investigation of interactive hillslope and channel processes that control the partitioning between surface and subsurface flows. In this study, we utilize high-resolution, long-term measurements of water balance components in an instrumented watershed of the Chihuahuan Desert to set up, parameterize, and test a process-based, distributed hydrologic model modified to account for channel losses. A transient method for capturing capillary effects in channels results in simulations with a reliable representation of the watershed energy balance, soil moisture dynamics, hillslope infiltration, channel transmission (or percolation) losses, and streamflow yield over the study period. The simulation also reproduces a conceptual model of hillslope infiltration-excess runoff generation linked to downstream channel percolation losses that depend on the rainfall event size. Model-derived thresholds were obtained for the amount of hillslope runoff (6 mm) and rainfall (12.5 mm) necessary for streamflow yield, such that 40\% of percolation occurs for small events that do not reach the outlet. Using a set of scenarios, we identify that hillslope infiltration controls the rainfall threshold necessary to initiate percolation, while channel infiltration affects the partitioning into percolation and streamflow yield. Thus, the connectivity along hillslope-channel pathways is deemed an essential control on the streamflow generation and groundwater recharge in arid regions with complex terrain.</p>
},
	keywords = {channel transmission losses, Chihuahuan Desert, groundwater recharge, hillslope infiltration, hydrologic model, hydrology, percolation losses, piedmont slopes, runoff, soil moisture dynamics, streamflow yield, water balance},
	doi = {10.1029/2018WR022842},
	url = {files/bibliography/JRN54905.pdf},
	author = {A. P. Schreiner-McGraw and Enrique Vivoni}
}
@article {JRN54812,
	title = {Percolation observations in an arid piedmont watershed and linkages to historical conditions in the Chihuahuan Desert},
	journal = {Ecosphere},
	volume = {8},
	year = {2017},
	pages = {Article e02000},
	abstract = {<p class="rtejustify">A critical hydrologic process in arid and semiarid regions is the interaction between ephemeral channels and groundwater aquifers. Generally, it has been found that ephemeral channels contribute to groundwater recharge when streamflow infiltrates into the sandy bottoms of channels. This process has traditionally been studied in channels that drain large areas (tens to hundreds of square kilometers). Since the water table in arid and semiarid regions is typically far from the surface, measured streamflow losses or percolation into the deep vadose zone is equated to groundwater recharge. In this study, we use a water balance approach to estimate deep percolation in a first-order, instrumented watershed (4.7 ha) on a piedmont slope of the Jornada Experimental Range (JER) in the Chihuahuan Desert. Results indicate that runoff generated within the piedmont slope contributes significantly to deep percolation. During the short-term 6-yr study period, we estimated 385 mm of total percolation, 62 mm/yr, or a ratio of percolation to rainfall of 0.26. Based on the instrument network, we identified that percolation occurs inside channel areas when these receive overland sheetflow from hillslopes. We observed less streamflow leaving the watershed as compared to percolation during the study period, leading to an outlet streamflow to rainfall ratio of 0.02. Using long-term data sets available from the JER, we estimate that over the last 100 yr, 48 mm/yr of percolation occurs at the study site, a ratio of percolation to rainfall of 0.19. We then scale this up to determine the contribution of similarly sized watersheds on the piedmont slopes of the JER. These observations highlight the importance of arid piedmont slopes for generating groundwater recharge, in particular during above-average rainfall periods.</p>
},
	keywords = {Chihuahuan Desert, dryland ecohydrology, groundwater recharge, long term ecological research, Special Feature: Dynamic Deserts, watershed instrumentation},
	doi = {10.1002/ecs2.2000 },
	url = {files/bibliography/JRN00659.pdf},
	author = {A. P. Schreiner-McGraw and Enrique Vivoni}
}
