Benjamin Tobin

• PhD
• Director at New Mexico Institute of Mining and Technology

Piston flow is a term used to describe the phenomenon of the pressure pulse during pipe‐full flow in karst conduits. During piston flow, as dilute meteoric recharge displaces water present in the conduits, discharge increases and specific conductance decreases at karstic springs. The aim of this research is to gain a deeper understanding of how pis...

Researchers use sediment hysteresis in watershed sedimentation studies, however underlying processes controlling sediment hysteresis observations remain an open topic of investigation. We investigate the hypothesis that baseflow water and sediment can control sediment hysteresis in some cases by: (i) modelling water–sediment mixing permutations tha...

The Grand Canyon is famous for its awe-inspiring natural wonders, including its caves. Double Bopper and Leandras caves have some of the longest passage lengths in the world and are nestled within the limestone of the Redwall Formation, featuring an intricate maze-like pattern. This study explored previous hypotheses about the formation of these ca...

Karst aquifers are unique among groundwater systems because of variable permeability and flow-path organization changes resulting from dissolution processes. Over time, changes in flow-path connectivity complicate interpretations of conduit network evolution in karst hydrogeology. Natural and artificial tracer techniques have long provided critical...

Cave and karst is a multidisciplinary field where scientists with different backgrounds come together to study the intricacies of subterranean environments. Communication and understanding between people with different linguistic backgrounds is an important factor for research as well as transmission of that information between scientists, policyma...

Information graphics are an effective tool for delivering scientific information, and are used in a variety of different scientific contexts such as on research papers, poster and oral presentations, and textbooks. According to Mayer and Anderson (1991), students learn topics best when text or verbal information is presented along with a visual, as...

Summer rainfall is an important contributor to water budgets in western North American deserts, where intense rainfall sustains ecosystems while also causing flash floods and damaging erosion. A better understanding of Grand Canyon palaeoclimate and the long-term history of the summer monsoon from summer-sensitive palaeoclimate records will improve...

Sediment hysteresis analysis has recently been used more to investigate the behaviors of nutrients and sediments during storm events in surface systems and to some extent in karst systems. Karst characterizes almost 15% of the worlds terrain, however the mechanics of sediment transport and its prediction in karst river and cave systems remain under...

Cave entrances directly connect the surface and subsurface geomorphology in karst landscapes. Understanding the spatial distribution of these features can help identify areas on the landscape that are critical to flow in the karst groundwater system. Sinkholes and springs are major locations of inflow and outflow from the groundwater system, respec...

The Fern Cave System, developed in the western escarpment of the Southern Cumberland Plateau of the Interior Low Plateau karst region in Northeastern Alabama, USA, is a global hotspot of cave-limited biodiversity as well as home to the largest winter hibernaculum for the federally endangered Gray Bat (Myotis grisescens). We combined the existing li...

Karst characterizes almost 15% of the worlds terrain, however the mechanics of sediment transport and its prediction in karst river and cave systems remains underdeveloped. Hysteresis analysis has recently been used more to investigate the behaviors of sediments during storm events in surface systems and to some extent in karst systems. Historicall...

Karst aquifers are susceptible to contamination by pathogenic microorganisms, such as those found in human and animal waste, because the surface and subsurface drainage are well integrated through dissolution features. Fecal contamination of water is commonly assessed by the concentration of thermotolerant coliform bacteria, especially E. coli. Thi...

Karst springs and aquifers are significant resources globally yet continue to be poorly understood because of their heterogeneity in porosity and response to climate variability. In semiarid, mountainous regions where total precipitation and groundwater recharge rates will likely decline due to climate change, improved understanding of karst ground...

Karst river and cave systems have shown to be interconnected and transport external sediment that originate from surface soils through the caves and outlet at the spring. However, resuspension of previously deposited sediment within the karst caves have an unknown residence time and makes predicting the sediment flux at the karst spring complex. Pr...

Variability in landscapes drives patterns in biological communities and is often used to understand biological systems. Rarely, however, have biological systems been used to understand landscape evolution. Here, we review the geomorphic history of cave development in the southern Sierra Nevada Mountains and look at the detail that modern biological...

The United Nations Educational, Scientific, and Cultural Organization (UNESCO) has recognized more than 350 karst areas of global importance through various designations (Biosphere Reserve, World Heritage Sites, Ramsar Sites, and Global Geoparks) with at least one UNESCO protected area with karst in 86 countries (Gunn 2020). In August 2020, Western...

Understanding patterns of groundwater flow are important when quantifying and mitigating threats to critical groundwater resources. Environmental tracers, determined from discrete sampling, could aid in characterizing spring systems through determining flow paths, recharge areas, and carbon cycling. This study explores the novel inclusion of δ 13 C...

The unsaturated zone is a critical component of karstic groundwater systems and is shown to provide substantial storage capacities. Understanding the spatial patterns and controls on flow path activation is often a challenge. Previous research focused on remotely sensed data or inferential analyses to quantify these patterns. Here, we use two cave...

Springs are ecosystems influenced by the exposure of groundwater at the Earth's surface. Springs are abundant and have played important, highly interactive ecological, cultural, and socio-economic roles in arid, mesic, and subaqueous environments throughout human evolution and history. However, springs also are widely regarded as being highly threa...

Water in the Colorado River, USA, is known to be a highly over-allocated resource, yet managers and decision makers rarely consider one of the most important contributions to the existing water in the river, i.e. groundwater. This oversight may result from the contrasting results of base-flow studies conducted on the amount of streamflow into the C...

The epikarst is an area of complex interactions and processes and is an important component of the critical zone. Understanding how processes in the epikarst are similar and different between sites is of the utmost importance in determining how information about these systems can be used to understand broader concepts and implications in the unsatu...

River discharge in mountainous regions of the world is often dominated by snowmelt, but base flows are sustained primarily by groundwater storage and discharge. Although numerous recent studies have focused on base flow discharge in mountain systems, almost no work has explicitly investigated the role of karst groundwater in these systems across a...

The source area of groundwater for springs discharging from lithologically variably perched aquifers is essential to understand when establishing baseline aquifer characteristics. Stratigraphic data from hydrostratigraphic outcrops and geochemical data from springs were used to characterize the hydrogeology of a remote, data-poor aquifer. This stud...

Full citation: Mead, J.I., J.S. Tweet, V.L. Santucci, B. Tobin, C.L. Chambers, S.C. Thomas, and M.C. Carpenter, 2020. Pleistocene/Holocene Cave Fossils from Grand Canyon National Park: Ice Age (Pleistocene) Flora, Fauna, Environments, And Climate Of The Grand Canyon, Arizona. in Santucci, V.L. and J.S. Tweet, (editors), Grand Canyon National Park:...

This study investigates a method of karst-aquifer vulnerability modeling that modifies the concentration-overburden-precipitation (COP) method to better account for structural recharge pathways through noncarbonate rocks, and applies advancements in remote-sensing sinkhole identification. Karst aquifers are important resources for human and agricul...

We applied an eco‐hydrologic model (Regional Hydro‐Ecologic Simulation System [RHESSys]), constrained with spatially distributed field measurements, to assess the impacts of forest‐fuel treatments and wildfire on hydrologic fluxes in two Sierra Nevada firesheds. Strategically placed fuels treatments were implemented during 2011–2012 in the upper Am...

The lack of a simple system for integrating varying types of existing data while also incorporating newly collected data is a universal problem in digital data management. A geographic information system, relational database system, and content management system are required when managing related spatial, tabular, and archival data. Alternatives to...

Water infrastructure updates at Grand Canyon National Park (GRCA) provide an opportunity to restore natural flow to Bright Angel Creek, adding an additional ~20% to baseflow. This creek provides habitat for endangered humpback chub (Gila cypha) and invasive brown trout (Salmo trutta). We assess how increased flow may alter habitat and how that chan...

Protected areas are tasked with mitigating impacts to a wide range of invaluable resources. These resources are often subject to a variety of potential natural and anthropogenic impacts that require monitoring efforts and management actions to minimize the degradation of these resources. However, due to insufficient funding and staff, managers ofte...

An understanding of the hydrogeology of Grand Canyon National Park (GRCA) in northern Arizona, USA, is critical for future resource protection. The ~750 springs in GRCA provide both perennial and seasonal flow to numerous desert streams, drinking water to wildlife and visitors in an otherwise arid environment, and habitat for rare, endemic and thre...

The Kaibab Plateau and Grand Canyon National Park in the USA contain both shallow and deep karst systems, which interact in ways that are not well known, although recent studies have allowed better interpretations of this unique system. Detailed characterization of sinkholes and their distribution on the surface using geographical information syste...

Shinumo Creek, a tributary to the Colorado River within Grand Canyon, experienced a large debris flow after consecutive monsoon summer storms on the footprint of a recent 2484 ha wildfire. The debris flow aggraded the stream channel approximately 0.5 m, removed most riparian vegetation (impacts extending to 5 m above base flow), and changed the str...

Hurricane Crawl Cave in Sequoia and Kings Canyon National Parks, California, contains adjacent but varied passage morphologies including network and anastomotic mazes, large rooms, narrow canyons, prolific speleothems, and multiple levels that collectively are difficult to explain. We investigated the cave through cartography, geochronology, dye tr...

Hydrogeologic field work in remote settings is often challenging: assessing spring behavior and aquifer characteristics can be expensive in both time commitment and resources needed to assess these systems. In this study, we document the hydrology and geochemistry of 47 perennial karst springs in the Kaweah River, a mountain river basin in the Sier...

Buried deep within the Kaibab Plateau of the North Rim of the Grand Canyon, the Redwall-Muav aquifer (R-aquifer) is a well-developed karst system that allows for quick response to extreme weather events occurring over 1,000m above. As observed through constructed spring hydrographs and recession curve analysis, the majority of R-aquifer recharge oc...

Grand Canyon National Park (GRCA) relies exclusively on a karst spring to supply water to both the North and South Rim communities and approximately 5 million visitors per year. This spring, Roaring Springs, is fed entirely from focused, ephemeral snowmelt that sinks into the karst landscape above the rims and emerges in the canyon walls 3,500 feet...

Flash flooding is a common occurrence in the tributaries of the Colorado River and often have major impacts on tributary floodplains. Native plant and animal species have developed adaptations to the intensity of these floods and to exist in a dynamic equilibrium within the desert environment. In July and August of 2014 Shinumo Creek experienced tw...

The prevailing theory is that the majority of flow in tributaries to the Colorado River in the Grand Canyon, including Bright Angel Creek, is sourced from R-Aquifer springs. The R-aquifer is a karst aquifer with chemistry that is typically dominated by carbonate to dolomitic chemistry (Ca-HCO3 with varying amounts of Mg). As Bright Angel Creek appr...

The National Park Service is preparing to replace one of the Service’s largest and most complex civil engineering works: Grand Canyon’s TransCanyon Pipeline (TCP). The TCP was built in the 1960’s to provide potable water to Phantom Ranch, Indian Garden, and the South Rim village by conveying water from Roaring Springs on the North Rim via a gravity...

Nutrient mobility in strongly coupled surface water–groundwater systems is not well studied in fire dominated ecosystems. In 2008, the Hidden Fire in the Kaweah River basin in the Sierra Nevada, CA, USA provided an unexpected opportunity to document how nutrient concentrations change post-fire in a karstic groundwater—surface water system. The resu...

Seasonality in surface weather results in seasonal temperature and humidity changes in caves. Ecological and physiological differences among trogloxenes, troglophiles, and troglobionts result in species-dependent responses to this variability. To investigate these responses, we conducted five biological inventories in a marble cave in the Sierra Ne...

To improve water management in mountain systems, it is essential that we understand how water moves through them. Researchers have documented the importance of porous-media aquifers in mountain river systems, but no previous research has explicitly included mountain karst as part of conceptual models. To do so, we used discharge and geochemical par...

In the Redwood Creek basin, a tributary to the Kaweah River in Kings Canyon National Park, fluvial waters sink into a marble karst system and emerge at Big Spring, a single-orifice vauclusian resurgence. The lower 20% of this karst contains Lilburn Cave; currently mapped at 33.92 km (21.08 mi) Lilburn Cave is the longest in California. Lilburn Cave...