Kern River Research Articles

Optimizing Selection of Lateral-Re-Entry Wells Through Data-Driven Analytics

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 170702, “Optimizing the Selection of Lateral-Re-Entry Wells Through Data-Driven Analytics,” by Andrei S. Popa, SPE, Chevron, prepared for the 2014 SPE Annual Technical Conference and Exhibition, Amsterdam, 27–29 October. The paper has not been peer reviewed. A new intelligent model that successfully learns from high-dimensional data and effectively identifies high-production areas and optimum lateral-re-entry candidates is presented. The model is entirely data driven and uses Wang-Mendel (WM) rules extraction, fuzzy logic (FL), pattern recognition, and Voronoi mapping. The authors applied their model to a large field with thousands of wells and multiple production layers, finding that it outperformed previous methodologies significantly. Introduction This paper demonstrates the application of data-driven-modeling technology to a relatively new domain, petroleum engineering—in particular, to production-opportunity identification and well-work optimization. The Kern River field is the single largest producing onshore heavy-oil asset in North America. The structure is homoclinal, dipping southwest into the basin, with nine distinctive productive formations. The field has been produced with vertical wells through a combination of primary recovery and thermal enhanced recovery. The horizontal-well program was initiated in the Kern River field in 2007; because of its success, the program witnessed a significant growth year after year. An intelligent approach using fuzzy logic was introduced in 2012, which allowed identification of new horizontal-well opportunities previously missed by conventional methodology. More than 500 horizontal wells have been drilled in the field. This large number of wells provided an ideal data set for extracting reservoir knowledge for future optimization. Observation and Project Opportunity The average Kern River production per vertical well is currently under 7 BOPD. Analytics run on production data showed that more than 3,900 wells produce less than 3 BOPD, while approximately 2,200 produce below 1 BOPD. This observation creates a significant opportunity for production improvement. The large amount of poorly performing vertical wells contrasted with the success of the horizontal wells and led to the idea of reusing the existing wellbores by drilling lateral sections into zones with remaining opportunity. If successful, these new lateral drills would not only improve production output but also would help drain remaining reserves more efficiently. These sidetracks were named “re-entry laterals.” Re-entry-lateral sidetracks are directionally drilled high-angle sections (15°/100-ft dogleg severity) aiming at maximizing reservoir-contact area. The wells are completed with slotted liners and penetrate several target sands offering higher well exposure to each formation intersected. In contrast to the horizontal wells, which can reach horizontal sections of 2,000 ft or greater, the reentry laterals would extend no more than 400–500 ft at very high angle (85°) into formations. As with horizontal-well placement, lateral-re-entry wells are intended to target the remaining hot oil existing at the base of high-quality sand formations. Thus, the horizontal sections of the wells could penetrate multiple formations for a significantly longer section compared with vertical entries, thus maximizing the formation exposure to the well. For a discussion of the technological background of this project, including discussions of the WM method, FL systems, and Voronoi diagrams, please see the complete paper.

An Analysis of the 7 July 2004 Rockwell Pass, California, Tornado: Highest-Elevation Tornado Documented in the United States

Abstract This manuscript documents the tornado in the Rockwell Pass area of Sequoia National Park, California, that occurred on 7 July 2004. Since the elevation of the tornado’s ground circulation was approximately 3705 m (~12 156 ft) MSL, this is the highest-elevation tornado documented in the United States. The investigation of the storm’s convective mode was performed mostly inferentially on the basis of an analysis of the radar imagery from Edwards Air Force Base (which was in clear-air mode on this day), objectively produced soundings and/or CAPE estimates from two mesoscale models, an objectively produced proximity sounding and hodograph, and analyses of satellite imagery. The nearest Weather Surveillance Radar-1988 Doppler (WSR-88D) in Hanford, California, could not be used to observe this storm because of terrain blockage by the Sierra Nevada, and the nearest sounding sites were too distant and in a different meteorological environment on this day. The near-storm environment may have been favorable briefly for a supercell in the upper portion of the Kern River Canyon. The limitations of the radar data precluded the authors from making a definitive conclusion on the convective mode of the storm but do not rule out the possibility that the storm briefly might have been a supercell. There was insufficient evidence, however, to support the notion that the tornado itself was mesocyclone induced. High LCL heights in the proximity sounding also suggest that the tornado was formed by processes not associated with a mesocyclone (popularly known as a “landspout”), but do not allow us to dismiss the possibility that the tornado was mesocyclone induced.

Examining spatial and temporal variability in snow water equivalent using a 27 year reanalysis: Kern River watershed, Sierra Nevada

AbstractThis paper used a data assimilation framework to estimate spatially and temporally continuous snow water equivalent (SWE) from a 27 year reanalysis (from water year 1985 to 2011) of the Landsat‐5 record for the Kern River watershed in the Sierra Nevada, California. The data assimilation approach explicitly treats sources of uncertainty from model parameters, meteorological inputs, and observations. The method is comprised of two main components: (1) a coupled land surface model (LSM) and snow depletion curve (SDC) model, which is used to generate an ensemble of predictions of SWE and fractional snow cover area (FSCA) for a given set of prior (uncertain) inputs, and (2) a retrospective reanalysis step, which updates estimation variables to be consistent with the observed fractional snow cover time series. The final posterior SWE estimate is generated from the LSM‐SDC using the posterior estimation variables consistently with all postulated sources of uncertainty in the model, inputs, and observations. A reasonable agreement was found between the SWE reanalysis and in situ SWE observations and streamflow data. The data set was studied to evaluate factors controlling SWE spatial and temporal variability. Elevation was found to be the primary control on spatial patterns of peak‐SWE and day‐of‐peak. The easting coordinate had additional explanatory power, which is hypothesized to be related to rain shadow effects due to the prevailing storm track directions. The spatial patterns were found to be interannually inconsistent. However, drier years and lower elevations were found more variable than wetter years and higher elevations, respectively. Only a very small percentage of the Kern River watershed had a significant trend in peak‐SWE and day‐of‐peak. Trends deemed to be significant were found to be positive (peak‐SWE is increasing and day‐of‐peak occurs later) at higher elevations, but negative (peak‐SWE is decreasing and day‐of‐peak occurs earlier) at lower elevations. The reanalysis approach proved to be useful in terms of identifying subwatershed variability and trends, and could be extended to larger regions and areas where in situ data are sparse or unavailable.

Creation and utility of a large fit-for-purpose earth model in a giant mature field: Kern River field, California

Reservoir management studies of California’s Kern River field rely on a full-field 155-million cell three-dimensional (3D) earth model. This full-field model provides input for reserves estimation as well as the identification, targeting, and ranking of remaining opportunities. The earth model is regarded as “fit for purpose” in that characteristics of the model are aligned with specific needs for reservoir management. Normalized resistivity logs from more than 12,000 wells are used to establish lithology and reservoir architecture. Temperature, steam, gas, and oil saturation logs from over 650 boreholes provide regular periodic surveillance for identifying changes in fluids and temperature. Changes in fluid contacts and saturations are integrated with reservoir architecture three times each year. These model updates are important to the development teams for staying current on changes in their project area. The integration of these data provides the basis for linked reserves and resource estimation and the identification and development of remaining opportunities. Kern River reserves and resources are estimated from the model for over 130 internal reporting entities. For asset reservoir management purposes, reserves are updated for over 160,000 entities (based on patterns, zones, and reserves) across the 12-sq-mi (31-sq-km) field. The updated reserves supply input to reserves distribution maps and spreadsheets used for evaluating workover and new development opportunities. Some of these opportunities represent heat mining of untapped hot oil zones whereas other opportunities are cold and require the introduction of steam to mobilize the oil. Using multiple reservoir property characteristics as filter criteria for identifying remaining opportunities is an important tool used at Kern River. Reservoir volumes containing hot moveable oil below steam zones in non-producing areas can be quickly and efficiently identified and prioritized with this method. This has helped lead to the success of our current field-wide horizontal infill drilling program that identifies geobodies based on these filtering criteria.

Physiographic and climatic controls on snow cover persistence in the Sierra Nevada Mountains

AbstractThe persistence of snow cover across mountainous landscapes influences land‐atmosphere energy exchange, water availability, the partitioning of snowmelt into various hydrologic pathways, vegetation productivity, and fluxes of nutrients. Understanding the processes controlling snow cover persistence has been limited as relationships between physiography, climate, and snow persistence are nonlinear and difficult to characterize empirically. The work detailed herein uses 7 years of remotely sensed snow cover persistence observed from the Moderate Resolution Imaging Spectroradiometer over the Sierra Nevada Mountains as a dependent variable in binary regression tree models with a suite of independent variables comprised of both physiographic and climatic metrics. Annual snow cover persistence over 2001–2007 revealed significant inter‐annual variability, with domain‐average snow persistence values exceeding 4.01 (i.e. early April) in the wettest year of 2005 and reaching as low as 2.90 (i.e. late February) in the driest year of 2007. Regression tree models revealed that elevation was the most important explanatory variable regarding snow cover persistence, ranking first in the hierarchical models in 10 out of 13 watersheds. Precipitation (Feather and Owens River basins) and temperature (Kern River basin) were the first‐ranking variables in the remaining three watersheds. Second, the order variables of importance included vegetation, which ranked between 2nd and 5th in 10 of 13 watersheds, and slope, which ranked 4th and 5th in 12 of the 13 watersheds. Interestingly, solar radiation and aspect were of tertiary importance but were more influential in watersheds with north–south orientation (e.g. in the Feather, Mokelumne and Stanislaus watersheds). These results have implications for understanding the sensitivity of snow cover persistence to changes in climate as watersheds where elevation and/or temperature strongly influence snow cover persistence may be more sensitive to future warming. Further work is needed to identify associated ecosystem sensitivities to future changes in snow cover persistence. Copyright © 2014 John Wiley & Sons, Ltd.

Energy Usage Structure Adjustment in Kern River Oilfield and Illumination for Self-Used Oil Substitution in Chinese Oilfield

The substitution of the crude oil for private use in Chinese oilfield is one of the reducing oil production costs and relieving oil shortage ways. This paper introduced the energy usage adjustment and its contribution on energy saving in Kern River oilfield, as well as analyzed the advantage of using natural gas, coal, petroleum coke and renewable resources to replace the self-used oil in Chinese oil field.

Solar-generated steam for oil recovery: Reservoir simulation, economic analysis, and life cycle assessment

The viability of solar thermal steam generation for thermal enhanced oil recovery (TEOR) in heavy-oil sands was evaluated using San Joaquin Valley, CA data. The effectiveness of solar TEOR was quantified through reservoir simulation, economic analysis, and life-cycle assessment. Reservoir simulations with continuous but variable rate steam injection were compared with a base-case Tulare Sand steamflood project. For equivalent average injection rates, comparable breakthrough times and recovery factors of 65% of the original oil in place were predicted, in agreement with simulations in the literature. Daily cyclic fluctuations in steam injection rate do not greatly impact recovery. Oil production rates do, however, show seasonal variation. Economic viability was established using historical prices and injection/production volumes from the Kern River oil field. For comparison, this model assumes that present day steam generation technologies were implemented at TEOR startup in 1980. All natural gas cogeneration and 100% solar fraction scenarios had the largest and nearly equal net present values (NPV) of $12.54 B and $12.55 B, respectively. Solar fraction refers to the steam provided by solar steam generation. Given its large capital cost, the 100% solar case shows the greatest sensitivity to discount rate and no sensitivity to natural gas price. Because there are very little emissions associated with day-to-day operations from the solar thermal system, life-cycle emissions are significantly lower than conventional systems even when the embodied energy of the structure is considered. We estimate that less than 1g of CO2/MJ of refined gasoline results from the TEOR stage of production if solar energy provides all steam. By this assessment, solar thermal or supplemental solar generation systems appear to be a preferred alternative to fully conventional systems using natural gas in areas with large solar insolation.

Transcontinental methane measurements: Part 2. Mobile surface investigation of fossil fuel industrial fugitive emissions

The potent greenhouse gas, methane, CH4, has a wide variety of anthropogenic and natural sources. Fall, continental-scale (Florida to California) surface CH4 data were collected to investigate the importance of fossil fuel industrial (FFI) emissions in the South US. A total of 6600 measurements along 7020-km of roadways were made by flame ion detection gas chromatography onboard a nearly continuously moving recreational vehicle in 2010. A second, winter survey in Southern California measured CH4 at 2 Hz with a cavity ring-down spectrometer in 2012.Data revealed strong and persistent FFI CH4 sources associated with refining, oil/gas production, a presumed major pipeline leak, and a coal loading plant. Nocturnal CH4 mixing ratios tended to be higher than daytime values for similar sources, sometimes significantly, which was attributed to day/night meteorological differences, primarily changes in the boundary layer height. The highest CH4 mixing ratio (39 ppm) was observed near the Kern River Oil Field, California, which uses steam reinjection. FFI CH4 plume signatures were distinguished as stronger than other sources on local scales. On large (4°) scales, the CH4 trend was better matched spatially with FFI activity than wetland spatial patterns.Qualitative comparison of surface data with SCIAMACHY and GOSAT satellite retrievals showed agreement of the large-scale CH4 spatial patterns. Comparison with inventory models and seasonal winds suggests for some seasons and some portions of the Gulf of Mexico a non-negligible underestimation of FFI emissions. For other seasons and locations, qualitative interpretation is not feasible. Unambiguous quantitative source attribution is more complex, requiring transport modeling.

Genetic diversity, endemism and phylogeny of lampreys within the genus Lampetra sensu stricto (Petromyzontiformes: Petromyzontidae) in western North America

Phylogenetic structure of four Lampetra species from the Pacific drainage of North America (western brook lamprey Lampetra richardsoni, Pacific brook lamprey Lampetra pacifica, river lamprey Lampetra ayresii and Kern brook lamprey Lampetra hubbsi) and unidentified Lampetra specimens (referred to as Lampetra sp.) from 36 locations was estimated using the mitochondrial cytochrome b gene. Maximum parsimony and Bayesian inferences did not correspond with any taxonomic scheme proposed to date. Rather, although L. richardsoni (from Alaska to California) and L. ayresii (from British Columbia to California) together constituted a well-supported clade distinct from several genetically divergent Lampetra populations in Oregon and California, these two species were not reciprocally monophyletic. The genetically divergent populations included L. pacifica (from the Columbia River basin) and L. hubbsi (from the Kern River basin) and four Lampetra sp. populations in Oregon (Siuslaw River and Fourmile Creek) and California (Kelsey and Mark West Creeks). These four Lampetra sp. populations showed genetic divergence between 2.3 and 5.7% from any known species (and up to 8.0% from each other), and may represent morphologically cryptic and thus previously undescribed species. A fifth population (from Paynes Creek, California) may represent a range extension of L. hubbsi into the Upper Sacramento River.

Potential for hydrologic characterization of deep mountain snowpack via passive microwave remote sensing in the Kern River basin, Sierra Nevada, USA

Snow plays a critical role in hydrology and water resources, but snow properties in mountainous areas vary dramatically in space, making characterization difficult: in situ measurements represent a single point of spatially-variable snow properties. Spaceborne passive microwave (PM) remote sensing has spatially continuous coverage, but coarse spatial resolution. PM spatial footprints are nominally elliptical, with the spatial orientation changing relative to a given basin on the ground from one satellite pass to the next. The widely used Equal-Area Scalable Earth Grid (EASE-Grid) resamples the raw PM observations to a 25km×25km grid; this is far coarser than The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) 37GHz Level 2A (L2A) footprints with an area of 87.9km2. This paper presents methods for processing the L2A data in order to illustrate that PM measurements contain information about snow accumulation and ablation cycles in mountainous regions. Methods are presented 1) to calculate the average Tb over a hydrologic basin for monitoring SWE accumulation amount, and 2) to interpolate Tb to a point for monitoring SWE ablation timing. Across the six-year study period, the range of the Tb was 50K, while the range of the air temperature was only 30K, indicating significant surface emissivity variations. The minimum Tb of each water year (WY), which starts from October 1 of a calendar year and ends at September 30 of the next, showed a strong inverse relationship to SWE measured in situ; the correlation coefficient between Tb and an in situ basin average SWE was −0.94. The L2A data is three times more sensitive to than the EASE-Grid data to in situ SWE. The diurnal amplitude variability (DAV, or difference between daytime and nighttime Tb) was used to identify the day of melt onset and compared with in situ estimates of onset derived from daily SWE measurements. L2A data corresponded well with the in situ onset dates with a correlation coefficient of 0.94 and an RMSE of 5.04days. When using EASE-Grid data, the RMSE in onset date was 11.7days. In addition, Tb DAV was found to be correlated with Tair DAV during winter, with an average correlation coefficient of 0.72. Future work will explore methods to extract this information in order to improve estimates of snow accumulation and ablation patterns.

Morphological and molecular diversification of slender salamanders (Caudata: Plethodontidae: Batrachoseps) in the southern Sierra Nevada of California with descriptions of two new species

Slender salamanders of the genus Batrachoseps achieve relatively high diversity in the Kern Canyon region at the southernend of the Sierra Nevada of California through high turnover of species with small geographic ranges. The status of severalpopulations of Batrachoseps in this region is enigmatic, and both morphological and molecular data have suggested thatsome populations do not belong to any of the currently recognized species. Identification of species in this region is com-plicated by the apparent extinction of Batrachoseps relictus in the vicinity of its type locality in the Lower Kern RiverCanyon. Here we analyze a comprehensive morphological dataset to evaluate diversity in the Kern River Canyon region.We conclude that populations from Breckenridge Mountain are conspecific with B. relictus, while populations from northof the Kern River previously treated as B. relictus belong to an undescribed species. The morphological data also showthe distinctiveness of populations from the Upper Kern River Canyon. Thus, we describe two new species, Batrachosepsbramei sp. nov. for populations from the Upper Kern River Canyon and Batrachoseps altasierrae sp. nov. for populationsfrom the southern Sierra Nevada previously referred to B. relictus. B. bramei sp. nov. and B. relictus are members of thenigriventris group; B. altasierrae sp. nov. belongs to the group formerly called the relictus group, which we rename thediabolicus group. We conclude by presenting allozyme and mitochondrial DNA sequence data that support the distinctiveness of these newly described species and provide a hypothesis of relationships within the nigriventris group.

Revision of New World Species of the Shore-fly Subgenus Allotrichoma Becker of the Genus Allotrichoma with Description of the Subgenus Neotrichoma (Diptera, Ephydridae, Hecamedini).

The New World species of the subgenera Allotrichoma Becker and Neotrichoma (new subgenus) are revised, including a phylogenetic analysis of the species groups and subgenera within the genus Allotrichoma. For phylogenetic perspective and to document the monophyly of the genus Allotrichoma and its included subgenera and species groups, we also provide a cladistic analysis of genera within the tribe Hecamedini. The ingroup included seven exemplar congeners from within Allotrichoma. Outgroup sampling included exemplars of other genera within Hecamedini and from the putative sister group, Lipochaetini, and to root the analysis, we used an exemplar of the tribe Discocerinini. Analyses with successive weighting and implied weighting recovered a monophyletic Allotrichoma and indicated clades within the genus. Eight new species are described (type locality in parenthesis): Allotrichoma bifurcatum (Utah. Utah: Lake Shore (40°06.9'N, 111°41.8'W; 1370 m)), Allotrichoma dynatum (Oregon. Benton: Finley National Wildlife Refuge (44°24.6'N, 123°19.5'W)), Allotrichoma occidentale (Oregon. Lake: Lakeview (44 km E; Drake Creek; 42°11'N, 119°59.3'W)), Allotrichoma robustum (California. Kern: Kern River (35°16.1'N, 119°18.4'W)), Allotrichoma sabroskyi (New Mexico. Sandoval: La Cueva (Junction of Highways 126 and 4; 35°52'N, 106°38.4'W; 2342 m)), Allotrichoma wallowa (Oregon Baker: Goose Creek (35 km E Baker City; 44°49.2'N, 117°27.79'W; 825 m)), Allotrichoma baliops (Florida. Monroe: Key West (Willie Ward Park; 24°32.9'N, 81°47.9'W)), and Allotrichoma insulare (Dominica. Cabrits Swamp (15°35'N, 61°29'W)). Within Allotrichoma, we recognize three subgenera of which one, Neotrichoma (type species: Allotrichoma atrilabre), is newly described. All known species from the New World are described with an emphasis on structures of the male terminalia, which are fully illustrated. Detailed locality data and distribution maps for the New World species are provided. A lectotype is designated for Discocerina simplex Loew and a neotype is designated for Allotrichoma bezzii Becker. Allotrichoma filiforme Becker, Allotrichoma trispinum Becker, and Allotrichoma dahli Beschovski are reported as new synonyms of Allotrichoma simplex (Loew) and Allotrichoma yosemite Cresson is a new synonym of Allotrichoma atrilabre Cresson. We also clarify the status of previously described species, including those with Holarctic distributions. For perspective and to facilitate genus-group and species-group recognition, the tribe Hecamedini is diagnosed and a key to included genera is provided.

Process Innovation and Integration in Process-Oriented Settings: The Case of the Oil Industry

Scholars have long argued that in new product development integrated innovation processes replace sequentially organized ones because of changing capabilities, integration of knowledge, and the increasing importance of market orientation. The intention of this paper is to study whether this also applies in process-oriented industries. Process-oriented settings are fundamentally different from product-oriented ones as the emphasis is on efficiency, clear guidelines, and tacit knowledge, while radical innovation is less important. It is also less obvious why market orientation—a key driver of integration in new product development—should change the way the innovation process is organized, as there is no product to be developed in the first place. A Stage Gate Model could therefore be well-suited to achieve more efficiency and effectiveness. In order to investigate process innovation in a process-oriented setting, we decided to study the upstream oil and gas industry, a scale-intensive, process-oriented setting that substantially contrasts with traditional science-driven industries such as biotechnology and pharmaceuticals, where patents are relevant. The particular advantage of this setting is that virtually no product innovation occurs, allowing the isolation of process innovation. Relying on five inductive case studies of major projects (BP's Prudhoe Bay, Chevron's Kern River, Conoco Philips's Ekofisk, ENI's el-Bouri, and Shell's Troll field), we find that integration occurs in process-oriented settings but does so for different reasons than in product-oriented ones. Integration emerges from an innovation mode characterized by: (1) trial and error (not R&D) as the main mode of innovation; (2) the cooperation of experts from different knowledge backgrounds; (3) the development of Information and Communication Technology (ICT), which facilitates this cooperation across disciplines and projects; and (4) the need to increase efficiency as demand outstrips supply. More precisely, demand shapes reward systems and determines whether new raw materials will be used (creating new supply that requires innovation of processes in periods when demand outstrips supply). Supply and reward systems therefore create the conditions where trial and error, integration of knowledge, and ICT development mutually enforce each other, leading to the integration of the innovation process. Besides contributing to the literature on innovation the paper also offers interesting insights for managers. In order to foster innovation in process-oriented settings they need to provide specialists with room to experiment over extended periods of time, encourage cooperation across disciplines, and create both incentives and systems to facilitate this process. Finally, managers need to consider the ability of staff to cooperate at the outset, when they set up their recruitment process.

Pollinator‐mediated gene flow fosters genetic variability in a narrow alpine endemic, Abronia alpina (Nyctaginaceae)

For rare and endemic plants that exist in small, isolated habitats, natural selection is expected to favor self-compatibility, which can result in low genetic diversity due to inbreeding and genetic drift. Using Abronia alpina, a rare alpine endemic of the California Floristic Province, we demonstrate that there are exceptions to these predictions. We present the results of both a pollination experiment and a genetic study using AFLPs (amplified fragment length polymorphisms). Using controlled hand-pollination and pollinator observations, we examined the breeding system, pollination ecology, and mechanism for self-incompatibility in A. alpina. Abronia alpina exhibits an allogamous mating system with probable self-incompatibility resulting from limited growth of pollen tubes originating from self-pollination. Only xenogamous crosses and open-pollinated controls produced seed, and only xenogamous crosses produced pollen tubes that reached the ovary. The molecular study shows that A. alpina has substantial genetic diversity for a rare, endemic species, evidenced by the high percentage of polymorphic loci and average expected heterozygosity. Gene flow among subpopulations, as inferred from AFLP markers, appears to be substantial, although the Kern River is an important physical barrier. Our results indicate that A. alpina is dependent on insects for both seed production and the maintenance of genetic diversity. This finding suggests that pollinators may be crucial to the long-term adaptive potential of rare, endemic plants and that conservation of rare endemics is, in part, dependent on community-level interactions such as plant-pollinator mutualisms.

NON‐UNIFORM CHANGES TO WHITEWATER RECREATION IN CALIFORNIA'S SIERRA NEVADA FROM REGIONAL CLIMATE WARMING

ABSTRACTWhitewater recreation is an aesthetic ecosystem service potentially affected by climate warming alterations to runoff. In California's Sierra Nevada, climate change is likely to reduce water availability with warmer air temperatures and stationary or decreasing precipitation, which will likely alter whitewater recreation opportunities. In this study, we identified 128 whitewater runs on the west slope of the Sierra Nevada within a 13‐basin study area that ranged from serene float trips to remote, difficult, kayak expeditions. We used a spatially explicit, one‐dimensional rainfall‐runoff model to estimate the unregulated hydrology at specific locations within flow thresholds amenable to whitewater recreation. Climate warming scenarios were simulated by increasing air temperature by 2 °C, 4 °C and 6 °C and assuming no change in precipitation.With mild warming, the average number of boatable weeks per year increases, but more extreme warming decreases the average boatable weeks per year across the Sierra Nevada. Runs in low‐elevation drainages, such as the Cosumnes and the Tule River Basins, are most vulnerable to changes in boatable weeks. Yet, high‐elevation watersheds, such as the Kern River, also have a large reduction in boatable weeks. Watersheds in the central Sierra Nevada show an increase in boatable weeks. Overall, we found elevation and run type to be the best predictors of resiliency for Sierra Nevada whitewater runs.Recreation is important for management of rivers, yet it is difficult to quantify and to plan for. This research provides a sensitivity analysis approach to climate warming for the Sierra Nevada and presents a method that can be applied to other regions and whitewater rivers. The observed reduction in whitewater recreation opportunities in unregulated rivers because of climate warming and continued increases in population will likely increase the importance of whitewater boating on regulated rivers and thus the reliance on operations for meeting multiple demands. Copyright © 2011 John Wiley & Sons, Ltd.

The remarkable occurrence of large rainfall-induced debris flows at two different locations on July 12, 2008, Southern Sierra Nevada, CA, USA

On July 12, 2008, two convective cells about 155 km apart produced a brief period of intense rainfall triggering large debris flows in the southern Sierra Nevada. The northernmost cell was centered over Oak Creek Canyon, an east-flowing drainage, and its tributaries near Independence, CA, USA. About 5:00 p.m., debris flows passed down the South Fork and North Fork of Oak Creek to merge into a large single feature whose passage affected the historic Mt. Whitney Fish hatchery and blocked California State Highway 395. At about the same time, the southernmost cell was largely centered over Erskine Creek, a main tributary of the west-flowing Kern River. Debris flows issued from several branches to coalesce into a large debris flow that passed along Erskine Creek, through the town of Lake Isabella, CA, USA and into the Kern River. It was observed reaching Lake Isabella about 6:30 p.m. Both debris flows caused significant disruption and damage to local communities.

Late Quaternary slip rate on the Kern Canyon fault at Soda Spring, Tulare County, California

The Kern Canyon fault represents a major tectonic and physiographic boundary in the southern Sierra Nevada of east-central California. Previous investigations of the Kern Canyon fault underscore its importance as a Late Cretaceous and Neogene shear zone in the tectonic development of the southern Sierra Nevada. Study of the late Quaternary history of activity, however, has been confounded by the remote nature of the Kern Canyon fault and deep along-strike exhumation within the northern Kern River drainage, driven by focused fluvial and glacial erosion. Recent acquisition of airborne lidar (light detection and ranging) topography along the ∼140 km length of the Kern Canyon fault provides a comprehensive view of the active surface trace. High-resolution, lidar-derived digital elevation models (DEMs) for the northern Kern Canyon fault enable identification of previously unrecognized offsets of late Quaternary moraines near Soda Spring (36.345°N, 118.408°W). Predominately north-striking fault scarps developed on the Soda Spring moraines display west-side-up displacement and lack a significant sense of strike-slip separation, consistent with detailed mapping and trenching along the entire Kern Canyon fault. Scarp-normal topographic profiling derived from the lidar DEMs suggests normal displacement of at least 2.8 +0.6/–0.5 m of the Tioga terminal moraine crest. Cosmogenic 10Be exposure dating of Tioga moraine boulders yields a tight age cluster centered around 18.1 ± 0.5 ka ( n = 6), indicating a minimum normal-sense fault slip rate of ∼0.1–0.2 mm/yr over this period. Taken together, these results provide the first clear documentation of late Quaternary activity on the Kern Canyon fault and highlight its role in accommodating internal deformation of the southern Sierra Nevada.

Tectonic geomorphology of the southern Sierra Nevada Mountains (California): Evidence for uplift and basin formation

Hypotheses regarding uplift of the Sierra Nevada Mountains (Sierra), California, USA, vary from a single slowly tilting block to rapid Pliocene and/or Quaternary uplift in the south exclusively. To test these hypotheses, we examined geomorphic indices of the western Sierra. We interpret longitudinal profiles of the larger westerly flowing rivers, mountain front sinuosity, valley floor-to-width to height ratio, and relief ratio to show that relative tectonic activity is greater in the southern Sierra near the Kern River Gorge fault. The Sierra range crest profile indicates that the increased tectonism is related to more recent uplift in the southern Sierra. Only westward migration of Basin and range extension is consistent with the locus of uplift in the southern Sierra. We hypothesize that the Sierra topography is the result of Pliocene delamination-related uplift in the central Sierra and post-Pliocene interaction of the San Andreas, Garlock, and Sierra Nevada Frontal fault zones.

Hydrologic Response and Watershed Sensitivity to Climate Warming in California's Sierra Nevada

This study focuses on the differential hydrologic response of individual watersheds to climate warming within the Sierra Nevada mountain region of California. We describe climate warming models for 15 west-slope Sierra Nevada watersheds in California under unimpaired conditions using WEAP21, a weekly one-dimensional rainfall-runoff model. Incremental climate warming alternatives increase air temperature uniformly by 2°, 4°, and 6°C, but leave other climatic variables unchanged from observed values. Results are analyzed for changes in mean annual flow, peak runoff timing, and duration of low flow conditions to highlight which watersheds are most resilient to climate warming within a region, and how individual watersheds may be affected by changes to runoff quantity and timing. Results are compared with current water resources development and ecosystem services in each watershed to gain insight into how regional climate warming may affect water supply, hydropower generation, and montane ecosystems. Overall, watersheds in the northern Sierra Nevada are most vulnerable to decreased mean annual flow, southern-central watersheds are most susceptible to runoff timing changes, and the central portion of the range is most affected by longer periods with low flow conditions. Modeling results suggest the American and Mokelumne Rivers are most vulnerable to all three metrics, and the Kern River is the most resilient, in part from the high elevations of the watershed. Our research seeks to bridge information gaps between climate change modeling and regional management planning, helping to incorporate climate change into the development of regional adaptation strategies for Sierra Nevada watersheds.

Identification of Individual and Population-level Variation in Vocalizations of the Endangered Southwestern Willow Flycatcher (Empidonax traillii extimus)

Abstract.— An understanding of individuality in animal vocalizations can assist in tracking individuals spatially and temporally, and is particularly useful for species of conservation concern. We determined whether fitz bew vocalizations of the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus) showed vocal individuality, assessed the differences in vocal individuality among three populations, and tested the ability of predictive vocalization models to reidentify individuals. Fitz bew vocalizations were recorded from two populations in Arizona (Roosevelt Lake and San Pedro River) and one in California (Kern River). Individuality was determined using discriminant function analysis (DFA) and trained artificial neural networks (ANN). Southwestern Willow Flycatchers showed individuality in the fitz bew, with the models correctly classifying 81–86% of the vocalizations. We also found population-level variations: vocal structure differed substantially between Roosevelt Lake and Kern River, ...