Santa Cruz River Basin Research Articles

Managing the Santa Cruz River: Prospects for a Future Binational Minute

This paper examines the prospects for developing and implementing a binational water management agreement for the transboundary Santa Cruz River that crosses the US–Mexico boundary near the sister cities of Nogales, Sonora–Nogales, Arizona. After considering the geography, history, socio-economic context, and binational agreements affecting utilization of the Santa Cruz River, we review the conditions influencing recent binational progress on another transboundary river, the Tijuana River. Specifically, we ask what conditions created a favorable environment in which a binational agreement for management of the Tijuana River Watershed (TRW) was developed, what specific actions by relevant policy officials took place, and how the final agreement was reached. We then compare the dynamics that unfolded in the TRW with conditions in the Santa Cruz River to identify obstacles hindering progress towards achieving an International Boundary and Water Commission (IBWC) agreement (Minute) on shared management of the Santa Cruz River in its international reach. We find that the required political conditions that favored an agreement on the Tijuana River are not yet met on the Santa Cruz, although several favorable conditions do exist. We conclude with an assessment of current prospects for advancing binational cooperation that can inform discussion of how an IBWC Minute could be drafted to address water resource management issues in the Santa Cruz River Basin.

Stakeholder-Informed Hydroclimate Scenario Modeling in the Lower Santa Cruz River Basin for Water Resource Management

The Lower Santa Cruz River Basin Study (LSCRB Study) is a collaborative effort of regional and statewide water management stakeholders working with the US Bureau of Reclamation under the auspices of the 2009 SECURE Water Act. The impacts of climate change, land use, and population growth on projected water supply in the LSCRB were evaluated to (1) identify projected water supply and demand imbalances and (2) develop adaptation strategies to proactively respond over the next 40 years. A multi-step hydroclimate modeling and risk assessment process was conducted to assess a range of futures in terms of temperature, precipitation, runoff, soil moisture, and evapotranspiration, with a particular focus on implications for ecosystem health. Key hydroclimate modeling process decisions were informed by ongoing multi-stakeholder engagement. To incorporate the region’s highly variable precipitation pattern, the study used a numerical “weather generator” to develop ensembles of precipitation and temperature time series for input to surface hydrology modeling efforts. Hydroclimate modeling outcomes consistently included increasing temperatures, and generated information related to precipitation responses (season length and timing, precipitation amount) considered useful for evaluating potential ecosystem impacts. A range of risks was identified using the hydroclimate modeling outputs that allowed for development of potential adaptation strategies.

Co-Registration Methods and Error Analysis for Four Decades (1979–2018) of Glacier Elevation Changes in the Southern Patagonian Icefield

The main goal of this paper is to compare two co-registration methods for geodetic mass balance (GMB) calculation in 28 glaciers making up the Upper Santa Cruz River basin, Southern Patagonian Icefield (SPI), from 1979 to 2018. For this purpose, geospatial data have been used as primary sources: Hexagon KH-9, ASTER, and LANDSAT optical images; SRTM digital radar elevation model; and ICESat elevation profiles. After the analyses, the two co-registration methods, namely M1, based on horizontal displacements and 3D shift vectors, and M2, based on three-dimensional transformations, turned out to be similar. The errors in the GMB were analyzed through a k index that considers, among other variables, the error in elevation change by testing four interpolation methods for filling gaps. We found that, in 63% of the cases, the relative error in elevation change contributes 90% or more to k index. The GMB throughout our study area reported that a loss value of −1.44 ± 0.15 m w. e. a−1 (−3.0 Gt a−1) and an ice thinning median of −1.38 ± 0.11 m a−1 occurred within the study period. The glaciers that showed the most negative GMB values were Upsala, with an annual elevation change median of −2.07 ± 0.18 m w. e. a−1, and Ameghino, with −2.31 ± 0.22 m w. e. a−1.

A Review of Climate Change Impacts on the USA-Mexico Transboundary Santa Cruz River Basin

In the parched Upper Santa Cruz River Basin (USCRB), a binational USA–Mexico basin, the water resources depend on rainfall-triggered infrequent flow events in ephemeral channels to recharge its storage-limited aquifers. In-situ data from the basin highlight a year-round warming trend since the 1980s and a concerning decline in average precipitation (streamflow) from 1955–2000 to 2001–2020 by 50% (87.6%) and 17% (63%) during the winter and summer, respectively. Binational sustainable management of the basins water resources requires a careful consideration of prospective climatic changes. In this article we review relevant studies with climate projections for the mid-21st century of four weather systems that affect the region’s precipitation. First, the North American Monsoon (NAM) weather system accounts for ~60% of the region’s annual rainfall. The total NAM precipitation is projected to decline while heavy rainfall events are expected to intensify. Second, the frequency of the pacific cold fronts, the region’s prevalent source of winter precipitation, is projected to decline. Third, the frequency and intensity of future atmospheric rivers, a weather system that brings winter rainfall to the region, are projected to increase. Fourth, the frequency and intensity of large eastern pacific tropical cyclones (TC) are expected to increase. On rare occasions, remnants of TC make their way to the USCRB to cause storms with considerable impact on the region’s water resources. In contrast to the high confidence projections for the warming trend to persist throughout the mid-21st century, the precipitation projections of these four weather systems affecting the region encompass large uncertainties and studies have often reported contradicting trends. An added source of uncertainty is that the USCRB is located at the periphery of the four rain-bearing weather systems and small mesoscale changes in these weather systems may have accentuated impacts on their edges. Despite the high uncertainty in the projections of future precipitation, the early 21st century drying trend and the projected mid-21st century decline in precipitation events serve as a pressing call for planning and actions to attain sustainable water resources management that reliably satisfies future demands.

Spatial distribution of active and inactive rock glaciers and protalus ramparts in a sector of the Central Andes of Argentina

Rock glaciers and protalus ramparts are two of the main morphological features of the Central Andes in the Province of San Juan, Argentina. This sector of the Andes has one of the highest densities of occurrence of rock glaciers in the world. In this region, which has semiarid climatic characteristics, the presence of these landforms is important due to their solid state water reserves and as water resource regulators. Their occurrence is vital in several basins where, due to the lack of glaciers, debris-covered glaciers and perennial snow patches, rock glaciers are the only solid-state water reserves. However, the topo-climatic factors controlling the development and evolution of rock glaciers and protalus ramparts are not well known, which prevents an integrated management of the basins. This contribution, first, analyzes the spatial distribution of active and inactive rock glaciers and of protalus ramparts with respect to different topographic variables in the upper section of the Santa Cruz River basin. In total, 375 landforms have been inventoried, out of which 83 are active rock glaciers, 81 are inactive and 211 are protalus ramparts, covering an area of 13.09 km2 (3.03 % of the total area). The active periglacial environment belt occurs between 4000 and 4200 m a.s.l. and slopes with a southwesterly aspect have a greater development of active rock glaciers. Secondly, the evolution of such landforms is addressed. While the development of protalus ramparts does not seem to be mainly controlled by the topographic variables analyzed, the evolution of protalus ramparts in rock glaciers would be mainly controlled by elevation and aspect. Besides, there are local topo-climatic factors that contribute to the development of such landforms.

Hallazgos cerámicos y su cronología en el área comprendida entre el extremo sur del macizo del deseado y la cuenca del Río Santa Cruz (Patagonia Sur, Argentina)

Fil: Cirigliano, Natalia Andrea. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina

Rockslides and rock avalanches in the Central Andes of Argentina and their possible association with permafrost degradation

AbstractThe identification of hazardous slopes with degrading permafrost is a key task in the mountain periglacial environment. If rockslides have previously been preconditioned by rock wall permafrost, similar events may be triggered from present unstable rock walls. An inventory of rockslides and rock avalanches in the austral part of the Santa Cruz river basin (31°40′–31°50′S, 70°30′–70°10’W), San Juan, Argentina, was made. The study area comprises a surface of approximately 432 km2 (50% above 3,500 m asl); 15 rockslides, 12 complex rockslides evolving to rock avalanches and 19 rock avalanches were identified. The deposits were analyzed with remote sensory imagery and during fieldwork in order to study processes under permafrost degradation caused by global warming. Rock sampling procedures and laboratory rock‐resistivity testing were also carried out. We characterized the detachment scars and deposits for two rockslides. Two different mechanisms were identified. In one rockslide, shallow active layer detachment was favored by shear‐displacement along pre‐existing joints, as a result of short‐term periods of climate warming. In the other, long‐term permafrost degradation favored a deeper failure process. The studied landslide processes could not be explained by permafrost degradation alone. Faults, the geometric arrangement of their structural elements and seismic activity may contribute to trigger these phenomena. It is expected that the magnitude and frequency of rockslide hazards will increase during the 21st century.

Ecological requirements and relative impact of threats affecting the Austral RailRallus antarcticus: monitoring methodology considerations for an imperative conservation status re-evaluation

SummarySince its rediscovery in 1998, two major threats have been mentioned for the enigmatic Austral RailRallus antarcticus: cattle management by burning grass and rushes and predation by American minkNeovison vison. Added to the lack of a protocol to monitor this secretive bird, ever-growing threats make it necessary to study its global situation in depth to take accurate and urgent management decisions. We firstly studied how threats to the Austral Rail currently impact their occupancy and relative density (RD) at a wetland scale and habitat features associated with its presence at survey site scale inside wetlands in Santa Cruz province, Argentina. We additionally developed a monitoring protocol to detect the rail effectively and promptly by studying responses to playback with two different vocalisations at different times of the day and season. Both threats evaluated were negatively related to occupancy and RD of the Austral Rail, especially mink presence appearing to have an additive effect. We propose American mink control as crucial for Austral Rail conservation, while it would also be necessary to conserve a portion of wetlands exempt from burning and cattle presence. At survey sites, its presence was positively related with c.1–1.5 m tall rushes, whilst rails avoided low- density rush areas that resulted after management of rushes with fire to create pasture. To detect rails, both vocalisations can be confidently used at any time of the day and season. The poor knowledge about species ecology, mismanagement of vegetation in wetlands, expansion of American mink in Patagonia, construction on two dams in the Santa Cruz river basin, added to the already modified humidity conditions due to global climate change, force us to suggest that the Austral Rail should be considered as globally ‘Endangered’ (EN), to ensure the consideration of the species in management decisions.

Water allocation and management along the Santa Cruz border region

Abstract Water management along the transboundary Santa Cruz River basin overlapping Arizona and Mexico, faces a host of physical, economic and institutional challenges. The situation is worsened by a failure of bilateral strategies to achieve an administratively feasible solution to these problems. The current study, utilizing data from the Santa Cruz Active Management Area in Arizona and from Nogales in Sonora, Mexico, builds an integrated framework of intersectoral water allocation within each region, incorporating relevant economic, physical and institutional constraints. Results from the baseline model and from three scenarios representing population growth and water scarcity, suggest higher optimal water use and net benefits in the urban residential sector for both regions. The outcomes conform to previous studies emphasizing the need for better water supply infrastructure and reuse of treated wastewater to counter demand from a growing population and climate induced water shortages in the region.

The value and skill of seasonal forecasts for water resources management in the Upper Santa Cruz River basin, southern Arizona

The potential for adaptive water resources management based on seasonal forecasts in the arid Upper Santa Cruz River, southern Arizona was examined. We demonstrated that seasonal forecasts can be used to optimize water resources management and increase supply. Using El Nino Southern Oscillation (ENSO) to forecast the wet seasons (winter and summer) can provide information during extreme ENSO. We found that ENSO is a better indicator for dryer than normal winters during La Nina and dryer than normal summers during El Nino. As in indicator of wetter than normal seasons (i.e. El Nino and La Nina in the winter and summer, respectively) ENSO is often not a consistent predictor and moreover, on several occasions the wetter than normal rainfall did not yield above normal seasonal flows. We also examined the seasonal precipitation forecasts for the region from the Climate Forecast System (CFS). The CFS showed reasonable predictive skill for the winter that extends up to four months lead-time. The only CFS skill for forecasting summer rainfall was observed for predicting above normal rainfall in July with one-month lead-time. Seasonal forecasts can substantially improve water resources management but currently requires considerations of large uncertainties in the operationally available forecasts.

Opening the Black Box: Using a Hydrological Model to Link Stakeholder Engagement with Groundwater Management

Stakeholder participation is a foundation of good water governance. Good groundwater governance typically involves the co-production of knowledge about the groundwater system. Models provide a vehicle for producing this knowledge, as well as a “boundary object” around which scientists and stakeholders can convene the co-production process. Through co-production, stakeholders and scientific experts can engage in exchanges that create system knowledge not otherwise achievable. The process involves one-way transfer of information, active two-way conversations, and integration of multiple kinds of knowledge into shared understanding. In the Upper Santa Cruz River basin in Arizona, USA, the University of Arizona Water Resources Research Center (WRRC) convened a project aimed at providing scientific underpinnings for groundwater planning and management. This project, entitled Groundwater, Climate, and Stakeholder Engagement, serves as a case study employing the first two stages of knowledge co-production using a hydrological model. Through an iterative process that included two-way communication, stakeholders provided critical input to hydrologic modeling analyses. Acting as a bridging organization, the WRRC facilitated a co-production process, involving location-specific and transferability workshops, which resulted in new knowledge and capacity for applying the model to novel problems.

The invasion of an Atlantic Ocean river basin in Patagonia by Chinook salmon: new insights from SNPs

Chinook salmon spawning was first reported in the 1980s in the Caterina River tributary of the Santa Cruz River basin of Patagonia, which drains into the Atlantic Ocean. A naturalized population now persists and its source has been debated. Chinook salmon from California populations was directly released into the Santa Cruz River in the early twentieth century, but ocean ranching experiments on the Pacific coast of Patagonia (Chile) also released Chinook salmon of lower Columbia River origin (University of Washington hatchery stock) in the late twentieth century. We used genetic stock identification with single nucleotide polymorphisms to explore the origin of this Chinook salmon population. The genotypes of salmon that invaded the Santa Cruz River were compared with those derived from 69 known populations from the Northern Hemisphere. Chinook Salmon of the Santa Cruz River were found to be most similar to those from the lower Columbia River. This supports the hypothesis that the Santa Cruz River population was founded from the ocean ranching in southern Chile and the river was invaded by fish straying from Pacific coast basins. Moreover, we find that the life history of these naturalized fish, as inferred from scale analysis, was similar to that of the progenitor stock. We suggest that the successful invasion of the Caterina River in Patagonia by Chinook salmon was aided by pre-adaptations of some of the stocks used in the ocean ranching experiments to conditions in the new environment, rather than a post-colonization adaptation.

Raw material circulation at broad scales in southern Patagonia (Argentina): The cases of the Chico and Santa Cruz River basins

The purpose of this paper is to begin to understand human mobility through rock transport at different times in two areas with different environmental characteristics: the Southern Deseado Massif and the basaltic canyons north of the Santa Cruz River. We focus on obsidian, which has a clear geochemical signature and an uneven distribution. Additionally, we use macroscopic information on siliceous rocks, which at present have only been identified in northern areas, although they may also be recovered randomly and in low frequencies in southern ones.During the initial peopling of the Southern Deseado Massif (ca. 10,800 BP), inhabitants were transporting black obsidian as well as translucent chalcedony, probably as part of the individual gear. During the Late Holocene, the number of obsidian artifacts decreased in the Southern Deseado Massif, related to a better knowledge of the high-quality local lithic resources and/or to the existence of higher population densities. Obsidian artifacts are more abundant in the northern Santa Cruz River basin than in the southern Deseado Massif, suggesting the existence of a relationship with areas located to the northwest, close to the obsidian source, as other lines of evidence suggest. In addition, the presence in the basaltic canyons of artifacts made from high-quality siliceous rocks, more abundant and predictable in northern areas, could also be the result of human movements following a north-south direction.

Genetic and phenotypic variation among Galaxias maculatus populations reflects contrasting landscape effects between northern and southern Patagonia

Summary1. Understanding the influence of landscape characteristics on genetic and phenotypic intraspecific variability can yield insights into how evolutionary processes work as well as provide essential information for the conservation of biodiversity.2. Our aim was to compare the genetic structure and phenotypic variation among Galaxias maculatus populations inhabiting two Atlantic Ocean river basins in Patagonia in relation to historical and contemporary landscape characteristics associated with latitude.3. Population genetic analysis (based on eight microsatellite loci, 505 individuals) indicates that genetic structure is more pronounced in the Río Negro basin (RN) at 39–41°S (10 localities) than in the southernmost Santa Cruz River basin (SCR) at 49–50°S (seven localities). Spatial autocorrelation analysis showed different effects of geographic distance in shaping population differentiation patterns in the two basins.4. While in northern Patagonia, fragmented populations could have survived the severity of Quaternary climate cycles, at higher latitudes G. maculatus populations were probably extirpated by extensive ice sheets. Extant populations in the upper reaches of the southernmost basin probably originated from refugia close to the Atlantic Ocean.5. Based on otolith microchemistry, we have documented facultative diadromy for the first time for the species in the SCR basin, while no evidence of migration to the sea was found in individuals from the RN basin. Vertebral number increased with latitude, and within the SCR basin, the higher counts are possibly associated with a migratory life style.

Estudo da vegetação como subsídios para propostas de recuperação das nascentes da bacia hidrográfica do ribeirão Santa Cruz, Lavras, MG

Os objetivos deste estudo foram conhecer a composição florística do estrato arbóreo e regenerativo das nascentes da bacia hidrográfica do ribeirão Santa Cruz e selecionar espécies para serem utilizadas na revegetação das nascentes degradadas e perturbadas da bacia. Os levantamentos florístico e estrutural foram realizados em 12 nascentes. Para a comparação do perfil florístico entre as nascentes, empregaram-se a análise de correspondência retificada (DCA) e a análise de agrupamento de Cluster. A vegetação do estrato arbóreo apresentou maior diversidade nas nascentes perturbadas em relação às degradadas, assim como nas nascentes pontuais em relação às difusas. A similaridade florística do estrato regenerativo entre as nascentes de mesma categoria permitiu inferir que se devem utilizar espécies preferenciais em cada estado de conservação (perturbado ou degradado) e condições do ambiente (solo úmido ou bem drenado) nos programas de recuperação das áreas de preservação permanente das nascentes da bacia hidrográfica do ribeirão Santa Cruz.

Basic criteria for a sustainable water management at the U.S.-México border: the case of ambos Nogales

This article aims to analyze some basic criteria for a sustainable use of water in an international watershed shared by Mexico and the United States. The study area comprises the region of Ambos Nogales, which is located inside the Upper Santa Cruz River Basin. This portion of the watershed represents the main ecosystem and the main source of water for urban and rural populations located in this region. Following criteria of sustainability the authors revise and adapt to the case of Ambos Nogales, a set of guidelines proposed by the Pacific Institute for Studies in Development, Environment, and Security. These guidelines include the following elements: basic water requirements needed to maintain quality of life in the population and the health of ecosystems; water quality that meets certain minimum standards; human actions and their impact on long-term renewability of freshwater stocks and flows; collection of data concerning water resources, use and quality of water; institutional mechanisms to prevent and resolve conflicts; and a democratic process of water-planning and decision-making. These twin cities have a long history of cooperation and conflict linked to water resources, which makes available enough information to create a diagnostic about the water management inside a binational arena, and allowing to explore possibilities for a better water resources management under a sustainable regime and from an international perspective. Keywords: Sustainability, binational water management, ambos Nogales region.

Three New Pupfish Species, Cyprinodon (Teleostei, Cyprinodontidae), from Chihuahua, México, and Arizona, USA

Three new species of Cyprinodon (Teleostei, Cyprinodontidae) are described, each long recognized as distinct. Cyprinodon pisteri occupies a variety of systems and habitats in the Lago de Guzmán complex basin in northern Chihuahua, México. It is distinguished by its dusky to black dorsal fin and narrow or inconspicuous terminal bar on the caudal fin in mature males. Cyprinodon albivelis is distributed largely in relatively high elevation sites in the upper Río Papígochic (Río Yaqui basin), with a single occurrence in the Río Santa María basin. It is distinguished most notably by the striking white dorsal and anal fins displayed by breeding males. Cyprinodon arcuatus is a distinctive form most similar to Cyprinodon macularius and Cyprinodon eremus and is restricted to the upper Santa Cruz River basin in southern Arizona and Northern Sonora. It is distinguished in having a sharply convex dorsal body profile form the head to dorsal fin origin and in lacking yellow or orange pigmentation on the part of nuptial males. Extensive and careless human alterations to this system drove C. arcuatus to extinction, with the last natural population perishing in Monkey Spring (Santa Cruz County, Arizona), devoured by introduced sport fish. Where appropriate, biogeography and conservation issues are discussed with regard to these species.

Multiobjective Approaches to River Basin Planning

The impact of alternative water development strategies upon an urbanized area in the semi‐arid Southwest is examined within a multiobjective context. The main stem of the Santa Cruz River Basin is taken as a case study. The conflicting nature of wateraelated issues necessitates a broader approach to river basin planning than the frequently used single‐objective context in which each objective, such as flood protection, ground‐water recharges, and water supply, is considered in isolation of the other objectives. In reformulating the problem, a multiobjective approach is taken. Solutions are obtained from four multiobjective techniques briefly described and applicable to the selection among discrete alternatives: ELECTRE, compromise programming, cooperative game theory, and multiattribute utility theory. Review and comparison of these solutions as well as sensitivity analysis on each is provided. The difference between results may be explained by the manner in which the techniques use discordance. All four ...

Elastic expansion of the lithosphere caused by groundwater withdrawal in south-central Arizona

Relative crustal uplift observed from 1948–1949 to 1967 in the Lower Santa Cruz River Basin in south-central Arizona is attributed at least in part to elastic expansion of the lithosphere induced by the removal, and subsequent loss by evapo transpiration, of 4.35 × 10 13 kg of groundwater from alluvium. The area of unloading is approximately 8070 km 2 . Uplift, relative to an apparently stable area west of the unloaded area, was observed in two areas near Casa Grande and Florence where crystalline bedrock is either close to the land surface or crops out through alluvium from which groundwater was withdrawn. The magnitudes of uplift were approximately 6.3 and 7.5 cm respectively. The observations are based on first-order leveling. The observations are significant at three standard deviations for random surveying errors, and are not believed to be affected by systematic errors. However, the 7.5-cm uplift observed at Florence may be from 1 to 2 cm in excess of the actual uplift because of the possibility of subsidence of a tie point due to groundwater pumping during the leveling in 1948–1949. Uplift is attributed to groundwater withdrawal on three bases. First, the observed uplift is consistent with a theoretical evaluation of elastic expansion based on linear elasticity theory. For the observed distribution of unloading and uplift and a Poisson's ratio of 0.25, a Young's modulus for the lithosphere of approximately 0.68 Mbar is implied. This value is comparable to values of the lithosphere reported elsewhere. Second, the magnitude of uplift compares favorably with the magnitude of elastic depression caused by the formation of Lake Mead, Arizona—Nevada, 430 km northwest of the study area, when allowance is made for the different magnitudes and areal distributions of surface (un)loading. And third, in the area near Casa Grande, a reversal in the sense of bedrock displacement form subsidence of tectonic origin to uplift approximately coincided with the beginning of large groundwater overdraft. The uplift from 1948 to 1967 near Casa Grande was preceded from 1905 to 1948 by 7–8 cm of tectonic subsidence; no precise data for the area near Florence are available before 1948.

Alternatives for managing a finite groundwater supply in an arid region

Like many urban communities in arid regions, Tucson, Arizona, is totally dependent on underlying and nearby aquifers for its water supply. Tucson is sited in southern Arizona in the Santa Cruz River Basin. The Avra Valley Basin is just west of the City, over the north–south trending Tucson Mountains. Water is withdrawn from both basins, but mostly from the Santa Cruz River Basin. Combined urban, agricultural, industrial and mining groundwater withdrawal from the Santa Cruz River Basin alone exceeds natural aquifer replenishment by 5676 hectare-meters (ha.m) annually. This problem is discussed. Four ameliorative water management alternatives are presented singly and in combination with one another. These alternatives are importing Colorado River water, exchanging treated effluent with mining and agricultural interests for groundwater, interbasin water transfer, and retiring farmlands for groundwater rights. These management philosophies are applicable to most economically emergent urban areas in arid and semiarid regions.