The University of Arizona
School of Natural Resources and the Environment
The Sonoran Desert and Apache Highlands ecoregions of North America are areas of exceptionally high plant and vertebrate biodiversity. However, much of the vertebrate biodiversity is supported by only a few vegetation types with limited... more
The Sonoran Desert and Apache Highlands ecoregions of North America are areas of exceptionally high plant and vertebrate biodiversity. However, much of the vertebrate biodiversity is supported by only a few vegetation types with limited distributions, some of which are increasingly threatened by changing land uses. We assessed the impacts of two future urban growth scenarios on biodiversity in a binational watershed in Arizona, USA and Sonora, Mexico. We quantified and mapped terrestrial vertebrate species richness using Wildlife Habitat Relation models and validated the results with data from National Park Service (NPS) biological inventories. Future urban growth, based on historical trends, was projected to the year 2050 for (1) a ‘Current Trends’ (CT) scenario and (2) a ‘Megalopolis’ (MEGA) scenario that represented a transnational growth corridor with open-space conservation attributes. Based on CT, 45% of existing riparian woodland (267 of 451species) and 34% of semi-desert grasslands (215 of 451 species) will be lost, whereas in the MEGA scenario, these types would decline by 44% and 24%, respectively. Outcomes of the two models suggest a trade-off at the taxonomic class level: CT would reduce and fragment mammal and herpetofauna habitat, while MEGA would result in loss of avian-rich riparian habitat.
- by Kenneth Boykin and +1
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In the borderland region of the desert southwest, human health and the ecosystems upon which humans rely largely depend on the quality, quantity, and distribution of water resources. In the Santa Cruz River Watershed (SCW), located in the... more
In the borderland region of the desert southwest, human health and the ecosystems upon which humans rely largely depend on the quality, quantity, and distribution of water resources. In the Santa Cruz River Watershed (SCW), located in the Arizona and Sonora, Mexico border region, surface water is scarce and unreliable, and, during much of the year, is composed of effluent from the local wastewater treatment plant. This makes groundwater the preferred and, consequently, primary source for industrial, agricultural, and domestic use. USGS scientists are using an integrative approach, incorporating the expertise of the Geography, Water, Biology, and Geology disciplines to identify risks to water resources in the SCW, and the potential for impacts to riparian ecosystems and ultimately, human health. This includes tracking organic and inorganic contaminants and their effects from sources to sinks in sediment, water, plants, and animals. Existing ground- and surface-water models will be used and modified to assess contaminant and sediment transport. Water quality, sediment, aquatic macro invertebrates, aquatic plants (macrophytes), algae, riparian grasses, fish, and birds will be sampled at five locations along the Santa Cruz River. Field sampling data will be obtained at sites that coincide with historical sampling programs. Site locations include (i.) the Santa Cruz River headwaters (which should be unaffected by downstream contaminant sources), (ii.) a tributary routed through an abandoned mining district, (iii.) a binational tributary that flows though highly urbanized areas, (iv.) effluent from the local wastewater treatment plant, and (v.) the downstream confluence of the first four sources. The Soil and Water Assessment Tool (SWAT) model will be used in combination with field data to identify key sources of contaminants, contributing areas, and transport modes to track their movement to surface waters. These data will be used together to test relationships between sediment and hydrologic parameters, for the purpose of determining functional links. Further, it is planned that estimates of runoff and evapotranspiration resulting from the SWAT model simulations will be used to modify boundary conditions in the groundwater flow model to improve understanding of the effects of human activities on aquifer dynamics and contaminant transport. The SWAT model will then be used to identify critical sub-watersheds where implementing management practices could be most effective to abate pollution. An overview of our study design and preliminary results will be presented.
In the borderland region of the desert southwest, human health and the ecosystems upon which humans rely largely depend on the quality, quantity, and distribution of water resources. In the Santa Cruz River Watershed (SCW), located in the... more
In the borderland region of the desert southwest, human health and the ecosystems upon which humans rely largely depend on the quality, quantity, and distribution of water resources. In the Santa Cruz River Watershed (SCW), located in the Arizona and Sonora, Mexico border region, surface water is scarce and unreliable, and, during much of the year, is composed of effluent from the local wastewater treatment plant. This makes groundwater the preferred and, consequently, primary source for industrial, agricultural, and domestic use. USGS scientists are using an integrative approach, incorporating the expertise of the Geography, Water, Biology, and Geology disciplines to identify risks to water resources in the SCW, and the potential for impacts to riparian ecosystems and ultimately, human health. This includes tracking organic and inorganic contaminants and their effects from sources to sinks in sediment, water, plants, and animals. Existing ground- and surface-water models will be us...
Between 2001 and 2009, the Borderlands Jaguar Detection Project deployed 174 camera traps in the mountains of southern Arizona to record jaguar activity. In addition to jaguars, the motion-activated cameras, placed along known wildlife... more
Between 2001 and 2009, the Borderlands Jaguar Detection Project deployed 174 camera traps in the mountains of southern Arizona to record jaguar activity. In addition to jaguars, the motion-activated cameras, placed along known wildlife travel routes, recorded occurrences of ~ 20 other animal species. We examined temporal relationships of white-tailed deer (Odocoileus virginianus) and javelina (Pecari tajacu) to landscape phenology (as measured by monthly Normalized Difference Vegetation Index data) and the timing of wildfire (Alambre Fire of 2007). Mixed model analyses suggest that temporal dynamics of these two species were related to vegetation phenology and natural disturbance in the Sky Island region, information important for wildlife managers faced with uncertainty regarding changing climate and disturbance regimes.
- by Cynthia Wallace and +1
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Between 2001 and 2009, the Borderlands Jaguar Detection Project deployed 174 camera traps in the mountains of southern Arizona to record jaguar activity. In addition to jaguars, the motion-activated cameras, placed along known wildlife... more
Between 2001 and 2009, the Borderlands Jaguar Detection Project deployed 174 camera traps in the mountains of southern Arizona to record jaguar activity. In addition to jaguars, the motion-activated cameras, placed along known wildlife travel routes, recorded occurrences of ~ 20 other animal species. We examined temporal relationships of white-tailed deer (Odocoileus virginianus) and javelina (Pecari tajacu) to landscape phenology (as measured by monthly Normalized Difference Vegetation Index data) and the timing of wildfire (Alambre Fire of 2007). Mixed model analyses suggest that temporal dynamics of these two species were related to vegetation phenology and natural disturbance in the Sky Island region, information important for wildlife managers faced with uncertainty regarding changing climate and disturbance regimes.
- by Joel Sankey and +1
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ABSTRACT Flow at the outlet does not sufficiently represent underlying processes for an entire watershed in semiarid climates, where the flow from much of the catchment may not reach the outlet most of the time. For modeling these... more
ABSTRACT Flow at the outlet does not sufficiently represent underlying processes for an entire watershed in semiarid climates, where the flow from much of the catchment may not reach the outlet most of the time. For modeling these watersheds, calibration to discharge is required not only at the watershed outlet but also in various locations within the watershed to best capture real watershed conditions. The objective of this study is to develop a reliable model for the Santa Cruz watershed to analyze the impact of land use and climate change on hydrology and water quality in this semiarid basin. The semiarid Santa Cruz watershed (Lat:34oN and Long:-111oW) is 9,000 km2 and located in southern Arizona, United States (85%) and northern Sonora, Mexico (15%). In this study, the Soil and Water Assessment Tool (SWAT) was used to calibrate the flow at seven monitoring stations to increase the reliability of flow and therefore water quality predictions for the entire basin. The model performance was evaluated based on observed hydrograph, Mass balance error (MBE) coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE). We began the calibration by identifying the most sensitive parameters using the Latin hypercube global sensitivity approach, identifying that the baseflow recession coefficient, the effective hydraulic conductivity in main channel (transmission loss), the curve number and the soil evaporation compensation factor as the most sensitive parameters. Next, we manually calibrated the model at the USGS gage near the outlet by modifying these parameters. Although the model was validated well at the outlet, the model was not able to validate the flow at other USGS gages inside the watershed. Thus we calibrated the model in sequential order from upstream to downstream gages by further adjusting these parameters. A significant amount of water is lost through transmission loss in our modeling of the Santa Cruz. In SWAT, by default the loss from the streambed is set to zero and so needs to be calibrated to simulate transmission losses. The model calibrated well for all 7 stream gages based on model evaluation parameters. The model was validated for 5 stations but suffered from uncertainty of precipitation data for the other 2 stations, the model predicted high flow when there was low/no flow in the observed data and vice versa. Sufficient precipitation gages are required to reduce the effect of uncertainty in precipitation data and to improve model calibration and validation in semiarid watersheds. While the model calibrated only at the outlet was not able to validate the flow at other monitoring gages inside the watershed, further fine calibration using data from those gaging stations much improved the validation. This study thus emphasizes the importance of multi-gage calibration.
- by Laura Norman
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ABSTRACT The Sonoran Desert and Apache Highlands ecoregions of North America are areas of exceptionally high plant and vertebrate biodiversity. However, much of the vertebrate biodiversity is supported by only a few vegetation types with... more
ABSTRACT The Sonoran Desert and Apache Highlands ecoregions of North America are areas of exceptionally high plant and vertebrate biodiversity. However, much of the vertebrate biodiversity is supported by only a few vegetation types with limited distributions, some of which are increasingly threatened by changing land uses.We assessed the impacts of two future urban growth scenarios on biodiversity in a binational watershed in Arizona, USA and Sonora, Mexico. We quantified and mapped terrestrial vertebrate species richness using Wildlife Habitat Relation models and validated the results with data from National Park Service (NPS) biological inventories. Future urban growth, based on historical trends, was projected to the year 2050 for (1) a ‘Current Trends’ (CT) scenario and (2) a ‘Megalopolis’ (MEGA) scenario that represented a transnational growth corridor with open-space conservation attributes. Based on CT, 45% of existing riparian woodland (267 of 451species) and 34% of semi-desert grasslands (215 of 451 species) will be lost, whereas in the MEGA scenario, these types would decline by 44% and 24%, respectively. Outcomes of the two models suggest a trade-off at the taxonomic class level: CT would reduce and fragment mammal and herpetofauna habitat, while MEGA would result in loss of avian-rich riparian habitat.