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Groundwater is the most ubiquitous source of liquid freshwater globally, yet its role in supporting diverse ecosystems is rarely acknowledged1,2. However, the location and extent of groundwater-dependent ecosystems (GDEs) are unknown in many geographies, and protection measures are lacking1,3. Here, we map GDEs at high-resolution (roughly 30 m) and find them present on more than one-third of global drylands analysed, including important global biodiversity hotspots4. GDEs are more extensive and contiguous in landscapes dominated by pastoralism with lower rates of groundwater depletion, suggesting that many GDEs are likely to have already been lost due to water and land use practices. Nevertheless, 53% of GDEs exist within regions showing declining groundwater trends, which highlights the urgent need to protect GDEs from the threat of groundwater depletion. However, we found that only 21% of GDEs exist on protected lands or in jurisdictions with sustainable groundwater management policies, invoking a call to action to protect these vital ecosystems. Furthermore, we examine the linkage of GDEs with cultural and socio-economic factors in the Greater Sahel region, where GDEs play an essential role in supporting biodiversity and rural livelihoods, to explore other means for protection of GDEs in politically unstable regions. Our GDE map provides critical information for prioritizing and developing policies and protection mechanisms across various local, regional or international scales to safeguard these important ecosystems and the societies dependent on them.

To examine the impact of a hybrid-flipped model utilising active learning techniques, the researchers inverted one section of an undergraduate fluid mechanics course, reduced seat time, and engaged in active learning sessions in the classroom. We compared this model to the traditional section on four performance measures. We employed a propensity score method entailing a two-stage regression analysis that considered eight covariates to address the potential bias of treatment selection. First, we estimated the probability score based on the eight covariates, and second, we used the inverse of the probability score as a regression weight on the performance of learners who did not select into the hybrid course. Results suggest that enrolment in the hybrid-flipped section had a marginally significant negative impact on the total course score and a significant negative impact on homework performance, possibly because of poor video usage by the hybrid-flipped learners. Suggested considerations are also discussed.

In the new ecohydrology major at the University of Nevada, Reno (UNR), students learn about the relationships between hydrologic mechanisms and ecological patterns and processes in watersheds and aquatic systems. The curriculum provides students with the option of meeting the requirements for federal positions as a hydrologist (GS 1315) and is designed to provide physical scientists with a strong secondary emphasis in ecology. This paper describes the development of this novel undergraduate degree in ecohydrology and some of the challenges involved in its development and implementation. (Contains 2 tables.)

This paper presents results from a July 2005 workshop and course aimed at developing an interdisciplinary course on modeling aquatic ecosystems that will provide the next generation of practitioners with critical skills for which formal training is presently lacking. Five different course models were evaluated: (1) fundamentals/general principles of interdisciplinary modeling; (2) modular course; (3) survey of various interdisciplinary models; (4) seminar series of case studies; and (5) the art of modeling. Options 1 and 2 were most popular among workshop participants, while option 4 was the least popular. (Contains 2 tables and 4 figures.) [Additional funding for this project was provided by Nevada EPSCoR.]

To improve water quality and enhance habitat for fish and wildlife, a restoration project was initiated on the Truckee River at McCarran Ranch, Nevada. A water quality model was parameterized using Hydrologic Simulation Program-Fortran to represent the river's restored characteristics to test the hypothesis that restoration of the Truckee River improves the river's nitrogen (N) assimilative capacity. This model was calibrated to data collected postrestoration, and modified to represent prerestoration conditions and additional potential restoration scenarios. Restoration scenarios involved changes in benthic algae habitat that affect in-stream N and dissolved oxygen (DO) concentrations. Assimilative capacity was assessed by comparing N loads for restoration scenarios that would result in meeting or exceeding prerestoration minimum DO concentration simulated under 2004 conditions. Modeled algal dynamics affected model results, which indicated that there is a certain amount of increased habitat that is beneficial to N uptake while maintaining acceptable DO concentrations, and that the amount and species of N assimilated depends on the type and extent of restoration. However, evaluation of the modeling approach highlights some critical model limitations. Thus, interpretation of model results should be used with caution. CE Database subject headings: Nitrogen; Rivers; Restoration; Water quality; Simulation models; Vegetation.

An integrated curriculum, which draws material from different areas to teach students about design and problem-solving, offers civil engineering educators an option for accommodating new topics without increasing the number of courses. Freshman engineering and the senior capstone course are two examples of integrated courses, and the writers present a 5-year perspective on an approach that extends the concept of integration to six additional courses, comprised of an 8-course, integrated civil engineering core curriculum. Drawing on their combined experiences with the courses and assessment in a review by the Accreditation Board for Engineering and Technology, the writers conclude that the curriculum offers a useful vehicle by which to add material to the 4-year program without increasing the number of credit hours, and offers flexible courses to meet goals of professional groups. The paper describes lessons learned, challenges that remain, and current approaches to improvement. CE Database subject headings: Computer aided design; Computer software; Control systems; Engineering education; Curricula; Geographic information systems; Information technology (IT); Intelligent transportation systems; System engineering.

Recently, the United States Bureau of Reclamation agreed to increase spring releases from Upper Colorado River Basin reservoirs to create a more natural flow regime in the lower Gunnison River and Upper Colorado River. Fishery managers have expressed concern that new operations could change reservoir conditions and jeopardize popular and economically important reservoir sport fisheries. This study attempts to predict how one aspect of reservoir conditions, thermal structure, might respond to new dam operations at Blue Mesa Reservoir aimed at addressing downstream ecological concerns. A one-dimensional thermal model (CE-THERM) is applied to simulating thermal effects of 'traditional' and proposed 'new' dam operation scenarios. To evaluate the relative importance of climate and dam operations a sensitivity analysis of hydrologic (i.e., inflows and starting reservoir elevation) and meteorologic (i.e., air temperature, cloud cover, and dew point temperature) inputs was conducted along with an 'extreme' dam operation scenario. Results indicate that reservoir managers at Blue Mesa Reservoir have considerable latitude for new operations without negative thermal consequences. The natural variability of climate and hydrology appear to exert stronger control over reservoir thermal structure than reservoir operations at Blue Mesa. CE Database subject headings: Dams; Reservoirs; Simulation models; Climatic changes; Colorado River; Thermal factors.

A water-quality-data-management survey of 200 water-quality agencies in the United States was conducted in 1991. The survey solicited information from each agency regarding the methods of data storage and management used, the type of activities involving water-quality data that were performed by the agency, the types of water-quality data used, the sources of the data used, and interagency activities involving water-quality data. The survey results indicated that there is a high demand for data sharing, since almost all agencies responded that their water-quality data are used by others. There is also a potential for data sharing because of the predominant use of ARC/INFO geographic information systems and dBASE database software. Future software development for water-quality data applications should use this potential and be appropriate for IBM-compatible personal computers.

The economy of the Khorezm Province in Uzbekistan relies on the large-scale agricultural production of cotton. To sustain their staple crop, water from the Amu Darya is diverted for irrigation through canal systems constructed during the early to mid-twentieth century when this region was part of the Soviet Union. These diversions severely reduce river flow to the Aral Sea. The Province has >400 small shallow (<3 m deep) lakes that may have originated because of this intensive irrigation. Sediment cores were collected from 12 lakes to elucidate their origin because this knowledge is critical to understanding water use in Khorezm. Core chronological data indicate that the majority of the lakes investigated are less than 150 years old, which supports a recent origin of the lakes. The thickness of lacustrine sediments in the cores analyzed ranged from 20 to 60 cm in all but two of the lakes, indicating a relatively slow sedimentation rate and a relatively short-term history for the lakes. Hydrologic changes in the lakes are evident from loss on ignition and pollen analyses of a subset of the lake cores. The data indicate that the lakes have transitioned from a dry, saline, arid landscape during pre-lake conditions (low organic carbon content) and low pollen concentrations (in the basal sediments) to the current freshwater lakes (high organic content), with abundant freshwater pollen taxa over the last 50-70 years. Sediments at the base of the cores contain pollen taxa dominated by Chenopodiaceae and Tamarix, indicating that the vegetation growing nearby was tolerant to arid saline conditions. The near surface sediments of the cores are dominated by Typha/Sparganium, which indicate freshwater conditions. Increases in pollen of weeds and crop plants indicate an intensification of agricultural activities since the 1950s in the watersheds of the lakes analyzed. Pesticide profiles of DDT (dichlorodiphenyltrichloroethane) and its degradates and γ-HCH (gamma-hexachlorocyclohexane), which were used during the Soviet era, show peak concentrations in the top 10 cm of some of the cores, where estimated ages of the sediments (1950-1990) are associated with peak pesticide use during the Soviet era. These data indicate that the lakes are relatively young (mostly <150 years old) and that without irrigation and canal inputs from the Amu Darya, the lakes would not exist as freshwater lakes. [ABSTRACT FROM AUTHOR]