Integrating Multiscale Observations of U.S. Waters (2008) / Chapter Skim
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Pages 78-142
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From page 78... ...
A network of 1,195 active surface water stage gauges provides surface water stage data for various water bodies. Additionally, the District owns and operates a network of 425 active surface water flow monitoring sites that provide instantaneous and mean daily flow data in 15-minute intervals.
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From page 79... ...
The flow monitoring network is shown in Figure 4-3. The District works closely with the USGS, the USACE, and PREPUBLICATION COPY
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From page 80... ...
The "static" data include the geometric characteristics PREPUBLICATION COPY
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From page 81... ...
Due to the vastness (some 3 million acres) of the Greater Everglades, including the surrounding agricultural and urban environments, fixed monitoring stations (e.g., stage gages, PREPUBLICATION COPY
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From page 82... ...
, vegetation and food webs that support wading birds and tree island communities, changes in topography, and the nesting and feeding activities of alligators and various species of wading birds. The Florida Everglades are ripe for integration of embedded sensor networks for hydrological and ecosystem monitoring with the already existing monitoring systems.
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From page 84... ...
, expansion of irrigated agriculture, increased use of fertilizers, and limited irrigation through rainwater harvesting in rain-fed areas. Development of sustainable agriculture in newly converted agricultural areas and remediation of water quality and quantity problems in existing agricultural areas require a thorough understanding of how agriculture impacts water resources and land quality.
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From page 85... ...
Irrigated agriculture generally results in increased recharge from irrigation return flow (I)
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From page 86... ...
In many areas, cultivated lands are being converted to natural ecosystems through unmanaged land abandonment, afforestation for timber production or carbon sequestration, and government policies such as the Conservation Reserve Program in the United States; however, the impacts of many of these land-use changes on water resources are generally not evaluated. Irrigated agriculture is projected to increase by 20 percent by 2030, further stressing scarce water resources (Bruinsma, 2003)
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From page 87... ...
. Although the percentage of land use represented by irrigated agriculture in the southern High Plains is low, irrigation accounts for about 94 percent of groundwater use and has resulted in groundwater-level declines (average 43 m over 10,000 km2 over about 55 yr)
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From page 88... ...
in interplaya settings under natural ecosystems. Pressure heads close to 0 and low chloride concentrations in soil water beneath playas result from focused recharge.
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From page 89... ...
. Conversion of natural ecosystems to rain-fed, cultivated crops has increased recharge to about 25 mm/yr over a 3,200-km2 area (median value; about 5 percent of mean annual precipitation)
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From page 90... ...
. Recharge beneath rain-fed and irrigated agriculture has been estimated at about 10 sites using environmental tracers in the unsaturated zone and groundwater-level fluctuations in the saturated zone (Scanlon et al., 2005; McMahon et al., 2006)
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From page 91... ...
Before natural ecosystems are converted to agriculture, it is important to characterize the stores of salts and nutrients in the vadose zone because increased recharge related to cultivation can mobilize these salts and contaminate underlying aquifers, as seen in Australia (Allison et al., 1990)
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From page 92... ...
However, monitoring can provide process understanding related to impacts of cultivation on water and nutrient cycles. Monitoring ET over different land uses, such as natural ecosystems and rain-fed agriculture, can be used to determine whether reduced ET associated with winter fallow periods in agricultural areas can account for increased recharge beneath rain-fed agriculture.
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From page 93... ...
Estimates of groundwater recharge are needed for all the different land-use settings in the region, which can be partly addressed through unsaturated zone profiles using environmental tracers such as chloride (Scanlon et al., 2005; McMahon et al., 2006)
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From page 94... ...
Monitoring programs that quantify the various components of the water cycle and integrate ground-based and satellite information on precipitation, ET, runoff and groundwater storage, can provide process information to assess controls on land use change impacts on water resources. Sustainable water resource management in semiarid regions, such as the southern High Plains, will require an in-depth understanding of land-use change impacts on water resources and will likely require a shift from irrigation to rainfed agriculture in many areas.
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From page 95... ...
concluded that malaria will likely be on the rise as a result of climate change. However, investigators disagree about the extent of the effect of climate change on the rate and geographical extent of malaria incidence (Hay et al., PREPUBLICATION COPY
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From page 96... ...
, the interactions between the natural environment and the populations of mosquitoes, parasites, and humans. Such a tool will provide a suitable framework for integration of hydrological and PREPUBLICATION COPY
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From page 97... ...
. The design of this network integrates sensors that are traditionally used in hydrology for monitoring rainfall rate and soil moisture level, and in entomology for monitoring mosquito density and larva count, as well as standard meteorological sensors of temperature, humidity and PREPUBLICATION COPY
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From page 99... ...
Key elements to make significant progress in this important research area, as well as other similar areas of multidisciplinary research, would include the following: 1. Design the integrated observations network to suit the specific research problem at hand, instead of using observations that were collected with the objective of addressing a different research problem; for this project, the hydrologic and climatological sampling are being coordinated with the sampling of mosquito populations and health data so that the spatial and temporal sampling strategies will be comparable.
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From page 100... ...
This study demonstrates the importance of establishing consistency in the spatiotemporal resolution and locations of four very distinct types of data -- in this case data related to climatic conditions, hydrologic conditions, mosquito populations, and malaria incidence. These data exist in part, but they come from observations networks that were designed independent of each other.
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From page 101... ...
However, neither differentiates among the potential contributions of airborne and satellite sensors, nor identifies the research and supporting infrastructure needed to fully realize the potential of satellite remote PREPUBLICATION COPY
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From page 102... ...
The spatial scales of interest vary from point-scale for intrinsic measurements like temperature or soil moisture, to plot-scale for measurements like moisture fluxes in the active layer, to catchment scale to relate drainage to topography, to watershed scale for issues of water balance, to Pan-Arctic scales for the global water cycle. An example of an almost integrated Arctic hydrologic observing system would be the sum of the building blocks identified in the AON report.
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From page 104... ...
Embedded Sensor Networks Given the fragility of the active layer and the difficult access, Arctic areas would benefit greatly from the new and emerging sensor technologies described in Chapter 2. Use of in-situ microcosms for measurement of chemical weathering rates has been demonstrated in the Antarctic (Maurice et al., 2002)
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From page 105... ...
. A sensor network or sensor web allows increased spatial sampling with less time for deployment and data return, because the sensors are meant to be easily deployable and widely distributed with continuous data feed to webbased platforms.
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From page 106... ...
Airborne systems, like that in the design study shown in Figure 4-13, could be used to calibrate and validate land surface models of the energy and moisture fluxes that are being developed for the canonical terrains shown in Figure 4-10. Their data would also help disaggregate the inherently low spatial resolution satellite data for the canonical terrain types within the radiometer footprint.
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From page 108... ...
Opportunities range from micro-sensors and embedded sensor networks through airborne and satellite observations. Given the difficulty of access to Arctic sites and the sensitivity of the Arctic ecosystems, there is a pressing need for these technologies.
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From page 109... ...
Complex PREPUBLICATION COPY
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From page 110... ...
As an example, nitrification and denitrification, the microbially mediated transformation of nitrogen promoted by different redox PREPUBLICATION COPY
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From page 111... ...
To date, the collection and synthesis of hydrologic and ecosystem information has not been coordinated as part of a centralized informatics system, as contrasted to the South Florida Water District. A set of monitoring programs in the NRBE funded by state and federal agencies are building important data sets on specific aspects of watershed and estuary ecosystems but requires enhanced observational methods, modeling and institutional support and organization.
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From page 112... ...
grid cells, and are linked to time series of 3 hour and monthly simulated meteorological, energy balance and soil moisture values for the NARR time domain of 1979-2003. Additional information provided by a group of federal and state agencies and universities includes: PREPUBLICATION COPY
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From page 113... ...
soil moisture and temperature are measured at a several sites by the North Carolina State Climate Office (http://www.ncclimate.ncsu.edu/cronos/map)
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From page 114... ...
Groundwater measurements: USGS groundwater measurements are typically limited to one measurement at the time of well completion, concentrated in the Coastal Plain. More intensive groundwater monitoring networks include a site with ~66 wells installed and monitored by the USGS and North Carolina State Department of Water Quality in a CAFO in the Contentnea Creek subwatershed to study transport and transformation of hog waste derived nutrients in complex Coastal Plain groundwater systems (Spruill et al 2004, Tesoriero et al., 2005)
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From page 115... ...
The elements of a hypothetical extended network are summarized in Table 4-1. Readily available instrumentation, as well as emerging and envisioned measurement technologies that we expect PREPUBLICATION COPY
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From page 116... ...
, redox probes chemistry microsensors* through coupled to wireless sensor networks rooting zone Hillslope transects, oversampled in drainage lysimeters below riparian zones rooting zone Groundwater level, Transducer, grab samples, Well clusters in wireless sensor GRACE chemistry nitrate microsensors*
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From page 117... ...
In order to assess the flushing mechanism hypotheses, sampling spatial and temporal frequency in PREPUBLICATION COPY
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From page 118... ...
wireless "intelligent" sensor network design would be designed to increase prior to and following recharge events as indicated by precipitation gauge and radar networks. Sufficient sampling density would be carried out to estimate mean and variance of soil moisture conditions within areas commensurate to coarse resolution satellite sensors (e.g., MODIS TERRA and AQUA/AMSR)
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From page 119... ...
. Characterization of the hyporheic environment in each of these reaches would be carried out to provide details of reach hydraulic and biogeochemical conditions associated with downstream evolution of streamwater chemistry and used to develop relationships with easily PREPUBLICATION COPY
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From page 120... ...
To summarize, the NRBE is currently the site of a comprehensive set of measurement and monitoring efforts of federal, state and local agencies, as well as the several universities in the area. To integrate and coordinate these efforts into a framework to better support the major hydrologic science and management issues, additional activity could include: • Development of an integrated information system that could access information generated by the diverse set of research and management entities and synthesize the information into a framework emphasizing spatiotemporal trends in WCN storage, flux and residence time • Further development and integration of a nested monitoring and measurement system that incorporates in situ sensor networks, are adaptable to spatial and temporal events, PREPUBLICATION COPY
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From page 122... ...
Department of the Interior, 2005) , highlight the need for new water information to enable better decision making for water resources management, and for the myriad of other decisions that are influenced by water.
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From page 123... ...
Hydrologic feedbacks in mountainous regions control the availability of water, influence the distribution of vegetation, dominate biogeochemical fluxes, and contribute to global and regional climate variability. Snow in mountains of the West is the main source of the region's water, with downstream hydrologic processes (e.g., groundwater recharge)
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From page 124... ...
. Three aspects of the mountain water cycle in the Western United States are used to illustrate the needs and opportunities: precipitation and microclimate, snowpack, and soil moisture.
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From page 125... ...
. Distinguishing snowfall from rainfall remains a significant problem in satellite precipitation estimation, with current approaches relying on PREPUBLICATION COPY
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From page 126... ...
probes can be attached cheaply to a microprocessor with radio transceiver and solar battery for wide distribution in a sensor network. For integrated, comprehensive water-balance measurements, at least some of the sensor nodes should be equipped with additional measurement devices such as wind speed and direction measurement; atmospheric moisture sensors, snow, soil moisture and temperature and other sensors.
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From page 127... ...
Other clusters would consist of sensors and sensor networks but not a tall tower. Adapted, with permission, from Conklin et al.
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From page 128... ...
A comprehensive snow-measurement network would blend sparse but detailed, accurate measurements of snow water equivalent, microclimate and other water-balance variables with satellite remote sensing and spatially extensive lower-cost measurements of snow depth and other low-cost sensors. The ground-based system would ideally be composed of low-cost sensors in embedded sensor networks (Figure 4-22)
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From page 130... ...
, plus distance from trees. A number of low- to moderate-cost soil moisture sensors are available that can be incorporated into sensor networks, and new technology is emerging.
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From page 131... ...
Summary Mountain snowpack is the main source of the American West's water resource. However, this resource is particularly vulnerable to ongoing spatial and temporal changes in melt PREPUBLICATION COPY
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From page 132... ...
For these reasons, effective strategies such as the use of embedded sensor network technology would contribute greatly to the progressive use of new data sources and types in the water resources management process and for quantifying their benefits and associated costs. The organization and careful monitoring of prototype demonstration projects with the participation of measurement specialists, scientists (including communication and computer scientists)
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From page 133... ...
Measuring physical, chemical, and biological properties at multiple scales will increase our process-based and predictive understanding and improve management. An excellent example 133 PREPUBLICATION COPY
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From page 134... ...
• Embedded sensor networks -- Embedded sensor networks, consisting of spatially distributed sensor-containing platforms connected to and often controlled by computers, and with the sensors themselves often containing microprocessors, are also being demonstrated. For example, as presented in Chapter 2, wireless but interconnected instrument buoys at remote lakes in Wisconsin have provided frequent measurements of lake quality.
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From page 135... ...
MAJOR CHALLENGES Despite the promising advances enumerated above, there are at least nine major challenges that need to be overcome before the vision for integrated observations described in this report can be brought closer to reality. These relate to: • Developing appropriately scaled sites for water science; • Developing and field deploying land-based chemical and biological sensors; • Inspiring a greater agency commitment to developing airborne sensors; • Developing both new space-borne sensors and a "research-to-operations" strategy for existing ones; • Bridging the gap between sensor demonstration and integrated field demonstration; • Integrating data and models for operational use; • Adopting new integrated hydrologic measurement and modeling systems for water resource applications; • Funding interdisciplinary science; and • Addressing the fractured federal responsibility for hydrologic measurement, monitoring and modeling.
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From page 136... ...
are designed to be much larger -- on the scale of 104 to 105 square kilometers. Direct estimates of varying quality are now available for variables such as snow extent, snow water equivalent, surface water height, soil moisture, total water storage, and precipitation; indirect estimates for groundwater, evapotranspiration, and streamflow can also be made in some cases (see Chapter 2, Spaceborne Sensors section)
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From page 137... ...
The missions that study recommended –including missions to measure diurnal precipitation, soil moisture, water storage in lakes and wetlands, and snowpack water storage, especially in mountainous regions – would be consistent with the vision, findings, and recommendations of this study. Nonetheless, two related challenges are relevant to this report: (1)
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From page 138... ...
The greatest gap is between sensor demonstration and integrated field demonstration. Closing this gap would involve integrating the sensor networks and webs within hydrologic observatories and experimental demonstration sites, and interfacing the sensor networks with the broader development of cyberinfrastructure.
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From page 139... ...
Program, the USGS performs integrated assessments of a small number of watersheds. NOAA has the responsibility for monitoring precipitation and other meteorological variables and for monitoring PREPUBLICATION COPY
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From page 140... ...
Concepts such as CUAHSI's proposed "Hydrologic Measurement Facility" (HMF) Center, which would house community instruments based on mature technologies, and HMF "nodes," which would be university-based, have a 3-6 year life cycle, and support a specific PREPUBLICATION COPY
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From page 141... ...
As described above for sensor development, and earlier in the challenges facing the development and deployment of integrated hydrologic measurement systems, the pace of advancement is constrained by the fractured federal responsibility for the development and deployment of integrated measuring, monitoring, and modeling systems, which seems to impede their utilization. Recommendation 1-2: Serious consideration should be given to empowering an existing federal agency with the responsibility for integrated measurement, monitoring, and modeling of the hydrological, biogeochemical, and other ecosystem-related conditions and processes affecting our nation's water resources.
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