Hydrologic Sciences Taking Stock and Looking Ahead (1998) / Chapter Skim
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3 Hydrologic Measurements and Observations: An Assessment of Needs
3 Hydrologic Measurements and Observations: An Assessment of Needs
Pages 67-86
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From page 67... ...
The pioneers of modern hydrology were active observers and measurers, yet now designing and executing data collection programs, as distinct from experiments carried out in a field setting with a specific research question in mind, are too often 67
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From page 68... ...
Irrespective of this, there appears to be limited effort by the USGS and the National Weather Service (NWS) to demonstrate, on an economic and social basis, the benefits of an extensive and accurate observational system in support of flood forecasting and warning and to show the relationships among observations, forecasts and warnings, and reduced flood damages and less loss of life.
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From page 69... ...
69 i' _~ l ~ ~ ~1 o o o o o lo A in 00 a: i: C} ~ a ~ \ ,/N ~ u.
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From page 70... ...
An example is the removal of the gage on the Licking River in McKinneysburg, Kentucky (near Falmouth) in September 1994, which hindered the delivery of accurate flood stage information and contributed to increased loss of life and damages during the March 1997 floods.
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From page 71... ...
Consider another example of how fiscal pressures are affecting data collection. In Opportunities in the Hydrologic Sciences, the need to develop accurate long-term hydrologic data bases to improve scientific understanding is highlighted.
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From page 72... ...
This recommendation is made in light of a 1996 USGS survey of the agency's statebased water resources offices, with input from the NWS river forecast offices, which identified 1,500 sites where additional real-time streamflow gaging would improve flood forecasting and flood warnings. These sites included (1)
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From page 73... ...
For individual storms, differences between radars can be unacceptably large. Figure 4 shows total storm rainfall from an intense storm over the Rapidan River basin in West Virginia that occurred on July 17-18, 1996.
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From page 74... ...
215~. For the NWS, hydrologic water balance models are indis pensable tools for producing site-specific flood forecasts and warnings.
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From page 75... ...
HYDROLOGIC MEASUREMENTS AND OBSERVATIONS INX Radar-Gage Comparison, mm of rain (warm months) to us Radar Radar Radar to co to to to Lo to to to co A ., .~..- .
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From page 76... ...
The expanding role of operational models for water management and environmental monitoring and prediction has resulted in the need for continuous time (storm and interstorm) modeling of stream discharges and river basin water balances.
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From page 77... ...
(1996~. under the First international satellite land surface climatology project (ISLSCP)
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From page 78... ...
(1996~. was heavily constrained by a climatologically defined deep soil boundary condition for soil moisture and temperature, whereas in CY48 the model produces a dynamic, time-varying, surface soil moisture through time integration of the atmospheric forcings of precipitation and evaporation.
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From page 79... ...
These dramatic improvements of precipitation forecasts especially in the 48- to 72-hour forecasts have been the foundation of stated desires by the atmospheric community for extensive soil moisture measurements. In a similar manner, there has been a dramatic improvement in surface air temperature forecasts in high latitudes by incorporating improved winter time albedo measured as part of the ISLSCP Boreal Ecosystem Atmospheric Study (BOREAS)
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From page 80... ...
Coordinated Experiments During the past decade, the field programs developed under the auspices of the WCRP have provided critical data that have advanced scientific hydrology. Recent HAPEX-MOBILY, HAPEX-Sahel, ISLSCP-FIFE, and BOREAS experiments have shown the value of high temporal resolution water and energy flux measurements in evaluating land surface hydrological models (Shag and Henderson-Sellers, 1996; Chen et al., 1996)
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From page 81... ...
As another example, the BOREAS experimental plan made no allowance for accurate measurement of precipitation, and only through separate funding from the National Science Foundation and Environment Canada was a rain radar system installed for the Southern Study Area. Insufficient stream gaging and inadequate measurements of surface infiltration, interflow, percolation, and ground water movements have resulted in unresolved differences between measurements of water and energy fluxes at different BOREAS scales.
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From page 82... ...
This leads to the following recommendation: There is a need to better define the hydrologic data needed to achieve the stated goals of the WCRP climate experiments, including goals related to atmospheric and biophysical processes, and to strengthen the terrestrial hydrological studies within the WCRP, HAPEX, and ISLSCP climate experiments. As an aside, the GEWEX-Mississippi River basin study (GCIP)
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From page 83... ...
MEASUREMENTS AND OBSERVATIONS so ¢ so to o o .0 so Cal ·_.
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From page 84... ...
Table 1 gives a list of EOS instruments that are needed for land surface hydrologic modeling. In the terrestrial ecology community, more progress has been made in establishing a coordinated global set of terrestrial observations (Running et al., 1997~.
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From page 85... ...
Because of this, terrestrial hydrology has been the "stepchild" of climate field experiments, resulting in incomplete or inadequate measurements that prevent basic computations like determining water and energy balances over a range of scales. In addition, operational data collection remains under fiscal pressure, resulting in short-term savings at the expense of long-term benefits.
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From page 86... ...
1994. A simple hydrologically based model of land surface water and energy fluxes for general circulation models.
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