How would your hydrometric data stack up to a test like this? When you are thinking about your data management system, be mindful of the rule of ten: “it costs ten times as much to complete a unit of work when the data are flawed in any way as it does when they are perfect.”
This paper was presented at the IAHR 2017 World Congress in Kuala Lumpur, Malaysia. The premise of is that in a morphologically active river, stage is a poor predictor of discharge due to river cross section instability. The authors analyzed 1,687 discharge observations collected at the Bahadurabad station on the Brahmaputra River for the period from 1976 to 2009.
A common water quality assumption is that water clarity is highly correlated with nutrient concentration due to the enhanced algal growth in eutrophic waters. However, this assumption does not apply to super-polluted water that is inhospitable even for algae. At nitrogen concentrations above 3 milligrams per liter, chlorophyll-a concentrations begin to drop off precipitously. Beyond this threshold, photolysis of nitrate may produce reactive oxygen species that damage DOM and phytoplankton. Reduction in N loading at high P could therefore increase Chl-a and decrease water clarity, resulting in an apparent worsening of water quality. This study suggests that monitoring Chl-a or Secchi depth may fail to indicate water quality degradation by extreme nutrient concentrations. These findings highlight how extreme nutrient regimes in lakes can produce novel relationships between phytoplankton and nutrients.
The Australian Bureau of Meteorology is inviting comment on hydrometric guidelines for hydrographers on Acoustic Doppler Acoustic Profilers (ADCP).
The ability of stream hydrographers to produce consistently reliable discharge data derived by stage-discharge rating curves is the subject of this enquiry. A method is proposed to identify temporal structure in deviations from the rating curve. I am not sure what the value of this paper is because any well-conceived rating model would consume all of the information in the gaugings, leaving no identifiable structure in any dimension of the deviations.
Articles include: Mapping Groundwater-Dependent Ecosystems; Getting an Early Look at the Climate Ahead; Estimating Where Our River Water Goes; Water Reserves Decline in 2015–16 Despite Average Rainfall; Seeking Comment on Hydrometric Guidelines; and more from the Australian Bureau of Meteorology.
Compilation of Streamflow Statistics Calculated From Daily Mean Streamflow Data Collected During Water Years 1901–2015 for Selected U.S. Geological Survey Streamgages
Open-File Report 2017–1108: statistics for 20,438 streamgauges that had 1 or more complete years of record during water years 1901 through 2015 were calculated from daily mean streamflow data; all the statistics are available in a USGS ScienceBase data release.
Analytical Model for Stage-Discharge Estimation in Meandering Compound Channels With Submerged Flexible Vegetation
This paper addresses a common problem in hydrometric science – specifically, how we relate stage to flow through meandering compound overbank channels full of terrestrial vegetation. Extrapolation of flow resistance factors to flood stage for the purpose of rating curve extrapolation can be improved by developing a relation between the velocity below the canopy and the depth-averaged velocity.
Data are an asset – not exhaust. Demand for clean, usable data far outstrips supply. Don’t put the AI cart before the data horse. Well-organized data is absolutely foundational to gain benefit from the latest and greatest tech. Thinking about data this way also makes data management and procurement a value generating activity – not a chore. Algorithms are relatively cheap – data can be the primary differentiator. When users are involved in the process of policing data quality and seeing improvements which help them in their work, they chomp at the bit to help and provide more feedback in order to get better data. It’s a virtuous cycle that the best organizations lean into.
Data from the Colorado River in Grand Canyon, Arizona and a laboratory experiment both demonstrate that when turbidity exceeds instrument-pegged conditions, increasing suspended-sediment concentration (and thus increasing turbidity) may cause 20 optical probes to record decreasing “false” turbidity values that appear to be within the valid measurement range of the probe. Therefore, under high turbidity conditions, other surrogate measurements of turbidity (e.g. acoustic-attenuation measurements or suspended-sediment samples) are necessary to correct these low false turbidity measurements and accurately measure turbidity.
A key result of this study is that “Plastic debris loads, both microplastic (particles <5 mm) and macroplastic (particles >5 mm) are positively related to the mismanaged plastic waste (MMPW) generated in the river catchments. This relationship is nonlinear where large rivers with population-rich catchments deliver a disproportionately higher fraction of MMPW into the sea.” The implication of this finding for water monitoring agencies all over the world is that the measurement and monitoring of plastics discharge is an increasingly important part of any comprehensive monitoring program.
David Tarbotton from Utah State University is leading an NSF funded initiative called HydroShare – an online database system that simplifies the storage and sharing of hydrological data and models.
Quantifying the Relation Between Electrical Conductivity and Salt Concentration for Dilution Gauging Via Dry Salt Injection
Salt dilution gauging is an essential skill for anyone who needs to measure streamflow in turbulent streams. A new article in the journal Confluence examines the uncertainty in dry salt injection salt dilution discharge measurements that is a result of the calibration factor. Careful attention to procedures can reduce the error to less than 1%.
An unmanned surfboard is being used to collect water quality data after Hurricane Harvey to find out how record-breaking rainfall is affecting coral reefs and ecosystems. The freshwater plume could cause dangerously low salinity, harmful algal blooms, and low oxygen levels in the Gulf of Mexico. The autonomous wave-glider will be on a 60-day mission collecting this valuable data.
USGS: A Review of Surface Energy Balance Models for Estimating Actual Evapotranspiration With Remote Sensing at High Spatiotemporal Resolution Over Large Extents
The biggest challenge in closing a water balance for a watershed has always been quantification of evapotranspiration. It is so difficult to get an accurate estimate that it is often assigned as the residual of known inputs minus known outputs. However, with a changing climate driving hydrological processes in changing landscapes, it is becoming increasingly important to have a measure of ET that is defensible. The USGS Scientific Investigations Report 2017-5087 is a valuable reference for the current state of the art of ET modeling.