Solution specific articles for Water & Environmental Resources.

Llandegfedd Reservoir Optimization

Llandegfedd Reservoir is an off-channel reservoir operated by Welsh Water, located in Wales, United Kingdom. The reservoir is filled by pumping from the nearby River Usk and was operated to maintain full storage throughout the year, to maximize water supply availability. However, Welsh Water was interested in changing the reservoir operating rules to allow for more water in the river throughout the year, thus improving fish habitat and fishing conditions within the River Usk. Members of the Lynker team built a reservoir operations model to include inflows from the River Usk, pump station capacity, pipeline capacity, inflows from the local watershed, evaporation and precipitation, as well as releases (demands) from the reservoir. The reservoir model was designed using CRAM, which is a water allocation model, built as an add-in to Microsoft Excel. CRAM uses the out-of-kilter algorithm to efficiently compute the optimal distribution of water within a system. The Llandegfedd Reservoir system was optimized using the genetic algorithm add-in included with Microsoft Excel. This allowed for the optimization of the Llandegfedd Reservoir guide curve (normal reservoir pool elevation) subject to inflows, outflows and other system constraints.

The historical data for the River Usk was limited to 39 years of daily data, which was not long enough for a comprehensive system analysis, including the more stressful periods of drought. Therefore, a nonparametric stochastic daily streamflow model was developed using the k-nearest neighbor (KNN) algorithm, to extend the historical dataset and properly validate the optimized reservoir guide curve. The historical data set of 39 years of daily flow data was used to develop 500 simulations each 39 years in length that preserved the statistics of the original flow data.

The Llandegfedd Reservoir guide curve was optimized using the genetic algorithm within the CRAM system model, according to the historical inflows, demands, and constraints. The optimized reservoir guide curve was validated using the synthetic hydrology dataset developed as a part of the project. The final deliverable to the client was a reservoir operations model, synthetic hydrology, and an optimized reservoir guide curve, which provided for an increase in instream flows improving fish habitat, without significantly reducing water supply reliability.

Carlsbad Hydrologic Unit – Lagoon TMDL Monitoring

A monitoring program was developed for the quantification of phosphorus, nitrogen, chlorophyll-a, sediment, and bacteria within four lagoons located in the Carlsbad hydrologic unit in San Diego County. Water quality samples were collected throughout the duration of the one year monitoring period during dry weather conditions as well as wet weather storm events to accurately characterize nutrient loading within the lagoons.

Pollutograph grab samples and flow data were collected during storm events to calculate event mean concentrations, analyze first flush effects, and calculate load duration curves. Sample handling was consistent with EPA and California standards and included additional requirements set forth by the analytical laboratories. Samples were field filtered and preserved as necessary to preserve sample integrity and meet sample holding times.

Each lagoon was continuously monitored for flow, precipitation, temperature, specific conductivity, and turbidity which was to characterize the lagoons and calculate loading rates. The data from this project was to be used for the development of nutrient and sediment TMDLs within the lagoons. The project was funded by the stakeholders that have jurisdiction within the Carlsbad hydrologic unit.

Statistical Modeling to Study Climate Change Impacts on Municipal Stormwater Intensities

Lynker conducted modeling using the R statistical language to evaluate the effect of climate change on the Intensity-Duration-Frequency (IDF) curves used by Prince Edward Island to assess their municipal stormwater system.  Lynker obtained data and correlated specific climate variables with recorded storm intensities.  Once the ideal variables were selected, future projections of these variables from the Global Climate Models were used to predict the future distribution of the intensity and return interval of storm events.  These distributions were then used to evaluate the deviation from the IDF curves currently used by the municipality.

Development of Synthetic Hydrologic Records for Modeling Shasta Temperature Management

Lynker was tasked with developing synthetic streamflow records to be used for input to the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) Winter-run Life Cycle Model (WRLCM). A synthetic record of annual flow for the Sacramento River Index is needed for this application in order to construct a hydrology dataset that has a long period of record (i.e., 100 years) while also using a limited subset of the historical data period (1970-2014 – model calibration period).

Lynker implemented a well-documented Markov chain stochastic modeling approach to develop an ensemble of resequenced hydrology records. This stochastic hydrology method uses the empirical distribution of the historical data as a basis for simulating ‘new’ sets of flows using specific random or ‘probabilistic’ analyses. This results in sequences of data that are different from but consistent with the historical record.

Lynker performed a detailed analysis of the drought characteristics for each of the traces, and this report provides a summary of the methods and recommendations as to which simulated traces meet the criteria of ‘multi-year drought events consistent with historical conditions’ and which simulated traces meet the criteria of ‘more frequent multi-year drought events’.

 

Colorado Decision Support Systems

Lynker staff have completed a number of contracts related to the development and implementation of decision support systems for the State of Colorado’s Water Conservation Board (CWCB). Among these efforts are the

1) Water Rights Model of Colorado Water District 6 for the South Platte DSS, a DSS component that captures the hundreds of water rights diversions and operations on Boulder Creek, including irrigation demands and subsurface return flows, trans-basin diversions from the Western Slope, municipal demands, instream flow rights, reservoir fill and release operations and changed water rights;

2) Spatial Systems Component for the South Platte DSS, which uses satellite imagery, aerial orthophotography and other data together with remote sensing and GIS-based analysis and interpretation to map current and historic irrigated lands, delineate agricultural parcels, and classify crops, all to allow water users and administrators to analyze and make decisions regarding the surface water, groundwater, and irrigated lands for the South Platte River basin;

3) Colorado River Water Availability Study, Phases I and II, which utilized statistically downscaled Global Climate Model outputs to develop projected changes in runoff that were used, initially, to modify Colorado River model inflows and ultimately to modify statewide Colorado DSS inflows for analysis of climate change effects across Colorado;

4) Climate Change Drought DSS, a cooperative project between the CWCB and NOAA to develop a prototype web-based DSS to enable water managers at various operational- and time-scales to assess the impact of predicted climate change on natural flows at critical nodes along a river network;

and 5) Colorado Flood DSS, a prototype web-based tool bringing together floodplain, historical flood, and multi-hazard information to demonstrate how the state could provide a clearinghouse of flood-hazard and flood-related information for use by floodplain administrators, emergency managers, developers, the insurance industry, government agencies, and the public.

Lynker creates the Future Avoided Cost Explorer: Colorado Hazards (FACE:Hazards)

In the past two decades, Colorado has experienced wildfires, sustained droughts, and intense flood events – natural hazards that have had significant impacts on the Colorado economy. The State of Colorado recognizes that these hazards can be exacerbated as climate change intensifies the severity of events, and a growing population puts more people into harm’s way. In response, the Colorado Department of Public Safety, in collaboration with the Colorado Water Conservation Board and FEMA, commissioned a statewide assessment of current and future risks from flood, drought, and wildfire.

The project expresses risk in terms of monetary impacts to select sectors of the Colorado economy, including private housing, public infrastructure, agriculture, and tourism. The information assembled can be used to stimulate the implementation of smart adaptation strategies and policy frameworks that strengthen vulnerable sectors in a rapidly changing environment. The analysis, led by Lynker Technologies, takes a probabilistic approach to quantify and monetize current risks in terms of expected annual damage (EAD). Models of each sector’s vulnerability to flood, drought, or wildfire were run with future climate and population conditions to estimate how those expected damages might change by the year 2050. For flooding and wildfire, the impacts to commercial buildings, residential buildings, and infrastructure are similar to the types of impacts that Hazus is designed to quantify and follow the Hazus methodologies closely. For drought, the monetary impacts focused on reduced economic output from agriculture and recreation.

As a semi-arid, headwater state with terrain ranging from the High Plains to Rocky Mountains, Colorado is exposed to major economic impacts from floods, droughts, and wildfires. Recent events such as the 2013 flood, the 2002 drought, and 2012 wildfire season are examples of the physical magnitude and economic damages such hazards can exact. These extreme events are becoming more severe and potentially more frequent as global climate dynamics change regional patterns.

Researchers expect floods to increase in severity, droughts to deepen and become more spatially expansive, and wildfire seasons to become longer with more acres burned in a warming climate. In addition, Colorado’s growing population is projected to reach between 7.7 and 9.3 million by 2050. With more residents comes greater natural hazard exposure if floodplain margins become developed, agricultural land shrinks, and the number of people in the wildland urban interface increases.

The first step to understanding and preparing for these events is to assess the possible risks—both now and in the future. This is done by quantifying the difference in economic costs between historic relationships and modeled future scenarios. Tasked by the Colorado Department of Public Safety to perform such an analysis, the objective of this project is to estimate the expected costs of floods, droughts, and wildfires to a selection of economic sectors under historic and future climate and population scenarios.

These sectors varied by the hazard being examined. For flooding, we evaluated impacts to buildings and bridges. For drought, we examined agricultural—crops and cattle—and outdoor recreation—skiing and rafting—impacts. For wildfire, we again analyzed buildings and also computed the cost of suppression, which is the amount the state spends to fight and extinguish ongoing fires. In total, we analyzed eight sectors, all of which have experienced observed economic damages in the tens of millions to billions of dollars due to natural hazards.

View and explore the FACE: Hazards dashboards to understand how changes in global climate patterns can lead to more frequent and intense hazards in Colorado.

Future Avoided Cost Explorer: Colorado Hazards (FACE:Hazards)

Lower Poudre River Flood Recovery and Resilience Master Plan

In response to the devastating flood of September 2013, the Coalition for the Poudre River Watershed (CPRW) hired Lynker to develop a flood recovery and resilience master plan for the Lower Poudre River. The project was funded by a grant from the Colorado Department of Local Affairs (DOLA) Community Development Block Grant Disaster Recovery (CDBG-DR) Resilience Planning program.

The master planning effort combined scientific and engineering analysis with community collaboration to identify and prioritize opportunities to improve river resilience and river health. Components of the master plan include reach-by-reach analyses of changes to the historical channel, assessments of geomorphological and ecological values, identification of vulnerabilities, and sediment transport modeling. Lynker led a team of scientists, engineers, geomorphologists, ecologists, modelers and designers from Otak, AlpineEco and LVBrown Studio to create an informative, user-friendly master plan that provided recommendations through the project area.

A sediment transport model was built for the 36 miles of river in the project area, utilizing existing HEC-RAS model cross-sections to determine sediment transport capacity on a reach-by-reach basis. The model focused on the use of total effectiveness, which uses the river flow regime and their respective probability of occurrence to determine the river’s total sediment transport potential over time. Sediment bed samples were collected by performing pebble counts at pre-determined reach cross-sections. Each field visit was thoroughly documented with field data sheets and photos from a GPS camera.

The data collected for the project was used to compile a reach-by-reach river characterization and assessment to determine areas with the greatest need for future restoration work. The assessment included metrics for flood hazards, geomorphology, ecological and aquatic habitat, social vulnerability and local priorities. For instance, the project steering committee and the local community put a high emphasis on the integrity of the Poudre River Trail, a 21-mile paved path the closely follows the river for much of the project area. Therefore, the Poudre River Trail was included as an element of river assessment and the final Poudre River prioritization scoring.

The large project area showcased Lynker’s ability to develop river restoration projects through community outreach and adaptive priorities. The planning process included an extensive public outreach effort that drew on landowners and local community experiences to pinpoint vulnerable areas and important assets. Based on these meetings, a cultural aspect of the community was accounted for when developing restoration projects. Illustrative conceptual designs were developed for the high priority reaches while taking into consideration ongoing projects within the reaches. The master plan and sediment model developed for the Lower Poudre are intended to be continuously evaluated during future planning actions or assessments to make reach-scale decisions that can help inform the solutions that may be best for a reach.

NNDWR Gauge Network Optimization

The Navajo Nation Department of Water Resources (NNDWR) manages a network of rain cans, automated climate stations, stream gauges and snow monitoring gauges (both Snow Courses and SNOTEL sites).  The majority of these stations must be visited on a monthly basis by NNDWR staff to gather data and inspect the gauges for damage.  Nationwide budgetary constraints have forced the NNDWR to re-evaluate its gauge network to reduce field costs.

Lynker was hired to reduce the field effort required to maintain the NNDWR gauge network while optimizing the network’s ability to accurately predict rainfall across the entire Navajo Nation. At the project start, there were more than 110 stations that require regular visits across 27,000 sqmi of land, requiring a very large amount of monthly field work to visit, maintain and collect data from all the stations. The project team implemented an ArcGIS model to reduce by 30% the monthly field hours required to visit and monitor the rain gauge network while minimizing the measurement error introduced to the system by the removal of gages.

The impact of an increase in measurement error is best described in terms of the water that is “missed” as a result of the removal of a gauge.  The Volumetric Index of the Error of Water (VIEW) is the error in measurement multiplied by the average precipitation at any given grid cell.  The average precipitation used was the PRISM 30-year annual average dataset.

With a stringent requirement for field effort reduction, the primary means of network optimization was the removal of tipping bucket rain gauges.  A combination of factors led to the creation of optimized network test cases; gauge period of record, clustering with other gauges, rainfall measurement coverage within individual watersheds, and a qualitative evaluation by NNDWR staff of data quality and potential for vandalism at the gauge site.

Automated climate gauging stations were recommended to either be connected to the central NNDWR office through radio or cellular telemetry or were removed altogether to offset the high associated maintenance cost.  To improve precipitation prediction, scripted connections were created to existing data sources such as the NOAA-COOP rainfall network so the NNDWR could benefit from easy access to that data.

Reservoir and Irrigation District Water Supply Study

Lynker Technologies worked with a confidential client to provide water resources planning services in Western Europe. This work involved extensive collection and processing of rainfall, climate and hydrologic data from various European agencies. Once data collection was complete, Lynker developed a set of impacted future conditions under an ensemble of climate change projections. The hydrometeorological data as well as the future climate conditions were used to develop a water resources model to test different combinations of hydrology, water consumption, system operations and legal frameworks. Output from the model was used to provide the client with decision support for planning and infrastructure investment.

Projecting Climate Change Impacts to Extreme Temperature and Precipitation for Denver Water’s Infrastructure

Lynker worked with Denver Water, the University of Colorado and NCAR/UCAR staff to review a range of standard methods for characterizing future extreme precipitation and temperature events under climate change. The methods reviewed include downscaling projects like LOCA, MACA, BCSD and the CORDEX archive as well as point downscaling statistical approaches. This work involved both an extensive literature review covering the foundations of the methods as well as independent assessments of results from each method.  Once the literature review was complete, Lynker performed detailed statistical analyses to help Denver Water understand increases in frequency and intensity of extreme rainfall and heat events at a large set of locations.