An approach for modelling snowcover ablation and snowmelt runoff in cold region environments

Reliable hydrological model simulations are the result of numerous complex interactions among hydrological inputs, landscape properties, and initial conditions. Determination of the effects of these factors is one of the main challenges in hydrological modelling. This situation becomes even more difficult in cold regions due to the ungauged nature of subarctic and arctic environments. This research work is an attempt to apply a new approach for modelling snowcover ablation and snowmelt runoff in complex subarctic environments with limited data while retaining integrity in the process representations. The modelling strategy is based on the incorporation of both detailed process understanding and inputs along with information gained from observations of basin-wide streamflow phenomenon; essentially a combination of deductive and inductive approaches. The study was conducted in the Wolf Creek Research Basin, Yukon Territory, using three models, a small-scale physically based hydrological model, a land surface scheme, and a land surface hydrological model. The spatial representation was based on previous research studies and observations, and was accomplished by incorporating landscape units, defined according to topography and vegetation, as the spatial model elements. Comparisons between distributed and aggregated modelling approaches showed that simulations incorporating distributed initial snowcover and corrected solar radiation were able to properly simulate snowcover ablation and snowmelt runoff whereas the aggregated modelling approaches were unable to represent the differential snowmelt rates and complex snowmelt runoff dynamics. Similarly, the inclusion of spatially distributed information in a land surface scheme clearly improved simulations of snowcover ablation. Application of the same modelling approach at a larger scale using the same landscape based parameterisation showed satisfactory results in simulating snowcover ablation and snowmelt runoff with minimal calibration. Verification of this approach in an arctic basin illustrated that landscape based parameters are a feasible regionalisation framework for distributed and physically based models. In summary, the proposed modelling philosophy, based on the combination of an inductive and deductive reasoning, is a suitable strategy for reliable predictions of snowcover ablation and snowmelt runoff in cold regions and complex environments

Laajan taajama-alueen hydrologinen mallinnus SWMM-hulevesimallilla

Stormwater modeling has a major role in preventing issues such as flash floods and urban water-quality problems. However, in-detail modeling of large urban areas is time-consuming as it typically involves model calibration based on highly detailed input data. Stormwater models of a lowered spatial resolution would thus appear valuable if only their ability to provide realistic results could be proved. This study proposes a methodology for rapid catchment delineation and stormwater management model (SWMM) parameterization in a large urban area, without calibration. The effect of spatial resolution on the accuracy of modeling results is also being discussed. A catchment delineation and SWMM parameterization is conducted for an urban area in the city of Lahti in southern Finland. GIS methodology is utilized for simultaneous processing of data representing large areas. Literature values are also of importance where no spatial data is available. To evaluate the parameterization results, the SWMM application is run using an hourly data series of meteorological observations covering a period of four years.Hulevesimallinnus on tärkeä työkalu muun muassa taajamatulvien sekä kaupunkivesien laatuongelmien välttämiseksi. Yksityiskohtainen hulevesimallinnus vaatii kuitenkin paljon aikaa, sillä se edellyttää yleensä mallin kalibrointia tarkkojen lähtötietojen perusteella. Tämän vuoksi olisi hyödyllistä, mikäli myös vähemmän hajautettujen hulevesimallien voitaisiin todistaa tuottavan todenmukaisia tuloksia. Tässä työssä esitetään menetelmiä tehokasta taajamien valuma-alueiden rajaamista ja kalibroimattoman SWMM-hulevesimallin parametrisointia varten. Myös hulevesimallien maantieteellisen resoluution merkitystä tarkastellaan. Lahden kaupungin keskusta-alueelle tehdään valuma-aluejako sekä SWMM-hulevesimallin (stormwater management model) parametrisointi. Laajoja alueita koskevan tiedon käsittelemiseen kerralla käytetään paikkatietomenetelmiä. Myös kirjallisuusarvoja hyödynnetään niiltä osin, kuin paikkatietoja ei ole saatavilla. Parametrisoinnin tarkistamiseksi SWMM-hulevesimallia sovelletaan käyttäen tunneiltaista, neljän vuoden jakson kattavaa säähavaintoaineistoa. Valuma-aluejako ja osavaluma-aluejako voidaan tehdä työssä kehitetyillä menetelmillä nopeasti ja tarkasti, vaikkakaan prosessia ei voida kokonaan automatisoida lähtöaineistojen epätäydellisyyden vuoksi. Toisaalta osavaluma-alueiden parametrisointi on haastavaa ja sisältää suurempia epävarmuuksia kuin valuma-aluejako. Niistäkin huolimatta hulevesimallin sovellus tuottaa järkeviä tuloksia kirjallisuuteen ja muihin samalla alueella tehtyihin tutkimuksiin verrattuna. Tämän perusteella myös kalibroimaton, pienen maantieteellisen resoluution SWMM-malli voi olla riittävä joihinkin hulevesima1linnuksen sovelluksiin. Työssä kehitetyt menetelmät tarjoavat kaiken kaikkiaan toimivan tavan laajaa taajama-aluetta kuvaavan SWMM-hulevesimallin parametrisointiin

Supersonic combustion engine testbed, heat lightning

The design of a supersonic combustion engine testbed (SCET) aircraft is presented. The hypersonic waverider will utilize both supersonic combustion ramjet (SCRAMjet) and turbofan-ramjet engines. The waverider concept, system integration, electrical power, weight analysis, cockpit, landing skids, and configuration modeling are addressed in the configuration considerations. The subsonic, supersonic and hypersonic aerodynamics are presented along with the aerodynamic stability and landing analysis of the aircraft. The propulsion design considerations include: engine selection, turbofan ramjet inlets, SCRAMjet inlets and the SCRAMjet diffuser. The cooling requirements and system are covered along with the topics of materials and the hydrogen fuel tanks and insulation system. A cost analysis is presented and the appendices include: information about the subsonic wind tunnel test, shock expansion calculations, and an aerodynamic heat flux program

Characterizing Water and Water-Related Energy Use in Multi-Unit Residential Structures with High Resolution Smart Metering Data

As urban populations continue to grow and expand, localized demands on water supplies continue to increase as well. These water supplies, which have been historically stable, are also threatened by an increasingly erratic climate. Together, these two factors have significantly increased the likelihood of long-term drought conditions in the American West. In response, water suppliers are investigating new ways to record water use in urban areas to better understand how water is used. One of these methods is smart meters; advanced devices that can record and transmit water use information directly to the water supplier. However, these devices can produce extremely large amounts of data, which can often be difficult to manage. This research investigated methods for data collection and management to advance the feasibility of larger smart meter networks. The techniques we developed are described, as well as how these techniques were used to estimate water and water-related energy use in several student dormitories on Utah State University’s campus. We also detail how water and water-related energy use were estimated. These results offer insight into how water and water-related energy are used in buildings like these, which may be of interest to water suppliers looking for ways to increase their understanding of water use beyond just the number of gallons used

Quantifying groundwater interaction with streams and thermal regime implications

Groundwater interaction plays an essential role in aquatic ecosystems and is involved in a range of water quantity and quality issues. However, quantifying stream-groundwater interactions has been difficult and labor intensive due to the complex nature of the hydrological connectivity. Therefore, there remains considerable need for advancements that can help understand and quantify groundwater interaction with lower cost, better flexibility and convenience. The objectives of this study were to (i) understand the transient storage mechanisms due to surface exchange and hyporheic flow by applying a stream transient storage zone model to soil pipe systems; (ii) develop the thermal equilibrium method to estimate the time-averaged point groundwater flux using monitored stream water temperature at a single point and existing atmospheric and hydrological data and (iii) evaluate the effects of reservoir operations in the Kiamichi River as related to stream fish thermal tolerances during summer baseflow conditions with an emphasis of groundwater interactions. Tracer data from a pulse input were collected in four different soil pipes after a fluorescein dye was injected upstream of each soil pipe network. The transient storage zone model OTIS-P was successfully applied to estimate solute transport parameters. The result suggested larger transient storage potential compared to stream systems reported in previous research. In the second part, a thermal equilibrium method was developed to quantify point groundwater flux in streams, and was evaluated by comparing with measurements from seepage runs. Statistics evaluated by FITEVAL indicated result from two methods agreed with each other, and the thermal equilibrium method was proven to be a suitable technique for quantifying point groundwater flux. In the third part, the WASP stream temperature model was calibrated and validated for four summers with an emphasis of groundwater interactions. Downstream water temperature was predicted using the validated model for 15 hypothetical release scenarios and evaluated based on critical thermal maximum of three fish guilds. Results indicated the current release operation was insufficient to provide a suitable downstream thermal regime for most of the fishes tested. Increasing release magnitude and/or releasing from hypolimnetic layers could improve the downstream thermal habitat for these fishes

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Nienow, Sole and Cowton’s Greenland research has been supported by a number of UK NERC research grants (NER/O/S/2003/00620; NE/F021399/1; NE/H024964/1; NE/K015249/1; NE/K014609/1) and Slater has been supported by a NERC PhD studentshipPurpose of the review:  This review discusses the role that meltwater plays within the Greenland ice sheet system. The ice sheet’s hydrology is important because it affects mass balance through its impact on meltwater runoff processes and ice dynamics. The review considers recent advances in our understanding of the storage and routing of water through the supraglacial, englacial, and subglacial components of the system and their implications for the ice sheet Recent findings:   There have been dramatic increases in surface meltwater generation and runoff since the early 1990s, both due to increased air temperatures and decreasing surface albedo. Processes in the subglacial drainage system have similarities to valley glaciers and in a warming climate, the efficiency of meltwater routing to the ice sheet margin is likely to increase. The behaviour of the subglacial drainage system appears to limit the impact of increased surface melt on annual rates of ice motion, in sections of the ice sheet that terminate on land, while the large volumes of meltwater routed subglacially deliver significant volumes of sediment and nutrients to downstream ecosystems. Summary:  Considerable advances have been made recently in our understanding of Greenland ice sheet hydrology and its wider influences. Nevertheless, critical gaps persist both in our understanding of hydrology-dynamics coupling, notably at tidewater glaciers, and in runoff processes which ensure that projecting Greenland’s future mass balance remains challenging.Publisher PDFPeer reviewe

Controlled Ecological Life Support Systems (CELSS) conceptual design option study

Results are given of a study to explore options for the development of a Controlled Ecological Life Support System (CELSS) for a future Space Station. In addition, study results will benefit the design of other facilities such as the Life Sciences Research Facility, a ground-based CELSS demonstrator, and will be useful in planning longer range missions such as a lunar base or manned Mars mission. The objectives were to develop weight and cost estimates for one CELSS module selected from a set of preliminary plant growth unit (PGU) design options. Eleven Space Station CELSS module conceptual PGU designs were reviewed, components and subsystems identified and a sensitivity analysis performed. Areas where insufficient data is available were identified and divided into the categories of biological research, engineering research, and technology development. Topics which receive significant attention are lighting systems for the PGU, the use of automation within the CELSS system, and electric power requirements. Other areas examined include plant harvesting and processing, crop mix analysis, air circulation and atmosphere contaminant flow subsystems, thermal control considerations, utility routing including accessibility and maintenance, and nutrient subsystem design

Final Report of the DAUFIN project

DAUFIN = Data Assimulation within Unifying Framework for Improved river basiN modeling (EC 5th framework Project

Observation-Based Algorithm Development For Subsurface Hydrology In Northern Temperate Wetlands

This study investigates wetland subsurface hydrology, as well as biogeochemistry - which is strongly influenced by water and temperature dynamics - as these interactions are expected to be highly significant, yet remain poorly represented in current ecosystem and climate models. Northern wetlands have received widespread public attention due to steadily increasing summer mean global temperatures, extreme precipitation events and higher rates of natural greenhouse gas emissions, as well as the significant impacts on them due to human activities. The goal of my graduate research has been to improve quantification of the role of subsurface hydrology in northern wetlands by using a macroscale hydrological model, the Variable Infiltration Capacity (VIC) model. The existing VIC model was modified to better represent the effect of surface and subsurface water storage in managed wetlands. An improved water table depth calculation, based on a drained to equilibrium assumption, was incorporated into a new subsurface drainage algorithm. The spatial variability of water table depth across landscape positions has been represented using a topographic index approach. By incorporating a water table gradient into the VIC grid cell, subsurface-surface water exchange within the wetland can also be represented, dependent on land surface class. This algorithm was developed and evaluated using data at scales ranging from field to small watershed, which included a small wetland at the Agronomy Center for Research and Education (ACRE), the long-term drainage experiment at the Davis-Purdue Agricultural Center (DPAC), and a cooperators mint farm in Pulaski, Indiana. The improved model has been used at larger scales - from large watersheds to regional scale - to better understand the subsurface hydrology affected by drainage practices throughout the poorly-drained Midwest agricultural regions. Recent concern regarding high rates of soil organic matter decomposition due to artificial drainage enhancements motivated an integrated field and modeling experiment to quantify the influence of water management on cultivated organic soils in the Kankakee River basin, a flat outwash plain covered with relatively deep, poorly drained soil with high organic matter content. Methane and carbon dioxide emissions were simulated by using soil temperature, water table position and net primary production generated from the VIC model and evaluated using CO2 flux measurements, water table height and soil moisture measurements. The model simulations do support the high rates of subsidence previously reported for these high organic matter soils, but most of the subsidence took place soon after the introduction of agricultural drainage. Another case study evaluated the role of anthropogenic modifications to drainage conditions and wetland extent on streamflow in the upper Wabash River basin. An initial test case demonstrated that a depressional wetland perched on the Tipton Till Plain tends to recharge soil moisture in riparian areas by late summer, reducing the volume of baseflow downstream. When scaled up to the upper Wabash River basin , the study demonstrated that wetlands provided more temporal surface water storage and served to reduce peak flows. Subsurface drainage increased the high flow, mean flow, and Richard-Baker flashiness Index (RBI), and reduced the low flow and flow distribution. Stream network density analysis showed that simulations with lower drainage density (representing historic, natural conditions) had relatively lower high flow and smaller RBI. These results provide evidence that although drainage creates more pore space in the soil profile - reducing surface runoff - it also creates more flow paths, allowing water to travel to the watershed outlet more quickly