2013

Investigating Enso Signal In Ciliwung Streamflow Variability, Jakarta, Indonesia

Anonymous — Fri, 17 Aug 2018 17:02:42 +0000

Investigating Enso Signal In Ciliwung Streamflow Variability, Jakarta, Indonesia Anonymous (not verified) Fri, 08/17/2018 - 11:02 Yanto Yanto

Yanto, Yanto ¹ ; Zagona, Edith ² ; Balaji, Rajagopalan ³

¹ CEAE and CADSWES University of Colorado at Boulder
² CEAE and CADSWES University of Colorado at Boulder
³ CEAE and CIRES University of Colorado at Boulder

Ciliwung is the main river flowing through Jakarta, the capitol city of Indonesia. This river is the source of extreme flood occurences in Jakarta, more so in the last two decades. Furthermore, low streamflow in dry season is of concern for water supply, thus, making water management in this river basin challenging. To help with the management, understanding the year-to-year variability of stream flow in this basin is significantly important.

It is well known that El Nino and Southern Oscillation (ENSO) modulate the interannual variability of rainfall over Indonesia. Therefore, we posit that ENSO also impacts the variability of streamflow in this river basin. Here we diagnose the relationship between streamflow in Ciliwung basin and large scale climate variables associated with the ENSO phenomena. Subsequently, we develop a statistical prediction model for the wet season (Dec-Feb) streamflow based on the climate predictors developed from the above diagnostics. We find significant prediction skill, improving the prospects for efficient water resources management.

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Optimal Initial Configuration Of Treatment Solution For In Situ Remediation With Engineered Injection And Extraction In Homogeneous And Heterogeneous Aquifers

Anonymous — Fri, 17 Aug 2018 17:01:56 +0000

Optimal Initial Configuration Of Treatment Solution For In Situ Remediation With Engineered Injection And Extraction In Homogeneous And Heterogeneous Aquifers Anonymous (not verified) Fri, 08/17/2018 - 11:01 Julia H. Traylor

Traylor, Julia H. ¹ ; Neupauer, Roseanna M. ² ; Piscopo, Amy N. ³

¹ University of Colorado Boulder-CEAE
² University of Colorado Boulder-CEAE
³ University of Colorado Boulder-CEAE

Groundwater comprises about 30 percent of Earth’s available freshwater; however, this vital resource is often contaminated by industrial or agricultural sources. The efficiency of existing groundwater remediation methods must be improved, especially as global consumption of water and energy rises. During in situ remediation, a chemical treatment solution is injected into the contaminated aquifer to degrade the groundwater contaminant. Simulations have demonstrated that spreading of the treatment solution through a series of engineered injection and extractions (EIE) of clean water at wells surrounding the contaminated region increases the contact area between the treatment solution and contaminant, thereby increasing the amount of contaminant degradation reactions. Past studies have evaluated the amount of reaction during EIE in simulations where the initial injection of treatment solution was modeled as a circular, filled plume. This study modifies the initial configuration of treatment solution by injecting clean water at the center of the treatment solution plume to change its shape to a toroid, which increases the length of the shared interface with the contaminant plume. An optimal initial radius of the interior clean water plume that minimizes the amount of treatment solution injected and maximizes the amount of contaminant degraded is determined. Preliminary work conducted for a homogeneous aquifer shows that the volume of the treatment solution can be reduced by 25 percent compared to previous studies, while contaminant degradation only decreases by two percent. Since most aquifers are not homogenous, this study explores a similar scenario for a heterogeneous aquifer.As material conservation is important to any engineering project, this study also evaluates the trade-off between the cost of treatment solution and the impact of less contaminant degradation, as the interior clean water plume increases.

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Correlating The Spectroscopic Properties Of Organic Matter To The Photochemical Formation Of Hydroxyl Radical In Natural Waters

Anonymous — Fri, 17 Aug 2018 16:59:18 +0000

Correlating The Spectroscopic Properties Of Organic Matter To The Photochemical Formation Of Hydroxyl Radical In Natural Waters Anonymous (not verified) Fri, 08/17/2018 - 10:59 Eli B Townsend

Townsend, Eli B ¹ ; Glover, Caitlin M ² ; Rosario-Ortiz, Fernando L ³

¹ University of Colorado

The production of reactive oxygen species, including hydroxyl radical (HO•), from organic matter (OM) is a driver for the degradation of organic contaminants found almost ubiquitously in natural systems. To determine the role efficacy of OM, advanced analytical techniques are required to monitor the ROS production and quantum yield. In this study fifteen surface, ground and wastewaters samples were analyzed to determine if a correlation exists between the quantum yield of HO• and certain optical properties of water. The optical properties examined included specific UV absorbance (SUVA), E2:E3 and the Spectral Slope Ratio (SR). A positive correlation was found with the E2:E3 ratio, but a slightly better correlation was achieved when the spectral slope from 275 nm to 295 nm was coupled with this ratio. Researchers could use this optically based model to replace advanced analytical techniques for estimating quantum yield and apply it in natural systems.
Organic matter is primarily composed of fulvic, humic, and non-humic substances such as proteins or decaying lignin i.e., an intermediate in the degradation of terrestrial plant matter to organic matter. Fulvic acids are low molecular weight humic substances. Humic substances are naturally occurring multivalent acids. Fulvic acids are the major light-absorbing fraction between 800-200 nm (the UV-Vis range). These substances are hydrophobic in nature, act as proton donors or acceptors, and may act as a pH buffer (Weishaar, Aiken, Bergamaschi, Fram, Fujii, & Mopper, 2003). The difference in the source of OM leads to a difference in structure, and structure is the main factor influencing the reactivity and, therefore, the fate of OM. The information of this study may also help in clarifying the mechanism of HO• formation from organic mater, the fate in natural systems, and the intermolecular interactions of organic mater due to light exposure.

Dalrymple, R.M.,et al.(2012).Correlations Between Dissolved Organic Matter Optical Properties and Quantum Yielsd of Singlet Oxygen and Hydrogen Peroxide. Environmental Science and Technology,44,5824-5829.
Del Veccio,R., & Blough, N. V. (2004).On the Origin of the Optical Properties of Humic Substances. Environmental Science and Technology,38,3885-3891.
Helms, J.R., et al.(2008).Absorption Spectral Slopes and Slope Ratios as Indicators of Molecular Weight, Source, and Photobleaching of Chrompohoric Dissolved Organic Matter. The American Society of Limnology and Oceanography, Inc.,53(3),955-969.

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Small Scale Spatial Variations Within The Snowpack On Niwot Ridge, Long Term Ecological Research Site

Anonymous — Fri, 17 Aug 2018 16:57:50 +0000

Small Scale Spatial Variations Within The Snowpack On Niwot Ridge, Long Term Ecological Research Site Anonymous (not verified) Fri, 08/17/2018 - 10:57 Robert J Semborski

Semborski, Robert J ¹ ; Gotthelf, Kendal M ² ; Snyder, Danielle E ³ ; Howe, James B ⁴ ; Hewitt, Kelsey ⁵ ; Butler, Brent ⁶

¹ University of Colorado, Geography Department
² University of Colorado
³ University of Colorado, Environmental Studies
⁴ University of Colorado
⁵ University of Colorado
⁶ University of Colorado, Geography Department

Abstract: To understand how spatial variation on a small scale influences the snowpack, two snow-pit sites 100 meters apart are sampled at the Niwot Ridge (NWT) long-term ecological research (LTER) site 45 minutes west of Boulder, Colorado. Every Friday from January 2013 through March 2013 data is collected from two snow-pit sites: Soddie East and Soddie North. Student interns from the Institute of Arctic and Alpine Research (INSTAAR) dig snow-pits to measure and record snow depth, density, temperature, grain size, grain type, and hardness for each layer that forms within the snowpack. Using the collected data, we aim to investigate how small scale spatial variability can influence the snowpack with regard to snow water equivalence (SWE) and snow metamorphism. Data collected at a small time scale and space scale annually provides excellent validation for modeling snow water equivalence and snowmelt timing in the Rocky Mountains, essential for water management in Colorado.

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A Regression-Based Approach For Blending Remotely Sensed And In-Situ Snow Water Equivalent Estimates In The Colorado River Basin

Anonymous — Fri, 17 Aug 2018 16:57:05 +0000

A Regression-Based Approach For Blending Remotely Sensed And In-Situ Snow Water Equivalent Estimates In The Colorado River Basin Anonymous (not verified) Fri, 08/17/2018 - 10:57 Dominik Schneider

Schneider, Dominik ¹ ; Molotch, Noah ²

¹ Institute of Arctic and Alpine Research
² Institute of Arctic and Alpine Research

Snowmelt is the primary source of water supply in many parts of the world so it is important to understand the spatial and inter-year variability of snow accumulation and ablation. Several studies have analyzed the effect of physiographic variables on snow distribution so as to improve the basin-wide interpolations of point measurements. Concurrently, efforts exist to estimate snow water equivalent (SWE) distribution via hind-cast energy balance modeling (i.e. reconstruction) without the need for in-situ measurements. We developed a method that merges these two approaches by treating hind-cast energy balance snow distribution estimates as independent variables used to interpolate in-situ measurements. In this regard, we used a multiple linear regression to model SWE distribution based on physiography and reconstructed SWE estimates (independent variables) and observed SNOTEL SWE (dependent variable). Through this approach we were able to improve the explained variability of the model when including both reconstructed SWE and physiography as independent variables. For the years 2001 to 2010, the r-squared value improved an average of 0.23 for April 1st SWE predictions. R-squared values are statistically significant (>0.05) for all years for the months Mar-Jun and the increase in R-squared ranged from 0.04 to 0.59 (mean = 0.25). These preliminary results support the hypothesis that past patterns of snow cover depletion used in the reconstruction estimates may be useful for estimating the spatial distribution of SWE in real time.

Fassnacht, S. R., Dressler, K. A., & Bales, R. C. (2003). Snow water equivalent interpolation for the Colorado River Basin from snow telemetry (SNOTEL) data. Water Resour. Res., 39(8), 1208. doi:10.1029/2002WR001512
Molotch, N. P. (2009). Reconstructing snow water equivalent in the Rio Grande headwaters using remotely sensed snow cover data and a spatially distributed snowmelt model. Hydrological Processes, 23(7), 1076–1089. doi:10.1002/hyp.7206

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3D Modeling Of Groundwater Flow And Solute Transport In A Watershed Underlain By Salt Deposits In Southeast Utah

Anonymous — Fri, 17 Aug 2018 16:55:55 +0000

3D Modeling Of Groundwater Flow And Solute Transport In A Watershed Underlain By Salt Deposits In Southeast Utah Anonymous (not verified) Fri, 08/17/2018 - 10:55 Nadine Reitman

Reitman, Nadine ¹ ; Ge, Shemin ² ; Mueller, Karl ³

¹ University of Colorado at Boulder, Department of Geological Sciences
² University of Colorado at Boulder, Department of Geological Sciences
³ University of Colorado at Boulder, Department of Geological Sciences

Groundwater flow is an important control on subsurface salt dissolution. Natural evaporites are salt deposits that crack when dry or unloaded and flow ductilely when wet or loaded. These dynamics drive faulting and associated subsidence on the land surface. Dissolution of evaporites has increased salinity in groundwater and salt loading in river systems. A better understanding of the groundwater system is important for determining groundwater’s role in active fault slip, evaporite deformation, and salinity variations in freshwater resources. This study is conducted in the Gypsum Canyon watershed within the Paradox Basin in southeast Utah, south of Canyonlands National Park. The area comprises regional sedimentary formations underlain by evaporite cycles of the Paradox Formation. Active faults in the region slip at a rate of approximately 1 – 2 mm/year (Furuya et al., 2007), possibly due to evaporite dissolution. This study characterizes the groundwater flow and solute transport system of the Gypsum Canyon watershed using a 3D finite element groundwater flow and solute transport model, SUTRA. The lack of prior data and instrumentation and remote location of the watershed led to the use of creative methods for constraining and validating the model. Methods include sampling and mapping groundwater seeps and springs, analyzing stable isotopes of water (δ18O and δD) and total dissolved solids (TDS) in springs samples, and collecting rock samples for conducting hydraulic conductivity tests. Modeling results suggest that there is not enough groundwater-driven salt dissolution to account for the observed rate of fault slip in the region, and this watershed contributes on the order of 0.5 ton of salt per year to the Colorado River.

Furuya, M., Mueller, K., and Wahr, J., 2007, Active salt tectonics in the Needles District, Canyonlands (Utah) as detected by interferometric synthetic aperture radar and point target analysis: 1992–2002: Journal of Geophysical Research, v. 112, no. B6, p. 1–18, doi: 10.1029/2006JB004302.

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Many-Objective Design Of Engineered Injection And Extraction Sequences To Optimize In Situ Remediation Of Contaminated Groundwater

Anonymous — Fri, 17 Aug 2018 16:54:42 +0000

Many-Objective Design Of Engineered Injection And Extraction Sequences To Optimize In Situ Remediation Of Contaminated Groundwater Anonymous (not verified) Fri, 08/17/2018 - 10:54 Amy Piscopo

Piscopo, Amy N ¹ ; Neupauer, Roseanna M ² ; Kasprzyk, Joseph R ³ ; Mays, David C ⁴

¹ University of Colorado Boulder
² University of Colorado Boulder
³ Pennsylvania State University
⁴ University of Colorado Denver

Groundwater is an important resource that is often contaminated by various industrial and agricultural sources. Techniques to remediate contaminated groundwater exist but could be improved. Specifically, in situ remediation is a favorable form of groundwater remediation, in which a treatment solution is injected into the contaminated aquifer to degrade the contaminated groundwater in place. However, the degradation that occurs during in situ remediation is limited to areas where the treatment solution and groundwater contaminant contact each other, which are often small and invariable. Natural phenomena, such as ambient groundwater flow and natural heterogeneity, provide a degree of spreading which can influence the position of the treatment solution relative to the contaminant, allowing for degradation reactions to occur. Engineered injection and extraction (EIE) is a novel technique that can enhance spreading significantly, using a sequence of injections and extractions of clean water at wells that surround the groundwater contaminant plume and the added treatment solution. In consequence, EIE leads to more contaminant degradation than natural phenomena and ultimately reduces the duration of treatment. While the improvement over natural phenomena is significant, EIE can likely increase contaminant degradation beyond the amount demonstrated previously, since prior work was conducted for one unique sequence of EIE. New approaches are needed to optimize the EIE sequence according to engineering performance objectives and constraints, where the primary objective is to maximize contaminant degradation, for example. This study develops a multi-objective evolutionary algorithm (MOEA), a search algorithm based on the mechanics of natural selection and genetics, for that purpose. The ultimate value of the MOEA lies in its ability to determine the optimal EIE sequence for any contaminated site (e.g. for sites with varied degrees of aquifer heterogeneity, aqueous versus sorbing contaminants, numbers of wells, and locations of wells); therefore, it is a valuable tool that expands the relevance and applicability of EIE.

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An Adjoint Approach To Estimating Stream Depletion

Anonymous — Fri, 17 Aug 2018 16:53:48 +0000

An Adjoint Approach To Estimating Stream Depletion Anonymous (not verified) Fri, 08/17/2018 - 10:53 Roseanna M. Neupauer , Daniel F. McCarl

Neupauer, Roseanna M. ¹ ; McCarl, Daniel F. ²

² Presenting Author

¹ University of Colorado
² University of Colorado

Pumping groundwater can draw water from a nearby stream and decrease the flow rate of water in the stream. We call this effect “stream depletion.” Stream depletion is quantified as the difference between the river flow rate in the absence of pumping and in the presence of pumping. Stream depletion has many negative consequences; for example, stream depletion can disturb riparian habitats and infringe on water rights. Thus, when a new well is to be drilled, it may be desirable to choose a well location that will minimize stream depletion. To find such a location, previous methods required that a separate computer simulation be run for each possible well location. We develop an adjoint-based method. Our adjoint-based method requires only one computer simulation to determine the stream depletion at all possible well locations. Thus, the adjoint method is computationally more efficient. Previously, the equations for the adjoint-method have been derived for (1) a model in which the streambed was assumed to a “wide” rectangle and (2) a model in which the streambed was rectangular and the water level in the river was independent of groundwater pumping. We derive the equations for a model with a generic rectangular streambed, and we assume that the water level in the river is dependent on pumping. In the future, we will derive equations for more complex streambed geometries, including an eight-point cross section.

Neupauer, R.M., and S.A. Griebling, 2011, Adjoint Simulation of Stream Depletion Due to Aquifer Pumping, Ground Water, doi:10.11/j.1745-6584.2011.00901.x.
Sykes, J.F., J.L. Wilson, and R.W. Andrews, 1985, Sensitivity analysis for steady state groundwater flow using adjoint operators, Water Resources Research 21, no. 3: 359-371.

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Impact Of Different Large-Scale Hydrologic Model Forcing Data On Hydrologic Simulations Over Mountainous Regions

Anonymous — Fri, 17 Aug 2018 16:52:38 +0000

Impact Of Different Large-Scale Hydrologic Model Forcing Data On Hydrologic Simulations Over Mountainous Regions Anonymous (not verified) Fri, 08/17/2018 - 10:52 Naoki Mizukami

Mizukami, Naoki ¹ ; Clark, Martyn ² ; Mendoza, Pablo ³ ; Gutmann, Ethan ⁴

¹ NCAR
² NCAR
³ University of Colorado at Boulder
⁴ NCAR

Process-based hydrologic models are valuable tools to understand physical mechanism of hydrologic impact under climate change. However, such models require extensive meteorological forcing data, including precipitation, temperature, shortwave and longwave radiation, humidity, surface pressure and wind speed. Data on precipitation and temperature are more common than the other variables – consequently, radiation, humidity, pressure and wind speed often must be either estimated using empirical relationships with precipitation and temperature, or obtained from numerical weather prediction models. We examined two climate forcing datasets, which use different methods to estimate radiative energy fluxes and humidity, and investigated the impact of the choice of forcing data on hydrologic simulations over the mountainous Upper Colorado River basin. Comparisons of model simulations forced by two forcing data illustrate that the methods used to estimate shortwave radiation have a large impact on hydrologic states and fluxes particularly in high elevation (e.g., ~20% difference in runoff above 3000 m elevation), substantially altering the timing of snow melt and runoff (~20 days difference) and the partitioning of precipitation between evapotranspiration and runoff. The different forcing datasets also potentially exhibit large differences in hydrologic sensitivity to inter-annual temperature and precipitation. The results suggest that the choice of forcing dataset is an important consideration when conducting climate impact assessments, and subsequent applications in water resources planning and management. This presentation also discusses on-going study on impact of forcing datasets generated with different downscaling methods on hydrologic simulations.

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Towards A Better Understanding Of Hydrologic Sensitivity To Climate Change: Impact Of Hydrologic Model Choices

Anonymous — Fri, 17 Aug 2018 16:51:33 +0000

Towards A Better Understanding Of Hydrologic Sensitivity To Climate Change: Impact Of Hydrologic Model Choices Anonymous (not verified) Fri, 08/17/2018 - 10:51 Pablo A Mendoza

Mendoza, Pablo A ¹ ; Clark, Martyn P ² ; Rajagopalan, Balaji ³ ; Mizukami, Naoki ⁴

¹ University of Colorado at Boulder
² National Center for Atmospheric Research
³ University of Colorado at Boulder
⁴ National Center for Atmospheric Research

Over the last few decades the hydrological community has intensively used the “cascade of uncertainty” paradigm in climate change studies, which considers several sources of uncertainty such as emissions scenarios, different general circulation model (GCM) structures and parameters, distinct GCM initial conditions, several downscaling methods and multiple hydrological model structures. Nevertheless, this approach does not help to advance process understanding or predictive capabilities. Therefore, in this study we assess the hydrologic sensitivity to climate change for three different hydrologic/land surface models (PRMS, VIC and Noah-MP) over a small set of case study basins located in the headwaters of the Colorado River basin, USA. Our goal is to evaluate how hydrologic sensitivities vary across models in terms of 1) the main water balance components, and 2) seasonal changes in individual states and fluxes. Results show that despite all the models predict an increase in ET and decrease in SWE and runoff for a future climate scenario, the partitioning of precipitation into ET and runoff is clearly model-dependent. Noah-MP is the most sensitive model in water balance budget components, and all models reflect very similar seasonal changes in basin-averaged snowpack. Some individual fluxes are more sensitive to changes in climate than others (e.g. baseflow). Ongoing research is focused on parameter perturbation experiments to improve understanding of the relative role of parameters and model structures. Furthermore, future work will help to determine the actual role of model calibration and forcing datasets in climate impact assessments.

Rasmussen, Roy, and Coauthors, 2011, High-Resolution Coupled Climate Runoff Simulations of Seasonal Snowfall over Colorado: A Process Study of Current and Warmer Climate. J. Climate, 24, 3015–3048.
Vano, J. a., T. Das, and D. P. Lettenmaier, 2012, Hydrologic Sensitivities of Colorado River Runo to Changes in Precipitation and Temperature. Journal of Hydrometeorology, 13 (3), p. 932-949.

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