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

¹ 精品SM在线影片-CEAE
² 精品SM在线影片-CEAE
³ 精品SM在线影片-CEAE

Groundwater comprises about 30 percent of Earth鈥檚 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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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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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鈥�1089. doi:10.1002/hyp.7206

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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鈥檚 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 鈥� 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 (未18O and 未D) 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鈥�2002: Journal of Geophysical Research, v. 112, no. B6, p. 1鈥�18, doi: 10.1029/2006JB004302.

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

¹ 精品SM在线影片
² 精品SM在线影片
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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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 鈥渟tream depletion.鈥� 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 鈥渨ide鈥� 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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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 鈥� 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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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 鈥渃ascade of uncertainty鈥� 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鈥�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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Macpherson, Brian ¹ ; Rajaram, Harihar ²

¹ 精品SM在线影片, Department of Civil, Environmental, and Architectural Engineering
² 精品SM在线影片, Department of Civil, Environmental, and Architectural Engineering

Our research focuses on two aspects of ice sheet thermodynamics - (i) comparsion of enthalpy and temperature-based approaches for incorporation into thermo-mechanical models, and (ii) refinement of thermodynamic models to incoroprate processes such as cryo-hydrologic warming in the wet snow and ablation zones.

Alternative formulations of thermodynamic equations for continua include temperature-based, and various types of enthalpy-based formulations. The enthalpy-based formulations are ideally suited to situations where phase change or temperate conditions are encountered. Ice sheet thermomechanical models often employ one-dimensional column implementations of vertical energy transport coupled to horizontal transport. We compare column models incorporating temperature-based, and two types of enthalpy-based approaches (apparent heat capacity and enthalpy gradient) under a range of conditions. Our comparison confirms that these approaches are mutually consistent, even in cases where temperate ice is encountered at some internal depth. However, there are distinct computational advantages to enthalpy-based methods that require no iteration to find the cold-temperate interface and compute temperature and water content directly from the state variable, enthalpy.

Cryo-hydrologic warming (CHW) is a recently proposed mechanism for the rapid thermal response of ice sheets to melt inputs resulting from a warming climate. CHW is expected to be a significant component of ice sheet thermodynamics, specifically in areas that have only recently begun to receive melt (the estimated upstream expansion of the area receiving melt is 10-20km along a wide swath in western Greenland). We evaluate the physical underpinnings of CHW using high-resolution enthalpy-based models surrounding water-filled englacial features. We demonstrate the potential warming influence of these englacial water bodies in isolation, and in conjunction with other mechanisms, including advection and strain heating. Our results suggest that significant warming (to the extent of a temperature change that doubles the value of the flow-law parameter "A") occurs within decadal time-scales. Our simulations also suggest that deep englacial water bodies are required for significant thermo-mechanical influence of CHW. Deep englacial water bodies are shown to produce greater warmth near the bed where large gradients in velocity result in stretching and efficient dissipation of latent heat. In some situations, CHW may induce cold to temperate transitions near the bed, within decadal time-scales, priming the bed to permit year-round basal sliding.

Aschwanden A., Bueler, E., Khroulev, C., and Blatter, H., 2012, An enthalpy formulation for glaciers and ice sheets: Journal of Glaciology, v. 58, p. 441鈥�457.

Phillips, T., Rajaram, H., and Steffen, K., 2010, Cryo-hydrologic warming: A potential mechanism for rapid thermal response of ice sheets, Geophys. Res. Lett., v. 37, L20503

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