41st annual hydrology days (2021) - online proceedings

The 41st Annual AGU Hydrology Days event at Colorado State University was hosted online March 30-31, 2021.Includes the schedule and presentation abstracts only. The 41st Annual American Geophysical Union Hydrology Days meeting provides a unique opportunity for students, faculty, staff and practitioners to engage in wide range of water-related interdisciplinary research topics. Unfortunately, the global pandemic has left students with limited opportunities to share their research and satisfy graduation requirements. This year the spotlight focused on students to highlight the interconnections of water and linked systems. The 2021 Student Showcase provides an opportunity for students to exchange ideas, present their research findings and refine their science communication skills

Earth Systems Modeling in the Brazos River Alluvium Aquifer: Improvement of Computational Methods and Development of Conceptual Model

Traditional hydrologic modeling has compartmentalized the water cycle into distinct components (e.g. Traditional hydrologic modeling has compartmentalized the water cycle into distinct components (e.g. rainfall-runoff, river routing, or groundwater flow models). In river valley alluvium aquifers, these processes are too interconnected to be represented accurately by separate models. An integrated modeling framework assesses two or more of these components simultaneously, reducing the error associated with approximated boundary conditions. One integrated model, ParFlow.CLM, offers the advantage of parallel computing, but it lacks any mechanism for incorporating time-varying streamflow as an upstream boundary condition. Previous studies have been limited to headwater catchments. Here, a generalized method is developed for applying transient streamflow at an upstream boundary in ParFlow.CLM. The upstream inflow method was successfully tested on two domains – one idealized domain with a straight channel, and one small stream catchment in the Brazos River Basin. The stream in the second domain is gaged at the upstream and downstream boundaries. Both tests assumed a homogeneous subsurface, so that the efficacy of the transient streamflow method could be evaluated with minimal complications by groundwater interactions. Additionally, an integrated conceptual model is presented for the Brazos River Alluvium Aquifer (BRAA), the Brazos River, and the overlying terrain. The BRAA is a floodplain aquifer in central to southeast Texas. This aquifer is highly connected to the Brazos River and experiences localized semi-confined conditions beneath thick surface clay layers. The conceptual model is designed to be implemented in an Earth system modeling framework and is limited to the central portion of the aquifer in Brazos and Burleson Counties, Texas. Unlike previous models in ParFlow.CLM, this is a high-order subbasin with large inflows from upstream. Additionally, the model incorporates no-flow, transient head, and free drainage boundaries. Preliminary tests suggest the need for a long spin-up period. Long-term simulations will require calibration of surface and subsurface parameters before using the model to assess system behavior

Integrated Environmental Modelling Framework for Cumulative Effects Assessment

Global warming and population growth have resulted in an increase in the intensity of natural and anthropogenic stressors. Investigating the complex nature of environmental problems requires the integration of different environmental processes across major components of the environment, including water, climate, ecology, air, and land. Cumulative effects assessment (CEA) not only includes analyzing and modeling environmental changes, but also supports planning alternatives that promote environmental monitoring and management. Disjointed and narrowly focused environmental management approaches have proved dissatisfactory. The adoption of integrated modelling approaches has sparked interests in the development of frameworks which may be used to investigate the processes of individual environmental component and the ways they interact with each other. Integrated modelling systems and frameworks are often the only way to take into account the important environmental processes and interactions, relevant spatial and temporal scales, and feedback mechanisms of complex systems for CEA. This book examines the ways in which interactions and relationships between environmental components are understood, paying special attention to climate, land, water quantity and quality, and both anthropogenic and natural stressors. It reviews modelling approaches for each component and reviews existing integrated modelling systems for CEA. Finally, it proposes an integrated modelling framework and provides perspectives on future research avenues for cumulative effects assessment

Understanding and Predicting Vadose Zone Processes

Vadose zone hydrologic and biogeochemical processes play a significant role in the capture, storage and distribution of contaminants between the land surface and groundwater. One major issue facing geoscientists in dealing with investigations of the unsaturated zone flow and transport processes is the evaluation of heterogeneity of subsurface media. This chapter presents a summary of approaches for monitoring and modeling of vadose zone dynamics in the presence of heterogeneities and complex features, as well as incorporating transient conditions. Modeling results can then be used to provide early warning of soil and groundwater contamination before problems arise, provide scientific and regulatory credibility to environmental management decision-making process to enhance protection of human health and the environment. We recommend that future studies target the use of RTMs to identify and quantify critical interfaces that control large-scale biogeochemical reaction rates and ecosystem functioning. Improvements also need to be made in devising scaling approaches to reduce the disconnect between measured data and the scale at which processes occur

Adaptive Water Management-land Use Practice for Improving Ecosystem Services – a Hungarian Modelling Case Study

During the 20th century in the Hungarian lowlands the emphasis was put on maximizing provisioning ecosystem services (ES), which caused the weakening of regulating and other services. With the growing environmental pressures, it is crucial to apply a more adaptive landscape management. This, however, leads to territorial conflicts, as large areas with water-tolerant land cover (i.e., wetlands, meadows, riparian forests) are needed to buffer extreme hydrological events.We present some findings of the WateRisk project, a research that focused on the possible solutions of these conflicts. In a scenario-based case study, we analyze the outlined issue for the Szamos-Kraszna Interfluve, a 510 km2 lowland catchment heavily affected by excess water. Scenarios were evaluated with an integrated methodology that focuses on the water budget and the total values of ES. The efficiency of the drainage network was found to be minor/moderate as it provided only -1–5% reduction in the spatial extents of inundations, and it contributed only ~20% to the elimination of water coverage. Furthermore, comparing the present (defense-focused) and the alternative (water retention focused) scenarios, the latter turned out to provide higher monetary value for the summed individual and social benefits of ES. This underlines the need for extensive adaptive measures in both water management and landscape planning to create resilience and the ability to cope with contemporary environmental challenges

FORECASTING CLIMATE AND LAND USE CHANGE IMPACTS ON ECOSYSTEM SERVICES IN HAWAIʻI THROUGH INTEGRATION OF HYDROLOGICAL AND PARTICIPATORY MODELS

Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018