Contact: Yadu

Dr. Pokhrel’s research interests are in the following broad areas: interactions between water management practices (e.g., dam operation, irrigation, and groundwater pumping) and the water cycle; modeling water resource availability and use; impact of climate change on water availability; competing use of water for different societal sectors (e.g., domestic, industrial, agricultural); surface water-groundwater interactions under changing water use and climate.

A hydrological-agricultural-ecological modeling framework that simulates the integrated effects of human water management and climate change on water resources and the interactions among these natural-human systems constitutes the foundation of Dr. Pokhrel’s research. He uses this novel framework to address pressing science and societal issues related to Food-Energy-Water systems from global to local scales. The strength of his work also lies in the integration and assimilation of wide ranging remote sensing products in hydrologic modeling. He previously led studies on the impacts of irrigation and groundwater pumping on groundwater depletion in the Central High Plains and California Central Valley in the US.

His current research efforts are focused on using these modeling tools and satellite data to assess changing hydrologic, agricultural, and ecological systems in regions including the Mekong and Amazon river basins, and the continental US.


CAREER: Humans, Water, and Climate: Advancing Research and Education on Water Resource Sustainability in Managed Land-Water Systems Using an Integrated Hydrological Modeling Framework

A critical challenge in sustainable water resource management is to ensure adequate supply of water to meet the rapidly growing demands for food, energy, and water, while minimizing negative social, environmental, and ecological impacts. Striking this balance requires a clear understanding of the human-induced changes in freshwater flows and storages, agricultural systems, and ecosystem services, as well as the complex interactions and feedback among coupled natural and human systems. The goal of this project is to advance the research and education of water resource sustainability in managed land-water systems by using a novel numerical modeling framework and a wealth of data from ground and satellite observations, climate models, and socio-economic analysis. The framework, which comprises of a suite of hydrological, agricultural, and ecological models, is used to identify ways to optimize the use of land and water resources by systematically examining the trade-offs between upstream basin management for food-energy production (e.g., hydropower, irrigation) and downstream changes in river-floodplain dynamics and groundwater systems (e.g., reduction in sediment load, seawater intrusion). The project will provide new insights about ways to best utilize the information on global change and practices for local-regional water management through its integration into coupled hydrological-agricultural-ecological models to develop adaptation strategies for sustainable water resource management as well as achieving water and food security. The research project integrates a substantive set of educational initiatives for promoting knowledge about hydrology and water resources among high school and community college students, motivating them to pursue STEM education and inspiring them to study freshwater systems toward addressing pressing societal challenges regarding food, energy, and water security. The educational component involves an interactive web-based version of the modeling system for classroom use in undergraduate and graduate teaching, for educating high school and community college students, and as resource for teachers especially in community colleges. The education program also includes mentored international research and training through online initiatives.

The modeling framework is based on the Community Land Model (CLM) but includes critical enhancements made by incorporating advanced schemes representing crop growth, irrigation, groundwater pumping, and river-floodplain-reservoir routing. The strength of this novel framework lies in its ability to explicitly resolve the coupled behavior of a range of natural hydrologic and biophysical processes (e.g., surface hydrology, groundwater dynamics, sediment transport, land use change, and crop growth), human land-water management practices (irrigation, reservoir operation, groundwater pumping), and ecological processes (seawater intrusion, floodplain-wetland dynamics). The framework is designed to simulate large-scale water cycle dynamics at regional to continental scales while also mechanistically resolving fine-scale, topography-driven hydrologic-groundwater processes such as lateral groundwater flow and river-floodplain-groundwater interactions. Thus, the study will significantly advance our capability to simulate coupled surface water, groundwater, and agricultural systems, which is critical for achieving food security through better assessment and prediction of water resource. Since CLM is a land component of an Earth System Model (ESM), the new framework and insights gained from the study are expected to inform the development of the next generation of ESMs through the incorporation of human components for the holistic study of coupled natural-human systems, and to assess human-climate interactions. The new framework will also enable us to better assess and predict water resources in highly managed land-water system around the world including the High Plains in the central US and Central Valley in California where declining water supplies are likely to adversely impact regional, national, and global food security in the future.

Funded by: National Science Foundation

Collaborative Research: Anthropogenic water management, Climate Change, and Environmental Sustainability in the Southwestern US (ACCESS)

There have been growing concerns about water security in the southwestern US because of dwindling supplies and rising demands. The hydrology of the region is changing in ways that could critically undermine water supplies, agricultural production, power generation, and river-dependent ecosystems. Of particular concern is the declining flows in the Colorado River, a lifeblood for over 40 million people in seven southwestern states. Frequent and prolonged droughts have brought reservoir water levels in the Colorado River to record lows, raising concerns about a water crisis if current trends continue. This project examines whether future water demands in the southwestern US can be met under projected climate and current water management practices while maintaining environmental flow requirements, and if not, whether there are alternative approaches to achieving sustainability. The project directly engages regional stakeholders for participation in co-producing key aspects of the research and ensuring deliverables that are of the greatest value for improved water resource management. It also provides exposure to K-12 and undergraduate students regarding one of the nation’s most pressing water resource sustainability issues.

The project uses high-resolution, long-term hydrologic simulations from a state-of-the-art hydrological modeling system to systematically examine the complex interplay between decreased water supplies under climate change, future demands, and the role of water management (e.g., reservoir operation, groundwater use, and out of basin water transfer) in mitigating climate impacts. The specific project objectives are to (1) quantify the future changes in water supplies and demands and examine their spatio-temporal trends and variabilities, (2) examine the changes in surface reservoir and groundwater storages, and quantify risks of storage depletion associated with intensified future droughts, and (3) co-develop potential sustainability pathways with regional stakeholders by considering tradeoffs between competing inter-sectoral water use and environmental flow requirements, and evaluate these pathways under a range of climate change and socio-economic growth scenarios. By considering various climate change and water use scenarios, combined with stakeholder-informed management options, the project holistically examines various possible pathways for water resource sustainability in the southwestern US. The integrated modeling framework developed in this project will provide major advances in the ability to simulate coupled natural-human systems in highly water-scarce regions. Project outcomes will be used in informing water resource management and educating K-12 and college students on growing water scarcity issues under climate change..

Funded by: National Science Foundation

Belmont Forum Collaborative Research: Biosphere and Land Use Exchanges with Groundwater and soils in Earth system Models (BLUEGEM)

This award provides support to U.S. researchers participating in a project competitively selected by a 9-country initiative on global change research through the Belmont Forum. The Belmont Forum is a consortium of research funding organizations representing over 55 countries focused on support for transdisciplinary approaches to global environmental change challenges and opportunities. It aims to accelerate delivery of the international research most urgently needed to remove critical barriers to sustainability by aligning and mobilizing international resources. Each partner country provides funding for their researchers within a consortium to alleviate the need for funds to cross international borders. This approach facilitates effective leveraging of national resources to support excellent research on topics of global relevance best tackled through a multinational approach, recognizing that global challenges need global solutions. This award provides support for the U.S. researchers to cooperate in consortia that consist of partners from at least three of the participating countries. The research teams will work to identify sustainable pathways to help alleviate the increasing and unprecedented pressure on the natural resources that interact to provide sustainable life support systems and essential benefits to societies such as food production and water quality and quantity. The impacts of changes in land management and urbanization will be evaluated to develop sustainable soils and groundwater management options that will help create and maintain sustainable terrestrial ecosystems.

The project seeks to explore the evolution of groundwater, irrigation, and climate during the Anthropocene (1900-2100), to better understand their interdependencies, foresee their potential changes, and identify possible social consequences. The team will assess these factors to identify sustainable pathways with respect to water resources, food security, biodiversity, and human well-being and socio-economic activities. The team will combine advanced numerical modeling of biophysical and social systems, as well as participatory methods with stakeholders, to address establish the fingerprint of interactions and irrigation on global and regional climate, water resources, biosphere, and soil carbon pools. The project results will provide improved projections of global and regional climate, water resources, biosphere and soil carbon pools, fully taking into account the influence of groundwater irrigation and groundwater-soil moisture interactions. The team will Integrate local and regional knowledge and expertise as well as socio-economic data to refine the land use and irrigation scenarios used in state-of-the-art climate projections and to explore pathways for sustainable critical zone management.

Funded by: National Science Foundation