The HUES group (Hydro-Environmental Systems) studies sustainability challenges at the intersection of hydrology, economics, and social systems, often in data-scarce contexts. We focus on two main themes: water cooperation and conflict, including governance of transboundary aquifers, treaty resilience under climate change, and links between water scarcity and armed conflict; and the Water–Energy–Food–Environment nexus, where we examine how land acquisitions, irrigation, and mining reshape food security, water access, and local livelihoods. Methodologically, we integrate remote sensing, machine learning, causal inference, microeconomic theory and hydrological modeling to generate actionable evidence. Our goal is to bridge research, practice, and policy to address pressing global water challenges.

Research Highlights

Land Grabs and Commercial Agriculture

Water and Armed Conflict

Transboundary Groundwater

National Science Foundation Grant ICER 1824951: "CNH: What does it take to collaborate over transboundary groundwater resources?"

Transboundary Rivers

Governance of Water Tenure

A substantial share of the global population lacks formal rights to the water they depend on for health and livelihoods. Muller is part of a global expert group supporting an initiative led by the UN Food and Agriculture Organization to identify, recognize, and protect these informal forms of access—referred to as water tenure. Building on successful efforts to strengthen tenure security for land, fisheries, and forests through the Voluntary Guidelines on the Responsible Governance of Tenure (VGGT), this initiative aims to define principles and responsible governance practices to safeguard water tenure through an inclusive process of global dialogue.

How to reconcile the broad and universal nature of the human right to water with the local realities of water security and water governance? 

Our new framework addresses this question to facilitate a preemptive implementation of the human rights to water in the context of water-intensive industrial operations, such as mining, commercial agriculture, hydropower beverages and textiles. 

Check out the video of our session at World Water Week 2022, and access the white paper describing the framework.

​We recently presented this work at the Social Forum of United Nations High Commission for Human Rights in Geneva (Switzerland), and at the UN Water conference at the United Nations HQ in New York City in March 2023 

Sociohydrology and Climate Change

National Science Foundation Grant EAR 2142967: "CAREER: CAS-Climate: Sociohydrology to link climate change and its societal impacts"

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Research Agenda