Research

Rivers in semi-arid regions swing between floods and drying. We study how climate and people are shifting those swings, and what that means for the life rivers support and the work they do.

Guiding questions

How do climatic extremes and human water use alter river flow regimes, from floods to low flows and drying, and what does that mean for water security and environmental flows?
How do changes in flow, intermittency and connectivity shape freshwater biodiversity and the ecological functions of streams?
How can we bring hydrology, ecology and modelling together to help agencies, water managers and communities keep rivers resilient to extremes and human alteration?

From flow to habitat

We follow changes in river flow through to the habitat and organisms that depend on it.

A lowland river running high and fast between grassy banks at flood peak — The same lowland river at flood peak (top) and low flow (bottom).

The same river at low flow, with exposed banks, shallow water and woody debris — The same lowland river at flood peak (top) and low flow (bottom).

Microscope photo of a freshwater insect larva with a 1 mm scale bar — A freshwater macroinvertebrate larva. Macroinvertebrates are one of the groups we use to link flow to biodiversity. Scale bar 1 mm.

Diagram of a modelling framework: climate change scenarios drive SWAT+ hydrology, 1D and 2D hydraulic models and CASiMiR habitat suitability, leading to environmental flow thresholds and future changes in indicators — Integrated hydrological–hydraulic–habitat modelling framework linking climate scenarios to environmental flow thresholds (Chattopadhyay et al., 2024).

Approach

We combine empirical work in the field with modelling.

FieldHydrological, water-quality and biodiversity observations, including environmental DNA
DataLong-term records from national and global streamflow and climate networks
ModelsWatershed and habitat models, such as SWAT+ and hydraulic–habitat models
AnalysisStatistical and data-driven methods

Where we work

Our field research centers on rivers of the Texas Hill Country and Edwards Plateau. Earlier work took the group to lowland rivers in Poland, river basins in southern India, and watersheds in Kentucky and North Carolina.

Collaborations

We work with colleagues at Texas State University and research groups across the United States and Europe, including long-running collaborations on environmental flows and catchment modelling with Warsaw University of Life Sciences, Poland.

A tree-lined Hill Country stream pool at low flow, seen from a low-water crossing — A tree-lined stream pool at low flow in the Hill Country.