# Hydrology in the 21st century: challenges in science, to policy and practice

## TL;DR

This paper discusses the future of hydrology in the 21st century, emphasizing the need for advanced science, policy integration, and collaborative approaches to address climate and water challenges.

## Contribution

The paper introduces a transdisciplinary approach to hydrology, advocating for open science, AI integration, and co-produced knowledge to enhance resilience and policy impact.

## Key findings

- Hydrology requires open, reproducible science and integration of machine learning and AI for better forecasting.
- Collaboration and co-produced knowledge are essential to support adaptation and resilience in the face of climate extremes.
- Education and equity play critical roles in advancing hydrology that is both technically and socially responsive.

## Abstract

To mark the 40th anniversary of the British Hydrological Society, a landmark Discussion Meeting was held at the Royal Society in June 2024, bringing together a transdisciplinary community, including hydrologists, policymakers and practitioners, to reflect on four decades of progress and chart future directions for hydrology. This special issue presents a collection of papers from that meeting, addressing advances in data, modelling, forecasting and decision-making in the context of intensifying climate and hydrological extremes. Key themes include the need for open, reproducible science, greater integration of machine learning, AI and convection-permitting models and a shift towards transdisciplinary, co-produced knowledge that better supports adaptation, resilience and policy impact. The issue highlights the critical roles of education, collaboration and equity in shaping a hydrology that is not only technically advanced but socially and environmentally responsive to the challenges of the 21st century.

This article is part of the Royal Society Science+ meeting issue ‘Hydrology in the 21st century: challenges in science, to policy and practice’.