Handbook of Catchment Management

Robert C. Ferrier, Alan Jenkins, Robert C. Ferrier, Alan Jenkins

• Publisher: Wiley-Blackwell
• Year: 2021
• ISBN:
  9781119531258
• Edition: 2
• Topic: Physical Sciences
• Subtopic: Hydrology

HANDBOOK OF CATCHMENT MANAGEMENT

In 2010, the first edition of the Handbook of Catchment Management provided a benchmark on how our understanding and actions in water management within a catchment context had evolved in recent decades. Over ten years on, the catchment management concept isentering a new phase of development aligned to contemporary and future challenges. These include climate change uncertainty, further understanding in ecological functioning under change, the drive for a low-carbon, energy efficient and circular society, multiple uses of water, the emergence of new pollutants of concern, new approaches to valuation, finance and pricing mechanisms, stewardship and community engagement, the integration of water across the Sustainable Development Goals (SDG) and the link between water, energy and food. These developments are framed within an increasingly data rich world where new analytics, sensor technology and processing power are informing increasingly real-time decision making. The challenge is also to increase cross-compliance and policy integration to meet multiple stakeholder objectives, and to link actions to achieve cost-effective outcomes. In addition, there are a number of new and exciting city, region and basin-scale real-world examples of contemporary and new catchment thinking; integrating science, technology, knowledge and governance to address multiple drivers and complex problems from across the globe. The time is now right, to capture the new challenges facing catchment management and water resources management globally.

This revised and updated edition of the Handbook of Catchment Management features:

• Thoroughly rewritten chapters which provide an up-to-date view of catchment management issues and contexts
• New case study material highlighting multi-sectoral management in different globally significant basins and different geographical locations
• Up-to-date topics selected for their resonance not only in natural sciences and engineering, but also in other fields, such as socio-economics, law and policy

The Handbook is designed for a broad audience, but will be particularly useful for advanced students, researchers, academics and water sector professionals such as planners, consultants and regulators.

1
Introduction to Catchment Management in 2020

Robert C. Ferrier¹ and Alan Jenkins²

¹ James Hutton Institute, Aberdeen, UK

² UK Centre for Ecology & Hydrology, Wallingford, Oxfordshire, UK

Source: S. Charman, James Hutton Institute, UK.

1.1 Introduction

The hydrological cycle is the fundamental earth system process supporting life on our planet. In essence, the basic physical principles of how water moves through the environment and how it interacts with the atmosphere, landscape, and oceans are consistent with contemporary thermodynamic paradigms, and nothing in that regard has changed over the history of the Earth.

The interaction of water with the landscape has resulted in a myriad of aquatic habitats, all with individual physico‐chemical characteristics and in many cases unique biodiversity. The importance of fluvial processes and sediment transport to estuarine and coastal environments has supported the productivity of coastal ecosystems and their role as important nursery areas for marine species as well as providing integral protection from coastal erosion. Natural terrestrial habitats reflect the dynamics of the earth's surface in the interplay of the hydrological cycle, shaping features such as lakes, streams, river channels, deltas, the interaction between ground and surface water and evaporative salt lakes that have taken millennia to form and develop. Geological and biogeochemical processes influence the composition of water as it flows over the landscape and infiltrates into subsurface flow and out to the sea, changing over time driven by flow dynamics and connectivity in turn reflecting global climate patterns and seasonal and daily weather patterns.

1.2 Historical Synopsis

In concert with these natural processes, however, human interaction with the hydrological cycle has significantly changed and at an increasing pace. This change is expressed during the current geological age, the Anthropocene, which is viewed as the period during which human activity has been the dominant influence on climate and the environment. The new world of the Anthropocene is dangerous, complex, unstable, and uncertain (Dean et al. 2014), differing significantly from the Holocene, the world humans lived in during the previous 10 000 years (Pereira and Freitas 2017). Ferrier and Jenkins (2010) reviewed the concept of catchment management in relation to human influence and management of the interplay of water and landscape, and what approaches and tools were being employed through which to manage that interaction. They highlighted how physical, chemical, and ecological management of resources follows principles and guidelines informed by both science and policy communities and how these were being addressed through geographical and context‐specific challenges in flagship basins across the globe.

A decade on from that review and mankind's influence on the water cycle has manifestly changed in terms of both chronic and acute drivers of change. Climate change, driven through the increase in greenhouse gas (GHG) emissions and an increase in carbon dioxide (CO₂) concentration in the composition of the global atmosphere, has been expressed through many changes, most of which are expressed in a negative way. Since 2010, there has been an approximate 5% increase in CO₂ concentration (from 390 parts per million [ppm] to 410 ppm); the past four years (2015–2019) have been the hottest on record with global temperatures rising; ice mass loss in Antarctica has tripled since 2012; glacial retreat and the loss of the Greenland ice shelf have continued (and in some locations accelerated); Arctic sea ice has declined in both extent and thickness; and the amount of seasonal snow accumulation in the northern hemisphere has decreased and snow melt is occurring earlier in the year (WMO 2019). The outcome of this is increasing loss of our global ice and snow reserves, which affect seasonal flow dynamics and biogeochemistry of our rivers, and flux to the coast combined with sea‐level rise.

In relation to atmospheric response, global warming has increased the energy of the global circulation manifesting in increased storminess, changes to seasonal and annual cycles of flood, prolonged periods of drought, and changed geographical distributions of rainfall and temperature rise. This has been reflected in record‐breaking droughts in Australia (‘Millennium’ drought); record summer temperatures experienced in Europe (record in France of 46 °C in 2019) and Japan (39.6 °C in 2019); altered Monsoon patterns in India (Turner 2018); and increased frequency of cyclonic depressions in the Atlantic (Bhatia et al. 2019). The outcome of this has had a direct impact on countries, regions, and communities, particularly those most vulnerable to climate risk, namely, the poor. Droughted crops and damage to yield through weather induced damage has increased (FAO 2016), and global supply chains are now having to adapt to increase resilience to climate. Agriculture suffers from 25% of all the economic damage caused by climate‐related disasters, and on average over 80% of all damage is generated from drought (FAO 2015). Provision of potable supplies and the vulnerability of our ever‐growing cities and the proportion of the global population living under water stress have been exposed as a real twenty‐first‐century threat (IPCC 2014), as has the incidence of disaster‐induced and climate‐driven health issues affecting citizens. The ‘countdown to day zero’, when the city of Cape Town could have potentially run out of water, was a clear message on how water resources planning is out of synchrony with our changing environment (The Economist 2018). This means that nations, regions, and communities of people will increasingly compete for available water resources (Box 1.1).

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Box 1.1 Global Cities Under Threat of Water Security

In 2010, 51% of the world's population was living in cities, and by 2050, that percentage is expected to climb to 70%. In the next 40 years, world cities are expected to receive 800 000 new inhabitants every week. In Latin America, more than 80% of the population live in cities. Many cities have expanded due to regional economic pressures and migration to urban and peri‐urban environments with a concomitant decline in rural populations. Cities can become vulnerable or at risk due to being located in already water sparse environments, where the available resource is not of significantly high quality, where management and infrastructural needs are not met, or simply where consumption outstrips supply (Justo 2019). In addition, cities in river deltas are especially vulnerable to flooding (Di Baldassarre et al. 2013). In developing cities, the existence of slums and families living below the poverty line may add to the pressures as these areas have no proper water and sanitation infrastructure (Hoekstra et al. 2019). Many cities experience some or all of these pressures.

Global cities currently considered to be exposed to water stress are

• São Paulo, Brazil
• Cape Town, South Africa
• Bangalore, India
• Beijing, China
• Cairo, Egypt
• Jakarta, Indonesia
• Moscow, Russia
• Istanbul, Turkey
• Mexico City, Mexico
• London, United Kingdom
• Tokyo, Japan
• Miami, United States of America
• Chennai, India
• Lima, Peru

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In addition, we are a growing population, now estimated to be 7.6 billion people, with a shift in the balance between urban and rural increasing from approximately 50% in 2010 to an estimated 66% by 2050. In additi...