by Bruce Stewart*
Karl Hofius in his article in this issue of the Bulletin entitled “Evolving role of WMO in hydrology and water resources management” ably describes the evolution of the Hydrology and Water Resources Programme in WMO over the past 50 years. These developments have seen the integration of operational hydrology into the activities of WMO and the recognition of this through the adoption of the slogan “Weather, climate and water” for WMO. The questions I have been asked are: Where to from here? What are the challenges for the next 50 years?
An important first step in deciding on future directions and therefore the challenges we face is to look closely at what are the key issues which water resources managers must address today and considering how these will evolve with time. For example, Mr Hofius quite correctly focuses at the end of his paper on the importance of hydrology in the climate change discussion.
I would summarize the key issues today as:
Climate change: while we have always had to deal with a variable climate, the majority of studies, analyses and management techniques have been based on the belief that the hydrological series was stationary, i.e. while there may be fluctuations, the mean value would remain roughly the same. There is now mounting evidence of trends in hydrological series. Many areas face a drying and warming climate and thus potentially less water availability;
Increasing vulnerability to severe weather events: the Intergovernmental Panel on Climate Change Technical Paper on Climate Change and Water highlights the potential for more frequent and more severe weather events. With increasing populations at risk and the potential for a shift in the risk profile in many areas, safety of life and property will remain high on the agenda;
Growing urban demand: the population of urban centres continues to grow and urban areas continue to spread, thus placing greater pressure on water supply systems as well as reducing the availability of arable land, and, in some cases, placing increased pressure on water supply catchments;
Over-allocation of existing supplies: the water in many supply systems has been allocated on the basis of past availability or existing demand and has not been kept in line with current or future availability; thus, many systems are over-allocated;
Unrestricted extractions: in many areas, there are no management plans or restrictions on water extractions (for example, pumping from rivers and groundwater extractions). These have resulted in less water being available and have in some case led to mining of the resource. The expansion of farm dams in some areas also reduces the supply of water entering river systems;
Land-use change: clear-felling, expanding plantations and the opening of new areas to agriculture all have impacts on the water resource; unintended events, such as bushfires, can lead to a reduction in the availability of water and water-quality problems. Changes to land use, even within agricultural areas, have implications for both water availability and water use;
Environmental requirements: there has been an increasing emphasis on the requirement for environmental flows to maintain ecosystems such as wetland and in-stream environments. Community expectations are that we should see the environment as a rightful and high-priority user of water.
These areas of concern will continue to be the drivers for the actions and responses of National Meteorological and Hydrological Services (NMHSs). The mission of NMHSs in general has been described as the provision of reliable, impartial, timely information that is needed to understand the water resources of their area of responsibility, including:
- Minimizing the loss of life and property as a result of water-related natural hazards, such as floods, droughts and land movement;
- Effectively managing ground-and surface-water resources for domestic, agricultural, commercial, industrial, recreational and ecological uses;
- Protecting and enhancing water resources for human and aquatic health and environmental quality; and
- Contributing to wise physical and economic development of the area’s resources for the benefit of present and future generations.
|There is increasing emphasis on the requirement for environmental flows to maintain ecosystems such as wetlands. Community expectations are that we should see the environment as a rightful and high priority user of water.|
Responding to these drivers will require NMHSs to set in place programmes that lead to the management of the resource in an environmentally and economically sustainable manner. The need for improved water resources information and water-management tools and techniques to deal with a changing climate will therefore be key challenges for the future.
In identifying the challenges, I would like to focus on the four major areas that contribute an end-to-end system for the provision of hydrological services, namely, observations (including measurement, transmission and ingestion), monitoring, analysis and assessment (including modelling), products and services (including their delivery) and supporting research (including blue sky research).
The requirement for water information has never been higher than it is today and I believe it will be even more essential in the future. The adage “you cannot manage what you cannot measure” will continue to be applicable in a more resource-constrained future.
However, by its very nature (for example, remote locations, event-based and direct measurement difficulties), high-quality water information is difficult and costly to collect. While there have been significant advances in the recording of information (data loggers) and transmission of information (telephone and satellite telemetry), there has been limited progress in improvements to the measurement of streamflow itself.
Perhaps the greatest advance has been the development of acoustic Doppler current profilers (ADCPs). The ADCP is used measure how fast water is moving across a water column. An ADCP anchored to the seafloor can measure current speed not just at the bottom, but also at equal intervals all the way up to the surface. The instrument can also be mounted horizontally on seawalls or bridge pilings in rivers and canals to measure the current profile from shore to shore, and to the bottom of a boat or float to take constant current measurements as the boat moves. In very deep areas, they can be lowered from the surface on a cable.
Major improvements in communications and database management have occurred in the past and will continue in the future and we can expect that many of the data ingestion, data assimilation and other analysis techniques applied in meteorology will also be applied in hydrology, especially as we move towards joint modelling frameworks.
However, in recent times, there has been relatively little activity in the way of intercomparisons between the various instruments, measurement methods and data delivery and storage mechanisms and also little in the form of technical guidance and training in instrument use. The primary challenges for the future will be:
The development of instrumentation and measuring techniques that will improve the accuracy of water resources information, noting that this includes level, flow, quality, use, re-use, allocations, trades, etc.;
Ensuring that measurement techniques meet required standards;
Ensuring that appropriate meta-data are collected, held and made readily available;
Improving the access to and availability of streamflow information in real-time and in concert with other information about the resource and its use;
Making appropriate use of satellite measurement techniques, while ensuring information on their accuracy and reliability is available, as well as being able to relate and express the observations from a variety of measurement techniques to each other and to agreed standards;
Defining an internationally agreed standard water information exchange format through the development and evaluation of a conceptual model of water resources information, corresponding mark-up language.
WMO has a lead role in this area and, with the new arrangements established with the International Organization for Standardization, should continue to provide guidance, advice and supporting evaluations (such as intercomparisons) within the Quality Management Framework-Hydrology. National, regional and international consistency and understanding of limitations and uncertainties will be essential in the future. Guidance to the less developed countries and assistance to them through initiatives such as the World Hydrological Observing System (WHYCOS), should also be continued.
Monitoring, analysis and assessment
Observation of the information is the first step on the data value ladder. For the data to reach its full potential, they must undergo analysis and be used in the development of water information products and services that lead to improved development and management of the resource.
The WMO Guide to Hydrological Practices provides guidance on the scientific basis for the hydrological modelling which forms the basis of water resources assessment and hydrological forecasting.
Water resource monitoring: observation is the first step on the data value ladder. (Photo: Department of Water Resources, State of California, USA)
The challenges for the future in this area will be the development of analysis and modelling techniques that enable a holistic approach to resource management. Advances in modelling capabilities are closely tied to advances in the capabilities of computers. Models are usually developed on the basis of scientific research and investigation into the physical properties of the movement of water in the landscape. In recent years, modelling capabilities have improved in terms of greater integration between elements of the hydrological cycle and also closer relationships between meteorological and hydrological modellers. Specific examples include radar and satellite- based rainfall estimation, numerical weather prediction inputs to hydrological models and improved seasonal climate outlook information incorporated in hydrological forecasting systems.
Also, there have been significant advances in spatial information-modelling capabilities and products using geographical information system (GIS) technology. Hydrologists use GIS technology to integrate various data and applications into one manageable system. For example, the suite of tools contained in Arc Hydro facilitate the creation, manipulation, and display of hydro features and objects within the ArcGIS environment. The challenge here will be to ensure that the models are realistic and able to be applied in practice.
It must be always kept in mind that the quality of the outputs and products from modelling will still depend heavily on the quality of the water information collected in the field.
WMO can assist by keeping its technical guidance and access to the latest proven technologies up to date and improving their accessibility and supporting documentation. Providing advice on the use and suitability of new techniques in data-sparse regions will also be a valuable contribution.
Products and services
As we move forward, it will become increasingly essential for there to be close relationships between all the elements of observations, analysis and research with the users of the services and products developed by the NMHSs, whether they be assessments of water resources availability, key design information for hydraulic structures, monitoring and management tools or flood/flow forecasts and flood warnings. The use of the new communication mechanisms, Short Message Service (SMS) and the Internet and future developments in these areas will therefore be of vital interest to NMHSs. These close relationships will be important mechanisms for both the design and development of new and better tools, provision of information on limitations and uncertainties, as well as for feedback on the improvements that can be made and the benefits achieved.
Two examples are the provision of hydrological information in the form of assessments of water availability and forecasts of flood levels. The availability of the Internet and Web-based provision of information has resulted in major changes to the manner in which information can be accessed and also the timeliness of information provision. It is now not uncommon for water information to be available in real-time (in graphical and tabular format) and to be able to obtain historical information through the Internet. Also, reports and case-studies of water-related topics are often available for access or download through the Internet. Future advances will lead to improvements in the quality and accessibility of this information and also in its presentation. For example, the provision of flood inundation maps as part of the flood forecasting and warning process will enable emergency services groups to be more proactive and plan response actions based on improved information.
Based on the discussion above, it is almost certain that a major challenge for the future will be the development of models and methodologies to enable the delivery of products and services that support the management of water resources in a changing environment. Climate change and population growth will continue to be drivers for new and improved hydrological services and products. Accordingly, the Commission for Hydrology has proposed joint activities with the Commission for Climatology that will focus on the following areas:
Complete the identification of climate-sensitive stations and analysis of their data (including obtaining the data (with the assistance of the Global Runoff Data Centre) and undertaking trend detection studies);
Prepare guidance material on seasonal flow forecasting (in association with hydrological forecasting and prediction and hydrological disaster risk reduction theme)—including quantifying uncertainties;
Prepare guidance material on the potential use of the current capabilities in regional climate modelling for water resources assessment and management;
Prepare guidance material on the climate information requirements of water resources managers for operations, long-term planning and design;
Prepare guidance material on drought forecasting and indices—including quantifying uncertainties.
|Population growth and climate change are the main drivers of new and improved hydrological services and products and sustainable water resource management.|
Research and development in support of the provision of hydrological products and services can be coordinated under four specific categories, namely:
Water information systems: activities would focus on the development of a systems architecture for water information that is robust and evolvable with changes in data sources, applications and technologies. This includes a framework of open standards for information exchange, data and computational services, and tools for visualization, quality assurance and analysis of historical data and real-time data from monitoring infrastructure;
Data products: activities would include developing methodologies, data models and techniques for creating and maintaining fundamental hydrological information products to support water information management, reporting, forecasting, assessment and accounting;
Water accounting and assessment: developing spatial and temporal information about the past and present generation and distribution and use of water resources. This information will be used to develop water balances, water resource assessments, national water accounts and interactions of components of the water cycle at many scales;
Water forecasting and prediction: extending the hydrological forecasting services from short-term flood forecasting to continuous forecasting of flows, water inundation and water demand out to several days, as well as water resources availability forecasts out to one or more seasons.
To provide fully effective water management, the capability to understand and predict the movement and availability of water within all components of the hydrological cycle and to be able to simulate the impacts of various landscape changes on the distribution and availability of water is essential. The development of an Earth System Simulator provides this capability through full Earth-atmosphere simulation. Such simulations can provide predictions of water availability and distribution across space scales ranging from small catchments, through river basins to larger regions and time-scales varying from hours to weeks and longer. Outputs can include water availability in terms of river flows for storage management and water allocation and also variables such as soil moisture that will be valuable to decision-making in many agricultural applications such as water delivery and applications management.
Collaboration between National Meteorological Services and National Hydrological Services
The future of hydrological services will be increasingly tied to that of meteorological services. Therefore, other areas which WMO must address as challenges for the future are:
- More accurate and longer duration weather forecasts, especially precipitation forecasts;
- More accurate seasonal outlooks;
- Radar and satellite-based rainfall estimates; and
- Integrated product provision.
With the pressure of drivers such as population growth and climate change, National Hydrological Services (NHSs) will continue to focus on the sustainable management of the water resource. Therefore, any tools that can be developed to aid decision-making and assist NHSs in meeting their mission will be well received. National Meteorological Services are in a key position to assist NHSs in this regard and continuing cooperation and coordination between these groups will be essential.
Intergovernmental Panel on Climate Change: Technical Paper on Climate Change and Water