WRA

Arid zones present special problems to hydrologists. Describing the hydrological balance is difficult as very little of the potential evaporation demand is satisfied. Only a small proportion of the rainfall becomes runoff except in extreme storms. Also, rainfall tends to be highly variable in arid regions both in time and space, which leads to very high variability of runoff. Water, especially groundwater, is the key to life in semi-arid and arid zones. In this climatic type, the role of hydrology and understanding climatic change, in particular, is vital and without it all other arid zone research would be pointless.

Groundwater can be a major source of water, but similar problems exist in estimating the long-term yield of an aquifer. Recharge of groundwater can be very small in most years but groundwater levels can recover dramatically in a few wet years. In many desert areas, groundwater accumulated in past climatic regimes, and if exploited, would not be replenished.

Although surface water is not always a major source of water, it is sometimes feasible to build dams for domestic water supply or for irrigation. Some over-year storage is usually desirable despite the high losses by evaporation because of the high variability of runoff from year to year. Spate irrigation by diversion of flood runoff is also a possibility.

Water Resource Associates has experience of these issues gained through many studies in arid zones primarily in the Middle East and Africa.

Arid zones are usually areas of scarce hydrological data, which require an iterative approach to be adopted to water resource development, with initial information often derived from other geographical regions which have similar aridity characteristics. Specific local data can then be progressively added to project studies, while carrying out the first stages of planning and development.

In 1997, the United Nations recognized that water was “one of the main issues facing the world. It is as important as atmospheric change, protection of biodiversity and desertification, all of which are linked to water management”, UN Commission on Sustainable Development. In most arid countries, the scarcity of renewable water supplies implies that there is a serious threat to sustainable coupled and balanced socio-economic growth and environmental protection [UNESCO, 2000]

Experience as a company and directors

Chad
Rainfall-runoff and flow forecasting models were developed for the Lake Chad drainage basin for the strategic planning of regional water resources.

Jordan
Analysis of the potential for surface water storage and groundwater recharge in the Hammad and Sirhan basins.

Morocco
Master Plan development for water supply and wastewater strategy at the town of Settat, Berrechid Plain. For SGI in association with Rabat-based Morrocan company.

Due to the scarcity of resources, and increasing salinisation of groundwater in the Berrechid Plaiun used for water supply, consideration was given to the re-use of wastewater, and investigating the potential impact on groundwater

Yemen
Analysis of the statistics of daily rainfall for generation of spate flood series. Regional modelling of spate runoff and the potential for diversion of flood water for irrigation in the Tihama plain.

Oman
Primary water resources survey of northern Oman. Analysis of the impact of spate floods originating from rainfall on Jebel Akhdar on the shallow groundwater storage in the wadi channels and the alluvial plains. Detailed study of the interaction between surface and groundwater flow in the wadi gravels as evidenced by discharges observed in the aflaj (qanat) systems.

Dubai
Hydrological studies for 53 wadi dams in the Dubai mountains, for KBR in association with Lebanese consultant, CONSER.

The increasing need to optimise water resources brings with it an increasing need to understand and to quantify all components of flow in a river or aquifer system. For analysis of water resources, with the aim of optimising existing resources or introducing new ones, there is a need for a "natural" flow record. That is a flow record which would have occurred had there been no anthropogenic effects. Whilst flows in most rivers of significance for water resources have been measured for many years, and often, for important rivers, for several decades, the same is not true of the factors such as abstractions and discharges, which change the flow regime. Often where these factors have been measured there are gaps in the records and in many cases relatively important factors have not even been measured.

Some of the principal forms of artificial influence are: public water supply and sewage treatment works, impounding reservoirs, spray irrigation, small consumptive abstractions, canals, groundwater pumping, inter-basin transfer, catchwaters, power stations, mine/quarry de-watering. All of these have their own characteristics which affects the way they are dealt with. For example whilst public water supply abstractions and sewage discharge are linked, the linkage, being a result not only of supply but of losses and complex distribution systems, in not always easy to determine.

Many of the forms of artificial influence reflect underlying trends in water use which, whilst they do not necessarily explain all the variability, can go some way to achieving a consistent explanation for it. Some of the factors are: Population growth (e.g. public water supply), Season (e.g. irrigation), Economics (e.g. steel production), Periodicity (e.g. diurnal variation).

• River Rother (Sussex)
  Flow data were collected for the Rother at Udiam and two upstream flow gauging stations. Data were also collected on precipitation and PET and artificial influences. HYSIM was used to infill gaps in the flow record taking account of these influences.
• Sussex Ouse
  The WRA catchment model, HYSIM, was used with all available rainfall, discharge, PE and artificial influence data. The effects of various patterns of abstraction and discharge could be simulated as could the consequences of climatic change (by modifying rainfall or PE sequences)
• Resources study of Severn and Trent
  WRA worked in two main areas. Firstly it was necessary to produce a long-term flow record for all the major surface resources Secondly, using this data the RESSIM model was updated and modified to simulate all the surface resources of Severn-Trent. The flows have been calculated in such a way that the effects of different patterns of artificial influences (irrigation, leakage control and sewage) can be studied. The resource model has enabled a complete re-evaluation of the reliability of the surface resources of Severn-Trent to be carried out.
  
  During this project we also became increasingly aware of linking the naturalisation process to the resource simulation process; unless they are calculated on the same basis than inconsistency can be introduced into the calculation.
• SNIFFER (Scotland and Northern Ireland Forum for Environment Research)
  We are currently working on a project with SNIFFER. The clients identified the need to develop a consistent methodology which could be used by the various organisations with water resource responsibilities in the two countries.
  
  Existing programs from WRA, HYSIM and RESSIM are being adapted to meet the particular needs.
• Reservoir study for British Waterways
  WRA produced a daily inflow sequence for all 16 reservoirs forming part of the study. As use of water for canals is often a significant artificial influence this gave us valuable insight to this particular problem.

• Water resource modelling for Thames Water
  Operating through the sister company, Oxford Scientific Software, WRA staff have provided Water Resource Modelling expertise to Thames Water over many years. This has involved the understanding of the many artificial influences in the Thames catchment. In particular the recent re-write of the London model simulates the behaviour of the Thames and Lee within London and models the artificial influences that take place in that area.

Climate change predictions. It is now widely accepted that the Earth’s climate has warmed since the Industrial Revolution at a rate greater than that expected through natural variation. Current predictions suggest a further rise in the global mean temperature of 3 ºC by 2100. The emissions of carbon dioxide and other ‘greenhouse gases’ such as nitrous oxide and methane, which result from industry, energy production and transport, have caused the increase in temperature.

Potential impacts. A warming climate has implications for water resources and water quality; increases in the air and sea temperatures will affect global circulation patterns, and as a result, at the regional or catchment scale, this will affect:

• The occurrence and length of droughts;
• The occurrence and magnitude of flood events;
• The seasonal pattern of runoff, including flow from snow melt.
• The irrigation of crops and land management;
• The cycling and transport of nutrients and pollutants within the river-system;
• The ecology, by alterations in the flow regime and water quality.

Application of General Circulation Models
At present, it is difficult to quantify the likely impacts of climate change on water quantity and quality since there is uncertainty in future climate forecasts and how river-systems will respond. Any study of the impacts of climate change must account for this uncertainty. Climate change is expected to be greatest in the tropics and low latitudes, and therefore an assessment of these regions is as important as the likely affects in the more developed countries.

Water Resource Associates Ltd has expertise in the field of estimating the likely impacts of climate change on water resources and water quality; with experience of down-scaling the outputs from the latest General Circulation Models for use in hydrological and water quality models; dealing with the uncertainty in both climate model and hydro-chemical models; and applying models to examine adaptation strategies. In particular, two of the company’s directors are leading research on the impacts of climate change on freshwater ecosystems.

The likelihood of extreme rainfall events may change in the future with consequences for flooding and drought.

Pan Europe
A pan European model-based assessment of the factors and processes controlling nitrogen export is being done. Models of flow and nutrient dynamics have been applied at sites across the current climate gradient of Europe from the artic north to the Mediterranean. The outputs from General Circulation Models are being down-scaled for input to catchment scale water quality models. The results will then be compared across the different sites to provide a pan European assessment of the affects of climate change on nitrogen in rivers.

In addition the Principles have also worked in:
A study of climate change for Severn-Trent Water by downscaling the results of GCMs to the Severn and Trent river basins. In this study HYSIM was used to simulate flows on all the major water resources rivers of the company. Initially it was calibrated to observed flow and climatic conditions then a range of climate scenarios was tested to evaluate the likely effect on runoff.

Two Directors of WRA were co-authors of a paper examining downscaling methodology which is being adopted as a standard in the UK. This was tested on a catchment likely to suffer water stress and the impacts on flows and water quality were examined. (Integrated modelling of climate change impacts on water resources and quality in a lowland catchment: River Kennet, UK, R.J. Wilby, P.G. Whitehead, A.J. Wade, D Butterfield, R.J. Davis, G. Watts, Journal of Hydrology (2006) 330, 204-220.)

The HYSIM rainfall runoff/model  developed by a Director of WRA and marketed by them has been used in a number of  studies of climate change impact. These include: Assessing The Impact Of Climate Change On Water Supply and Flood Hazard in Ireland Using Statistical Downscaling and Hydrological Modelling Techniques. Rosemary Charlton, Rowan Fealy, Sonja Moore, John Sweeney and Conor Murphy Climatic Change, Volume 74, Number 4, February 2006 , pp. 475-491(17)

High resolution climate change scenarios: Implications for British runoff, Pilling, C. and Jones, J. A. A.: 1999, Hydrol. Process. 13, 2877–2895.

Flood forecasting relies on the fact that a computer can calculate the response of a river basin to extreme rainfall or snow melt - using an appropriate model - in a shorter time than the response takes in real life. Rainfall, other climatological data and river levels must be transmitted to the computer system in "real-time". Forecasts can be updated and the time horizon extended continually as new information becomes available.

The hydrograph shows a sample forecast for the Niger at Niamey, a rather unusual case where the response time of the river is extremely slow - around three months.

Flow forecasting programs should be sufficiently robust to continue functioning when a failure in the transmitting network reduces the amount of data received. They should also adapt to variation in the values of the model parameters as indicated by continual self-checking of forecast performance.

The expertise of Water Resources Associates covers both the design of the computer programs and the specification of the hardware for measuring and transmitting data.

• Southern Region, Environment Agency
  The Southern Region of the Agency wished to improve the accuracy and lead time of forecasts with the use of PC based models linked to their real-time telemetry system. Reliable software, delivered on time and to budget was required handle the interaction with the user, telemetry data files, execution of an arbitrary number of hydrological models and presentation of results. Time and budget were both critical for this project and WRA provided the required software within the imposed constraints.
• Bangladesh
  Design and implementation of a networked PC Unix-based system for forecasting operations at the Flood Forecasting and Warning Centre in Dhaka. A microTIDEDA hydrological database and MIKE 11 hydraulic model were configured to enable the seasonal forecasting of floods on the Ganges and Brahmaputra rivers. A training programme was provided for counterpart staff.

• Niger
  A flow forecasting system for the Niger river basin - contributing basin 1.2 million km2 - was funded by WMO. The network comprised 65 stations measuring river level and rainfall, linked by satellite to an international forecasting centre in Niamey and to national forecasting centres in each of the eight participating countries. Each of the stations also transmitted diagnostic data to facilitate preventative maintenance. The network was able to forecast flows up to 3 months in advance, making it a valuable tool for water management and agricultural production.
• Indonesia
  A pilot forecasting system was established in the Cimanuk basin in Java to improve the country’s capability in flood forecasting. The system comprised 30 stations; all measured rainfall and nine of them measured flow. Three of the stations also measured turbidity on an experimental basis. The data were transmitted by UHF radio links. As the two receiving stations were outside of the basin two repeater stations were needed. The system was designed to provide forecasts to towns and to the operators of major hydraulic structures diverting water for rice irrigation.
• UK
  The river Dee in north Wales was a test bed in the 1970s and 1980s for telemetry systems and forecasting models. It provided the first UK demonstration of real-time linkage between radar-measured rainfall linked to a rainfall-runoff model. Three of our principals had key roles throughout the project, which was carried out by IH and the Welsh National Water Development Authority.

At WRA we like to keep our clients "in the loop" rather than presenting ourselves as superior beings with esoteric knowledge grudgingly (and expensively) revealed. This guide is aimed at professionals, who are concerned with legal, insurance and development aspect of floods, but who have no specialist knowledge of hydrology. It aims to explain how floods are caused, the extent to which they can be considered as "acts of God" and how the activities of man can make floods more or less severe.

Flooding Guide

The service provided by WRA can be particularly helpful to owners facing difficulties in obtaining insurance of their house and belongings, as a result of flood risk, as well as owners and developers wishing to progress building plans.

In cases where there is doubt over the level of risk or whether a particular house is liable to flood, insurance companies have required preparation of a flood risk report by professional hydrologists, to clearly identify the risks of flooding at the site in question.

WRA can carry out a flood risk assessment for clients, which comprises topographic survey of the site and building levels [supported by Sitech Survey Services, when more extensive areas of survey are required]. For borderline cases of flood risk, the detailed studies often show that the property under investigation lies above the maximum flood level, yet lies within the floodplain envelope defined by the Environment Agency Flood Map. The WRA report provides a fully-documented basis for the insurance company to then provide cover for the property in question.

WRA is a small specialist consultancy comprising experienced and nationally-acknowledged scientists at the forefront of work involving flood hydrology and flood forecasting. Directors and associates have been involved in the development of flood prediction methods and software since the 1970s, which now form the basis for flood estimation in the United Kingdom.

WRA’s clients include the Environment Agency, water companies, research agencies, and the tourism industry. After the 2003 floods, WRA provided expert support to The Upstream Group [TUG] during the deliberations of the Flood Risk Action Group [FRAG] for the Thames valley from Hurley to Wraysbury.

Here is a selection of sites studied since 2003: Ascott-under-Wychwood, Northmoor, Woolstone Mill & Sutton Courtenay in Oxfordshire, Bisham Brook in Berkshire, Thameside properties in Bourne End, Marlow & Temple [Bucks], Chertsey [Surrey], Downham Market [Norfolk], Gt Finborough & Gt Gabbard in Suffolk, Longwick Mill in Buckinghamshire, Chertsey & Nutfield in Surrey, and Bocking & Wix in Essex.

WRA prepared guidelines to help TUG members in acquiring property insurance, and this document was adopted in 2005 by the Environment Agency, as a roadmap which would guide property owners through the insurance maze. The following flow diagram shows the stages at which WRA expertise may be sought.

See also our background guide on flooding.

Water Resource Associates has considerable experience in hydrological data processing both in the UK and overseas. Our expertise in this field includes technical advice and assistance to hydrometric departments, hydrometry, training, in-house processing of hydrological data and the supply of standard or the development of bespoke computer software. WRA has experience in data acquisition through electronic loggers, telemetry, autographic charts and field observers, and we have digitising facilities for handling hydrometric charts and maps.

In some countries, data are being ‘lost’ because the data handling procedures do not keep pace with the rapid developments in computing facilities and software. Investment in data gathering can be wasted, and the reliability of hydrological analysis is weakened, when valuable historical data cannot be retrieved.

Our world-wide experience of data handling and retrieval makes us ideally suited to undertake any project involving new or updated hydrological data processing facilities. We have the knowledge to recommend hydrometric equipment, computer hardware and software and to carry out installation and training.

• Middle East
  As part of the Middle-East Peace Process, the European Union and other donors have initiated a series of activities to enhance and/or create water data banks in the region. WRA has been appointed to set up and monitor a ECU 2 million (£1.6 million) project funded by the European Commission. The company’s tasks include writing the Terms of Reference, obtaining the agreement of core parties to the ToR and supervising project execution.
• UK
  Further development of the HYDATA hydrological database and analysis system for the Institute of Hydrology, Wallingford. Enhancements include additional analysis facilities in the DOS version, and the design and initial development of a Microsoft Windows® version.
  
  Bespoke software for several regions of the NRA.
  
  Produced the draft British Standard on Hydrometric Data Management.
  
  Two of our principals provided a comprehensive (2 volume) review of the NRA’s Hydrometric Data Processing Systems.
  
  A hydrometric audit for BNFL, Sellafield in which field and office procedures for data collection and processing were reviewed and improvements recommended.
• Kenya
  Hydrometric data in the Athi, Tsavo, Sabaki and coastal river systems were processed for the 2nd Mombasa bulk water supply project. Rating equations were derived for over 100 stations and water levels were converted to flows. An extensive data validation programme was carried out including processing and validation of rainfall data from a 114 daily gauges.
  
  Assistance for the HYDATA training course held at the Kenya Meteorological Department.
• Tanzania
  Installation and training on the use a standard hydrological data processing and analysis package for the Arusha Region Water Master Plan.
• Malaysia
  Hydrometric network design in the coastal plain of Sarawak. Most of the rivers are tidally affected and gauging by newly-developed acoustic Doppler instruments was proposed.

• Burundi
  A comprehensive expansion of the hydrometric network was proposed to meet the foreseeable need for data to support future scheme analyses and regional flood studies. Recommendations for staffing and equipping the data processing centre were also made.
• Honduras
  Installation and training on the use a standard hydrological data processing and analysis package in Tegucigalpa.
• Lesotho
  Installation and training on the use of a standard hydrological data processing and analysis package for the Lesotho Highlands Water Project.
• Somalia
  Development of a hydrological database and analysis system for the Ministry of Agriculture. Staff training and provision of an interface to electronic logging equipment.
• Fiji
  Installation and training on the use a standard hydrological data processing and analysis package in Suva.
• Thialand
  Installation and training on the use a standard hydrological data processing and analysis package for the Mekong Secretariat as a prelude to a low flow study. Rating equations were reviewed on all Lower Mekong stations and major tributaries.
• Solomon Islands
  Installation of a recording raingauge network on Guadalcanal and assistance with data processing using the microTIDEDA database.

Hydrological models serve a range of purposes but they are used primarily to estimate runoff from sequences of rainfall and the meteorological information needed to estimate potential evaporation. They can be used to estimate river flows at ungauged sites, fill gaps in broken records or extend flow records with respect to longer records of rainfall.

Powerful areally-distributed models are based on physical principles governing the movement of water within a catchment area, but they need detailed high-quality data to be used effectively.

More commonly, simpler conceptual models are used to represent the basin as a whole. The main controls on water movement are represented by quasi-physical model elements whose action is governed by a set of model parameters. In some circumstances, these parameters can be adjusted to represent changes to land-use in the catchment area. The flow diagram illustrates HYSIM, one of this type of model used by WRA, which is also capable of simulating many of the artificial influences on a river basin.

Other classes of model include stochastic models that can relate runoff to rainfall or be used to synthesise contemporary flows in a number of basins by preserving the spatial and temporal correlation structure defined from a common record.

WRA has experience in the development and use of many of these different types of model. We are aware of the limitations of all forms of modelling and of the need to take account of the limitations of data quality or data availability in a particular river basin and to select a model that meets the precise needs of the project.

• UK
  The River Rother in Kent is an important river for water resources. Its flow record is incomplete and, for certain periods, of doubtful accuracy. The HYSIM model was calibrated to three sub-catchments in the basin. The input data to the model (precipitation and PET) were checked for consistency and the simulated flow record was used to provide a consistent basis for evaluating changes to the observed flow record and for infilling missing data.
• UK
  The river Trent, a complex drainage area of 20,000 km2, rises in the English Midlands and flows into the North Sea. Its upper reaches are highly urbanised with much industry. In the past this river has been considered unsuitable for potable use but recent improvements in quality have led to that decision being revised. This led to a need for a long-term naturalised flow record. The HYSIM rainfall/runoff model was calibrated to six years of recent flow data for which data on abstractions and discharges were also available. An extended naturalised flow sequence was produced using rainfall and evaporation data going back to 1920.
• Ethiopia
  The Omo-Gibe basin, in southern Ethiopia, had a drainage area of 80,000 km2 and a population of six million. The basin is at present largely undeveloped. As part of a Master Plan Study a flow sequence was need to determine the potential of the basin for irrigation and hydropower development. A monthly rainfall-runoff model was developed to produce extended flow records for those sub-catchments with flow data and synthetic flow series for ungauged sub-catchments.
• Chad
  Lake Chad plays an important part in the regional economy. The lake is filled by the rivers Logone and Chari which flow from wetter areas of Cameroon, Nigeria and the Central African Republic. As the time lag between rainfall in the upper basin and the lake is 3 or 4 months it was possible to develop a monthly hydrological model for flow forecasting purposes.
• Kenya
  A river flow model was developed to investigate the environmental impact of increased abstractions from the Mzima springs in the Tsavo National Park on the Tsavo, Athi and Sabaki river system in eastern Kenya. The model operates on a five day time step over the period 1932 to 1991 and was used to evaluate different pipeline capacities, pipeline operating strategies. It also simulates the effects of climate change and man-made influences on the Athi river.
• India
  Development of river basin models capable of routing the estimated runoff through a series of irrigation control structures as part of a UNDP-funded programme to strengthen the capability of the Institute for Water Studies in Madras.

• Thailand
  Use of rainfall-runoff models to investigate the impact of deforestation, changes in cropping and irrigation and hydropower development on the hydrology of the Mekong basin.

Dramatic short-term changes in climate or over-exploitation of the resource can produce major changes in lake regime with corresponding effects on other environmental and ecological variables. The sharp rise in Lake Victoria in the early 1960s, which took many years to subside, and the continual fall in level of the Dead Sea due to potash extraction, are examples of major changes that can occur.

Water Resource Associates has experience of a range of these issues. Each study should be based on a thorough understanding of the resource balance of the lake and the historical evidence of seasonal and longer term natural fluctuations. The lack of historical rainfall data over large lakes is a serious problem in accounting for lake behaviour, and it is helpful to compare implied lake rainfall with records from shore stations.

Stochastic models defined from the historical data can give indications of likely future behaviour, against which planned measures can be tested for control or exploitation of the water resource.

• Botswana
  Review of proposed engineering works in the Okavango Delta based on hydrological modelling including the conjunctive development of surface and groundwater resources and the impact of development on the riparian population.
• Chad
  Hydrological modelling and forecasting of inflows to Lake Chad for strategic planning of resource development.
• Turkey
  Study of the environmental impact of sewerage schemes and tourism on Lake Köycegiz and Dalyan Beach in southern Turkey. Preliminary water balance studies showed that there is a net inflow from the sea each summer and that the ecology of the lake is finely balanced.

• Jordan
  A study of the hydrology of the Dead Sea based on rainfall records over the past century showed that abstraction of water from the river Jordan basin has caused sea levels to fall in recent decades. However, a much greater impact is due to the evaporation of brines for potash production.
  
  Prediction of future sea levels was based on stochastic models of rainfall fitted to historic data and used to generate a large number of future sequences. These were transposed into series of sea level change allowing for modern developments. Thus, the probability of sea levels falling to specified ranges could be estimated.
• Thailand
  Study of the hydrology of the Songkhla Lake basin in southern Thailand and the development of parallel time series of river flows in all the rivers entering the lake.
• East Africa
  An extensive study of the hydrology of Lake Victoria included a review of the basic data back to 1900, synthesis of river inflows for the ungauged periods, and development of a water balance of the lake able to explain the dramatic rise of lake levels in 1961/64. The writings of early explorers and evidence from lake shore sediments were used in conjunction with stochastic models of lake and basin rainfall to estimate the likelihood of similar events in future.

WRA has been involved in a number of projects involving the rehabilitation of hydraulic structures associated with mills. Over the past 20 years the debate around whether the production of electricity in this way is efficient, and how best to incorporate the power into the local grid continues to be a focal point. The viability of schemes has returned to the limelight, as government support increases for alternative energy sources and micro-power generation.

The service provided by WRA can be particularly helpful to owners and developers of new mini-hydro schemes associated with mills or weirs in the UK. There are three target activities in demand, which the Environment Agency would require to obtain the necessary approval of new schemes: hydrology, hydraulics and ecology. Such studies would examine the impact on flood characteristics of a site, and whether change in the fluvial regime would alter the ecological dynamics of the river in question. Consideration would need to be given to the hydraulic head and flow characteristics to determine viability, and WRA can provide expertise in dam safety and hydraulic design for refurbishment.

WRA and ASEDA can carry out an integrated hydrological and ecological assessment for clients, which includes hydrographic and ecological surveys of the river, lakes and floodplain. Flow in the river would be determined using current methods such as application of the Flood Estimation Handbook and through acquisition and analysis of nearby gauging station data. Flows would be interpreted using suitable hydraulic equations and hydrodynamic modeling of the river and floodplain to provide a range of flood levels for different return periods to compare conditions prior to and post-development. The WRA report provides a fully-documented basis for presenting the case to the Environment agency and local authorities for planning approval.

ASEDA specialises in a wide range of freshwater aquatic surveys in both still and flowing water, and in the graphical and statistical analyses of environmental data.

The ecological studies for hydro-power would focus on identifying the current status of aquatic habitats in the river corridor, and investigate the target ecological receptors, which may be affected by the proposed scheme. Such studies would examine whether change in the fluvial regime would alter the ecological dynamics of the river in question, and designated sites of conservation.

Conservation assessments would include a survey of the benthic macro-invertebrate fauna of the river and associated floodplain channels and ponds. Information and historical surveys would be sought from the relevant authorities, in particular, the Environment Agency, to obtain prior River Habitat Surveys, Natural England and the Wildlife Trust.

The standard river survey techniques proposed for the ecological work comprise a suite of river surveys including River Corridor Survey [RCS], JNCC macrophyte survey, Mean Trophic Rank [MTR] survey and GeoRHS. This combination of methods will provide data on the physical structure of the river, sediment dynamics, and river plant communities. This allows a robust assessment to be made of condition and impacts that are affecting a river system.

WRA’s clients include the Environment Agency, water companies, research agencies, foreign governments, industrial partners and the tourism industry.

Here is a selection of mill sites studied since 2003: Woolstone Mill [Oxon], Longwick Mill [Bucks], Bocking [Essex], Vilar das Almas [Portugal], Waterbury Mill, Horsted Keynes [Sussex].

Angola, Mozambique, Portugal, Nepal, Bhutan, Malaysia, Uganda, Pakistan, Cote d'Ivoire, Mauritius, China

WRA maintains a partnership with small specialist businesses which have particular specialism within the field of hydrology, in particular with Wallingford HydroSolutions [WHS] and Oxford Scientific Services. WHS is now the distributor of LowFlows2000, which is relevant software for estimating the flow duration curve at ungauged sites. This service would also be considered for the hydropower studies, depending on the availability of actual streamflow data.

The operation of a single reservoir for a single function does not present many analytical problems, but the same is not true when a reservoir fulfils a number of potentially conflicting objectives or where several reservoirs are operated conjunctively. Maximising the benefit of one or more reservoirs balances information on the likely resource against the multiple demands on it, while maintaining the safety of the dam(s) in times of severe flood. Sometimes, historical records are sufficient to define the resource reasonably well and design and operating criteria can be derived by simulation or optimisation techniques. In other cases, a stochastic approach might be needed to test the design criteria against an uncertain future resource.

Water Resource Associates has experience of many of these reservoir design and operational issues including:

• Reservoir analysis for multiple objectives including irrigation, hydropower, urban and industrial water supply, and flood control;
• Analysis of reservoirs in cascade or other network formation;
• Derivation of optimal flood routing to maximise downstream benefits;
• Operational changes in time to allow for alteration in the balance of priorities between irrigation and flood control;
• Analysis and review of historical performance.

The form of analysis depends on the stage of the project from pre-feasibility through to operation, but WRA can respond with appropriate software. This includes simulation, probability matrix analysis, flood routing, and the use of standard software packages, such as HEC-5, and sophisticated mathematical approaches including dynamic programming, linear programming and multi-objective planning models. The AQUATOR (RESSIM) model, developed by WRA, has wide application in the UK.

• Severn-Trent Water, UK
  WRA worked in two main areas. Firstly it was necessary to produce a long-term flow record for all the major surface resources. This was done using the HYSIM rainfall/runoff model. It built on work done earlier on the Trent but included updating simulation of the Trent basin and new simulation for the Severn and Wye basins. Secondly, using this data the RESSIM model was updated and modified to simulate all the surface resources of Severn-Trent. There is a high degree of inter-linking of the available resources and this demonstrated the ability of RESSIM to simulate complex water resource systems.
• SNIFFER (Scotland and Northern Ireland Forum for Environmental Research)
  The Company, together with Oxford Scientific Software, has in-house experience of software development in two key areas – catchment rainfall-runoff models and water resource system simulation. The HYSIM model would need some adaptation to accommodate recent scientific thinking and the RESSIM model applied in England would be developed further, with powerful new facilities enabling users to mould specific implementations, and renamed AQUATOR. These modification are in course of being completed.
• China
  Simulation modelling of a multi-reservoir system for the North Hainan Water Resources Development Project including irrigation, urban and industrial water supply and hydropower elements.
• Pakistan
  Reappraisal of the flood control operational strategy for Mangla Dam on the Jhelum river as part of an analysis of design flood levels for a protection bund for Jhelum City some distance downstream.
• Pakistan
  Review of the scope for rehabilitation of Bund Khushdil Khan, an off-stream irrigation reservoir built in the 1890s.
• UK
  Research into probability matrix methods applied to the analysis of monthly and annual reservoir operation. Development of an improved methods and of an iterative procedure to define operating rules for water supply reservoirs.

• Ethiopia
  Operational analysis of irrigation development in the Awash basin in Ethiopia including the stochastic derivation of flow sequences and the development of a computer model of the basin to assess the need for additional storage to sustain the hydropower and irrigation programme.
• Iran
  Modelling of a complex water resources system including dams and tunnels for irrigation development.
• Mozambique
  Reappraisal of the flood operation of Cabora Bassa dam and studies of flood frequency in the lower Zambezi to assess the potential for flood alleviation and flood warning. Revision of operating rules to maximize flood alleviation while maintaining power and energy levels.
• Sudan
  Studies of the hydrology of the Nile in Sudan with reference to reservoir operation including hydropower development at Jebel Aulia and Sabaloga.
• Sudan
  Operational study of the Khashm el Girba reservoir on the upper Atbara river in Sudan with particular emphasis on the effects of sedimentation.

Good environmental management requires that all development be sustainable, i.e. meets the needs of the present without compromising future needs. This conflict between present and future needs impacts on surface and groundwater management. The balance of skills and experience within Water Resource Associates Ltd makes us uniquely qualified to execute projects where the need for sustainability is paramount.

People have always been drawn to water - it is after all a prerequisite for survival. Whilst the rivers, in many of our cities, or the ponds, in villages, now seem picturesque they were originally the vital source of water, for people and for their livestock. Later these same rivers were a source of energy and transport. But as industrial power developed, rivers and streams increasingly came to be used as open sewers - with devastating consequences. The influence of development affected water in many other ways: wetlands were drained for agricultural land, rivers were dredged or embanked to control flooding, dams were built which changed natural patterns of flow.

The impact of these changes became increasingly negative - both for humans and for wildlife. Superimposed on these direct effects is that of climate change which, as the picture of the drowned village of Epicuen in Argentina shows, is already happening.

Groundwater development has always required an assessment of safe yield of an aquifer system. It is only recently that the long term impacts of development on quality of water are beginning to be understood. Saline intrusion or increased salinity from effected naturally saline layers can occur. Recently widespread contamination of water supply wells by arsenic has resulted from aeration of aquifers resulting from water table fall as a result of pumping. The other prime environmental concern is the contamination of groundwaters by leaching from agricultural or other man-made practices.

Water Resource Associates has experience of many aspects of water and the environment in most of the world's climate zones. In the UK this includes studies of measures to counteract the effects of acid rain and of climate change. Overseas it includes studies of a polluted lagoon in Ghana and of plans to abstract water upstream of the Okavango delta in Botswana. We also have experience of many analysis tools to study the degree of impact. This includes a range of mathematical models which are recognised as national standards.

In analysing water and the environment Water Resource Associates has always taken a balanced approach and, regardless of the client, has always given an objective appraisal.

• Botswana and Namibia
  The river Okavango rises in the humid mountains of Angola and flows southwards into the Kalahari desert. There, at the southernmost limit of the great African rift valley, the water is held behind a small geological displacement a few metres high and spreads out to form the Okavango Delta - an area internationally famous for its wildlife.
  
  Vigorous international opposition to proposals for water supply abstractions upstream of the Delta led to an independent review which concluded the proposals would have a negligible impact on the environment.
• Nigeria
  The Hadeija-Nguru basin in Northern Nigeria has a valuable wetland. WRA was called on to review a project, funded by IUCN, which looked at ways of conserving the wetland and providing benefit for local residents.
• Ghana
  The Korle lagoon receives most of the runoff from the city of Accra. The runoff is untreated and as a consequence the lagoon has suffered. WRA advised on the hydrology and feasibility of alternative methods of alleviating the problem.
• Turkey
  The Goksu delta on Turkey's Mediterranean coast receives drainage water from an irrigation system. This water has helped to create the lagoon but at the same time the excess nutrients carried by the water have led to eutrophication. WRA advised on the water balance and how the characteristics of the lagoon could be improved.

• Oman
  Review of all water resources surveys to define the scope for irrigation development including conservation projects and the use of spate flows in the wadi channels.
• Thailand
  Study of the impact of deforestation, changes in cropping pattern, and irrigation and hydropower development in NE Thailand on the hydrology of the Mekong.
• Zimbabwe
  Review of the hydrology of the Zambezi with emphasis on the apparent change in the regime of the Upper Zambezi to define the basis for further hydropower development at Kariba.
• Iraq
  The marshes of southern Iraq, at the confluence of the Tigris and Euphrates rivers, have for long provided the basis of a unique lifestyle in this otherwise arid region. Drainage works in recent years could be damaging, or even drying out, some of the marsh areas, and they are also affected significantly by upstream development.
  
  An international study supported by the AMAR Appeal reviewed the impact of these developments. The operation of all storage, diversion and flood control works in the Tigris and Euphrates basins were modelled over the historical time series to predict the continual reduction in water supply to the marshes. The study concluded that present and planned works upstream of the delta are such that little could be left of the marshes after 10 to 15 years.
• Romania
  The Danube delta in Romania is important as a source of fish protein and for many bird species. Dredging work over the last few decades has enabled flows from the river to pass more quickly into the shallow lakes, bringing silt and pollutants such as phosphates.
  
  A mathematical model of part of the delta was prepared as part of a strategic planning study, which proposed to reduce the spread of eutrophication by closing off some of the newly dredged channels encouraging flow through reed beds.
• Turkey
  Study of the environmental impact of sewerage schemes and tourism on Lake Köycegiz and Dalyan Beach in southern Turkey. Preliminary water balance studies showed that there is a net inflow from the sea each summer and that the ecology of the lake is finely balanced.

In 2000, the European Union adopted the Water Framework Directive (2000/60/EC) which aims to protect and enhance the status of aquatic ecosystems on inland surface waters, transitional waters, coastal waters and groundwater and to promote sustainable water use.  It is hoped these aims will be achieved by setting standards on water quality and ecological status that will be met mainly by reducing pollutant inputs, particularly priority hazardous substances, from the surrounding catchment.

Improving the water quality and ecology status of European rivers is difficult for four reasons:

- Whilst the study of the relationships between physical and chemical processes and the ecology in lakes is established, the equivalent science in rivers and wetlands is still relatively new. The understanding of how fluvial hydrochemistry controls the ecology and the feedback mechanisms are not sufficiently understood to predict the ecological response in rivers and wetlands with certainty;

- Pollutants which affect the ecology, either directly or indirectly by contributing to air pollution or climate change, are typically by-products of industry, farming, transport and power generation. All are currently of benefit to the economy of Europe, and therefore pollution controls in these sectors will have social and economic consequences, which are not fully understood;

- Changes in the climate, which are predicted to exceed natural variability, may confound our current understanding of chemical cycles in soils, groundwater, lakes, rivers and wetlands;

- Questions remain over what ‘good’ ecological status means. The WFD is based upon restoration to reference conditions, but the definition of an undisturbed river-system is uncertain and left to each Member State to define.

 Water Resource Associates Ltd is well placed to help those managing the environment and the Competent Authorities, charged with policing the directive, to deal with the four problems. The directors and associates of WRA have a wide range of experience in hydrology, water chemistry and ecology and together can provide the integrated science required to implement the WFD; in particular WRA can provide a range of hydrological and water quality models to help investigate catchment management options.

Within the EU a common implementation strategy has been worked out. This takes accounts of other directives such as those on flood risk management, priority substances and groundwater. The EU has also issued a series of guidance documents covering such topics as: economics, water bodies, pressures and impacts, heavily modified water bodies, intercalibration, public participation, wetlands and ecological status.

The above photos show, on the left, the Classical Chalk Stream with abundant Ranunculas and, on the right, a highly eutrophic stream showing dead and decaying stream plants . The WFD emphasises improving the ecological as well as chemical status of freshwaters.

On the photo above we see sediment Transport from the Canal to the River Kennet at Copse Lock. Sediment transport in catchments is a key component of the WFD since it can affect flooding, ecological habitats and is a vector for contaminants.

Experience as a company and directors

Pan Europe
Directors of WRA have used a catchment-scale model of nitrogen dynamics to investigate the key factors and processes controlling nitrogen dynamics in river-systems throughout Europe. The model has also been used to investigate the impacts of climate and land use change on nitrogen dynamics. A model to understand the relationship between flow, phosphorus and macrophyte dynamics in rivers has also been developed; this model is currently being used to understand how changes in the physical state of a river controls the biological status.
WRA reviewed the current scientific understanding of the hydrology, nutrient hydrochemistry and ecology of the River Kennet for use in the Collaborative Research Programme funded by DEFRA. This programme is developing an economic assessment of the implementation of the Water Framework Directive in complex catchments.
 
In addition the Principles have also worked in:
Projects in Eastern Europe aimed at initiating the production of river basin management planes in line with the WFD. Countries involved include, Ukraine, Belarus, Macedonia and Greece.

Assessment of the scale and variability of water resources is basic to many development projects and environmental studies. The scope of possible inputs varies from national and regional studies to site specific audit, and over a range of time scales. In some developing countries, scarcity of reliable data presents serious problems of resource assessment, which requires careful consideration of the uncertainties inherent in the estimates.
 
Water Resource Associates have experience of many of the physical and climatic regions of the world, and of working within many different frameworks from primary resources estimation to identifying the impact of land-use and agricultural change on the available water resource.
 
Many procedures including rainfall analysis, rainfall-runoff modelling and direct measures of river flow variation are relevant. Sometimes it is necessary to naturalise flow sequences to allow for developments that have taken place during the historical period for which records are available.
 
WRA has the relevant experience and software to handle all the issues involved in water resource assessment, and to help assess the feasibility of projects proposed for development of the water resource.

• UK
  Under contract to Severn-Trent Water plc we carried an analysis of their deployable yield. This was a statutory requirement. Severn-Trent Water is one of the largest water undertakings in the UK with over 8 million consumers.
• SNIFFER (Scotland and Northern Ireland Forum for Environmental Research)
  The Company, together with Oxford Scientific Software, has in-house experience of software development in two key areas – catchment rainfall-runoff models and water resource system simulation. The HYSIM model would need some adaptation to accommodate recent scientific thinking and the RESSIM model applied in England would be developed further, with powerful new facilities enabling users to mould specific implementations, and renamed AQUATOR. These modification are in course of being completed.
• Botswana
  Review of proposals for development of the resources of the Okavango delta. An environmentally more acceptable alternative was proposed for which the Client has commissioned a detailed design.
• Cambodia
  Investigation of the water resource base for irrigation and rural infrastructure development in Takeo and Kompong Speu provinces.
• China
  valuation of the water resource available to the North Hainan Water Resources Development Project. This included the naturalisation of flow series and an investigation of the potential for inter-basin transfers through system simulation modelling.
• India
  Strengthening the capability of the Institute for Water Studies in Madras in resource assessment, systems analysis and river basin modelling.
• Malawi
  Estimating the water resource available in a number of rivers in northern Malawi to support development of run of river hydropower projects. This involved an assessment of the natural storage of the Nyika Plateau, which strongly influenced the dry-season flows.
• UK
  Review of water resources of the River Rother (Sussex). This required identification of all surface and groundwater issues, review of data, data infilling through regression, low flow frequency studies and operational recommendations.
• Yemen
  Technical support for countrywide water resource assessment and modelling to support water sector master planning.

• Malawi
  Assessment of the water resources of the Shire Highlands and an appraisal of the reliability of flows in the Shire river, for Blantyre water supply.
• Oman
  Primary water resource survey of northern Oman comprising the analysis of rainfall and flood flows and the estimation of long term runoff and rates of aquifer recharge.
• Oman
  Review of all water resources surveys to define the scope for irrigation development including conservation projects and the use of spate flows in the wadi channels.
• Nigeria
  Water resources and flood studies for alternative water supply reservoirs on the Ogun and Ofiki rivers in Oyo state, Nigeria.
• Thailand
  Study of the impact of deforestation, changes in cropping pattern, and irrigation and hydropower development in NE Thailand on the hydrology of the Mekong.

Water Quality presents special problems to environmental managers who have to control rivers, lakes, groundwaters and wetlands to meet both environmental standards and water supply standards. For example, the new EU Water Framework Directive is having a major impact on the control of water quality and ecology as the new standards are set and applied at the catchment scale. New techniques on modelling catchments are required in order to cope with the increasing complexity of water quality issues.

Water Resource Associates have developed a range of water quality models for modelling river systems and catchments. These include the HERMES and INCA software packages. HERMES simulates the transport of pollution events down river systems and this model simulates flow, Dissolved Oxygen, Biochemical Oxygen demand, Ammonia, E Coli and any conservative or nominally unreactive pollutant.

In association with research at Reading University, Water Resource Associates has also developed a suite of catchment-based models collectively known as the INCA (Integrated Catchment) models. These take into account the land surface and land use and route the water and associated quality into the river network. Current versions of the software include INCA-N for flow, nitrate and ammonia, INCA-P for phosphorus, sediments, macrophytes, epiphytes and phytoplankton, INCA-SED for a sediments and INCA-Metals for a range of metals as well as a carbon model for DOC or water colour problems. All the models are process based, dynamic, daily and generate fluxes estimates and concentrations of all the variables at key locations along river systems.

Download our Water Quality Brochure

Wetlands play a special role in the hydrology of many river systems. While being inundated for all or part of the year, the depth of flooding is usually fairly shallow and seasonal. These special characteristics - different from those of surrounding regions - provide habitat for rare animals and birds.

Inevitably, wetlands are very sensitive to upstream development. Storage of water in reservoirs, diversion for irrigation, and flood control works can all impact on the natural balance of wetlands. Water quality can also be affected. Thus, an understanding of the hydrological system is a prerequisite to other environmental and ecological studies.

Nevertheless, wetlands can play a vital role in some aspects of development.

Water resources: storing water at times when other river systems are dry, they can be used as a perennial source of water.

Flood control: wetlands have tremendous capacity to act as buffers to floods. Indeed, flood plains can be considered as a specific case of wetlands. Riparian development often removes the buffering effects and leads to increased flooding downstream.

Pollution buffering: suspended sediment settles out in wetlands that hold water for a long period with very low flow velocities. Reeds and other aquatic vegetation can absorb some organic pollutants.

Fish hatcheries: the shallow water depths and low velocities are ideal as hatcheries for certain types of fish.

• Turkey
  Until the development of artificial irrigation in the Goksu delta on Turkey’s Mediterranean coast, there were only a few lagoons with very salty water which dried out completely in the summer. Since the development of irrigation the return water from the irrigation system has created a series of lagoons which are important for migratory birds and fishing. The overall aim of the project was to assess the long-term viability of the lagoons. WRA provided a short term specialist hydrological input. Using data collected by project staff and DSI (the organisation which had developed the irrigation system) a model of the lagoons was developed. The data were sparse, at best monthly (rainfall and evaporation) and in some cases every two months (quality data in the lagoons) for a five year period. There was little information on flow between lagoons so the model was calibrated using data on levels of salinity.
• Botswana
  The Okavango river rises in the humid mountains of Angola. From there it flows through Namibia and into Botswana where it forms an inland delta. The Okavango Delta is an internationally recognised wetland and home of a wide variety of wild life. Due to a persistent drought the Government of Namibia was considering abstractions from the Okavango river as an emergency measure. As part of the study of the possible abstraction a number of complementary studies were undertaken including one on the downstream environmental effects. This study was co-ordinated by the South Africa CSIR and WRA was brought in as a specialist consultant to study the possible hydrological effects on the delta. The wetland model used was a development of a model developed earlier by a WRA Director which took account of the losses from open water and vegetated land around the delta. The model divided the delta into 12 cells and simulated flows and areas in each cell.

• Botswana
  The river Okavango rises in the humid mountains of Angola and flows southwards into the Kalahari desert. There, at the southernmost limit of the great Africa rift valley, the water is held behind a small geological displacement a few metres high and spreads out to form the Okavango Delta - an area internationally famous for its wildlife.
  
  Vigorous international opposition to proposals for water supply developments at the southern end of the Delta led to an IUCN-funded review, which included hydrological investigations and modelling of the swamp system. Conjunctive use of surface and groundwater was found to be more economical and reliable and to have negligible impact on the environment.
• Iraq
  The marshes of southern Iraq, at the confluence of the Tigris and Euphrates rivers, have for long provided the basis of a unique lifestyle in this otherwise arid region. Drainage works in recent years could be damaging, or even drying out, some of the marsh areas, and they are also affected significantly by upstream development.
  
  An international study supported by the AMAR Appeal reviewed the impact these developments. The operation of all storage, diversion and flood control works in the Tigris and Euphrates basins were modelled over the historical time series to predict the continual reduction in water supply to the marshes. It concluded that present and planned works upstream of the delta are such that little could be left of the marshes after 10 to 15 years.
• Romania
  The Danube delta in Romania is important as a source of fish protein and for many bird species. Dredging work over the last few decades has enabled flows from the river to pass more quickly into the shallow lakes, bringing silt and pollutants such as Phosphates.
  
  A mathematical model of part of the delta was prepared as part of a strategic planning study, which proposed to reduce the spread of eutrophication by closing off some of the newly dredged channels encouraging flow through reed beds.