D.E. Walling

International Hydrology Prize 2007
Prix International d'Hydrologie 2007

Prof. Desmond Eric WALLING

The 2007 International Hydrology Prize has been presented to D.E. Walling (left) by A. Askew (right), IAHS President and S. Demuth representing A. Szöllösi-Nagy, Director of the UNESCO Water Sciences Division, A. Tyagi, Director of the WMO Hydrology and Water Resources Departement being excused. The ceremony took place on July 13, 2006, at Perugia (Italy) during the second IAHS plenary of the XXIVth IUGG General Assembly.

Citation by A. Askew

Desmond Eric Walling was born in Essex on the outskirts of London but spent much of his childhood in Surrey. He later followed the call to – “Go West young man” – and headed first to Somerset and then on to Devon where, in the early 1960s, he entered the University of Exeter to study Geography.

He obtained his BA in 1966 and his Doctorate five years later. Those of us who know Exeter, can well understand why he chose to go no further West. Who would want to leave such a beautiful campus in such a delightful county?

Many will remember the First Scientific Assembly of IAHS, which was held at Exeter University in 1982. The success of that Assembly owed much to the untiring efforts of Des and his colleagues. The success was scientific, but it was also financial – the two do not always go hand-in-hand – and the profits made led to the establishment of the other Prize that is awarded annually by IAHS: the Tison Award for young hydrologists. It was also used to set up the Exeter Travel Fund, which still helps to support young scientists to attend IAHS and IUGG conferences. This gave Des much justified recognition within the international hydrology community

He had been appointed Lecturer in 1971 and by the time of the Exeter Assembly he was a Reader in the Geography Department. He later rose to the position of full Professor and since 1998 he has held the post of Reardon Smith Professor at the University. One cannot help but remark on the fact that, while Des has spent his entire academic life of over 40 years in one institution, he has become known and respected throughout the World for his work. In fact, I think it is true to say that never has a candidacy for the International Hydrology Prize been supported by so many countries.

What is it that has made Professor Walling so well known that the World beats a path to his door?

First and foremost is Des’ commitment to the study of erosion and sedimentation: a topic which is now more important than ever given the continual increase in demand for land for urban development and food production while vast areas are being degraded by erosion and water courses and reservoirs are being filled with sediment. His is a commitment not only to much-needed research, based on meticulous field experiments – real data - but also to the application of the research results in operational practice, and to teaching. This last focus is well illustrated by the fact that he has supervised more than 60 PhD students over the past 35 years.

Key topics within the field of erosion and sedimentation where his contribution are readily recognised include:

  • Global sediment yields and the sensitivity of river loads to environmental change. The global map of sediment yields that he produced with Bruce Webb back in the 1980s is still widely cited.
  • Suspended sediment dynamics. His classic work on sediment rating curves remains some of the most important in the field and is widely cited.
  • Sediment measurement problems. He was amongst the first hydrologists to emphasise the major errors associated with many measurements of the suspended sediment loads of rivers.
  • Suspended sediment properties. Des’s work has addressed the gap that existed in the past between establishing the magnitude of suspended sediment fluxes and considering the properties of the sediment.
  • The use of environmental radionuclides in the study of erosion and sedimentation. He pioneered important advances in the use of caesium-137, lead-210 and beryllium-7 in studying the mobilisation, transfer and storage of sediment in river basins, collaborating in this with the International Atomic Energy Agency and is without doubt a world leader in this field.
  • Sediment source fingerprinting. Des Walling and his team have pioneered advances in the use of ‘fingerprinting’ techniques.
  • Floodplain sedimentation. His work in establishing the importance of floodplains as major sediment sinks is widely cited and has underpinned much subsequent work in the field.
  • Catchment sediment budgets. Looking back over Des’s research career, it is clear that one of his main objectives was to quantify the sediment budget of a catchment. It is good to see that as his career moves into its later stages he has now succeeded in constructing full sediment budgets for several of the catchments that he has studies and the papers that he has produced documenting this work and its findings must be seen as making a major contribution in the field.
  • Sediment problems in river basins. Recent increase in concern for the role of fine sediment loadings in degrading aquatic habitats and ecosystems has meant that it has an increasing relevance for river basin and catchment management and Des has responded to these new challenges through his work on the role of fine sediment in diffuse source pollution, the transfer and fate of nutrients and contaminants, particularly phosphorus, and the siltation of salmon spawning gravels.

The results of this work are recorded in some 30 books, monographs and edited volumes and more than 430 scientific papers. In all this he has brought a reputation for care, consistency and clear thinking which have led others to rely on him as a source of sound advice and leadership.

The second reason for Professor Walling’s international reputation is the fact that, while his home base has always been Exeter, he has not sat immobile among the leafy lanes of the Devonshire countryside. He has travelled extensively and collaborated in projects in many other countries, including Algeria, Belize, Chile, China, France, Greenland, Italy, Kenya, Laos, Lesotho, Morocco, Norway, Poland, Russia,.Spain, Thailand, Zambia and Zimbabwe. The list of countries he has visited is far longer, of course, and the experience he has gained from his travels has led to his having a global view of erosion and sedimentation problems that is evident from the universal nature of much of his work, making it relevant, not just to the County of Devon or even to the UK, but to the wide range of situations faced on other countries.

The third reason follows naturally but not automatically from the second. From his very earliest days as a research worker, Professor Walling chose to put his considerable ability at the service of the international hydrological community, in particular but not exclusively IAHS.

Des has been a strong supporter of the Association’s publications, editing or co-editing 15 volumes of “Red Books” and publishing more than 70 papers in the series. He almost certainly holds the record in this regard. His interest in IAHS Press has never been purely as an outlet for his own work, however, and he has given much in return. Some years ago he was very much involved in establishing IAHS Ltd as a not-for-profit company and has for some time been the Chairman of IAHS Ltd, a role he takes very seriously, being at all times aware that the Board that he chairs is effectively the employer of four staff.

Quite naturally, Des has been closely involved in the International Commission on Continental Erosion of IAHS, being its Secretary from 1975 until 1983 and then its President until 1991. His fellow members of that Commission hold that its current healthy state owes much to Des’ leadership in past years. During those years he convened or co-convened a number of successful symposia, including one at the Assembly in Foz do Iguaçu in 2005 which generated two volumes of proceedings.

His commitment to IAHS has not been at the expense of other organizations and, from 1996 to 1999, Des served as President of the International Association of Sediment Water Sciences and in October 2004 he was elected founding President of the World Association for Sediment and Erosion Research (WASER). He has served as a member of the Advisory Council of the International Research and Training Center in Erosion and Sedimentation (IRTCES) in Beijing for several terms. The link here is of course with UNESCO through which he has been actively involved in its International Hydrological Programme, serving at one time as co-ordinator of various IHP projects on erosion and sedimentation and being currently a member of the Steering Committee of the UNESCO International Sedimentation Initiative. He has worked with the International Atomic Energy Agency on the use of environmental radionuclides and, within the non-governmental community, one can also mention his close involvement with various components of the International Geosphere-Biosphere Programme.

With a curriculum vitae such as this, it is not surprising that Professor Walling has been awarded a number of national and international honours over the years. He received the Vollenweider Award of Environment Canada in 1990 for `Contributions to Excellence in International Freshwater Research and Scientific Leadership' and in 1995 he was the first recipient of the President's Prize of the British Hydrological Society. In 2000 he was awarded the Victoria Medal of the Royal Geographical Society of London for ‘Outstanding Contributions to Hydrology and Fluvial Geomorphology’.

In view of his outstanding contributions to the science of hydrology and to international co-operation, not only within his own field of erosion and sedimentation, but in hydrology in general, there can be no doubt that Des Walling is a worthy recipient of the International Hydrology Prize. It is therefore with great pleasure that, together with UNESCO and WMO, the Association awards him the Prize for 2007.

Response by D.E. Walling

Mr President, representatives of UNESCO and WMO, friends and fellow hydrologists:

It was a very great pleasure and indeed a surprise for me to receive an email from our President back in March informing me that I had been awarded the International Hydrology Prize for 2007. This is a great honour, particularly when I have recently seen the Prize referred to as the Nobel Prize of Hydrology. I am very grateful to those amongst the international community that nominated me for this prize and to the panel that made the award. I feel both proud and humbled to join the ranks of previous recipients of the prize. As someone who started to participate in IAHS activities back in the mid 1970s, thirty years ago, my sense of pride is further strengthened by the fact that with the exception of the first recipient, Professor Tison, I have met all the previous recipients and I feel greatly honoured to join their ranks. There are three other UK hydrologists on that list, and the addition of my name brings this to four. However, if it is permissible to introduce an element of friendly rivalry, I should indicate that the UK is still some way from matching the record of the US, who currently have six recipients.

Arthur has, in his inimitable way, provided a beautifully crafted and very generous summary of my achievements over the past 35 years or so and it is somewhat sobering to have those years and my different achievements paraded in front of me. I feel somewhat like the drowning man, whom, we are told, sees the whole of his life flash past before he succumbs to his fate. Fortunately my fate is rather kinder!

Arthur focussed on my achievements, but of course many, if not most of these, would have been impossible without the support, help and collaboration of the many people with whom I have had the privilege to work and interact over the years. It is difficult to single out individuals from a long list, but I would like to mention just a few:

Firstly, Professor Ken Gregory my undergraduate tutor and PhD supervisor at the University of Exeter, who encouraged me to work on rivers, catchments and muddy water.

Secondly, a number of UK engineering hydrologists, including Peter Wolf, Michael Hamlin and Jim McCulloch, who encouraged a young geographer to both follow his interests in erosion and sediment transport and to join the national and international hydrological communities.

Thirdly, the large group of former PhD students, research fellows and colleagues in both the UK and overseas with whom I have been fortunate to work over the past 35 years. I will not list these, but I would like to direct particular recognition to Bruce Webb, who should be here this evening and with whom I have worked as a colleague and friend for some 30 years. With W as the 23rd letter of the alphabet, I had to search very hard to find someone who would come after me when listing authorship in alphabetical order! I was very fortunate to find Bruce.

I would also like to acknowledge the many gentleman scientists from overseas, including Harold Guy, Dick Hadley and Bob Meade from the USGS and Fred Fournier, a former President of ICCE, who generously passed on their knowledge and enthusiasm to a young researcher from the UK, where the accepted position was that soil erosion was not a problem and the rivers were not muddy enough to cause problems and where some therefore thought that I was wasting my time in devoting attention to erosion and sediment yields. I can well remember very early in my career being taken to task by one very eminent UK hydrologist, who, after I had given a short paper on suspended sediment yields, argued that there was no such thing as suspended sediment, because the word sediment was derived from the latin word sedere meaning to sit and could therefore not be suspended! I was firmly put down, but I recovered!

IAHS, UNESCO and WMO are the sponsors of this award and I would like to thank them once again for bestowing this honour upon me. More broadly, however, I would like to recognise their important contribution to the development of my career. It is my links with IAHS that enabled me to branch out from my roots in physical geography and become a true hydrologist. I think that I probably have John Rodda to thank for this, when, back in 1975, he arranged for me to be nominated as Secretary of ICCE. At that time the acronyms IAHS and ICCE meant little to me, but they have subsequently become a very important part of my life. I attended my first IAHS symposium in Paris, 30 years ago, in 1977 and my first IAHS General Assembly in Canberra, Australia in 1979 and I have attended all subsequent General Assemblies and Scientific Assemblies. I have greatly valued the opportunities provided by ICCE to collaborate with other hydrologists working on erosion and sedimentation in many different parts of the world. Equally, I have greatly appreciated the way that our Association has promoted hydrology as a discipline in the international arena and its camaraderie. I have many fond memories of past Assemblies and, for example, of encouraging Jean Rodier to sing Clementine and pushing Jim Dooge to treat us to a rendition of Molly Malone. UNESCO was also very important in stimulating my interest in catchment hydrology and hydrological processes back in the 1960s through the IHD and it raised the profile of sediment studies by providing support for several projects on erosion and sedimentation within the IHP, in which I was fortunate to be invited to participate. The UNESCO International Sedimentation Initiative, ISI, with which I am now closely involved, continues that support. Equally, although perhaps more indirectly, WMO has provided important support for sediment studies as part of hydrology, by including sediment measurement as a key component of their initiative to develop standardised measurement programmes.

In his generous review of my achievements, Arthur has clearly shown where my interests lie. It is in the field of erosion and sedimentation, a fascinating area, where I have been able to range from studies of global patterns of sediment yield, through the development of new measuring techniques and the application of fallout radionuclides as sediment tracers, to investigations of the characteristics of sediment particles and the sediment budgets of small catchments. It has proved very a fulfilling field of study. IAHS has always recognised this as a part of hydrology and ICCE, its International Commission on Continental Erosion, was established way back in 1948 at the General Assembly in Oslo. Initially it was the International Commission on Land Erosion, but, because of the emphasis of the work of members such as Professor Tixeront and Fred Fournier in looking at global patterns of erosion sediment transport, it was renamed ICCE. This gave it a distinctive focus, which I also have enjoyed pursuing by looking at the global pattern of sediment yield and recent changes in the sediment loads of the world’s major rivers.

Looking back through the list of recipients of the International Hydrology Prize, I am conscious that I am the first from the area of erosion and sedimentation to have received the award and I would like to feel that this in some ways brings further recognition to this field and to ICCE. It is a field, which, I would suggest, is assuming increasing importance, as hydrology concerns itself with the problems of environmental protection and sustainable development. Soil erosion has long been recognised as threatening the soil resource and reservoir sedimentation is a major problem in many areas of the world. These problems remain and sediment is likely to represent a major constraint on future water resource development in many areas of the world. If reservoirs fill up with sediment, they are difficult to replace. However, it is the more widespread and insidious impacts of sediment on water quality and environmental quality that have in recent years raised its profile worldwide. Sediment has been referred to as the world’s number 1 pollutant and its important role in the transport of nutrients and contaminants through terrestrial and aquatic systems is being increasingly recognised. Thus, for example, if you want to understand the mobilisation, transfer and fate of phosphorus and organic contaminants in terrestrial and aquatic systems, a knowledge of sediment mobilisation, sediment sources and sediment budgets is essential. Equally, sediment is increasingly seen as a key influence on aquatic ecology and within EC countries it is at last being recognised as being of central importance to the Water Framework and Habitats Directives. As I mentioned previously, when I started research in his area in the UK back in the late 1960s, I was told that neither soil erosion nor sediment represented significant problems and that I was wasting my time! I persevered and my presence here today shows how, in retrospect, that advice proved wrong. Sediment is a key pathway for material transport at all scales ranging from the global earth system to the individual farmer’s field. Our understanding and knowledge has expanded greatly over the past few decades, but there is still more to be done and I would urge IAHS to continue to encourage and support work in this field and to promote its closer interaction with other areas of hydrology. I hope that I will not be the only ‘mudlark’ to join the ranks of recipients of the International Hydrology Prize and that others will join me in the coming years.

Mr President and colleagues, thank you once again for the great honour that you have bestowed on me by awarding me the International Hydrology Prize.

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