REPORT OF THE IAHR-IHP LECTURER 1994, BANDUNG, INDONESIA, DECEMBER 1994

HYDRAULIC STRUCTURES IN TROPICAL RIVERS

Professor 1.1. Peters, Consultant, Brussels , Belgium

IAHR and UNESCO adopted the Research Institute for Water Resources Development in Bandung, Indonesia as host for the 1994 IAHRJIHP with as subject "Hydraulic Structures in Tropical Rivers". The target group was composed of about 20 engineers and geologists belonging to various Indonesian organisations: Ministry of Public Works, Research Institute for Water Resources Development, Government and private consultants. The course was held in Bandung, West Java, from 11 to 17 December 1994.

The one week schedule comprised five full day lectures and one day field visit. As the invited IAHR/IHP lecturer, I covered the subjects "Potamology" , "General principles of river training", "Hydraulic structures for river control" and "Recurrent measures" , Methodology for selecting hydraulic structures" , Site investigations", Design and design criteria", "Case studies from tropical rivers in Asia, South America and Africa". Prof. M. Memed, the Indonesian lecturer, presented the following subjects in the Indonesian language: "Planning of water resources management for environmental and sustainable development", "Deterioration criteria of river morphology in Indonesia due to development and mining activities" and "Special hydraulic structures for rivers in Indonesia".

Scale model investigations on hydraulic structures were discussed during a short visit to the Hydraulic Laboratory of the Research Institute for Water Resources Development. Several original solutions for weirs, low head pumps and hydro-power schemes were demonstrated.

The course participants received a set of lecture notes with illustrations taken from various sources, the main part form the very didactic book "Erosion and Sedimentation in the Nepal Himalayas",

published by Dr. V. Gal ay in 1987. Other reference books and manuals were available during the lectures.

During the sessions on "Methodology for selecting hydraulic structures", special attention was paid to the interaction between structure, flow and sediment movement. A proper understanding of river behaviour is a key for the success of river works, especially in tropical rivers. This was illustrated with examples from various tropical rivers all over the world.

Several participants were concerned about the possibility, or usefulness , of "importing" design developed in other regions of the world . Some expressed the idea that design criteria should be specific for the Indonesian rivers , as they were confronted with many failures . During the session on case studies, the possibilities offered for Indonesia by original solutions developed in other regions, e.g. in South American rivers were discussed. Failures of hydraulic structures and in river works

Course participants in front of the CJPELES weir. West Java

Archive Prof.Ir.J.J. Peters

from Asia, Africa and South America were presented, trying to explain the causes for malfunction, ins1stmg again on the necessity for a proper understanding of the behaviour of each particular river.

A broad range of hydraulic structures and river works were visited during the interesting field trip organised on the fourth day of the course: grade control structures, headworks in rivers with steep and mild slopes, bank revetments, groynes, retards, bridge, cut-offs . The trip was an opportunity to illustrate the concepts explained during the lectures, but also to comment on alternative solutions . Slides were taken in view of a discussion during the last session, useful to illustrate the need for establishing the geomorphic setting prior to the choice and design of a structure.

The participants were asked to make an overall assessment at the end of the course. It was evaluated as valuable, "because the material of the course was not only taken from text books, but most of it from

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experience, especially the real(life) experience of the lecturer". Nevertheless, some shortcomings were also identified: I) the course was too short for the extensive material to be taught, 2) the particular behaviour of Indonesian rivers needed to be commented and compared with what was found in other tropical regions, 3) the need for more reference material and data, 4) the necessity of workshops sessions during the course for problem solving exercises. Most of these shortcomings could probably have been overcome by a more extensive briefing prior to the course. The organisation of the course and the stay was excellent, the technical facilities were of more than adequate level and the Organising Committee worked efficiently. My experience with this course, but also with workshops organised by the World Meteorological Organisation, brings me to formulate the following recommendations :

About the organisation of the IAHRIIHP lectureship: i. The theme and content of the course should be well defined from the start by the organisation applying for the IAHRIIHP lectureship, and the lecturer should receive all necessary information and possible reference documents well before the lectures;

11. in similar courses in which the participants are all working on specific cases, they would be asked to present briefly those cases or their problems, individually or in group, this would allow the lecturer to focus on themes of direct interest to the participants; iii . although one can understand the language barrier for many participants, sessions for presentation of the local experience by a local lecturer should be held in English, so that fruitful discussions could be generated and, as a rule, all lecturers should attend all sessions .

About the training aspect: i. There is clearly a need for training in river engineering- hydraulic structures and river works - for tropical rivers, with appropriate technology, certainly because of the large number of failures ; ii . books and manuals with design of hydraulic structures and river works often lack a "potamology" approach: a large number of failures are due to a poor understanding of the fluvial processes and of the importance of the physiographic elements; iii. valuable experience exists in many countries, like in Indonesia, but is not sufficiently reported.

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Each year vast amounts of national and international funds are used to build maintain and repair hydraulic structures and river works all over the world. A significant part of these are lost because of improper conception or design. There is a need for dissemination of the experience gathered in this area and it could be a task for a working group within the IAHR Section on Fluvial Hydraulics to make an inventory of useful experiences and to have it published. Such a working group would comprise experts from the Section and from the tropical regions, ensuring a South-South transfer of technology with the help of the North .

I would like to thank IAHR and UNESCO for giving me the opportunity to lecture on this fascinating subject "Hydraulic Structures in Tropical Rivers" in Bandung, Indonesia, at the Research Institute for Water Resources Development. Thanks also go to the Director of the Institute, Dr Badruddin Machbub, and the Organizing Committee of the course, to the Secretariat and the technicians of the Institute . I extend special thanks to Mr Agus Pudji Prawoto who took care of me during the entire stay, from my arrival in Indonesia to my departure from Jakarta.

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