Background

The theme chosen for IHP-IV was : Hydrology and Water Resources Sustainable Development in a Changing Environment. It comprised three sub-programmes :

Sub-programme H : Hydrological research in a changing environment

Sub-programme M : Management of water resources for sustainable development

Sub-programme E : Education, training and the transfer of knowledge and information

The three sub-programmes were broken down into five themes covering forty-four projects in a hierarchical framework. Particular emphasis continued to be given to global change, water quality, hydrological regimes and the need to give special attention to the humid tropics, arid and semi-arid zones. The need for a more holistic approach was also emphasized by undertaking activities with policy-makers and planners within the framework of integrated water resources management.

Hydrological research in a changing environment (Sub-programme H)

The aim of this sub-programme was to improve knowledge of interface processes of water in the atmosphere-vegetation-soil system and to investigate how these processes could be best described on different time and spatial scales, particularly when establishing proper couplings to climate models.

Climate variability :

In order to increase the possibilities of making hydrological predictions, the study of the impact of climate variability led to the implementation of a project entitled "Collection of climatic data using historical archives" (ARCHISS, Archival Climate History Survey), implemented in collaboration with WMO and ICA (International Council on Archives); a first test was made in Europe, then extended to Cuba and Mexico. It contributed to the expansion of current knowledge of past climates of the world. Other research activities were concluded by the publication of a document entitled Impact of climate variations on water management systems and related socio-economic systems.

The following monographs were prepared in conjunction with these research programmes :
   - Impacts of climate change and climate variability on hydrological regimes
   - Global climate changes during the Holocene and impacts on water resources
   - HYDROCOAST '95 monograph which examines water-related problems/hazard reduction in low-lying coastal areas, linked with the impacts of socio-economic activities related to high population densities.

Snow and ice :

To increase the understanding of the basic physical processes and the role snow and ice play in the hydrological cycle, several major publications were released on past and present variations of snow covers on the earth on a global and regional scale; glacier mass balance bulletins; fluctuations of glaciers 1985-1990.

Humid Tropics Hydrology Programme :

The Humid Tropics Hydrology Programme developed several activities - pilot projects were launched in the Solomon Islands and in Abidjan, Côte d'Ivoire, to implement applied research activities and training at regional level.

A Humid Tropics Hydrology Center for Latin America and the Caribbean (CATHALAC) was established in Panama, and initiated research activities in the field of climate variability and its impact on hydrology and water resources management.

A Regional Steering Committee for South East Asia and the Pacific was established and published a Catalogue of Rivers from South East Asia and the Pacific which provided the first comprehensive survey of 25 rivers of the region.

It is foreseen that related activities will promote international data exchange as well as a collaborative research network in the region. Several popularized publications for non-professionals were issued highlighting water-related issues and problems of the humid tropics, including :
   - The disappearing tropical forest
   - Small tropical islands : water resources of paradise lost
   - Water and health
   - Tropical cities : managing their water
   - Women in the humid tropics
   - Groundwater

Arid and semi-arid zones :

Activities within the arid and semi-arid zone concentrated on four topics, viz.:
   - major deep aquifers;
   - hard rock aquifers;
   - groundwater recharge;
   - flash floods.

They were concluded by the publication of several technical documents presenting the state-of-the-art of these topics. The main findings of these publications were presented and discussed at an international symposium held in Tashkent, Uzbekistan, which also reviewed the Aral Sea-related hydrological problems and outlined their possible solutions. [More about the proceedings of the symposium]

Flow Regimes from International Experimental and Network Data (FRIEND) :

The FRIEND project aims to develop knowledge of flow regimes. It was extended from Europe to Africa where two new groups were established in Western and Central Africa (FRIEND/AOC) and Southern Africa (FRIEND/SA). Regional databases were developed within the Northern Europe Group (European Water Archive with data from over 5000 small catchments), in Alpine and Mediterranean Groups (the AMHY database contains data from 250 hydrological stations and 100 rainfall stations), in Southern Africa (data collected from 680 catchments) and Western and Central Africa (the BADOIE database stores data from 522 river gauging stations and 1120 rain gauges).

They provide the basis for the development of research activities on regional flow regimes, floods, low flows, rainfall-runoff, modelling and sediment transport. Results of these research activities were presented at the 2nd FRIEND Conference held in Braunschweig, Germany. Several hydrologists have been trained in the use of modern technologies for hydrological data analysis, especially in Western and Southern Africa where new software for this purpose has been introduced.

Management of water resources for sustainable development (Sub-programme M)

IHP-IV provided a forum for scientific deliberations on techniques and approaches to water resources assessment. These are presented in the monograph on World water resources at the beginning of the 21st century, a contribution to the 5th session of the UN Commission on Sustainable Development (CSD) report on Comprehensive assessment of freshwater resources of the world. In addition, collaboration continued with the International Association of Hydrogeologists (IAH) resulting in manuals and guidebooks for the mapping and assessment of groundwater resources.

Geographic Information Systems (GIS):

The use of Geographic Information Systems (GIS) in hydrological and water resources studies was introduced through several conferences and training workshops. A training manual was compiled by ITC (International Institute for Aerospace Survey and Earth Sciences), and field projects were implemented in Kenya and Indonesia. A GIS-based water balance model was developed in co-operation with FAO.

Groundwater :

Guidelines on monitoring groundwater management were published. A guidebook on the cartography of groundwater resources and their vulnerability, displaying models of maps and legends, was published : Guidebook on mapping groundwater vulnerability. In the field of surface and groundwater resources evaluation, several former IHP publications were updated.

Ecotones :

In co-operation with MAB (Man and the Biosphere), a programme on ecotones was launched in order to improve the understanding of water/land interfaces of crucial importance to landscape evolution. Comparative studies were undertaken with respect to the limnology and hydrology of the Great Africa Rift Valley Lakes, resulting in several publications on Lakes Victoria, Tanganyika and Malawi :
   - Limnology and hydrology of Lakes Tanganyika and Malawi
   - Limnology and hydrology of Lake Victoria
   - Management and conservation of the African Great Lakes (Lakes Victoria, Tanganyika and Malawi)

Education, training, the transfer of knowledge and public information (Sub-programme E)

The educational component of the Programme, covering all educational levels, was designed for the requirements of developing countries in particular. Preference was given to the training of hydrologists from countries without local training facilities and a network comprising all educational levels was developed. Hydrology was included in several areas of university education. Various disciplines were analyzed and a practical system of possible combinations was developed, together with model curricula and syllabi.

Computer-Aided Learning (CAL) technology in hydrology was also introduced during IHP-IV. The 32 postgraduate courses organized under the auspices of IHP continued their activities.