ICARDA CARAVAN 11

loudless skies, empty plains, a scattering of dusty  salt bushes, rock outcrops jutting from the shallow  soil, a flock of sheep, some small boys, and a donkey slowly moving in the distance. A universal and seemingly timeless picture of the dry areas, etched in the minds of ICARDA's natural resource management scientists.
          It is an image that disguises to some extent the continuing eco-system based on seasonal rainfall that allows the dry areas to support flocks of sheep and food crops. The picture may, however, have to be re-drawn without those visible signs of sustained life unless the latest technological aids are focused on dry area management.
           Ever-increasing human demands seem to have exceeded the carrying capacity of our natural resources. Sustainable management practices that will reduce the pressure on these natural resources are urgently needed. A participatory, problem-solving approach, involving the rural population, planners, scientists, and policy makers from all levels and disciplines is essential to the successful implementation of natural resource management programs.
           To conduct such effective natural resource management, geographic areas should be delineated by their natural boundaries. Watersheds or catchments are hydrologically-defined areas that drain into a stream or surface water body. The flow of water, sediments, and nutrients through watersheds connects the up- and downstream users of these natural resources. By operating and coordinating programs on a watershed basis, stakeholders can better understand the cumulative impacts of various activities and determine the most critical problems within each watershed.
          In areas where renewable groundwater resources are available and of good quality, the judicious use of this resource for household activities, watering of animals, or supplemental irrigation is an extremely valuable, stabilizing factor for the livelihoods of the rural population. Hidden groundwater divides, which separate aquifers or groundwater basins, do not always coincide with the topographic surface water divides. However, due to the relatively fast nature of surface water processes, as compared to groundwater processes, a watershed approach helps us to focus our attention on capturing this resource, before it disappears into salt sinks, or evaporates into the atmosphere.
           Traditional agricultural research conducted in laboratories, pots, and plots has increased our understanding of small-scale processes, but is still not enough to explain the interdependency of these processes at the watershed scale. The characterization of the spatially- and temporally-variable water, soils, and vegetation, and the effects of natural and human activities on this system is an almost impossible task. However, techniques such as remote sensing, GPS (global positioning systems), automated monitoring equipment, digital elevation models, GIS (geographic information systems), and computer-based mathematical models have increased our capability to measure, analyze, and synthesize the spatially-distributed and time-variable

interaction of a broad spectrum of our natural resources.
ICARDA is currently testing and evaluating these technologies for their application throughout the Central and West Asia and North Africa region.
          More information is needed on the long-term effects of different land uses and management practices on the natural resource base of spatially-variable watersheds. Simulation models allow us to extend our knowledge of the current system to predict future effects. ICARDA is focusing on the state of the art in watershed modeling, integrating simulation techniques directly with GIS to provide scientists and planners with maps, graphs, and numbers for natural resource impact analyses of different development scenarios. Daily rainfall and temperature data, soil and land management data are collected from meteorological databases, soil maps, satellite imagery, and field surveys to serve as input to the model. Surface flow processes, erosion, nutrient transport, grazing effects, and crop yield are predicted throughout the watershed.
           However, to make the best possible use of available natural resources, it is necessary to go beyond the biophysical constraints to consider socioeconomic effects. Whereas the physical, chemical, and biological processes in the watershed can be reasonably well described, the institutional arrangements that affect the activities in the watershed are often less obvious. To determine optimal land use practices, the watershed simulation modeling will be integrated with a socioeconomic component for assessing the financial and environmental costs, the benefits of alternative practices, and the willingness and ability of land users to invest in different land management alternatives. The challenge is to design, implement, and evaluate watershed systems that are environmentally sustainable, economically efficient, and socially acceptable, based on full participation by all stakeholders.

Dr Adriana Bruggeman is Agricultural Hydrology Specialist; Dr Aden Aw-Hassan, Agricultural Economist; Mr Nicholas Thomas, GIS Analyst at ICARDA; and Dr Sobhi El-Naggar is Deputy Director General of the Matrouh Resource Management Project, Marsa Matrouh, Egypt.