V FRIEND World Conference, Havana, Cuba, 2006 Hydrological Impacts of Climate Variability and Change Selected presentations on Latin America and the Caribbean

The science of water is an endless world for scientific research and creativity, in the water all the needs converge, the feelings and human traditions, water is the origin of life and its sustain, water is food supply, and it is also a base of the culture, traditions and religions; and, unfortunately, the cause of diverse conflicts among people and countries. Water is a renewable, but finite resource, endangered in many places by its non-rational use, in such a proportion, that the unmeasured disposal of pollutants in the water bodies or its exploitation over its natural capacity of renewal, might also put at risk its condition of renewable resource. Water is under the threat of climatic change that will affect its spatial and temporal distribution in a negative way in every place. The environmental situation of Latin America and the Caribbean is fragile, and particularly in relation to water many threats exist that justify the need of urgent actions. The intensive deforestation in the tropical forest and woods from temperate and cold regions; the modification or destruction of coastal ecosystems, the high degree of erosion due to inadecuated agriculture practices and incorrect use of the soil; the indiscriminated use of chemical and synthetic products in agriculture and urban industries; integrated to global environmental problems, among them, climate change and the ozone layer depletion, are being felt in different degrees in various parts of the continent. An evaluation of the Forum of Ministries of Environment in Latin America and the Caribbean, carried out in Bridgetown, Barbados, in 2000, recognized the continuation of the environmental deterioration in the region and in analizing the problem of water, the following were indicated among the main problems:

Unusual Hydrograph Characteristics, Upper Río Chagres, Panamá

Justin M Niedzialek, "Unusual hydrograph characteristics, upper Rio Chagres, Panama" (January 1, 2007). Dissertations Collection for University of Connecticut. Paper AAI3265788.

Inaccessible locations and inhospitable working conditions have resulted in a lack of detailed hydrological knowledge in the tropics. I have established a new field observatory located near the town of Gamboa, Panama, adjacent to the mid-point of the Panama Canal. This observatory allowed detailed measurements of the hydrologic cycle at the first-order catchment scale. My investigations reveal that competing runoff production mechanisms are responsible for the observed streamflow. Both of these mechanisms are strongly dependent upon rainfall rate and secondarily upon cumulative rainfall volume. I have identified a small but hydrologically significant riparian zone that is decoupled from the hillslope. In contrast to the remainder of the catchment this riparian zone shows signs of frequent overland flow. Upslope regions occasionally produce overland flow during high-intensity rainfall. Parallel to the small scale studies in Gamboa, sub-watersheds of the 414 km2 upper Rio Chagres were instrumented. These gages showed that the Rio Chagres rarely reacts uniformly; instead, the observed runoff is usually the result of a limited portion of the watershed. Based on inspiration from field research a new conceptual model, Sac3, was developed. Sac3 was successfully calibrated and verified on several study watersheds. Sac3 was also used to explore the relationship deep groundwater storages had on seasonal changes in baseflow runoff behavior.

Hydrological Processes in a humid Tropical Rain Forest: A Combined Experimental and Modelling Approach

Schellekens, J. 2000. Hydrological processes in a humid tropical rain
forest: a combined experimental and modeling approach. Ph.D.
Thesis, Free University of Amsterdam, Amsterdam University
Press, 158 p.

With populations growing explosively in the tropical parts of the world, and the per capita water demands increasing where living standards improve, optimisation of water resources is becoming increasingly important [Bonell et al., 1993]. Similarly, the strong demands for industrial wood (pulpwood, saw and veneer logs), fuelwood and charcoal, require the establishment of large areas of fast-growing plantation forests, often on land that is currently not forested [Evans, 1992; Brown et al., 1997]. Coupled with (i) the continued indiscriminate clearing of the world’s tropical forests [Jepma, 1995; Nepstad et al., 1999] which in many areas serve as the traditional supplier of high quality water; (ii) the associated deterioration of soil and water quality due to erosion and pollution [Oldeman, 1994], plus (iii) the possibility of gradually less dependable precipitation inputs and (in certain ‘maritime’ tropical areas away from the equator) an increasing frequency of devastating hurricanes due to ‘global change’ [Wasser and Harger, 1992], a sound understanding of the hydrological functioning of tropical forests is arguably even more important nowadays than ever before [cf. Bruijnzeel, 1990, 2000a]. Bruijnzeel and Abdul Rahim [1992] suggested that in a time of dwindling resources, additional forest hydrological research in the humid tropics could best be carried out at a limited number of carefully selected data-rich key locations that could be loosely joined together in a network that captures the environmental variability encountered in the humid tropics. Furthermore, Bruijnzeel [1993] and Bonell and Balek [1993] considered a catchment-based approach to offer the best framework for such research as this allows for the integration of hydrological, geomorphological, pedological and ecological observations in a spatial context, particularly if supplemented by process studies and physicallybased distributed modelling.
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