Estimates indicate that the region produces nearly half of the sum of the discharge of the Amazon and Orinoco Rivers, the first and third largest rivers in the world in terms of discharge. The Amazon as a whole is the largest source of fresh water in the world and the Guiana Shield is a major subsection of the total discharge, accounting for as much as 10-15% of the world’s fresh water. The three Guianas were recently listed among the world’s ten most water-rich countries in the UN World Water Development Report. However, the quality of this supply is threatened, amongst other things by pollution from mining activities.
Most of the effects of forest conversion and poor watershed management directly relate to changes in the hydrological regime of a watershed. The adverse effect of poor land use can be felt both on site and off site. Erosion and decreased infiltration of water in the ground can lead to local flash floods and clogging of downstream reservoirs and river channels with sediment, leading to decreased discharge capacity. In addition, the diminished capacity of the soil to hold water and the change in balance between surface and subsurface water flows, can also lead to lower flows during the dry season. Once watershed degradation has set in, it is very hard to reverse or even to stop the process.
Payments to those who manage watersheds could become an aspect of the regional financial mechanism. There are examples of places where downstream regions pay for conservation projects upstream in order to ensure the provision of fresh drinking water. During GSI – Phase II, these options will be investigated and tried out on our pilot sites.
The report “Hydrology in the Guiana Shield and Possibilities for Payment Schemes” written by Dr Judith Rosales of the Universidad Nacional Experimental de Guayana in Venezuela, published in December 2003, describes not only the main features of the hydrology of the Guiana Shield, it also focuses on the possibilities to design payment mechanisms. These mechanisms could provide incentives to those maintaining the essential hydro-services for man and nature in and beyond the region. You can download a PDF version of the report from this website (see Downloads section).