For the many reasons listed in this guide, paddling new rivers in Costa Rica is often more difficult than it is in Europe or the United States. No guide, including this guide, can provide a thorough enough description of any river to make an unaided trip safe by North American standards. We have not tried to explain how to run the rapids, but rather to describe the general characteristics of the rivers and their relative difficulties. Whitewater boating can be a hazardous sport; even whitewater of moderate difficulty can be dangerous.
Walt Blackadar's death in a Class III rapid that he had run many times is a classic example. The purpose of this guidebook is to provide access information and a description of river conditions that can be expected. It must be remembered, however, that there are simply no substitutes for experience, individual judgment, and careful examination of river conditions.
To a degree unmatched in any other part of the world, tropical river systems are hydrologically and geomorphology unstable. Rainfall arrives in copious amounts here, allowing rivers to rise rapidly. River channels are frequently altered by floods and flotsam, so the character and degree of difficulty of the individual rapids are subject to change.
In the individual river profiles, we have tried to provide the information most needed by paddlers wishing to paddle a river. The degree of difficulty assigned to each river is obviously a subjective decision; we have listed our criteria and standards of reference in the section above.
River gradients were measured from 1:50,000 scale topographic maps and listed in both English and metric units. Rounding of values has resulted in minor discrepancies as compared to the listed elevations and length of the river segment. Where parts of the river have substantially higher gradients than the section as a whole, we list partial gradients. For example, the upper Pacuare is listed as "76 feet per mile (3 @ 94 feet per mile)". This means that the average gradient of the entire section is 76 feet per mile (14.4 meters per km.) but a three mile stretch drops at a rate of 94 feet per mile (17.8 meters per kilometer).
The listed length of each section was also determined from 1:50,000 maps and rounded to the nearest tenth of a mile. Rivers that frequently split into multiple channels, such as the lower Pe�as Blancas, could be several tenths of a mile longer, depending on which channels you choose to take. Elevations listed for the put-ins and take-outs are accurate to the nearest 10 meters, as determined from the available topographic maps. This information can be quite useful in cross-checking information listed here against topographic maps in the event that there is any confusion about specific access points.
In most cases, the drainage areas listed in each river heading were obtained from the Costa Rican hydrologic survey office at the "Instituto Costarricense de Electricidad" (ICE). Drainage areas of engaged streams were measured with a planimeter from topographic maps. The size of the drainage area above a given river reach will usually reveal a lot of information about the character of the river and the duration of high and low flows. Rivers with a drainage area of less than 200 square miles (500 km.2) are usually quite small and technical and tend to have rapid runoff. As the drainage area grows larger, the dependability of flow increases as the extremes of flow decrease. In addition, these larger streams such as the General and Reventaz�n end to have more open rapids than the smaller creeks.
Average discharge values reinforce what the drainage area values suggest, but these yearly averages can be misleading due to great seasonal variations. For this reason, we have provided representative hydrographs for all streams for which the necessary information is available. On each of these hydrographs, the average monthly discharge is shown as a bar graph in the background and the average daily discharge for a single representative year is shown as a bold, irregular curve.
In the Pacuare River, the average discharge for the month of January is only 48 meters per second, which is a low but adequate level for paddling. However, during the single year represented by the solid line on the hydrograph, the stream discharge varied from a low flow of 23 cm to a high of over 300 cm. The important lesson to be learned from this is that stream flow can be quite volatile and excessive flows are possible even during the dry season.
Monthly averages are indicative of typical conditions for each month, while the daily values for a single year reveal the characteristic fluctuations that are likely to occur on a short-term basis. The paddling season listed is based on average or typical conditions, although occasional heavy rains will make any of the rivers paddleable for a day or two at a time even during its normally dry season. Conversely, occasional dry periods may render streams unpaddleable even during the peak wet season. Such occurrences are rare, however, and the dam-controlled Reventaz�n always has enough water for paddling.
|
Ecotourism and Nature 
