Today's Stories · Cavers trapped by flood- water! · A quick fag in Horror Inlet.

CAVERS TRAPPED BY FLOOD-WATER!
This is not the sort of headline we want to see on our website. Flooding is a hazard that affects many caves particularly in Mexico.

The 4 main river caves around Cuetzalan all flow through the limestone, combine, and eventually emerge at a resurgence in the Zempoala valley 9 km away to the north, and 950m lower. Heavy rain on the surface will result in a rapid increase in water levels underground. Not all of the water is able to drain out of the narrow restricted resurgence and the lower cave passages fill up with water and overflow out of Alpazat, which is situated 150m higher up the side of the hill

Alpazat is one of the main areas of exploration for the Cuetzalan 2000 expedition and rain, which results in a rise in underground water levels, is a real danger to anyone in that cave. Heavy rain on the surface will only take 5 to 6 hours to affect conditions underground in Alpazat. There are two main dangers associated with flooding in the cave. Firstly, the narrow constricted stream passages become increasingly difficult and dangerous to negotiate. The water level may rise slowly, which can be detected, or may come as a huge surge of water roaring and foaming down the cave passage; these is known as a flood pulse and areincredibly dangerous as they give the cavers little or no time to climb out of the way. Secondly, a rise in water level in Alpazat can completely flood the lower sections of the cave, which prevents the cavers getting out of the cave. It can then take many days of dry weather for the water levels to drop back down and release any trapped cavers.

• Because of the risk of flooding and the resulting danger to team members, the following safety measures have been put in place. Accurate weather forecasting using the "CAMPBELL SCIENTIFIC" portable weather station and a daily forecast faxed/emailed from the British Meteorological Office.
• A 3 km long telephone line has been laid from outside the Alpazat entrance to the bottom of "Horror Inlet", deep within the cave. This enables actual and predicted weather conditions to be relayed to the cavers underground. The telephone can also be used to remain in contact with cavers who get trapped inside the cave by floodwater. The telephone system has been developed by the BCRA's Cave Electronics Group www.bcra.org.uk The phone is also used to tell the surface safety person that a caving team are on their way out so that a hot drink can be ready for the weary cavers.
• An emergency camp has been established in a dry area of the cave so that cavers trapped by floodwater can survive until water levels subside. The camp contains food supplies for 20 man-days, carbide for the caving lamps and water purification tablets.
• A bright yellow "Divers Line" has been placed through the section of cave that floods to the roof. This would allow, if necessary, a fully equipped caver diver to follow the line through the maze of flooded passages and contact any trapped cavers. The expedition is fortunate enough to have such a fully equipped diver; Jonathan Sims.

There will always be risk in cave exploration; however, by good planning and taking sensible precautions the risks from flooding can be reduced to an acceptable level.