GPS and GIS study of the western slope of the Chiquihuite hill in Mexico City

Abstract

THE DEMOGRAPHIC EXPLOSION OF THE CITY OF MEXICO HAS FORCED THE ANARCHICAL GROWTH OF URBAN DEVELOPMENT IN ITS MOUNTAIN SLOPES. THE GEOLOGIC RISK CONDITIONS THAT PREVAIL IN SUCH AREAS ARE ROCK FALLS AND DOWN SLOPE CREEP. THE TOPOGRAPHIC SLOPE ANALYSIS SHOWS THAT THE SE SO ME AREAS POSE A HIGH RISK CONDITION FOR THE HOUSING DEVELOPMENTS LOCATED DOWN SLOPE. A GEODETIC NET WORK WAS THUS DEVELOPED FOR THE ESTABLISHMENT OF A REFERENCE FRAME TO DETECT MEDIUM AND LONG TERM SLOPE MOVEMENT. THE LOCATION OF THE SE BENCHMARKS INCLUDED ROCK OUT CROPS, STRUCTURAL CONTAINMENT CIVIL STRUCTURES AND STREET SIDE WALKS. THIS NET WORK WAS DE SIGNED TO BE OCCUPIED USING GPS FAST STATIC METHODS, WITH TIMES OF OCCUPATION NO GREATER TO 45 MINUTES PER STATION. IN ORDER TO KEEP SHORT BASE LINES TO THE REFERENCE STATION AND ITS POSITION ERRORS WITHIN LOW LEVELS WE INSTALLED A REFERENCE GPS SITE (UCHI) ON THE SOUTHERN PART OF CERRO DEL CHIQUIHUITE. THE CHIQUIHUITE GPS NET WORK WAS MONITORED FOR 5 YEARS. THE GPS SOLUTIONS WERE OBTAINED BY DIFFERENTIAL TECHNIQUES WITH AMBIGUITY SOLUTION AND PRECISE OR BITS, AND USING UCHI STATIONS AS A REFERENCE. THE CHIQUIHUITE GPS NET WORK DOES NOT SHOW SIGNIFICANT VARIATIONS, EXCEPT FOR THE VERTICAL COMPONENT AT STATION CH55. THIS SITE IS LIKELY TO BE AFFECTED BY REGIONAL SUBSIDENCE.