The Intersection of Cadastral The Intersection of Cadastral Surveys and Floodplain Maps in Surveys and Floodplain Maps in

GISGIS

Daniel Dean YatesDaniel Dean YatesUndergraduateUndergraduate

Department of Civil EngineeringDepartment of Civil EngineeringThe University of Texas at AustinThe University of Texas at Austin

The Cadastral MapThe Cadastral Map

Cadastral – adj., showing Cadastral – adj., showing or recording property or recording property boundaries, subdivision boundaries, subdivision lines, buildings, and lines, buildings, and related details.related details.

Commonly used for tax Commonly used for tax purposespurposes

Often referred to as plat Often referred to as plat mapsmaps

Source: The Cadastral Map in the Service of The State, Kain and Baigent, 1992

The Yates ParcelThe Yates Parcel

Plat map with delineated property parcels

“A plot rightly drawn by true information, describeth so the lively image ofa mannor, and every branch and member of the same, as the lord sittingin his chayre, may see what he hath, and where he lyeth, and in whole use and occupation of every particular is upon suddaine view.”

Surveyor’s Dialogue by John Norden, 1607Source: The Cadastral Map in the Service of The State, Kain and Baigent, 1992

Travis County ParcelsTravis County Parcels

Close up of Travis County Parcels and Structures

Source: Lower Colorado River Authority

Travis County Parcels and TheTravis County Parcels and TheLCRA 100 Year FloodplainLCRA 100 Year Floodplain

Fun with DatabasesFun with Databases

Joining the tax appraisal roll Joining the tax appraisal roll database with the parcelsdatabase with the parcels

Organizing the DataOrganizing the Data

Separating the parcels by city

Taking a closer look at Lago VistaTaking a closer look at Lago Vista

Selecting by attribute and exporting data as a shapefile

Taking a closer look…Taking a closer look…

Spatial JoinSpatial Join

Improvement Values by CityImprovement Values by City

Number of Parcels Intersecting 100

yr FloodplainImprovement value

per parcel Totals by CityAustin 233 570876 133014018Briarcliff 71 86215 6121264Del Valle 131 23108 3027134Eanes 212 196927 41748538Jonestown 64 17085 1093427Lago Vista 366 99056 36254397Lake Travis 526 60392 31766062Lakeway 130 285576 37124821Leander 273 68260 18634826Marble Falls 112 51969 5820525Westlake 3 210218 630653

Total 2121 315235665

3176 structures intersecting the 100 yr Floodplain

Del Valle NeighborhoodDel Valle Neighborhood

Del Valle NeighborhoodDel Valle Neighborhood

ThanksThanks

Lower Colorado River Authority Lower Colorado River Authority – Wes Birdwell, John McLeod, Sunny SimpkinsWes Birdwell, John McLeod, Sunny Simpkins

The University of Texas at AustinThe University of Texas at Austin– Dr. David Maidment Dr. David Maidment

Questions ?Questions ?

Boathouse going over Austin Dam, 1935 Flood