Monitoring Land Use and Land Cover in the Jobos Bay National Estuary Watershed
July 1, 1997 - April 30, 1999
Problem and Research Objectives
The Jobos Bay National Estuarine Research Reserve (JBNERR) is located in the south coast of Puerto Rico. Most of the land north to the reserve is devoted to the agriculture, although there is a high demand for urban and industrial development. Surface runoff and groundwater flow is toward the seashore, where the reserve is located. Changes in the land use, irrigation methods, and the increase in groundwater extraction, due to industrial and urban development, represent a serious threat to the overall water supply and water quality of the area. For this reason, JBNERR needs a tool to assess and manage these types of problems.
There are three main objectives to this project. The achievement of the objectives will allow JBNERR's technical staff to use BASINS as a watershed management tool to assess specific agricultural practices and proposed urban developments over the quality of the waters reaching the Reserve area. These objectives are to develop the database required by BASINS and document its development so other users can benefit from this effort, adapt the BASINS program package to JBNERR, and assess the point and non-point sources of specific pollutants within the watershed.
First the required data and format for BASINS was identified, and an Internet search was done for the data available. The data was downloaded and stored locally. For the data not available online potential sources of data were contacted, including key government agency personnel.
All collected data was converted into the required format. For the case of Hardcopy data, the maps were digitized into GIS format using a digitizing table, the tables were converted into dBase format so they could be joined to GIS files and they were scanned and converted into a digital file using an optical character recognition (OCR) software. For the case of Digital data, GIS files were converted to a common map projection in the ARC coverage or ARC shape GIS file format. The projection used was State Plane NAD 27 and the changes in coordinates were done using ERDAS IMAGINE 8.4 and the ArcView projection utility. Spreadsheets and other digital tables were converted into the dBase file format so they could be joined or associated to the GIS files.
Principal Findings and Significance
The prevailing land use and land cover classification of the study area showed that the predominant use was for agricultural land followed by closed forestland. Each land use and land cover classification was established with their total area and percentage of coverage. A color map entitled Jobos Bay Watershed 1999 was produced. The map shows the study area and the main product of this research.
With the data generated by this research the JBNERR ended with adequate information about its nearby land use and coverage. The digital database generated in this project provides baseline information that will serve to compare land use trends through time. The information provided by this project is a valuable tool in the development of priorities for the management of the reserve resources that are under natural and man induced stress. The general database will be useful for the development of land use dependant models such as BASINS.
- Land Use