Urban River Planning Tools Using Internet Mapping:

A Case Study with the Tecate River

Group 8:  Katie Comer, Susie Pike Humphrey, Alyssa Tugend

            Geographic Information System (GIS) tools such as internet mapping can be used by urban planners and the public to ask "what if" questions about alternative land use strategies. Our website was developed to provide information and planning tools for a small section of land along the Tecate River (Tecate Creek) in Mexico. The study area is located within the Tijuana River Watershed along the U.S. - Mexico border and is part of a larger proposed urban river project.  The website includes interactive maps, static maps and relevant information about the region that a viewer can use to explore alternative land-use options.

PURPOSE AND NEED

Urban River Planning utilizes many scientific fields such as hydrology, geomorphology, chemistry, biology and engineering.  It also requires that demographic and socioeconomic information be incorporated with land-use and watershed analyses in order to provide a complete picture of the area in question.  Internet mapping tools provide a mechanism whereby all of this information can be incorporated into one location and then disseminated to a wide range of users. In addition, interactive maps aid in visualization of the various alternatives by allowing users to explore different options through map queries.  Moreover, providing all of this information via the internet helps to facilitate public participation, thus making the planning process more democratic. Therefore, an interactive mapping website provides benefits to both planners and the public.  Members of the public are able to obtain information and provide input, and planners are able to disseminate information and receive feedback from individuals who might not ordinarily be involved in the process.

Our website was inspired by several studies on urban rivers in Tijuana and Tecate Mexico that have been conducted by San Diego State’s Institute for Regional Studies of the Californias (IRSC).  As identified in the literature, the region is facing a number of environmental and cultural issues. Some of the area’s most pressing problems include rapid population growth (Ganster 1996; Michel 2001) and the quantity of water needed to support this population; flood control (Wakida 1998); poor water quality, including health risks from heavy metals and sewage (Gersberg 1996; EPA 2000); and the loss of biodiversity (Service; IUCN 1997; Delgadillo 2000). Other cultural issues include the lack of green areas for recreation and quality of life and the importance of preserving Native American and archaeological resources (Ganster 1996; Wilkens 2001).

            In order to deal with some of these problems, there are several pending proposals for the Tecate River region, including one that involves channelizing the river and one that recommends creating a river park in the area.  A draft paper by Suzanne Michel and Carlos Graizbord of the ISRC entitled “Urban Rivers in Tecate and Tijuana: Strategies for Sustainable Cities” provides some information about the pros and cons of the various options.  According to the report, the river park land-use plan includes preservation areas, recreational activities and development areas.  It serves to protect against flooding but also retains and reinforces the benefits of the natural stream system.  On the other hand, channelization has been proposed in order to make more land available for urban development and to contain flooding.  The Borderlink 2000 Program conducted a similar suitability study for seven miles of the Alamar River using photo interpretation and fieldwork.  The final report from this study recommends a river park for this area and provides extensive information on the importance of effective management for conserving the critical water resources in this region (Michel 2000).     

Our website was designed to provide maps and basic background information about the Tecate River study area in order to allow a user to form an opinion or make a decision about the future of the watershed.  Because there are a large number of issues involved in management decisions of this type, it was only feasible to provide a small introduction to the critical issues, with links to other documents or websites where interested parties could go to get more detailed information.  Static maps are included to provide locational information on the study area and allow a person to “zoom in” to the area from the region to the Tijuana River Watershed (TRW) down to the sub-basin, and finally down to the study area.  The most unique feature of the website, however, is the interactive map section, which allows the user to create their own queries, draw their own polygons, or reorder existing map layers.  

Information about the Tecate study area is provided through a series of summary pages.  There is a general information page that provides a map of the area, as well as some statistics about the size and physical characteristics.  The proposal page lists the various land-use options that are being considered (river park, river channelization or no action) and the pros and cons of each action (Table 1).  Other background information pages include one on the ecology of the area, one on socioeconomics and a public health page.  Each of these pages was designed to provide a small amount of information so that users could get an idea of the issues involved, but in an effort to keep the viewers attention, do not go into great detail.  Links to other websites and references to the appropriate documents are provided for those interested in more in-depth analyses.  In order to fully appreciate the need for this website, it is important to understand some history and background of the Tecate River region.

Tecate Study Area Background Information

Humans have historically settled near water bodies.  Fluvial systems are ideal for bringing fresh water, taking away wastes and providing transportation, irrigation and recreation.  To maximize these benefits and minimize flooding, humans have altered river systems by diverting, channelizing and damming them.  Ultimately, however, rivers lose their ability to benefit humans when they are overused or abused.  For example, the Colorado River once serviced the entire western United States and northern Mexico with fresh water, riparian habitat and estuaries.  However, now the river runs dry before reaching its destination.  One problem with past management of rivers was the lack of long-term planning and consideration or understanding of ecosystem functions.  Nowadays, however, there is an increased awareness of the importance of managing these important resources, therefore studies are being undertaken and preservation measures are being prescribed. 

The Tijuana River Watershed (TRW) straddles the U.S./Mexican Border (Figure 1) and encompasses the Tecate-Cottonwood sub-basin. The Rio Alamar (Alamar River) Corridor drains the upper watershed (Cottonwood and Campo Creeks in the U.S. and Tecate Creek in Mexico) in the northern third of the Tijuana River Basin.  Flooding along the Tijuana River and Rio Alamar is responsible for property damage and human death during flood events, as well as severe sedimentation that damages the Tijuana Estuary, which is the last fully functioning wetland remaining in Southern California.

Figure 1. Map of the Tijuana River Watershed

The Tecate-Cottonwood sub-basin encompasses 620 square kilometers, including the Campo Indian Reservation on the U.S. side and the city of Tecate in Mexico.  The area is characterized by steep hilly terrain, a Mediterranean climate and is dominated by chaparral and coastal sage scrub, wetlands (vernal pools and riparian zones) and conifers in the mountains.  The temperature ranges between 8 and 18 degrees Celsius and precipitation ranges from 150 to 650 mm per year (Wright 1999).  The sub-basin is a predominantly rural area, which in 1998 was 88% non-developed.  The major land use categories are agricultural (6.5%) and dispersed residential (3.1%).   

The website study area is the main stream channel in this basin, the Tecate River, which is also referred to as the Rio Tecate or Tecate Creek.  The Tecate River drains a large area of 39,660 hectares (Figure 2).  Discharge from the Tecate Municipal Sewage Treatment Plant and the Tecate Brewery feed into the Tecate Creek (Gersberg 1996).

Figure 2. Map of the Tecate-Cottonwood Sub-basin and Study Area

Economic growth in the region over the last 20 years has caused significant impacts on the watershed.  Maquiladoras (companies who take advantage of Mexico’s lax environmental and labor laws) offer salaries that are higher than the minimum national wage, drawing migrants from other parts of Mexico.  Migration has resulted in a population explosion (see table 1) of unplanned squatter settlements without access to water supply or wastewater systems (Ganster 1996).

                        Table 1. Population and Growth Rates for 4 Regional Cities

The urgency of these regional issues is caused by Tijuana’s eastward expansion that threatens to reach Tecate between the years 2007 to 2012.  Estimates are that the population in this area is likely to double in the next 20 years.  However, while demand in the region is rising, water supplies remain steady.  With an average rainfall of only 10 inches (Wakida 1998), there is more evapotranspiration then precipitation.  Imported water from the Colorado River currently serves 85-90% of the area.  However, due to dams and diversions, the flow from the Colorado is inconsistent and has decreased dramatically between 1935 and 1993, with little to no water reaching the outlet in non-flood years (Glenn 1995).  It is apparent that the current practices are not sustainable. 

Increased urbanization and encroachment of humans into the flood zone of the Tecate River has resulted in the need to modify the banks with rocks and other items to prevent flooding.  However, channelization (concrete surfaces) stops infiltration into the soil and increases the rate at which pollutants reach rivers and streams.  Storm water runoff appears to be the major source of heavy metals in the Tijuana Estuary, with zinc found in high concentrations (EPA 2000). 

Studies of the Tecate River reveal poor water quality.  In 2001, significant amounts of cadmium, chromium, copper and nickel were detected downstream from the city’s wastewater plant. Studies by SDSU also document high levels of metals and fecal waste into the Tecate Creek, and stress the need for a comprehensive wastewater and storm water management plan (Gersberg 1996).

According to the Environmental Protection Agency (EPA), the most critical factor for the Tecate-Cottonwood sub-basin on the U.S. side is the lost of biodiversity (EPA 2000).  Biodiversity enhances ecosystem functioning such as nutrient cycling and fixing.  Other ecosystem benefits include water and air purification and soil generation. High biological diversity is important both for ecosystem health and for resistance/recovery from disasters (Swanson 1992).

            It is evident from the literature review that there are a number of critical issues that must be considered as management decisions are made regarding the Tecate River.  As previously indicated, the internet can serve as a mechanism whereby information on these issues can be communicated to the public, as well as to managers and urban planners.  In addition, interactive maps aid in visualization of the various alternatives.  Therefore, our website was developed in order to provide these services.  

METHODS AND RESULTS

Website

            Frontpage was used to design the website.  Since a wide audience of Mexican and American urban planners, residents and other interested parties are the targeted users of this site, an effort was made to keep a relatively simple design that would be easy to navigate and understand.  Therefore, the information is provided in a concise bulleted format, with easy access to additional information for those who want it.  An attempt was made to provide as much information as possible in both English and Spanish, however time constraints prevented us from being able to translate all of the text. 

            The website hierarchy is included as Figure 3.   It has a broad shallow design, with links to each of the main pages from the home page. Navigation link bars were provided at the top of each page so that users could easily navigate back and forth to various pages within the site.  An attempt was also made to fit each page onto one screen so that viewers did not have to scroll down to see all of the information, however we were not able to accomplish this. 

Figure 3. Website Organization

            The home page consists of our mission statement and some pictures of Tecate to allow viewers to familiarize themselves with the river site, the general area and some of the landmarks.  Each of the pictures on the home page is a thumbnail that displays the name of the feature when the cursor is moved over it, and users are able to click on the thumbnail to see a larger image.  The general information page provides a regional map of the area and brief information on the physical characteristics of the study area in addition to links to the socioeconomic, public health and ecology pages.  Each of these pages provides some brief information on the most critical issues that were identified in the literature.   The ecology page mainly focuses on the loss of biodiversity in the region and includes a table of vegetation changes.  The socioeconomic page includes population and economic growth information.  The public health page includes a table of potential river pollutants, their sources and the health effects associated with exposure to them.  This page also includes other information on both surface and groundwater quality in the region.

            The static map page includes a map of the Tijuana River Watershed region, with the study area hotlinked to the sub-basin map page.  The user is able to click on this area and “zoom in” to the sub-basin page, which includes location and relief maps of the Tecate-Cottonwood sub-basin and study site, each with an outlined area that is hotlinked to the interactive map page. The interactive map page is where users are able to choose between the feature server and image server, depending upon the level of interaction that they want to, or are able to perform. “Map Help” pages are provided for each type of server.  These pages provide some basic information to help users navigate the features of the interactive maps.  Both types of maps (image and feature server) are offered so that a wider range of users can use the services.

            In addition, a metadata page is included.  Since the authors created the data for the interactive maps from an aerial photograph, metadata is provided.  The user can access the metadata page from either the interactive map page, or from the map of the Tijuana River Watershed.  The interactive maps are discussed in more detail below. 

Another feature of the website is the Links page, where the user can find more information on the Tijuana River Watershed, hydrology studies, other river parks, water quality studies and reports, tourist information for Tecate, and information on the groups involved with the Tecate River park proposal.  The links list is not particularly long, but includes the most complete and accurate sources of information that we could find. 

            The final feature of the website is the “Contact Us” page.  Since this website is intended to serve as a communication mechanism between project proponents and interested parties, this page offers a way for users to provide their comments, and for the river park planners to receive feedback on the plans and website information.  Although this page is not functioning correctly when the provided form is filled in and sent, there is an email address provided for those that wish to respond.

Static Maps

            All static maps were created in ArcGIS (8.1, ESRI, Redlands, CA 2001) and exported as JPEG files for display in FrontPage.  All coverages and shapefiles of the Tijuana River Watershed, the Tecate-Cottonwood Sub-basin and San Diego County were obtained from the Center for Earth Systems Analysis Research (CESAR) at SDSU.  The aerial photograph and layers for the study area were obtained as described below.

Interactive Maps     

            The primary source was a geo-rectified NOAA aerial photograph that was taken of the Tecate River region in 2000.  The photograph was supplied to us for the purpose of constructing a web-based interactive map by CESAR at SDSU, after being processed there by Dave McKinsey.

            New vector coverages with the same coordinate system and projection as the aerial photograph were created in Arc Catalog (ArcGIS v.8.1, ESRI, Redlands, CA, 2001).  Once the new coverages had been created, they were opened in Arc Map, where new features could be digitized using the editor tool.  Arc (line) features were created for the river, roads and possible channelization.  Polygon features were created to represent the study area, neighborhoods, commercial areas, parks, recreation, industrial zones, well locations and our proposed riverpark site. 

            There were four additional digital vector layers obtained from CESAR that were of the Tecate-Cottonwood sub-basin:  the basin boundary, the sub-basin rivers, soils and vegetation. These layers were digitized in 1995, as part of a different project by individuals at SDSU.  The sub-basin boundary and river layers were left unaltered for internet display.  The soils and vegetation layers were clipped to the study area using the geoprocessing wizard in ArcGIS.  Though created in two different time periods, there was good agreement between the locations of features in the sub-basin layers and those in the 2000 image.

            Because ArcIMS (ESRI, Redlands, CA, 1999), the final destination of the maps, does not support coverages as a file type, the new layers were opened in ArcView (v3.2, ESRI, Redlands, CA 2000) and converted to shapefiles.  Once in shapefile format, new fields were added to the attribute tables to display information in both English and Spanish.

            The full image was over 1.5 gigabytes in size: too large to be supported by the ArcIMS server.  To provide a way for the image to be included as a layer in the interactive map, it was necessary to have it cropped to the area of the study site and decompressed to a much poorer resolution than the original image.  Harry Johnson at CESAR completed this portion of the image processing using ERDAS Imagine software (v.8.4, ERDAS, Atlanta, GA, 2001).  Both the modified image and the shapefiles were stored on a local network drive.

            ArcIMS was the internet mapping program used for the site. We created two maps:  an HTML based image server that could support the image file, be accessed by anyone with an internet connection, but with limited customization functions; and a JAVA based feature server, without the image that would have greater functionality for the more advanced user.  Both maps were created and customized to select the best display properties for each layer using the Author component of ArcIMS.

            Once the maps were constructed, our course instructor utilized the IMS Administrator to designate the location and name of the new maps on the server and the location of the shapefiles from which the maps were created.  The next step was customizing the look of the browsers and choosing the components we wanted our viewers to have.  This was done with the Designer component of ArcIMS.  Our design choices were based, again, on the functionality we wanted the two interactive maps to have.  The image server was intended to be display oriented; we wanted the user to be able to click layers on and off and perform simple queries to find out where features are and what they are called, but not a lot more than that.  For the feature server, we focused on function, keeping the display more simple; we wanted the user to “play” with the map and tryout different options, create map notes and edit the look of the map to suit their own purposes. 

            Invariably, the look of the map on the desktop, in the design phase was different from the finished product on the server.  Changes to the appearance were easily made by modifying the axl file in notepad and republishing the map or by opening the map in Author and adjusting the feature properties to make a more aesthetic map that could be re-sent to the server.  Both maps were modified multiple times in this manner with varying degrees of success.  The current “final maps” are published on the site.

DISCUSSION

            Although our website provides good background information and maps of the area, there are a number of other resources that could potentially be added in the future.  For instance, daily stream flow gauges on the Cottonwood and Campo Creeks (1936 to present) are available online at the United State Geological Survey (USGS) website (USGS 2001).  These data can be used to determine maximum, minimum and average flows, and to estimate extreme flood or minimum flow events.  In the future, perhaps this information could be combined with water quality data from other studies to model water quality in the region (Gersberg 1997).  It could also be used to help design future water sampling points and aid in temporal designs to monitor important flow events (Heathcote 1998). The ideal would be to link this flow data into a user-friendly viewer so that real-time modeling analyses could be performed.

            A digital elevation model (DEM) for the sub-basin is available for calculating stream direction, flow accumulation, drainage density, slope and relief ratio.  When this is combined with soil, vegetation, land-use and other coverages, erosion hazard maps and flood hazard maps can be created.  Currently, it is only possible for users to view the DEM, however future access to these combined GIS layers may allow users to perform modeling functions. 

In order to provide a complete and full-service urban planning tool, additional GIS layers still need to be created.  Aquifers, or groundwater supplies that are concentrated in Tecate need to be mapped and the water quality assessed for potential storage purposes.  This would be a critical tool for planners who are concerned about water quality and quantity.  In addition, lists of potentially affected species have been created (MSCP 1996; Cooperation 2000; Delgadillo 2000), however maps of their habitats are still needed so that multi-species modeling can begin.  Finally, although difficult to produce, carbon stores and nitrogen paths could be modeled and this information provided in order to improve natural resource planning. 

There are currently several other River Park sites in the internet, including San Dieguito River Park in San Diego at http://www.sdrp.org/, Guadalupe River Park in Sacramento at http://grpg.org/, Cloverdale River Park in Cloverdale, CA at http://www.cloverdale.net/visit/riverpar.htm and the James River Park System in Richmond, VA at http://www.ci.richmond.va.us/department/Parks_Rec/james.asp.  These are all primarily information–only sites that do not include interactive mapping tools.  Our Tecate website represents an effort to go one step beyond, by providing a mechanism for users to ask "what if" questions about alternative strategies and visualize the options.

REFERENCES

Cooperation, C. f. E. (2000). Biodiversity Conservation: Concservation of Migratory and Transboundary Species. Montreal, Canada: 79.

Delgadillo, J. (2000). “Floristica y ecologia del norte de Baja California.” Divulgare 29: 46-63.

EPA (2000)Cottonwood-Tijuana Watershed Profile. www.epa.gov/surf3/hucs/18070305/index.html.

EPA (2000). Draft EIS Tecate, BC water and wastewater improvement project.  EPA: 31.

EPA (2000). Surf your watershed website.

Ganster, P. (1996). “Environmental Issues of the California-Baja California Border Region.” Border Environment Reports June(1): 1-14.

Gersberg, R. M. (1996). “Monitoring and Modeling of Water Quality in the Tijuana River Watershed.” Final Report SCERP Project WQ PP96II-10: 355-369.

Gersberg, R. M. B., Chris (1997). “Predictive modeling of the interactions between land use and storm water quality in the Tijuana River Watershed.” SCERP Project W97-2: 16.

Glenn, E. P. L., Christopher; Felger, Richard; Zengel, Scott (1995). “Effects of water management on the wetlands of the Colorado River Delta, Mexico.” Conservation Biology 10(4): 1175-1186.

Heathcote, I. W. (1998). Integrated Watershed Management:Principles and Practice. New York, John Wildey & Sons, Inc.

IUCN (1997)United Nations List of Protected Areas. www.unep-wcmc.org/cgi-gin.pa_un97. Last Update. Date

Michel, S. (2001) "The Alamar River Corridor:  An Irban River Park Oasis in Tijuana, Baja California, Mexico" Borderlink 2000 Final Report

Michel, S. (2001). “Defining hydrocommons governance along the border of the Californias: a case study of  transbasin diversions and water quality in the Tijuana-San Diego Metropolitan Region.” Natural Resources Journal.

Michel, S. and C. Graizbord (2002) "Urban Rivers in Tecate and Tijuana:  Strategies for Sustainable Cities" Unpublished draft report by the Institute  for Regional Studies of the Californias, SDSU.

MSCP (1996). MSCP Plan. San Diego.

Perry, A. W., Kate (2001)TWR Online Planning Atlas. http://map.sdsu.edu/group2001/group5/home.htm. Last Update. Date

Service, N. P. www.nps.org. Last Update. Date

Swanson, F. J. N., R.P; Grant, G.E. (1992). Some Emerging Issues in Watershed Management, Springer.

USFWS (2000). Finding of no significant impact (FNSI) for water and wasterwater infrastucture improvements fo Tecate, BC Mexico. San Francisco, EPA: 2.

USGS (2001)Stream gauge data. www.usgs.gov. Last Update. Date

Wakida, F. R., Karen (1998). The Tijuana river basin: basic environmental and soicioeconomic data. San Diego, Institute for Regional Studies of the Californias: 104.

Wilkens, M. (2001). pers. comm. CUNA. Ensenada.

Wright, R. (1999) TWR. www.typhoon.sdsu.edu/tjwater/.

Wright, R. R., Kathryn; Winckell, Alain (1995). “Identifying priorities for a GIS for the Tijuana River Watershed.”: 93.

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Appendix A.  Pros and Cons of Various Land-Use Options

 † Husted, Rachel. 1997. Wetlands for Clean Water. How Wetlands Protect Rivers, Lakes and Coastal Waters from Pollution. Washington, D.C.: Clean Water Network and Natural Resources Defense Council. 

†† Dallman, Suzanne, and Piechota, Tom. 2000. Storm Water: Asset not Liability. Los Angeles: The Los Angeles and San Gabriel Rivers Watershed Council.