real-time streaming ofenvironmental ï¬eld data

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Computers & Geosciences 29 (2003) 457–468 Real-time streaming of environmental field data Enrique R. Vivoni*, Richard Camilli Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Received 20 March 2002; received in revised form 21 October 2002; accepted 20 November 2002 Abstract Field measurements in the environmental sciences still depend upon the pencil and paper notebook for data collection. Although robust, this method is labor-intensive and susceptible to recording and georeferencing errors during transcription. Recent advances in mobile computing and wireless communications allow the geoscientist to process and transmit data while still in the field, thereby minimizing human errors and time delays. We describe an integrated system developed for environmental and geolocation data acquisition that is intended to streamline the collection process. The system consists of software applications and hardware components that enable wireless, mobile and Internet computing during field campaigns. In particular, two-way transfer and display of collected data is achieved between the field site and a remote location, a concept referred to as field data streaming. A prototype system has been tested in field trials in Cambridge, Massachusetts, USA and Newcastle, New South Wales, Australia. Field studies demonstrate the noticeable gains in efficiency and precision achieved with the use of the field streaming technology. Potential applications include biogeochemical and hydrologic studies, water quality monitoring, emergency response to water-borne disasters and intensive field sampling campaigns. r 2003 Elsevier Science Ltd. All rights reserved. Keywords: Mobile computing; Wireless communications; Environmental monitoring; Geographic information systems; Field data collection 1. Introduction The recent advances in mobile information technol- ogy have created opportunities for developing tools that bring computing power to field workers. As a result, applications for mobile devices have been developed in various disciplines, for example, in geographical infor- mation systems (Pundt and Brinkk . otter-Runde, 2000), resource management (Stern and Kendall, 2001), geology (Briner et al., 1999), archaeology (Ancona et al., 1999), geomorphology (Cornelius et al., 1994) and ecology (Pascoe et al., 1999). These disciplines share a common need to associate field measurements with unique locations in space and time. However, the analysis required to place sampled data within a spatial–temporal context is usually performed after field study completion. For the geoscientist, the use of mobile computers can facilitate data collection (Loudon, 2000) and also provide a means for discovering data relation- ships while still in the field. In situ field mapping, data analysis and sharing is currently achievable by integrating environmental and geolocation sensors with mobile, wireless computers. A mobile data collection system for these purposes should: (1) efficiently collect and store various parameters; (2) acquire and merge data from multiple teams; and (3) accurately map data within a geographic context. Performing these tasks while various teams are still in the field requires the capacity to transmit data wirelessly *Corresponding author. Tel.: +1-617-253-1969; fax: +1- 617-258-8850. E-mail addresses: [email protected] (E.R. Vivoni), [email protected] (R. Camilli). 0098-3004/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0098-3004(03)00022-0

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Page 1: Real-time streaming ofenvironmental ï¬eld data

Computers & Geosciences 29 (2003) 457–468

Real-time streaming of environmental field data

Enrique R. Vivoni*, Richard Camilli

Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology,

Cambridge, MA 02139, USA

Received 20 March 2002; received in revised form 21 October 2002; accepted 20 November 2002

Abstract

Field measurements in the environmental sciences still depend upon the pencil and paper notebook for data

collection. Although robust, this method is labor-intensive and susceptible to recording and georeferencing errors

during transcription. Recent advances in mobile computing and wireless communications allow the geoscientist to

process and transmit data while still in the field, thereby minimizing human errors and time delays. We describe an

integrated system developed for environmental and geolocation data acquisition that is intended to streamline the

collection process. The system consists of software applications and hardware components that enable wireless, mobile

and Internet computing during field campaigns. In particular, two-way transfer and display of collected data is achieved

between the field site and a remote location, a concept referred to as field data streaming. A prototype system has been

tested in field trials in Cambridge, Massachusetts, USA and Newcastle, New South Wales, Australia. Field studies

demonstrate the noticeable gains in efficiency and precision achieved with the use of the field streaming technology.

Potential applications include biogeochemical and hydrologic studies, water quality monitoring, emergency response to

water-borne disasters and intensive field sampling campaigns.

r 2003 Elsevier Science Ltd. All rights reserved.

Keywords: Mobile computing; Wireless communications; Environmental monitoring; Geographic information systems;

Field data collection

1. Introduction

The recent advances in mobile information technol-

ogy have created opportunities for developing tools that

bring computing power to field workers. As a result,

applications for mobile devices have been developed in

various disciplines, for example, in geographical infor-

mation systems (Pundt and Brinkk .otter-Runde, 2000),

resource management (Stern and Kendall, 2001),

geology (Briner et al., 1999), archaeology (Ancona

et al., 1999), geomorphology (Cornelius et al., 1994)

and ecology (Pascoe et al., 1999). These disciplines share

a common need to associate field measurements with

unique locations in space and time. However, the

analysis required to place sampled data within a

spatial–temporal context is usually performed after field

study completion. For the geoscientist, the use of mobile

computers can facilitate data collection (Loudon, 2000)

and also provide a means for discovering data relation-

ships while still in the field.

In situ field mapping, data analysis and sharing is

currently achievable by integrating environmental and

geolocation sensors with mobile, wireless computers. A

mobile data collection system for these purposes should:

(1) efficiently collect and store various parameters;

(2) acquire and merge data from multiple teams; and

(3) accurately map data within a geographic context.

Performing these tasks while various teams are still in

the field requires the capacity to transmit data wirelessly

*Corresponding author. Tel.: +1-617-253-1969; fax: +1-

617-258-8850.

E-mail addresses: [email protected] (E.R. Vivoni),

[email protected] (R. Camilli).

0098-3004/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved.

doi:10.1016/S0098-3004(03)00022-0

Page 2: Real-time streaming ofenvironmental ï¬eld data

and methods for sharing, analyzing and displaying data

over a network. Application software resident on a

remote server can provide data access, mapping and

analysis functionality to the field worker through the

same network. Interactive data collection and mapping

has been shown to significantly enhance the scientific

discovery process (Carver et al., 1995).

This paper presents the development of a field data

collection system that streamlines the collection process

and provides data sharing between multiple field teams

and remote locations. The collection and transmission of

environmental field data is executed without the loss of

precision that typifies manual data transfer. By using a

geographic information system (GIS), the system adds a

new dimension of spatial localization and provides the

user with cartographic displays of relevant field data.

The exchange of georeferenced environmental data

between a field site and a remote location provided by

the system is referred to here as field data streaming

(Fig. 1).

This study focuses on the collection of geospatial and

water quality data during a watershed field study. To

this end, the system is tailored to sampling biological,

chemical and hydrologic parameters along river cross-

sections. We describe the field testing of the ENVIT

Integrated Data Collection System during trials in

Cambridge, USA and Newcastle, Australia. First, we

present the technologies required to store, acquire,

transmit and display environmental field data. We then

assess the utility of the integrated system for a water

quality study based on field tests in the Williams River.

Finally, we discuss the key merits of the data collection

system and potential applications areas.

2. ENVIT integrated data collection system

The field data collection system consists of a series of

ruggedized mobile computers and a roving station

equipped with a field server, wireless router and mobile

telephone. The system components are similar to the

‘‘tele-geomatics’’ framework outlined by Zingler et al.

(1999) for wireless field data collection. Fig. 2 presents a

generalized schematic of the integrated system. Table 1

presents the components of the prototype system while

specific details are discussed in the following sections.

2.1. Field data acquisition and storage

The process of gathering field data in many geos-

ciences is typically a time-consuming task due to the

need for measurement and transcription of data often in

remote regions. To be worthwhile, mobile computing

should streamline the data collection process and allow

users to rapidly acquire, record and submit data to a

broader system infrastructure. With this in mind, a

software application, known as ENVIT-Note, was

developed for the hand-held device. The application

consists of a graphical user interface (GUI) with features

that lead the user sequentially through the following

Fig. 1. Conceptual diagram of field data streaming technology.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468458

Page 3: Real-time streaming ofenvironmental ï¬eld data

general steps: (1) connection to the database; (2)

initialization of the sampling session; (3) selection of

environmental and geolocation sensors; (4) automated

or manual input of selected parameters; and (5) data

verification and submittal to local and remote databases

(Fig. 3).

The mobile software encapsulates a suite of applica-

tions that provide several functions to the field worker,

including: manual input of velocity measurements using

a hand-held flow meter;1 manual input of biological

samples using a field biology kit;2 manual input of

chemical samples using a field-portable spectrophot-

ometer;3 manual input of water quality measurements

using a multi-parameter probe;4 manual and automated

input of geographic position using a mobile GPS;5

manual input of field comments and geometric measure-

ments; data submittal to an independent mobile GIS

application6; and review and submittal of local database

contents.

In a watershed or estuarine study, the river cross-

section is the basic geometric unit across which

discharges and biogeochemical fluxes are typically

computed. For this reason, chemistry, biology or

velocity measurements are entered into the system

through a graphical representation of a river cross-

section (Fig. 4A). Manual input occurs, for example,

when entering velocity data along a cross-section. After

the user specifies the geometry, the software application

computes the required sampling locations through

standard stream gauging procedures (Wahl et al.,

1995). Upon completion of the measurements, the

computed channel discharge is displayed. Similar

Fig. 2. Functional diagram of ENVIT System.

1Global Water Instrumentation, Inc. Velocity Meter.

FP101.http://www.globalw.com/.2Millipore, Inc. Membrane Filtration Microbiology Kit.

http://www.millipore.com/.3HACH, Inc. DR/2010 Portable Spectrophotometer. http://

www.hach.com/.4Hydrolab, Inc. Minisonde 4a Multiprobe. http://www.

hydrolab.com/.

5Teletype GPS, Inc. WorldNavigator PCMCIA GPS. http://

www.teletype.com/.6ESRI, Inc. ArcPad 6.0 Beta. http://www.esri.com/arcpad/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468 459

Page 4: Real-time streaming ofenvironmental ï¬eld data

functionality is provided for collecting biology or

chemistry samples and computing chemical fluxes.

Using this cross-section sampling strategy, sensor data

can be mapped to a specific location within each section.

Measurement is further automated by using signal-

averaged GPS data at each stream bank to calculate the

stream cross-sections (Fig. 4B). For increased accuracy,

a differential GPS measurement could potentially be

Fig. 3. Flow diagram of ENVIT-Note mobile device application.

Table 1

Components of ENVIT system

Functionality Generic product Manufacturer Model

Computing Hand-held device Compaq Corp. IPAQ 3600 Series

Computing Laptop computer Compaq Corp. Presario 1700T

Computing Desktop server Dell computer Optiflex

Environmental sensing Water quality sensor Hydrolab Inc. Multisonde 4a

Environmental sensing Chemistry sensor HACH Inc. Spectrophotometer

Environmental sensing Biology sensor Millipore Inc. Membrane Kit

Environmental sensing Velocity sensor Global Water Inc. FP101 Flow Meter

Geolocation sensing GPS sensor Teletype Inc. WorldNavigator

Software development Mobile GUI Microsoft Inc. Embedded VB

Software development Laptop GUI Microsoft Inc. VB.Net

Software development Web services Microsoft Inc. C#.Net

Software development Mobile database Microsoft Inc. SQL server CE

Software development Laptop database Microsoft Inc. SQL server

GIS mapping Mobile mapping ESRI Inc. ArcPad 6.0

GIS mapping Laptop mapping ESRI Inc. ArcView 3.2

Communications Field wireless router Orinoco Inc. COR-1100

Communications Wireless PC card Orinoco Inc. Silver PC cards

Communications Mobile phone Motorola Inc. P280 GSM

Communications Mobile service Telstra Inc. Voice/data

Communications Omnidirectional antenna FAB Corp. 15 dBi Comet

Field deployment Field power supply HydroLab Inc. Battery pack

Field deployment Waterproof casing Aquapac Inc. PDA case

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468460

Page 5: Real-time streaming ofenvironmental ï¬eld data

used with the existing system. Combining the sampling

location with the position of the banks is a means for

efficiently determining the geographic position of each

sample without the need for including position fixes at

each point (Fig. 4C).

Georeferencing the environmental parameters is

automated within the system database application,

which consists of a master copy operating on a field

laptop and local copies on the mobile devices (Fig. 5). A

key feature is the capability of the master database to

simultaneously gather and process newly acquired data

from multiple mobile devices. The design is made robust

and expandable by abstracting the components of the

field data collection process. In general, the database

consists of data tables describing the project, location,

field operator, equipment and data. The database can be

tailored to the sampling study and the availability of

specific system components. Preconfiguring the master

database allows entering descriptive properties of the

field study into the database prior to the actual

expedition. In addition, the preconfigured database

supports user interaction with the system.

2.2. Field data transmission and integration

In order to simultaneously share data amongst

geoscientists in both the field and at a remote location,

the ENVIT System includes a portable, wireless, radio-

frequency communication network. This network trans-

mits data from each mobile device to a field laptop

functioning as the central data server. To connect the

portable network, an outdoor wireless field router,

operating at 2.4 GHz,7 is mounted on a roving van

along with a 1W amplifier and omnidirectional anten-

na8. The wireless router communicates with a series of

wireless PC cards9 attached through the PCMCIA port

to the hand-held devices.10 A signal radius of tens of

kilometers is potentially available, depending on the

availability of line-of-sight and the signal amplification

provided. This range permits various field teams to

update the central database simultaneously (Fig. 6).

Merging of data collected from field teams requires

transmission from each mobile device to the master

relational database on the field laptop. To ensure

optimal networking efficiency, only updates of changes

between the local and server databases are transmitted,

Fig. 4. Cross-sectional field sampling: (A) manual input of velocity measurements; (B) automated capture GPS data and (C) sampling

strategy at each cross-section.

7Orinoco, Inc. COR-1100 Outdoor Wireless Router. http://

www.orinocowireless.com/.8Fleeman, Anderson & Bird. Omnidirectional Antenna.

http://www.fab-corp.com/.9Orinoco, Inc. Silver PC Wireless Card. http://www.

orinocowireless.com/.10Compaq Computer Corp. iPAQ 3600 Series PDA. http://

www.compaq.com/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468 461

Page 6: Real-time streaming ofenvironmental ï¬eld data

thus eliminating redundant transfers. Local database

copies provide system back-ups in case of potential

problems during transmission. Upon receiving data

from each team, the server database organizes these

records, associates parameters with their sampling

location, and provides a field data summary table in a

format accessible to other software. In order to create a

summary table, the database utilizes key identifiers that

relate the measurement records with a sampling location

(Table 2).

Data transmission and integration can be complicated

by the lack of a wireless transceiver in each mobile

device. In the prototype system, for example, the GPS

sensor and wireless card both utilize the PCMCIA

expansion pack on the hand-held device,11 precluding

simultaneous use of all sensors on a single device. With

alternative hardware components or wireless capability,

however, this situation can be easily circumvented.

Given the constraints of the prototype, a method for

transmitting data across mobile devices without direct

access to the radio-frequency network is required.

Therefore, the mobile device infrared sensors are utilized

to transmit the local database contents between hand-

held computers. Infrared transmission was shown to be

an effective means to transfer data onto a mobile device

that has long range, radio-frequency, capability.

Field data streaming requires that the deployed field

workers have the capacity to transmit and receive data

from a remotely located server. Therefore, data transfer

to an off-site location requires an alternative commu-

nications network. In principle, each mobile device

could function as a client to a remote host. Given the

associated costs of hardware and services, however, a

more efficient solution is to have a single access point

and utilize the wireless field network to distribute and

gather data. In the integrated system, the field laptop is

connected via a mobile phone to the Internet. Based on

available coverage, a dual-frequency mobile phone (e.g.,

GSM/GPRS service at 900 MHz and 1.9GHz) is used to

enable connection across different mobile standards.12

Wireless transmission of the database contents is

periodically made to a remote web server where it is

captured by a customized web services application. The

field data is subsequently displayed in tabular or

cartographic format on an Internet site available to

the field laptop for content distribution to the multiple

devices.

2.3. Field data display and mapping

Visual representation of the environmental field data

obtained during a field campaign is typically produced

after completion of the study and analysis of the

recorded data. In the ENVIT System, a major innova-

tion is the capability to immediately stream processed

data to an off-site user or back to the field worker. In

order to display data to the mobile user, two mechan-

isms are implemented: (1) local map generation utilizing

a mobile GIS (see footnote 6); and (2) uploading of a

customized web mapping service through the wireless

network. For a remote user, the web services application

served as a means for querying, displaying and mapping

the environmental data collected in the field.

Map generation on the mobile device is achieved

through a customization of the mobile GIS application

to graphically display the database summary table

(Fig. 7). Overlaid on thematic map layers (e.g., topo-

graphy, streams), the sampling points reveal the spatial

Fig. 5. Flow diagram of multi-platform database.

11Compaq Computer Corp. PCMCIA Expansion Pack

http://www.compaq.com/.

12Motorola, Inc. P280 GSM mobile phone. http://www.

motorola.com/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468462

Page 7: Real-time streaming ofenvironmental ï¬eld data

and temporal variation of the measured parameters in

the field site. This data may be a product of a single team

or the integrated efforts of many teams, depending on

whether the summary table is generated by the mobile

device or the field laptop. In either case, the capability

for extracting the spatial–temporal context of the field

data and its relationship to regional characteristics is

enhanced.

Mobile GIS also offers limited spatial analysis

capabilities for extracting information from the collected

data. Advanced processing, however, requires more

powerful GIS software.13,14 To meet this need, a web

services application captures the transmitted data from

the mobile phone and displays it on a web browser. The

cartographic display consists of a background image

depicting the topography and streams overlaid by color-

coded points representing the georeferenced environ-

mental parameters (Fig. 7). This service provides various

other functionalities including: (1) selection of the

parameter to be displayed; (2) mapping of a user-

provided geographical location; (3) zoom and pan

Fig. 6. Diagram of multiple-team field deployment in a watershed study.

Table 2

Measurement parameters in Williams River field study

Parameter type Parameter name

Geolocation Longitude

Latitude

Hydrology Velocity

Water quality pH

Dissolved oxygen

Conductivity

Oxygen reduction potential

Turbidity

Temperature

Geometry Depth

Width

Chemistry Nitrate

Nitrite

Phosphate

Biology Total coliform

E. coli13ESRI, Inc. Arcview 3.2 GIS http://www.esri.com/arcview/.14ESRI, Inc. ArcIMS 3 http://www.esri.com/arcims/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468 463

Page 8: Real-time streaming ofenvironmental ï¬eld data

capabilities; and (4) tabular view of the summary

output. Both tabular and graphic displays provide

capabilities for quickly analyzing the spatial and

temporal trends in the field data from any location

during an on-going study. Access to this data by an off-

site manager or decision-maker allows for rapid evalua-

tion of progress and preliminary results. Providing this

data to the mobile device browser closes the field

streaming loop by allowing field workers immediate

access to processed data (Fig. 1).

3. Application and field study deployment

Prior to full-scale field deployment, the integrated

data collection system was pilot-tested in a study of the

Charles River Basin in Cambridge, Massachusetts. Two

sampling teams tested various system components

including the mobile device software, geopositional

sensor, water quality probe and wireless data transmis-

sion. A roving van equipped with the field laptop,

wireless outdoor router, amplifier and antenna served as

the central data server. This trial study verified that

environmental field data could be successfully collected,

stored and transmitted utilizing the integrated system.

Further testing determined a maximum range of one

kilometer for the radio-frequency network given clear

line-of-sight. Coverage beyond 1 km range or under

obstructed conditions necessitates a higher broadcasting

power normally requiring a license.

The site chosen for carrying out a full-scale field test

was the Williams River watershed in New South Wales,

Australia (Fig. 8). This catchment is an area of active

hydrological and water quality monitoring15 and re-

search and is confronted with issues of non-point source

pollution. A detailed GIS database for the Williams

River was available prior to the field study (A. Krause,

pers. comm., 2001). In addition, a network of water

quality and flow gauging stations is maintained within

the watershed.16 The availability of the preexisting

infrastructure and historical data was an attraction for

testing the integrated system within the Williams River

watershed.

The catchment, 1260 km2 in size, is located within the

lower Hunter Valley, about 30 km north of Newcastle.

The watershed is characterized by a mountainous,

forested region in the north and a series of low, rolling

hills, used for cattle grazing, in the central and southern

portions. The warm, temperate climate is modulated by

an orographic effect and a maritime influence due to its

coastal proximity (Wooldridge et al., 2001a). Previous

Fig. 7. Field-work mapping capabilities: (A) mobile GIS; and (B) GIS Web service.

15NSW Department of Land and Water Conservation http://

www.dlwc.nsw.gov.au/.16Hunter Integrated Telemetry System http://hits.nsw.

gov.au/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468464

Page 9: Real-time streaming ofenvironmental ï¬eld data

hydrologic studies have documented the correlation of

rainfall and runoff to large-scale climate phenomenon

(Wooldridge et al., 2001b), modeled the effect of land-

use on hydrologic response (e.g., Wooldridge and

Kalma, 2001) and studied the spatial distribution of

soil moisture (Walker et al., 2001).

The Williams River deployment consisted of three

field teams of six to seven members. Team members were

responsible for tasks such as water quality and hydro-

logic sampling, operation of sensors and computers, and

data transmission and display. Each team was equipped

with two ruggedized hand-held computers and asso-

ciated environmental sensors (Fig. 6). The field teams

traveled independently visiting various predetermined

sampling locations. Upon sampling at each location, the

collected data (Table 2) was transmitted to the central

data server in the roving van. From this field server, data

was periodically transmitted back to the field teams, as

well as to a remote web server in Cambridge, MA. Data

sharing between the multiple teams included the

transmission of summary tables and remotely processed

maps of the sampled parameters.

For field deployment, the system also provided

equipment ruggedization and extended battery life.

Modifications to a waterproof case17 protected the

mobile computers from dust, submergence and impact,

while allowing user interaction with minimal interfer-

ence including data transmission via infrared and radio

frequencies (Fig. 9). To extend battery life, a lightweight,

rechargeable battery was used to power the mobile

devices and water quality probe from a single source.

Given the different power requirements, power manage-

ment circuitry was designed, built and integrated into

the battery pack to provide approximately 40 h of

continuous field use. This efficient power system was

essential since the mobile computers have high con-

sumption rates.

4. Results and discussion

The pilot-scale and full-scale field tests of the ENVIT

System successfully demonstrated the field data stream-

ing technology. For the Williams River study, a

thorough test of the system was conducted within an

intensive field campaign in a remote setting. During the

four-day campaign, the Williams River watershed was

sampled at 35 locations spanning several tributaries

throughout the watershed (Fig. 10). Various deployment

configurations were tested, including a dispersal of the

three-field teams at distances greater than two kilo-

meters. In addition, an impromptu estuarine study was

conducted to assess the longitudinal variation of water

quality parameters at 500-m intervals along a 10 km

Fig. 8. Field study in Williams River watershed, New South Wales, Australia.

17Aquapac, Inc. http://www.aquapac.com/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468 465

Page 10: Real-time streaming ofenvironmental ï¬eld data

river span. The field data collection system proved

versatile enough to accommodate this new sampling

strategy.

As the field study progressed, environmental data

collected from the various sensors provided an in-

creasingly resolved view of the spatial variation of

Fig. 9. Deployed field equipment including ruggedized computer, external battery pack with power meter, water quality sensor and

GPS sensor.

Fig. 10. Field sampling within Williams River watershed: (A) distribution of sampling sites and (B) application of ENVIT System.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468466

Page 11: Real-time streaming ofenvironmental ï¬eld data

hydrological, biological and chemical features within the

watershed. This allowed the teams to plan future

sampling as well as navigate through the watershed in

the context of the sampled data. In addition, visualiza-

tion of the data from multiple field teams in Australia

documented progress for remote viewers worldwide

through the web-based map and photographic displays.

The field streaming concept was realized by transferring

georeferenced environmental data from individual teams

into a processed map product accessible to the field workers

and any interested party while the study was in progress.

Although the ENVIT System was successfully used

during the field campaign, various potential improve-

ments to system performance were identified, including

use of: (1) a higher powered radio-frequency network to

overcome line-of-sight and range limitations across

complex terrain; (2) satellite transmission in remote

areas not covered by the mobile network; (3) improved

integration of system components including GIS and

mobile application user interfaces; and (4) continuous

transmission, updating and sharing of raw and pro-

cessed environmental data products. Nevertheless, the

integrated sensors and mobile computers expedited

gathering environmental and GPS data at each river

cross-section. Data transfer rates to the field roving

station were adequate for the content exchanged

between the mobile and master databases. Overall

system reliability across the hilly pasturelands and

streams during dry, summer conditions was satisfactory.

The field study experience indicates that the ENVIT

System improved the efficiency, timeliness and transfer

of field data into scientific results. The accuracy of the

geolocation data have been verified with available GIS

thematic layers (e.g., soils, landuse, topography, hydro-

graphy) for the watershed region. In addition, results

suggest that the field portable environmental sensors

provided measurements within expected ranges relative

to the historical data for the Williams River. A detailed

analysis of the water quality, hydrologic and geolocation

data and their spatial variation is currently in progress.

The quality-controlled, georeferenced environmental

data will serve various purposes including augmentation

of historical databases and water quality and hydrologic

modeling of the watershed using a semi-distributed basin

model.18

Linking environmental field data streaming with

modeling is a key extension of the current framework.

The field data streaming technology can accelerate not

only the process of data collection and scientific

discovery, but also the incorporation of observations

into predictive models. Real-time transmission of

environmental data from field sites allows for updating

models of complex environmental systems with in situ

measurements. For example, field discharge measure-

ments along a river cross-section may serve to update

model forecasts of stream flow. Conversely, real-time

model predictions could serve to target sampling efforts.

For example, in emergency response to chemical spills,

model-directed field data collection can expedite plume

characterization.

In addition, field-streaming technology can enable the

continuous monitoring of environmental systems and

function as a distributed sensor network.19,20 The

prototype system provides the key elements for dis-

tributed collection, transmission and display of environ-

mental field data. Further enhancements may include

features such as: (1) collection and documentation of

photographic data; (2) data transmission in regions

without mobile phone coverage using satellite technol-

ogy; (3) incorporation of additional environmental

sensors using automated or manual input; and (4) web

services dedicated to providing additional support such

as communications coverage, model or data retrieval

and advanced geospatial processing.

5. Potential applications

Although specifically tailored for water quality

assessments, the ENVIT System design is sufficiently

flexible to address other environmental data collection in

a variety of contexts, including research, monitoring,

resource management and emergency response. One

potential application is the response to water-borne

chemical or biological disasters. Field scale testing has

demonstrated the system’s capability to serve in situa-

tions that require a coordinated response by multiple

field teams. The advantages of this system are evident in

emergency response situations with: (1) a critical time

constraint, (2) an expansive study area, (3) remotely

located decision support and management, and/or

(4) multiple individuals requiring processed field data.

A second potential application is for in situ sampling

during intensive field campaigns designed to verify data

from aerial or satellite platforms. Validating remote

sensing data requires a coordinated effort for deploying

multiple teams to measure ground-based environmental

parameters over large sensor footprints (e.g., Famiglietti

et al., 1999).

6. Conclusions

This paper provides an overview of the development

and application of an integrated field data collection

18HSPF Water Quality Model http://water.usgs.gov/

software/hspf.html.

19High Performance Wireless Research and Education http://

hpwren.ucsd.edu/.20Cal(IT2) http://www.calit2.net/.

E.R. Vivoni, R. Camilli / Computers & Geosciences 29 (2003) 457–468 467

Page 12: Real-time streaming ofenvironmental ï¬eld data

system designed to acquire, store, display and transmit

georeferenced environmental data during field cam-

paigns. The system encompasses advanced mobile,

wireless and Internet computing technologies that

together facilitate the sharing of field data between the

study site and remote locations in real-time. The

collection of field data was tested within the context of

a water quality study in the Williams River catchment in

New South Wales, Australia. Results from the field

study suggest that the prototype system is most useful

for time-critical, intensive field campaigns carried out by

multiple research teams. Furthermore, the general use of

distributed wireless sensors was shown to be advanta-

geous in environmental field research. Potential research

avenues include the integration of new sensing capa-

cities, enhanced server-client processing and improved

integration with environmental models.

Acknowledgements

The development of the ENVIT Integrated Data

Collection System was carried out as part of a MIT/

Microsoft Alliance project. We acknowledge the support

of Sheila Frankel, Eric Adams, Dara Entekhabi, Daniel

Sheehan and Mario Rodr!ıguez. In addition, various

students were involved in product development and

testing: Neeraj Agarwal, James Brady, Nancy Choi,

Chrissy Dobson, Arthur Fitzmaurice, Eric Lau, Anna

Leos, Linda Liang, Brian Loux, Aurora Kagawa, Kris

Kolodziej, Patricia McAndrew, Kevin Richards, Laura

Rubiano, Kim Schwing, Russ Spieler, Chin-Huei Tsou,

Lisa Walters and Amy Watson. We also acknowledge

Garry Willgoose, Jetse Kalma and Andrew Krause

(University of Newcastle, NSW). We also thank an

anonymous reviewer as well as Steve Carver for their

insightful comments on the manuscript.

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