TERRAHYDRO – a Distributed Hydrological System using Graph Structure for Unified Water Flow

Representation

Sergio RosimAntônio Miguel Vieira Monteiro

Camilo Daleles RennóJoão Ricardo de Freitas Oliveira

National Institute for Space Research - INPE

IGARSS29/ 07 / 2011

INPE

Mission - To foster science and

technology in earth and space

context to offer products and regular

services in benefit of the country.

TERRAHYDRO

TerraHydro is a Distributed

Hydrological System created to

develop hydrographic basin water

flow GIS applications.

TerraHydro

TerraHydro proposes a different

computational representation for

dealing with water flow in GIS

applications. These applications

involve the concept of local flow,

extracted from terrain, which is the

basis for most spatially explicit

distributed hydrological models.

TerraHydro

Different computer structures based

on regular grids, triangular irregular

networks, contour lines, and irregular

polygon tessellations have been used

to extract local flow, entirely linked to

the data structure chosen for terrain

representation. Then, each local flow

set requires its own specific extraction

algorithms, as well as different formats

to store its associated local flow.

TerraHydro

TerraHydro proposes a data structure

based on Graph Theory that unifies

computer local flow representation,

independent of the data structures

used for terrain representation

permitting that a set of operations for

water management be formally

defined over this new structure.

TerraHydro - Concept

Extract local flows

from different

computer surface

representation

The local flows are

mapped in a

structure similar

to computer

surface

representation

strucutre

TerraHydro - Concept

The local flows are mapped to only one structure that will be used to develop the applications

The applications become independent of the original computer surface representation structure

TerraHydro - LDD to graph map

Each LDD grid cell represents a graph

node and the flow from a given cell

to a neighbor cell defines a graph

edge that links these two cells

TerraHydro - Tin to graph map

As TIN local flow has two types of

propagation geometry, each type

needs a different approach to map

TIN local flow to graph.

Triangle crosses local flow

Each triangle side starting or ending as a

local flow represents a graph node. Local

flow goes from one side to another side of

a triangle, passing through their middle

points. The graph nodes identifiers are

the same associates to the triangles sides

during the triangulation process.

Common triangles edge local flow

When a local flow goes along a triangle side, the vertices of that side represent graph nodes. The graph node identifier corresponding to triangle vertex is computed adding the total number of triangles sides to the vertex identifier from triangulation.

TerraHydro – Contour lines to graph map

The local flow goes from each cell to one or more neighbors, passing through their centers. The graph node stores the cell identification number and a graph edge is a link between two cells. Multi flow issue is intrinsic in the contour lines data model. Each cell represents a water flow uniform space.

TerraHydro – Voronoi to graph map

Each Voronoi polygon is a graph node and each graph edge represents a link between two neighbor polygons. Graph nodes store the Voronoi identification numbers existing in the Voronoi data structure which is similar to the grid cell approach.

TerraHydro – Develop environment

TerraLib - Open-source GIS software

library. TerraLib supports coding of

geographical applications using spatial

databases, and stores data in different

DBMS including MySQL and PostgreSQL

Database

TerraLib

TerraView

Plugins Plugins Hidro

TerraHydro – Develop environment

TerraView - GIS application built using the TerraLib GIS library. TerraView  main goal is to make available to the GIS Community an easy geographic data viewer with resources that include database queries and data analysis, exemplifying the use of the TerraLib library

Database

TerraLib

TerraView

Plugins Plugins HidroTerraHydro is a

TerraView plugin,

using all

TerraView

funcionalities

TerraHydro – Funcionality

LDD Extraction: for each grid cell

the local flow is defined considering

the steepest downstream regarding

the 8 grid cell neighbors. LDD is the

basis for developing applications

involving water resources.

Upscaling definition: redefinition

of local flows in a grid of lower

resolution from the local flow

extracted from a high resolution grid

(LDD)

TerraHydro – Funcionality

Accumulation area: each grid cell

receives the accumulated value

along the paths that is linked with

that cell.

Drainage definition: all grid cells

subset having accumulated area

value greater than that of a user

defined threshold.Tocantis Amazonian River drainage definition example

Example of drainage: Tocantis River - Amazonian Basin

Tocantins Drainage Zooms

TerraHydro – Funcionality

River reaches: define drainage

segments, between water springs and

junctions, between junctions, or

between junctions and mouth of the

drainage.

Basin delimitations: the delimitations

can be done by selecting one or more

points over the drainage. TerraHydro

finds the basin for each given point or

for each river reach basin.

TerraHydro – ExampleAccumulation Area / Drainage

Basin Delimitation for a Point

River Reaches

Basin Delimitations for each River Reach

TerraHydro – ExampleBasin and Drainage (SRTM)

Red: Basin delimitationBlue: drianage of main Rivers, extracted from accumulation area

TerraHydro – ExampleBasin and Accumulation Area

Image size: 1.244.160.000 - Lines: 32.400 Columns: 38.400 - Processing time: 360:16:25

Initial pit number: 65.670.466 - Unsolved pit number: 0

TerraHydro X ArcGis Hydro ToolsPurus River

Yellow lines: ArcGisRed lines: TerraHydro

This work was partially supported by

FAPESP

São Paulo Research Foudation

THANK YOU !

sergio@dpi.inpe.brwww.dpi.inpe.br