Applications of GIS to Water Resources Engineering

1
Applications of GIS toWater Resources Engineering
Texas AM University Department of Civil
Engineering - SeminarSeptember 12, 2001
College Station, Texas

• Francisco Olivera
• Department of Civil Engineering
• Texas AM University

2
Geographic Information Systems
Where in the world?
3
The Problem
Opportunity

• To analyze hydrologic processes in a non-uniform
  landscape.
• Non-uniformity of the terrain involves the
  topography, land use and soils, and consequently
  affects the hydrologic properties of the flow
  paths.

Watershed point
Flow path
Watershed divide
Watershed outlet
4
The Solutions

• Spatially-distributed models Require
  sophisticated tools to implement, but account for
  terrain variability.

• Lumped models Easy to implement, but do not
  account for terrain variability.

5
Overview

• Soil Water Balance
• Flow Routing Methods
• Results

6
Soil Water Balance Model
7
Soil Water Balance Model
Evaporation
Given wfc soil field capacity (mm) wpwp soil
permanent wilting point (mm) P precipitation
(mm) T temperature (C) Rn net radiation
(W/m2)
Soil moisture and surplus
Calculated w actual soil moisture (mm) S
water surplus (mm) E actual evaporation (mm) Ep
potential evaporation (mm)
8
Global Data
Precipitation (Jan.)
Temperature (Jan.)
Net Radiation (Jan.)
Soil Water Holding Capacity
Precipitation and temperature data, at 0.5
resolution, by D. Legates and C. Willmott of the
University of Delaware. Net radiation data, at
2.5 resolution, by the Earth Radiation Budget
Experiment (ERBR). Soil water holding capacity,
at a 0.5 resolution, by Dunne and Willmott.
9
Monthly Surplus Niger Basin
Period between storms 3 days.
10
Monthly Surplus Niger Basin
Effect of disaggregation of monthly precipitation
into multiple storms.
11
Overview

• Soil Water Balance
• Flow Routing Methods
• Results

12
Flow Routing Models
Cell
Cell

• Cell-to-cell
• Element-to-element
• Source to sink

Sub-Basin
Reach
Junction
Sink
13
Cell-to-Cell Model

• Sets a mesh of cells on the terrain and
  establishes their connectivity.
• Represents each cell as a linear reservoir
  (outflow proportional to storage). One parameter
  per cell residence time in the cell.
• Flow is routed from cell-to-cell and hydrographs
  are calculated at each cell.

14
Mesh of Cells

• Congo River basin subdivided into cells by a
  2.8125 ? 2.8125 mesh.
• With this resolution, 69 cells were defined.

15
Low Resolution River Network

• Low resolution river networks determined from
  high resolution hydrographic data.

16
Low Resolution River Network

• High resolution flow directions (1-Km DEM cells)
  are used to define low resolution river network
  (0.5 cells).

17
Cell Length
1
2

• The cell length is calculated as the length of
  the flow path that runs from the cell outlet to
  the receiving cell outlet.

B
A
3
4
C
D
18
Element-to-Element Model

• Defines hydrologic elements (basins, reaches,
  junctions, reservoirs, diversions, sources and
  sinks) and their topology.
• Elements are attributed with hydrologic
  parameters extracted from GIS spatial data.
• Flow is routed from element-to-element and
  hydrographs are calculated at all elements.
• Different flow routing options are available for
  each hydrologic element type.

19
Sub-Basins and Reaches

• Congo River basin subdivided into sub-basins and
  reaches.
• Sub-basins and reaches delineated from digital
  elevation models (1 Km resolution).
• Streams drain more than 50,000 Km2. Sub-basin
  were defined for each stream segment.

20
Hydrologic System Schematic

• Hydrologic system schematic of the Congo River
  basin as displayed by HEC-HMS.

21
Hydrologic System Schematic

• Detail of the schematic of the Congo River basin.

22
Delineated Streams
23
Guadalquivir Basin
24
HMS Schematic of theGuadalquivir Basin
25
Source-to-Sink Model

• Defines sources where surplus enters the surface
  water system, and sinks where surplus leaves the
  surface water system.
• Flow is routed from the sources directly to the
  sinks, and hydrographs are calculated at the
  sinks only.
• A response function is used to represent the
  motion of water from the sources to the sinks.

Source
Flow-path
Source
Sink
Flow-path
26
Sinks

• Sinks are defined at the continental margin and
  at the pour points of the inland catchments.
• Using a 3x3 mesh, 132 sinks were identified for
  the African continent (including inland
  catchments like Lake Chad).

27
Drainage Area of the Sinks

• The drainage area of each sink is delineated
  using raster-based GIS functions applied to a
  1-Km DEM (GTOPO30).

GTOPO30 has been developed by the EROS Data
Center of the USGS, Sioux Falls, ND.
28
Land Boxes

• Land boxes capture the geomorphology of the
  hydrologic system.
• A 0.5x0.5 mesh is used to subdivide the terrain
  into land boxes.
• For the Congo River basin, 1379 land boxes were
  identified.

29
Surplus Boxes

• Surplus boxes are associated to a surplus time
  series.
• Surplus data has been calculated using NCARs
  CCM3.2 GCM model over a 2.8125 x 2.8125 mesh.
• For the Congo River basin, 69 surplus boxes were
  identified.

30
Sources

• Sources are obtained by intersecting
• drainage area of the sinks
• land boxes
• surplus boxes
• Number of sources
• Congo River basin 1,954
• African continent 19,170

31
Response Function
?(t)
Sink
Flow-path - i
Ui(t)
Source - i
Ui(t)
?(t)

• Pure translation
• Translation, flow attenuation, dispersion and
  decay

t
t
Qsink S Qi S Ii(t) Ui(t)
32
Overview

• Soil Water Balance
• Flow Routing Methods
• Results

33
Global Monthly Surplus
Animation prepared by Kwabena Asante
34
Global River Network
35
Hydrographs - Congo River
Flow
Runoff
36
Hydrographs - Amazon River
Flow
Runoff
37
Watershed Geomorphology
V 1 m/s D 150 m2/s
Niger River Basin A 2260,000 Km2, B 226
Km2, and C 22,600 m2.
38
Flooding t.u. Campus
Animation prepared by Esteban Azagra
39
Flooding t.u. Campus
Animation prepared by Esteban Azagra