SPATIAL HYDROLOGY

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SPATIAL HYDROLOGY

• Bahram Saghafian
• Presented at
• Civil Engineering Department
• Sharif Technical University
• Jan. 2002

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What is Spatial Hydrology?

• Study of the motion of the earths waters (and
  the transport of their constituents) with the
  explicit reference to the spatial dimension and
  using the data structure and functions of
  geographic information systems

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Major Developments

• Increasing availability of spatial hydrologic
  data (DEM, Images, etc.)
• Inclination towards the use of spatial data bases
  and GIS functions in hydrology
• Need to study detailed spatial distribution of
  hydrologic processes and their effects
• Development of distributed hydrologic models
• Need to disaggregate synthesized hydrologic
  responses (flood hydrograph, sediment load, etc.)
• Progress in high-powered computing equipments

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Active Areas in Spatial Surface Hydrology

• Effect of land use changes
• Floodplain mapping and hazard
• Flood potential and risk mapping within
  watersheds
• Spatial optimization of flood control
  countermeasures
• Site selection for hydro-climatological stations
• Distributed watershed erosion mapping
• Pollutant affected areas
• Distributed runoff/snowmelt/sediment modeling
• Spatial correlation of climatological factors
  with geo-environmental characteristics
• Distributed modeling of hydro-climatologic and
  geo-morphologic characteristics

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Geographic Information System

• Software tool for storing, managing, manipulating
  spatial (geographic) data
• Has four components data entry, data management,
  manipulation and analysis, and data output
• Models geographic features using points, lines,
  and cells in either vector or cellular data
  models

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GIS Relation to Spatial Hydrology

• Spatial hydrology deals with spatially
  distributed processes and features
• GIS can handle spatial (geographic) data
• Conjunctive use of GIS and hydrology is natural
  and unavoidable

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Distributed Rainfall-Runoff Modeling of
Golabdareh Catchment
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Distinctive Algorithms and Tools

• Upgrade time-area rainfall-runoff transformation
  into a distributed technique
• Determine travel time based on kinematic wave
  theory
• Introduce, for the first time, temporally-variable
  isochrone hydrograph estimation method

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Digitally extracted drainage network
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50-yr Flood Hydrograph
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Effect of Land Use Changes in Nekarood River
Basin

• Land use change detection using remotely-sensed
  data
• Hydrologic simulation of floods
• Prediction of future effects based of land use
  change scenarios
• Further application How to manage spatially the
  timber harvesting and other land activities

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View of Nekarood River Basin
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View of Nekarood River Basin
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Digital Elevation Model (DEM)
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Land Use Map, Year 1346
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Land Use map, Year 1372
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Land Use Map, Year 1379
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Land Use Change Over Years
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Change in peak floods
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Sediment Deposition Spatial PatternMinab Dam
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Spatial correlation between rainfall and
vegetation

• Daily rainfall maps using geostatistical tools
• Terrain mapping units defined
• NOAA satellite images processed for NDVI
  vegetation index
• Spatial correlation of rainfall and NDVI studied
  on 10-day and monthly basis with different lag
  times

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Terrain mapping Units
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Sample daily rainfall map
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Results

• Monthly NDVI vegetation index follow monthly
  rainfall data with a lag of one to two months and
  are best correlated with the bimonthly antecedent
  rainfall.
• The multiple regression method is best suited
  compared with others methods.
• Results may be used for rainfall spatial
  variation and drought mapping.

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Drought SDF Mapping

• Drought Severity-Duration-Frequency analysis
  using run theory
• Spatial extent of drought severity

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Flood Potential Prioritization and Spatial
Mapping

• Set up a selected semi-distributed hydrologic
  model for the watershed
• Identify and rank the areas (sub-watersheds)
  based on their quantitative contribution in
  discharge characteristics at the outlet
• Determine the impact of sub-watershed factors on
  the outlet flood peak
• Propose priority flood control measures
• Ongoing conduct research on observed discharge
  data and/or use a fully distributed model

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Snow Mapping Snowmelt Runoff Simulation

• Use satellite images for continuous mapping
• Propose an algorithm for snow/cloud/ground
  delineation
• Simulate snowmelt and rainfall runoff using SRM
  model and processed images

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The End