Spatial Data FE Lecture 1b

OSB 111 The Door your student card opens it don’t open for others don’t leave it open 20 seconds Machines at least two students per machine trade off on keyboard Logon: spit users/spit/yourname

Reading from ArcDoc Spatial modeling –Cell-based Modeling with GRID Grid features and capabilities Basic concepts of grid-cell processing Getting started with GRID Getting data into GRID

from Tuesday : Make a spreadsheet that will estimate the peak flow Q 5 =.157*A.9 *P a 1.35 *F -.21 for a five year storm in Region XII, using a table of road crossings with their respective contributing area A, percent forest cover F, and annual rainfall P a. - What does your spreadsheet look like? - How does changing F impact Q 5 ?

SCHEDULE

OUTLINE OSB 111 Spatial Data –Data Types –Attribute Tables –Gridding the World ArcView –opening data –viewing data –gridding data

SPATIAL DATA points, arcs, polygons

SPATIAL DATA Points

SPATIAL DATA Points Arcs Polygons

SPATIAL DATA Points Arcs Polygons Attribute Tables

HYDROLOGY processes are intrinsically spatial

POLYGON DATA how we tend to represent data y x soils(x,y) vegetation(x,y) topography(x,y)

NON-SPATIAL HYDROLOGY we model using a ‘black box’ time rainfall, runoff

POLYGON HYDROLOGY Recognition of spatial variability might lead to summing outputs from black boxes

POLYGON BLOCKS representing spatial variability with polygons produces a multitude of overlapping polygons Elevation Aspect Distance from stream

POLYGON vs. GRID replace the myriad overlapping polygons with a grid of identical square polygons

GRID HYDROLOGY summing point processes P ET I R SS

GRID BASICS - Thinking in GRID GRID-ing the World continuous discrete

Gridding polygons, lines, points

Gridding points, lines, polygons

ASSIGNING VALUES

A first view of ArcView Open Help first Project View Theme Element Extensions - Spatial Analyst Workspace - where work is saved Theme Table - attributes Legend Editor - right-click legend

Converting to GRID Grid size –specification –matching Grid extent –display –existing grid Attributes –specifying –attaching

Discussion Problems: Grid the roads and stands using various grid sizes. Overlay and comment. Grid the stands, roads, and landslides to match the DEM grids. Verify they match. Overlay the road lines on the road grid. Comment. Repeat with polygons.

Practice problem: Grid the polygon coverage using different methods and grid sizes

majority

centroid

weighted