IPN-ISRAEL, 17 th -19 th Sep, 2014 The WaTrend System Meir Rom, D.Sc. Statistician and System...
-
Upload
lilian-fulcher -
Category
Documents
-
view
217 -
download
0
Transcript of IPN-ISRAEL, 17 th -19 th Sep, 2014 The WaTrend System Meir Rom, D.Sc. Statistician and System...
IPN-ISRAEL, 17th-19th Sep, 2014
The WaTrend System
Rapid Characterization and Prediction of Long
Term Water Quality Changes in Ground Water
and Surface Water Resources
2
Contributors:
Sharon Hassid, Evgeny Kleiman, Ami Einav
Mekorot, System Information Unit
IPN-ISRAEL, 17th-19th Sep, 2014
Facts and Figures
3
3,000 Facilities12,000 km
of water lines
1,070 Water well drillings
IPN-ISRAEL, 17th-19th Sep, 2014
Objectives
4
Characterize and Identify large number of
water resources, thru historical records in few
seconds
Predict values of water quality using simple
statistical tools
No need to have special skills in Statistics.
Background calculations.
Interactive, friendly multi-utilities GIS
environment
IPN-ISRAEL, 17th-19th Sep, 2014
Usages (Already Operational)
5
Hydrological surveys
Reveal potential contamination and
its source
Prepare for new regulations and
standards
Exploratory Data Analysis (EDA)
tools
IPN-ISRAEL, 17th-19th Sep, 2014
Input
6
Mekorot’s water-quality data-base:
spatial and temporal historical data of all
quality parameters.
User must indicate, district, time-window
and choose specific quality parameter.
Mekorot’s water supply data-base
mainly for filter-out “inactive” water
resources
IPN-ISRAEL, 17th-19th Sep, 2014
Why use robust measures?
7
Regression (slope)%
Robust (slope)
100%
116%
207%
267%
Leverage Points
Nitrate (NO3) – Ein-Hod
IPN-ISRAEL, 17th-19th Sep, 2014
Trend measure
8
Calculate robust measure of trend monotony
Here we used “kendall’s tau”( ): a well known statistical measure.
In map, Adjust the “raduis” of the “star” shape label in proportion to the value of .
Use Green color to indicate decrease of values.
Important: High level of does not necessarily indicate high slope level !
IPN-ISRAEL, 17th-19th Sep, 2014
SD measure
9
• Categorize all values into 5 groups, corresponding to the threshold concentration acceptance level.
• Process the relative-frequencies of each category in the specified time-window.
• Transform the results into [0,1] index means that all values in the time-
window exceed the standard level.
.1
• In map, Adjust the radius of the “diamond” shape label in proportion to .
IPN-ISRAEL, 17th-19th Sep, 2014
Theil-Sen’s robust measure of slope
10
Use robust measure (Theil-Sen slope estimator) to
estimate the trend’s rate and test for its statistically
significance.
Determine linearity of trend by halving the time-window
and perform a significant comparison test. In case of non-
linearity report slope results of the window’s second half.
Set icon for each water resource to illustrate its dynamic
behavior in time which corresponds to the specific quality
parameter
IPN-ISRAEL, 17th-19th Sep, 2014
Summary table
12
Summary for all characteristics associated with each
water resource is given in dynamic table: