The State of Arsenic in Nepal - 2003 - Harvard University ...

6. Data and map preparation
The quality of information about the state of arsenic in the
groundwater in a region is determined by the quality and the
volume of the arsenic tested water data available in that
region. Water sampling and testing, and collection of related
well information in order to know the state of arsenic in
groundwater for a region is very time consuming and
expensive. It may not be affordable for a single organization
to carry out all these studies alone. Several organizations,
including DWSS, NRCS, RWSSSP, NEWAH, RWSSFDB,
have been involving in testing arsenic contamination and in
other arsenic related issues in different parts of the country.
Acquired data for 20 out of 75 districts of Nepal were involved
in this study. These twenty districts include the whole
southern part of the country. Each district is comprised of
several VDC and/or municipalities. Each agency has its own
individual arsenic test data sets for different regions.
Integrating these individual data sets into a single database,
analyzing the data, and displaying the data in several
different presentations is the approach used to describe the
state of arsenic in this report for southern Nepal.
Environmental data such as arsenic concentration in
groundwater represent a natural phenomenon. The arsenic
data are measured on the earth surface with spatial and
temporal resolution. Maps are one of the best techniques to
illustrate the spatial distribution of this data. This chapter
describes the process used to create an integrated database
of arsenic tested tube wells, to prepare spatial data layers,
and to produce different kinds of maps.
6.1. Integrated database of arsenic tested tube wells
This part of the chapter describes steps and methodology
implemented in preparing an integrated attribute database
of arsenic tested tube wells.
6.1.1. Acquisition of arsenic test data set
Individual arsenic test data sets were acquired from the
following organizations: DWSS, NRCS, RWSSSP, NEWAH
and RWSSFDB with the help of NASC. Most of these data
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sets were made available in digital form in Excel format. Data
sets for most organizations are maintained at the district
level. But the original fields and data types used by different
organizations to represent various attributes of arsenic
tested wells were not uniform. Each data set was checked,
cleaned, and updated in a standard Excel format with the
help of respective data owner. The minimum criteria for
accepting a well to be incorporated in database were: a well
should at least have arsenic test value and name of VDC
where it is located. The data for 18,775 wells were acquired
from different organizations at the beginning of this study;
however, only 18,635 wells met this criterion. About 104
wells did not have a VDC name and 36 wells were without an
arsenic value and therefore could not be included in the
database of this study. Table 6.1 gives the district data
acquired from different source organizations. This integrated
data set comprises of only those data sets which meet the
minimum criteria and reached to ENPHO by August 2003.
However, tube wells testing trend is increasing rapidly,
number of tested tube wells has been already reached to
28,956 according to the arsenic testing progress report
distributed in NASC meeting held on 19 th November, 2003
(Annex 1). The new post-august 2003 data have not yet
been added to the national database.
Table 6.1.
District/Organizationwise Arsenic Tested Wells
Organization
DWSS
NRCS
RWSSSP
NEWAH
RWSSFDB
Total valid
data
District
Banke 197 549 97 843
Bara 197 1757 1954
Bardiya 199 428 24 651
Chitawan 203 203
Dang 196 196
Dhanusha 165 120 285
Jhapa 94 137 49 280
Kailali 201 100 301
Kanchanpur 177 177
Kapilbastu 608 1750 132 2490
Mahotari 199 199
Morang 200 200
Nawalparasi 2134 716 361 3211
Parsa 195 1915 137 2247
Rautahat 198 1765 82 8 2053
Rupandehi 758 1222 63 2043
Saptari 198 100 37 235 570
Sarlahi 186 98 42 326
Siraha 100 10 124 234
Sunsari 172 172
Total 5211 8831 3333 413 847 18635