J. Water Resource and Protection, 2010, 2, 154-166
doi:10.4236/jwarp.2010.22018 Published Online February 2010 (http://www.SciRP.org/journal/jwarp/).
Copyright © 2010 SciRes. JWARP
ComGIS-Based Early Warning System of Rural Drinking
Water Safety in Ya’an City of Sichuan, China
Fuquan Ni1,2, Guodong Liu2, Liping Xu1,Chengwei Fu1
1College of Information & Engineering, Sichuan Agricultural University, Ya’an, China
2State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, China
E-mail: nfq1965@163.com
Received November 2, 2009; revised November 25, 2009; accepted December 10, 2009
Abstract
According to characteristic index of spatial-temporal variability of rural drinking water safety in Ya’an City
of Sichuan, China, such as water quantity, water quality, convenience degree and guaranteed rate, etc., this
study elaborated the basic framework, model’s methodology structure in early warning system of rural
drinking water safety on the basis of ComGIS and initially designed information collection, search and re-
trieval, evaluation and analysis of factors, dynamic prediction and dynamic early-warning and functions of
guidance and management in this system. The design of this system provided scientific basis to grasp the
state of rural drinking water safety timely, release early warning information and properly take necessary
control measures, etc. The evaluation results showed that the overall trend was getting better. It proved that
the rising pressure value and response value were main reasons which caused the rising evaluation value of
rural drinking water safety.
Keywords: Water Quality, Status Early Warning, Trending Early warning, Rural Drinking Water Safety,
Ya’an, ComGIS
1. Introduction
Water is very important for human development. Access
to reliable and safe drinking water supply and adequate
sanitation is not only a basic human right, but also an
unavoidable responsibility of a government.
In China, rural drinking water safety refers to not only
enough clean domestic water that residents can obtain
timely and easily, but also domestic water within the
scope of our financial capacity. There are two levels of
rural drinking water. One is to solve the problem of basic
need for water; the other is to ensure drinking water
safety. Rural drinking water safety is an important aspect
of human security. According to statistics of 2005,
among 940 million national rural population (Shanghai,
Hong Kong, Macao and Taiwan are not considered),
66% had safe and basically safe drinking water; the
population of unsafe drinking water was 320 million,
taking up 34% of rural population, in which, the popula-
tion of unqualified water safety amounted to 70% [1].
According to the affected population, problems of un-
qualified water quality could be sorted as follows: fluo-
rine content exceeding the standard, seriously polluted
groundwater, and badly polluted surface water, saltwater,
arsenic content exceeding the standard and other prob-
lems of water quality. In one word, over 300 million ru-
ral residents still have no access to safe drinking water,
facing problems of shortage, severe contamination, wa-
ter-borne disease and subsequent unhealed diseases. Thu-
s, meeting demand of water resources and access to safe
and reliable drinking water for rural communities have
become critically environmental and economic chal-
lenges, which are also hot spot issues in the 11th Na-
tional Five Year Plan of China.
Rural drinking water safety were closely related to
water quantity, water quality, convenience degree, guar-
anteed rate, climate, environment, water management,
education, diseases, society, etc. It is extremely essential
for the understanding and further study on rural drinking
water safety and spatial distribution of influencing fac-
tors. Therefore, research and application of Geographic
Information System (GIS) in rural drinking water safety
have got more and more attention, especially from over-
seas [2–7]. Meanwhile, the majority of domestic re-
F. Q. NI ET AL. 155
searches, which are focused on the study of rural drink-
ing water safety, are just uncomplicated applications,
which are simply compared with standards. However,
effect of uncertain factors and further researches based
on GIS are rare [8–11]. Study on early warning of rural
drinking water safety was very scarce at home in par-
ticular.
In order to analyze agricultural water resources supply
and demand in depth, discuss the long-term effects of
agricultural water resources on economic development in
society and maintenance rural drinking water safety so as
to simultaneously enhance the safety and security system
for agricultural water resources, according to the spatial
and temporal differences of rural drinking water safety,
factors such as regional integrity, the representative of
drinking water safety issues, information accessibility
being considered, this study takes the seven counties and
one district in Ya’an Sichuan for example and applies
ComGIS spatial analysis to design regional early warn-
ing system of rural drinking water so as to grasp the lat-
est impaired state of rural drinking water safety timely,
issue early warning information regularly or irregularly,
take necessary control measures opportunely, have time-
ly tracking control on the basis of ComGIS-based deci-
sion support system of rural drinking water safety in
Ya’an, Sichuan published earlier. As a result, it better
addresses issues of drinking water safety and difficulty in
rural areas on the western edge of the Sichuan moun-
tainous area, fulfills the purpose of sustainable develop-
ment, achieves the purpose of harmony between water
and humankind, and promotes the building of a new so-
cialist countryside.
The main purpose of this study is to develop an early
warning system of drinking water safety and apply it to
improve water resources management and maintain
drinking water safety in Ya’an City. Based on ComGIS
technology, such a system is developed by the integra-
tion of eco-environmental rehabilitation, water allocation
and sustainable development. The early warning system
is developed by applications of advanced information
technology and intelligent expert system (IES). The core
of this system consists of three modules. This system
allows decision makers to express their considerations
about various factors through a friendly interactive inter-
face. This basic information can be interpreted and con-
cluded via IES, which is an integration of knowledge
from a group of multidisciplinary experts, to generate a
number of indicators that can describe the level of risk
associated with drinking water safety.
Objectives of the study are listed as follows:
1) To manage basic information from all sides, estab-
lish map database of study areas, including administra-
tive map, water distribution map, village location map,
county location distribution map, achieve query and re-
trieval of spatial information, etc.
2) To fulfill the input, modify, query, retrieval and sta-
tistical analysis of data about the water quality, water
quantity, convenience degree and guaranteed rate.
3) To accomplish current state evaluation of drinking
water quality, water quantity, convenience degree and
guaranteed rate in each towns and counties, determine
the level of state of early warning and draw early warn-
ing of state map, by means of monitored data about water
quality, water quantity, convenience degree, and guaran-
teed rate, along with evaluation model and early warning
model.
4) To predict change trends of drinking water quality
and water quantity; complete the level classification of
early warning of trend, according to drinking water qual-
ity and water quantity in study areas.
Principles of the system design are listed as follows:
1) Applicable and advanced: it excavates the powerful
spatial analysis function of GIS to a great extent, deeply
realizes the blend of data and graphics, the combination
of analytical and calculated results with dynamic display,
and the coupling of GIS and mathematical modeling.
2) Strong feasibility: taking different levels of users
into account, the user interface of this system is of
friendly appearance and the operation is intuitionistic,
simple and easy to maintain. Works, such as system in-
stallation, parameter setting, use and operation, devel-
opment and maintenance and daily management, are
simple and easy. They accord with operating habits of
personnel in charge of development and maintenance
with optimal cost.
3) Good openness: for the purpose of continuous im-
provement and upgrades, it applies the open structure so
as to ensure good extensibility in both hardware and
software.
4) Good safety: the system sets different permissions
to different types of users so as to prevent the system
from unauthorized use and illegal modification and
copying of data, etc.
Overall structure of the system: See Figure 1.
System modules:
1) GIS spatial database module: GIS spatial database
module of some regions is saved as shp files to store ba-
sic information, such as state of natural geography, river
system, administrative division, in forms of figures and
attributes inside the computer.
2) Drinking water information database module: this
module contains following aspects: real-time detection of
water quality, water quantity, convenience degree and
guaranteed rate. Index of detection include saturation,
chromaticity turbidity, PH value, total hardness, total dis-
solved solids, iron, manganese, chloride, sulfate, arsenic,
mercury, cadmium, lead, nitrate, oxygen consumption,
total bacteria, total coliform, amount of available water per
person per day, the round-trip time of fetching water by
manpower and guaranteed rate of water supply from water
resources in generally arid years. The database module
implements basic functions in the database, including the
Copyright © 2010 SciRes. JWARP
F. Q. NI ET AL.
Copyright © 2010 SciRes. JWARP
156
System structure
GIS spatial
database module
Administrative
division
Road distribution
Water system
distribution
Town distribution
County distribution
Early warning
module
Early warning of
state
Evaluation level of
each component
Evaluation level of
all components
State estimation
Level of early
warning of state
Early warning of
trend
Change trends of
single component
Trend of integrated
index
Level of early
warning of trend
Drinking water information
database module
Guaranteed rate
Convenience degree
Water quantity
Water quality
Figure 1. Overall structure for early warning of rural drinking water safety.
quality standards, in which, 23,800 residents lived with
opening of data files, the adding, delete, refresh, sorting,
filtering of data, printing reports and positioning. water exceeding the standard fluoride content, 15,700
residents suffered from brackish water, 31,100 residents
lived with IV-level or above IV-level untreated surface
water, 171,400 residents took untreated surface water
with bacteriological index seriously exceeding the stan-
dards, 10,400 residents suffered from the untreated un-
derground water with heavy pollution, and 69,600 resi-
dents took the water with other index exceeding the
standards (mainly including Glauber’s salt, Fe, Mn and
mineral). 551,000 residents suffered from water shortage,
142,800 residents suffered from the inconvenience of
water supply, and guaranteed rate of source of water that
didn’t reach the standards affected 61,000 residents [12].
3) Early warning module: this module is the core of early
warning system of rural drinking water safety. It mainly
implements functions of model call, computing, outputs of
results, etc. By the development of application model
(using VB, C++ and other languages), it implements the
assessing, forecasting and early warning of rural drinking
water safety.
2. Material and Methods
2.1. Overview of the Study Area
The eco-hydrological characteristics of the seven
counties and one district of Ya’an City are listed as fol-
lows:
Ya'an City is located in the western part of Sichuan
Province, China, and belongs to mountainous area of
western margin in Sichuan Basin. It is a transitional area
between Sichuan Basin and Qinghai-Tibetan Plateau
with seven counties and one district. With the develop-
ment of industry and agriculture and the effect of human
activities, water pollution of Qingyi River in Ya’an City
is getting worse day by day. There are two types of water
pollution in rural areas of Ya’an: one is the schisto-
some-affected areas of Lushan County and Tianquan
County, where source of water is polluted by oncome-
lania; the other is the river pollution caused by the ag-
gravation of human activities, forest devastation and fer-
tilizer and pesticide abuse in agricultural production,
which all affected human life and drinking water produc-
tion. According to the investigation and statistics,
580,200 residents didn’t get safe drinking water, ac-
counting for 46.77% of agricultural population. About
Average annual precipitation of Lushan County
amounted to 1313mm. Water consumption and guaran-
teed rate of rural residents are relatively high. This area
was schwastosoma area and raw water was heavily pol-
luted by schistosoma. The population density was 80/
km2 and the proportion of cultivated land was 2.88%. It
belonged to areas moderately influenced by human ac-
tion and human impacts on this area were relatively no-
table;
As for Tianquan County, average annual rainfall was
1660mm, percentage of forest cover was 50.23%, gross
amount of water resources amounted to 6.714 billion
cubic meters, and the amount per capita was 2724 cubic
meters. Drinking water quality was dominated by cal-
cium carbonate, total hardness was on the high side, and
contents of dissolved solids and sulfate were high with
high incidence of gallstone disease. The population den-
321,600 residents drink the water that didn’t reach the
F. Q. NI ET AL. 157
sity was 90/km2 and the proportion of cultivated land
was 3.14%. It belonged to areas moderately influenced
by human action and human impacts on this area were
relatively notable;
As for Minshan County, average annual rainfall was
1501mm. There were relatively great differences in
background values of iron and manganese content in
groundwater in different soil parent materials and differ-
ent soil types, where iron and manganese content in
some regions of this area were high. Rural population
was dispersed, economic development was relatively
lagging behind, and infrastructure was relatively weak.
Source of drinking water mainly relies on groundwater
and population of groundwater consumption was as high
as 86%. The population density and the proportion of
cultivated land were 4200/km2 and 14.8% respectively. It
belonged to areas intensely influenced by human action
and human impacts on this area were relatively notable;
As for Yingjing County, precipitation was abundant,
spatial and temporal distribution was uneven with serious
mountain flood disasters. It has rich water resources,
average precipitation was 3.483 billion km3, runoff depth
was 1702mm, and runoff coefficient was 0.86. The num-
ber of total coliform in drinking water amounted to
360/ml, which has gone far beyond the standards. The
population density was 100/km2 and the proportion of
cultivated land was 3.44%. It belonged to areas moder-
ately influenced by human action and human impacts on
this area were relatively notable;
As for Baoxing County, its hilly area accounts for
99.7%, precipitation was 953mm and there was a trend
of water shortage. Dissolved solids in drinking water
were not detected; tested values of toxicology indicators
were low. However, the total number of bacteria was
210/ml, which was twice as much as the Standards for
Drinking Water Quality. The population density only
reaches to 20/km2 and the proportion of cultivated land
was just 0.84%. It belonged to areas slightly influenced
by human action;
As for Yucheng District, which was located in the
middle of Qingyi River Basin, precipitation of oro-
graphic rain was abundant, average rain days amounted
to 218, and average annual precipitation was 1732mm.
The population density reaches to 3200 /km2 and the
proportion of cultivated land was 7.0%. Affected by ef-
fects of human activities, industrial wastewater and do-
mestic sewage, water that could be directly consumed
was relatively not much, resulting in drinking water
shortage;
As for Hanyuan County, it has hot and dry air with lit-
tle precipitation, spatial and temporal distribution of
which was uneven. Average annual precipitation was
731mm, evaporation capacity was up to 1499mm, and it
belongs to water-poor area in proportion to water quan-
tity. Contents of heavy metals in drinking water were
relatively low; however, fluorine content was high. Inci-
dence of water-borne fluorosis of bone, Kashin-Beck
disease and dental fluorosis were high. The population
density was 50/km2 and the proportion of cultivated land
was 1.50%. It belonged to areas slightly influenced by
human action;
As for Shimian County, exploitable water resources
were abundant, however, precipitation and the amount of
water that could be used as domestic drinking water was
relatively not much. Winter and spring were dry seasons.
There was a critical shortage in drinking water from
wells, creeks and ditches was a severe shortage and that
was what caused seasonal water shortage and low guar-
anteed rate. The water quality of treated raw water from
creeks, ditches, ponds, weirs, reservoirs and rivers,
which were consumed by local people, don’t meet the
standards, i.e., drinking water was not safe. The popula
tion density was just 140/km2 and the proportion of cul-
tivated land was also just 8.68%. It belonged to areas
slightly influenced by human action.
During 20052008, 221 villages were detected about
water quantity, water quality, convenience degree and gua-
ranteed rate in rural drinking water safety. See Figure 2.
2.2. Methods of Early Warning of Rural
Drinking Water Safety
There are three kinds of methods:
1) Early warning of index: namely to integrate index
of warning sign and express them in the form of inte-
grated indicators. The elevation and subsidence of Warn-
ing Thing can be estimated according to the elevation
and subsidence of the integrated indicators of Warning
Sign after having standardization and weighted process-
ing to all variable values of Warning Sign index.
2) Early warning of statistics: this kind of early warn-
ing method is to have the relationship between warning
sign and warning affairs statistically processed, and then
predict warning degree according to the level of warning
sign. Early warning of statistics emphasizes on the sig-
nificant test of chosen warning sign index, but its inte-
grated approach is not requested; however, conditions of
early warning of index to chosen Warning Sign index is
more loosed and its integrated approach is relatively pro-
grammed and normalized.
3) Early warning of model: i.e., to have further early
warning analysis on the basis of early warning of index
and early warning of statistics. Its essence is to establish
Lag Model with warning sign as independent variables to
have prediction.
2.3. Early Warning Types of Rural Drinking
Water Safety
1) Early warning of state: firstly, to collect basic data
of rural drinking water, such as water quality, water qua-
ntity, convenience degree and guaranteed rate, establish
Copyright © 2010 SciRes. JWARP
F. Q. NI ET AL.
Copyright © 2010 SciRes. JWARP
158
Figure 2. The sampling sites and the location of Ya’an city.
background database and judge the level of water quality,
pollution intensity, place and range of occurrence; after-
wards, to issue early warning so as to achieve the pur-
pose of pollution prevention finally.
2) Early warning of trend: it starts working, which is
mainly based on state of rural drinking water quality and
water quantity, trends of development and rate of change,
on the basis of early-warning of state. It requests not only
understanding about dynamic changes of water quality
and water quantity in the past, but also understanding
of current state and future changes of trend.
2.4. Early Warning of Rural Drinking Water
Safety
2.4.1. Early Warning of Water Quality State in Rural
Drinking Safety
Index Method: to conduct early warning of water qual-
ity by means of index method is to regard each water
quality component as independent indicator to character-
ize water quality. When anyone or more indicators ex-
ceed the National Standards for the Daily Drinking Wa-
ter Quality, warning thing is considered to come out.
Specific warning degree can be determined according to
the criteria classification of warning limit, i.e. first-level
water (ideal state), second-level water (good state), third-
level water (general state), fourth-level water (relatively
poor state), and fifth-level water (bad state).
Integrated Index Method: integrated index method is
to use the integrated pollution index method to determine
the integrated pollution indicators of water quality and
determine the level of early-warning of water quality,
with reference values of five kinds of water in the na-
tional standards as a reference system. Calculated for-
mula are shown in Formula (1), state of early warning
are shown in Table 1.
0
1
1ni
i
i
C
PnC
(1)
where, Ci is the measured content of each water quality
indicator; C0i is the maximum allowable standard in
drinking water of each water quality factor; n is the
number of evaluated water quality factors.
2.4.2. Early Warning of Water Quality Trend in
Rural Drinking Safety
Early warning of trend in rural drinking water quality is
to conduct judgment on whether or not water quality
develops in the direction of deterioration, at the same
time, to make appropriate description about the rate of
change of water quality with respect to time. See calcu-
lation Formula (2).
() ()ET Et
Rt
(2)
where, E(t) is the integrated index of one particular
known moment; E(T) is the integrated index of one
moment in the future that can be predicted by temporal
Table 1. Determination on level of early warning of state
about water quality.
Integrated index
of water quality<0.1 0.10.4 0.40.7 0.71.0 >1.0
Level of
early warning:Ideal :good :General :poor:Bad
F. Q. NI ET AL. 159
extrapolation method and time series models; t is a pe-
riod of time; R is the rate of change about water quality.
Its value range and conceptions are shown in Table 2.
2.4.3. Early Warning of Water Quantity in Rural
Drinking Safety
1) Early warning of state in water quantity: according to
the requirements of evaluation criteria of water quantity,
the amount of available water per person per day is cal
culated to determine the level of early warning in study
areas.
2) Early warning of trend in water quantity: early
warning of trend of water quantity is to conduct judg-
ments on whether or not the amount of available water
per person per day develops in the direction of deteriora-
tion, at the same time, to make appropriate description
about the rate of change of water quantity with respect to
time. See calculation Formula (3).
()( )Qt QT
Rt
(3)
where, Q(t)is the amount of available water per person
per day of one particular known moment; Q(T) is the
amount of available water per person per day of one
moment in the future that can be predicted by temporal
extrapolation method and time series models. t is a pe-
riod of time; R is the rate of change about water quantity.
Its value range and conceptions are shown in Table 3.
2.4.4. Early Warning of Convenience Degree and
Guaranteed Rate in Rural Drinking Water
Safety
According to the requirements of evaluation criteria of
convenience degree and guaranteed rate in rural drinking
water safety, the round-trip time of fetching water by
manpower and guaranteed rate of water supply from wa-
ter resources in generally arid years (drought appears
every decade) are calculated to determine the level of
early warning in study areas.
2.4.5. Early Warning of Trend in Rural Drinking
Water Safety
According to the evaluation index of above four single
indicators, the comprehensive evaluation indicator (Rh)
can be drawn according to Formula (4).
Rh=
11
nm
j
ij
ji
A
R

 (4)
where, Aj is the weight. Values of water quantity, water
quality, water source guaranteed rate and convenience
degree are 0.3, 0.3, 0.2 and 0.2 respectively; Rij is the
evaluation value of the single factor; i is the number of
sampling sites; j is the amount of evaluation values of
single factors. The hierarchical relationship between
comprehensive index value and the rural drinking water
safety warning can be seen in Table 4.
Table 2. Determination on level of early warning of trend about water quality.
Rate R<0 0R0.1≦≦ 0.1<R<0.2 0.2<R<0.4 >0.4
Level of early
warning
:
Improving
trend
:
Stable
trend
:
Slightly deteriorated
trend
:
Moderately deteriorated
trend
:
Severely
deteriorated trend
Table 3. Determination on level of early warning of trend about water quantity.
Study areas Rate of change of water quantity Level of early warning of status
R0 V:Improving trend
0R12 IV:Stable trend
12R16 III:Slightly deteriorated trend
16R18 II:Moderately deteriorated trend
Abundant precipitation areas
R18 I:Severely deteriorated Trend
R0 V:Improving trend
0R4 IV:Stable trend
4R8 III:Slightly deteriorated trend
8R10 II:Moderately deteriorated trend
Deficient precipitation areas
R10 I:Severely deteriorated trend
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F. Q. NI ET AL.
Copyright © 2010 SciRes. JWARP
160
Table 4. The relationship among comprehensive index value and warning levels.
Level Characterization of warning state Characteristic
I Serious state (bad state)
Service functions of rural drinking water safety system are near collapse,
which manifested in: ecological processes are difficult to reverse; structures
of ecosystem are incomplete and functions are lost; it is very difficult to con-
duct ecological restoration and reconstruction; ecological problems are heavy
and often turn into ecological disasters.
II Moderate state (poor state)
Service functions of rural drinking water safety system are severely degraded,
which manifested in: ecological environment has been greatly damaged;
structures of ecosystem are destroyed badly, whose functions are degraded
and not overall, and it is difficult to recover after being disturbed by outside
interference; heavy ecological problems and many ecological disasters.
III Early warning state (general state)
Service functions of rural drinking water safety system have been degraded,
which manifested in: ecological environment has been damaged to a certain
degree; there are changes in structures of ecosystem, however, they can still
maintain basic functions, and it is easy to deteriorate after being disturbed;
ecological problems are emerged and ecological disasters occurs at times.
IV Relatively safe state (good state)
Service functions of rural drinking water safety system are more complete,
which manifested in: ecological environment is less damaged; structures of
ecosystem are still complete and functions are still good, which can be recov-
ered under general disturbances; no significant ecological problems and not
too many ecological disasters.
V Safe state (ideal state)
Service functions of rural drinking water safety system are basically com-
plete, which manifested in: ecological environment, basically, isn’t disturbed
and damaged; structures of ecosystem are complete with high level of func-
tionality; strong system recovery and regenerative ability; no significant eco-
logical problems and ecological disaster less.
3. Results
3.1. Early Warning of State
Results from early warning of state can be seen in Fig-
ures 312.
3.1.1. Early Warning of Water Quantity
According to Figure 3, early warning of water quantity
mainly appeared in counties other than Tianquan and
Lushan county.
As for Yucheng District, it mainly appeared in Zhongli
town, Bifengxia town, Hejiang town, Yanqiao town,
Liba, Babu town and Guanhua town, with involved
population of 235, 1013, 909, 340, 1345, 418 and 170
respectively. The total amount of involved population
was 4430;
As for Minshan County, it mainly appeared in Jian-
shan town, Mengdingshan town, Maling town, Hongyan
town, Cheling town, Yongxing town and Hongxing town,
with involved population of 276, 717, 1080, 1450, 640,
2077 and 3314 respectively. The total amount of in-
volved population amounted to 9554;
As for Yingjing County, it mainly appeared in Anjing
town, Baofeng town, Huatan town, Miaogang town,
Sanhe town, Shiqiao town, Shizi town, Tianfeng town,
Xinjian town, Xinmiao town and Yinghe town, with in-
volved population of 898, 399, 474, 322, 1677, 898, 233,
721, 857, 1034 and 825 respectively. The total amount of
involved population amounted to 8338;
As for Hanyuan County, it mainly appeared in Dashu
town, Qingxi town, Fuquan town, Tangjia town, Qianyu
town, Malie town, Shuangxi town, Guixian town, Xiao-
bao town, Anle town, Hexi town, Yidong town and
Dayan town, with involved population of 500, 3856, 500,
528, 3849, 500, 6435, 350, 49, 2216, 420, 2753 and 700
respectively. The total amount of involved population
amounted to 22656;
As for Shimian County, it mainly appeared in Fengle
town, Zaiyang town, Yongle town, Chaluo town and
Xinmin town, with involved population of 855, 2813,
2988, 650 and 943 respectively. The total amount of in-
volved population amounted to 8249;
As for Baoxing County, it mainly appeared in Long-
dong town, Minzhi town, Muping town, Lingguan town,
Zhongba town and Daxi town, with involved population
of 220, 60, 531, 125, 230 and 227 respectively. The total
amount of involved population amounted to 1393.
F. Q. NI ET AL. 161
3.1.2. Early Warning of Water Quality
According to Figures 4–11, early warning of water qual-
ity appeared in all the 7 counties and one district.
Involved population of Yucheng District was 65788,
in which, population of fluoride content exceeding the
standards amounted to 3022, which mainly appeared in
Bifengxia town, Shaping town, Zhouhe town and Guan-
hua town with involved population of 320, 114, 681 and
1907 respectively; population of brackish water amo-
unted to 15743, which mainly appeared in Zhongli town,
Bifengxia town, Daxing town, Caoba town, Hejiang
town, Nanjiao town, Xianghua town and Babu town with
involved population of 3230, 496, 618, 4817, 474, 1566,
4340 and 202 respectively; involved population of un-
treated surface water and bacteriological indicators seri-
ously exceeding the standards and amounted to 35402,
which mainly appeared in Bifengxia town, Daxing town,
Caoba town, Beijiao town, Duiyan town, Yanqiao town,
Zhouhe town, Yanchang town, Babu town and Helong
town with involved population of 1313, 2063, 75, 2997,
6154, 6874, 307, 1339, 5381 and 2646 respectively; in-
volved population of heavily polluted and untreated
groundwater amounted to 1517, which mainly appeared
in Bifengxia town, Beijiao town and Duoying town with
involved population of 860, 294 and 363 respectively;
population of other indicators exceeding the standards
amounted to 10104, which mainly appeared in Zhongli
town, Bifengxia town, Caoba town, Hejiang town, Feng-
ming town, Kongping town, Duiyan town, Zhouhe
Liba town, Babu town and Guanhua town with involved
population of 397, 10, 462, 25, 1883, 2442, 2514, 299,
1622, 290 and 160 respectively;
Involved population of Mingshan County was 45398,
in which, involved population of untreated -level and
above -level groundwater amounted to 25695, in-
volved population of bacteriological indicators seriously
exceeding the standards and untreated groundwater
amounted to 11000, involved population of heavily pol
luted and untreated groundwater amounted to 8703, and
population of other indicators exceeding the standards
amounted to 39045;
Involved population of Yingjing County was 46005, in
which, involved population of untreated -level and
above -level groundwater amounted to 5411, involved
population of bacteriological indicators seriously ex-
ceeding the standards and untreated groundwater amo-
unted to 25152, involved population of heavily polluted
and untreated groundwater amounted to 6639, and popu-
lation of other indicators exceeding the standards
amounted to 8803;
Involved population of Hanyuan County was 46005,
in which, population of fluoride content exceeding the
standards amounted to 7515, involved population of
bacteriological indicators seriously exceeding the stan-
Figure 3. Water quantity early warning. Figure 4. Water quality early warning.
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F. Q. NI ET AL.
162
Figure 5. Fluoride early warning. Figure 6. Brackish water early warning.
Figure 7. Other water quality early warning. Figure 8. Water quality severe contamination early warning.
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F. Q. NI ET AL.
Copyright © 2010 SciRes. JWARP
163
Figure 9. The fourth class water early warning. Figure 10. Bacteriology index water early warning.
Figure 11. Schistosomiasis severe district distribution and
raw water early warning. Figure 12. Water source guaranteed rate early warning.
F. Q. NI ET AL.
164
ards and untreated groundwater amounted to 14320;
Involved population of Shimian County was 12054, in
which, population of fluoride exceeding the standards
amounted to 1609, involved population of bacteriological
indicators seriously exceeding the standards and un-
treated groundwater amounted to 10445;
Involved population of Tianquan County was 51620,
in which, population of fluoride exceeding the standards
amounted to 11620, involved population of bacteriologi-
cal indicators seriously exceeding the standards and un-
treated groundwater amounted to 28545, and involved
population of other indicators exceeding the standards
amounted to 11455;
Involved population of bacteriological indicators seri-
ously exceeding the standards and untreated groundwater
of Lushan County amounted to 37811;
Involved population of Baoxing County was 11264, in
which, involved population of bacteriological indicators
seriously exceeding the standards and untreated surface
water amounted to 8797, involved population of heavily
polluted and untreated groundwater amounted to 200,
and involved population of other indicators exceeding
the standards amounted to 2267.
3.1.3. Early Warning of Guaranteed Rate of Source of
Water
According to Figure 12, early warning of water source
guarantee rate appeared in all the counties and one dis-
trict besides Yingjing County and Tianquan County. In
which:
Involved population of Yucheng District was 28003;
involved population of Mingshang County was 14228;
involved population of Hanyuan County was 3132; in-
volved population of Shimian County was 907; involved
population of Lushan County was 3878; involved popu-
lation of Baoxing County was 2630.
3.1.4. Convenience Degree
Early warning of convenience degree of water appeared
in all the 7 counties and one district.
Involved population of Yucheng District was 20179;
involved population of Mingshang County was 12575;
involved population of Yingjing County was 7957; in-
volved population of Hanyuan County was 52705; in-
volved population of Shimian County was 11790; in-
volved population of Tianquan County was 22048; in-
volved population of Lushan County was 8478; involved
population of Baoxing was 6665.
3.2. Early Warning of Trend
Results from early warning of trend can be seen in Ta-
bles 5–9.
Table 5. Safety levels of rural drinking water quantity from
2005 to 2008.
Year Evaluation value Safety level Warning state
2005 4.0 IV Stable trend
2006 3.5 IV Stable trend
2007 -0.5 V Improving trend
2008 -0.6 V Improving trend
Table 6. Safety levels of rural drinking water quality from
2005 to 2008.
YearEvaluation valueSafety level Warning state
20050.05 Stable trend
Relatively
good trend
20060.04 Stable trend
Relatively
good trend
2007-0.01 Improving trend Ideal trend
2008-0.02 Improving trend Ideal trend
Table 7. Safety levels of guaranteed rate of source of water
from 2005 to 2008.
Year Evaluation value Safety level Warning state
2005 0.05 Stable trend
Relatively good
trend
2006 0.03 Stable trend
Relatively good
trend
2007 -0.01 Improving trend Ideal trend
2008 -0.02 Improving trend Ideal trend
Table 8. Safety levels of convenience degree from 2005 to
2008.
YearEvaluation value Safety level Warning state
20050.04 Stable trend Relatively
good trend
20060.03 Stable trend Relatively
good trend
2007-0.01 Improving trend Ideal trend
2008-0.02 Improving trend Ideal trend
Table 9. Comprehensive levels of rural drinking water
safety from 2005 to 2008.
YearEvaluation valueSafety level Warning state
20051.233 Stable trend
Relatively good
trend
20061.074 Stable trend Relatively good
trend
2007-0.157 Improving trend Ideal trend
2008-0.194 Improving trend Ideal trend
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F. Q. NI ET AL. 165
4. Analysis and Discussions
The total population of the seven counties and one dis-
trict of Ya’an City was 1244136, in which, population of
safe drinking water and basically safe drinking water
amounted to 663521 and population of unsafe drinking
water amounted to 282827, in which, involved popula-
tion of water quantity failing to meet the standards amo-
unted to 52778; involved population of convenience de-
gree of water use failing to meet the standards amounted
to 142397; involved population of guaranteed rate failing
to meet the standards amounted to 52778; involved
population of drinking water quality failing to meet the
standards amounted to 330820, in which, population of
fluoride content exceeding the standards amo- unted to
23766, population of brackish water amounted to 15743,
population of untreated -level and above -level
groundwater amounted to 31106, involved population of
bacteriological indicators seriously exceeding the stan-
dards and untreated surface water amounted to 171472,
involved population of untreated groundwater amounted
to 17059, and involved population of other indicators
exceeding the standards amo -unted to 71674.
According to Figures 3–12, some villages of the seven
counties and one district of Ya’an City were in an early
warning state. Ecosystem structure and system service
functions of natural rural drinking water environment
were not all-around. Some villages are on the verge of
collapse and the ecosystem of water environment was
subjected to great pressure and lack of corresponding and
positive response measures. The main Warning Sources
were critical water shortage and poor water quality,
which were caused by the local population and agricul-
tural pressure and the weak sewage treatment system. If
this situation is not quickly changed, it will lead to inten-
siveness of all kinds of water pollution, thus causing the
rapid deterioration of ecological safety of water envi-
ronmental. With regards to this, we should timely adjust
water strategies to improve water utilization, reduce the
use of agricultural fertilizer and pesticide, and improve
and perfect the sewage collection and treatment system
of the 7 counties and one district. Only in this way, the
eco-safety state of water environment can be greatly im-
proved. The eco-safety of water environment in some
villages is in the moderate warning state, i.e., the entire
water environmental and ecological environment have
been damaged to a certain degree, which signifies that
the ecosystem structure has changed, service functions of
the ecosystem of water environment have been degraded
and there exists some ecological problems. Although the
ecological environment can still maintain basic functions
of water bodies, it will be easily deteriorated once dis-
turbed.
From Tables 5–9, the overall eco-safety of water en-
vironment in Ya’an City was in a state of early warning
and the warning situation had been restrained to a certain
degree. The overall eco-safety of water environment in
Ya’an City in 2005 and 2006 were in a state of moderate
early warning. From the year of 2007, the early warning
state of the overall eco-safety of water environment in
Ya’an City was beginning to be further improved; the
warning state is further eased and gradually improved to
the direction that was conducive to the maintenance of
eco-safety of water environment. The overall eco-safety
of water environment in Ya’an City in 2007 and 2008
were in a relatively ideal state. Rural drinking water
safety was eased under the control by people. Improve-
ment of the early warning state and responses to the
eco-safety of water environment by society were closely
related, however, present response measures and tech-
niques were hardly enough to restore the ecological
functions of water environment and to maintain the
eco-safety of water environment. What can be predicted
from above is, although the early warning state of the
eco-safety of water environment in Ya’an City can be
controlled in the future, the decline of the natural envi-
ronmental conditions is still inevitable, thus, water envi-
ronment protection and the maintenance of eco-safety of
water environment need to be done. Otherwise, the eco
-system of water environment that has been in a fragile
state will lead the eco-safety of water environment of
Ya’an City to accelerate the rate of deterioration with the
growth of socio-demographic and economic pressure. It
is extremely easy to develop toward the direction of se-
rious warning and its consequences will be unthinkable.
To sum up, according to analysis of interannual cha-
nge trend of rural drinking water safety in Ya'an, trend of
the eco-safety state of water environment is that there is
a slow upward trend in comprehensive evaluation values
of eco-safety in each county, however, in a longer period
in the future, eco-safety of water environment in most
counties are still in -level, meaning the moderate early
warning state; the eco-safety state of water environment
in part of the villages is hard to be improved greatly in
the near future and these areas should be laid heavy
stress on the follow-up constructions of the eco-safety of
water environment in rural drinking water in Ya’an City.
5. Conclusions
1) The early warning theory of rural drinking water saf-
ety in Ya’an includes early warning index of rural drink-
ing water safety, mathematical model of early warning,
theory of early-warning of state and early warning of
trend, which provides a new approach for the manage-
ment of rural drinking water safety and prediction of
early warning.
2) Early warning system of rural drinking water safety
in Ya’an City on the basis of ComGIS technology,
seamlessly integrates the functions of general geographic
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F. Q. NI ET AL.
Copyright © 2010 SciRes. JWARP
166
information system and professional knowledge in the
field of drinking water safety in science of water re-
sources into an organic part, improves the degree of in-
fomatization and level of management in rural drinking
water safety, and provides a platform for public welfare
to the solution of rational analysis and evaluation in rural
drinking water safety. Good results are obtained from
application.
3) Early warning system of rural drinking water safety
in Ya’an City is a software platform, which is a fusion of
information management database, evaluation, prediction,
early warning of rural drinking water safety. These func-
tions are applied on the same platform with a great con-
venience and are applicable to operation and use for
general administrative staff.
4) The evaluation results show that comprehensive
evaluation value of rural drinking water safety is rising
year by year, and the overall trend is getting better.
However, the state of evaluation values decline year by
year. That proves that rural drinking water safety of
Ya’an City is damaged continuously and the rising of
pressure value and response value are main reasons
which causes the rising of evaluation value of rural
drinking water safety.
6. Acknowledgement
This study was financed jointly by Sichuan Agricultural
University youth science and technology innovation fund
(00530300) and Sichuan Agricultural University intro-
duced the talented person fund (00530301).
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