Estimation and A llocation Water Environmental Capacity of Dadu River of Luding Segment
Yingjun WANG, Jie XIA, Minghao FAN, Yan CHEN
College of Resources and Environment
Sichuan Agricultural University
Ya’an, China
Abstract—Environmental capacity of the water basin was often ud as the basis of total amount control of pollutants, which was concerned by environmental workers for a long time. However, with the governance of the point source pollution, the non-point source (NPS) pollution drew people’s clo attention day by day. This article was lected to the main non-point source pollution of Dadu River of Luding Segment. Through the existed results of water quality monitoring and drainage area’s pollution load estimated by means of export coefficient method, then established a calculation model of water environmental capacity (WEC), and finally classified the distribution of the remaining water environmental capacity. The results showed that the water of Dadu River of Luding Segment w
ould be made full u of on the premi that the water quality of this area could reach the goal of environmental management, thus ea the water environmental pressure of this gment.
Keywords-Non-point source pollution, Water environmental capacity, Pollution load, Model
The experience of water pollution prevention and control has shown that the only pay attention to point pollution source is not enough to control contamination. And non-point source pollution is an important aspect, which can not be ignored in water pollution prevention and control work. Some studies indicate that 30% -50% of the surface water bodies have been polluted by non-point source in the world [1]. In China, in the Yellow River basin, Taihu Lake Basin and most of the lake and part key water resource area, the amount of pollutants from non-point source has been clo to or even more than the amount of simillar pollutants from other types of sources [2,3].
Dadu River of Luding Segment with very little industrial point source pollution is a typical basin of non-point source pollution. So the rearch about the impact that non-point source pollution made on the basin water environmental capacity is highly reprentative. In this article, through the existed estimation of water pollution load, established a suitable calculating model of water environment capacity for this river and finally gave the rational allocation of water environmental capacity bad on the results of the calculations.
I.AN O VERVIEW OF THE RIVER BASIN
Dadu River of Luding gment is in the eastern part of Ganzi Tibetan Autonomous Prefecture, between east longitude 101°49'~ 102°27', north latitude 29°28'~ 30°6'. The north entry of the mainstream is Lengzhuguan Village and the south exit is the Yusa River, stream length 82km, drop 332.1m, the average surface width 97.6m, average depth 5.5m, an average gradient of 3.9‰, the average annual flow of 893m3/s, dry ason flow of 338m3/s, runoff depth477.8mm, annual runoff 27.85 billion m3. The average diment concentration for many years is 442g/m3, average annual diment discharge 12.44 million t.
The quality of water in this river is generally good. 8 monitoring ctions are t up from upstream to downstream including Huangjingping, Kham Bridge, Nantou, etc. Except annual average concentration of TN in Huangjingping Monitoring Section (1.03mg/L>1.00mg/L), the other monitoring indicators meet Grade Ⅲ standard of quality standard for surface water.
II.M ATERIALS AND METHODS
A.Basic Data Collection and Data Analysis
The monitoring results of water quality, hydrological and meteorological information from June 2006 to July 2007 were provided by the local hydrological stations and weather stations. Population distribution of the basin, the utilization status of land, economic yield, fertilization, pollution distribution and pollutant discharge were provided by the local Bureau of Statistics, Land and resource Bureau, Agriculture Bureau, Environmental Protection Bureau, Pollution Source Census Office and other units.
Data dependence analysis and regression analysis adopted DPS and the MATLAB software.伯牙绝弦原文
B.Model of Water Environmental Capacity
The discharge of pollutants in the basin is dominated by non-point source with spatial and temporal variations, so the changes of the river water quality can’t be consider in a regular point-source water quality model. In this paper, estimate the capacity of the water environment directly from month to month on the ground of water pollution load of the basin, which has been the outcome of investigation and rearch.
In accordance with the mechanism for degradation of pollutants, in "National Water Environmental Capacity Verification Manual", the water environmental capacity is
978-1-4244-4713-8/10/$25.00 ©2010 IEEE
divided into diluting capacity and lf-purification capacity. The formula is:
W t=W d+W s (1) where W t=total WEC, t/a
W d=diluting capacity, t/a什么然屹立
W s=lf-purification capacity, t/a
According to Xiaode Zhou’s opions [4], when calculating WEC, the core idea is to control the inflow quality of the first ctions in the basin and achieve requirements of certain functional ction, which is ction-beginning control model. Due to the degradation of pollutants, the pollutant concentration in the ction can reach the control objectives. Namely this method can be strict control of the river's water quality that would not exceed. At the same time due to the actual situation of river basin, the total amount of the interval runoff and wastewater discharge accounts for only a very small proportion, which can be ignored, so the following equation can be drawn:
W d=31.536×Q×(C s-C o) (2) where Q= river flow, m3/s
C s=the concentration of pollutants of the water quality standards, mg/L
C o=the background concentration of pollutants in the first ction of the river, mg/L
According to the planning of watershed function zoning of Sichuan Province, the entire basin including the inlet ction and outlet ction should implement the "Surface Water Environment Quality Standard" (GB3838-2002) in the Grade Ⅲ standard. To not inpair the interests of the upper reaches administrative regions of the Dadu River, the background concentrations of pollutants in the water is C s instead of C o. As a result, the formula (1) can be turned into: W t=W s.
愚青According to the analysis of the material balance principle, the lf-purification capacity of water environment pollution is a result that the sum of the total amount of import pollution loads of the river and the amount from NPS then subtracts the amount of export pollution loads. The result was obtained as followed :
W s=W i＋W
n
-W e (3) where W i=the total amount of import pollution loads, t/a
W n=the amount from NPS, t/a
同心协力造句
W e=the amount of export pollution loads, t/a
C.Predictive Model of Self-purification Capacity of COD Cr
After rearch for years, the law of lf-purification is that water environment lf-purification capacity of COD Cr and the coefficient of synthetical degradation K are cloly linked. According to domestic rearch [5], K, the initial concentration of COD Cr, water temperature and other factors have a great relationship, which is manifested mainly with 1.047t-20 showed positive correlation. Bad on the above analysis, apply regression analysis with the COD Cr lf-purification capacity of every month in 2007 in the basin, the initial concentration and water temperature. Then the equation is:
W1=-1051+526×1.047t-20+21.578C12.206 (4) where W1=the monthly predictive lf-purification capacity of COD Cr, t/m
t=temperature, ℃
C1=the concentration of import COD Cr for the basin, mg/L D.Predictive Model of Self-purification Capacity of TN and
TP
The lf-purification process of TN and TP in the river mainly include bio-filtration, dimentation, chemical absorption, biological interaction, aquatic plant absorption and so on. Meanwhile the number of the TN and TP lf-purification correlate cloly to aquatic plants, sunshine, water quality and others. The total input load of TN and TP is the key factor. The Windolf [6] reported that the TN and TP lf-purification capacity would increa with the ri in total input load.
On the ground of the above analysis, apply regression analysis with the monthly predictive lf-purification capacity of the TN and TP and the total input load in 2007. Then the equations obtained are:
W2=413.7+0.6533×P2-1.579×P3-81.687×lg P2 (5) W3=1.337+0.493×P3-0.029×P2+1.594×lg P3 (6) where W2=the monthly predictive lf-purification capacity of the TN, t/m
P2=the total input load of TN, t/m
W3=the monthly predictive lf-purification capacity of the TP, t/m
P3=the total input load of TP, t/m
III.R IVER WATER ENVIRONMENTAL CAPACITY ALLOCATION
METHODS
According to the allocation property, the water environmental capacity can be divided into 2 different categories: assignable and non-assignable capacity. As the water environmental capacity of this study basin remaining large, there is no amount of pollution reduction, so this article here only study assignable capacity, namely the remaining water environmental capacity.
Considering that the water environmental capacity of the study is large, and there are very few industrial and mining enterpris, small discharge amount of the wage from tho sources, start the allocation of environmental capacity from the sources of pollution for water. The wage pollution of lifestyle is calculated firstly, the pollution of production class condly. In this article, lifestyle pollution sources are divided into 4 types, urban life, rural life wage, livestock wage and farm fertilizer. The pollution of production class is made from kinds of industrial pollution sources. According to the allocation, the formula is:
W r=W l+W p (7) where W r=the remaining river water environment capacity of the basin, t/a
W l=the capacity belonged to lifestyle wage, t/a
W p =the capacity belonged to the pollution of production class, t/a
The capacity belonged to lifestyle wage actually is the growth amount from the sources in a given period of time. In accordance with the composition of pollution sources, the growth amount of lifestyle wage is related to the growth of
population, livestock and poultry and fertilizer in the basin. The
ri of livestock and poultry and fertilizer wage is identified to the same increa of population as when the local people’s life level would not change greatly. The equation obtained is:
W l =W l *(1+X )n - W l * (8)
where W l *=the prent pollution emission load of the lifestyle in the valley, t/a
X=the local natural population growth rate, ‰ n=forecast period, years The capacity of different industries of lifestyle wage is assigned to urban life, rural life, livestock and poultry and farm fertilizer by proportional distribution method, which is attributed to the ri of lifestyle wage with the share principle. The equation is:
W l,i =W l ×K i (9)
where i=the group of lifestyle wage
W l,i =the remaining capacity assigned for each part, t/a
K i =the proportion of the prent pollution load for each part, %
Apply multi-objective weighted score method to the capacity allocation of different industries of production class, which include the social and economic benefits and the pollution emission status, which is related to employment, GDP and the pollution emission load of per unit product. Therefore the equation is:
p,p ()3
i i i i p G s W W ++=× （10）
不甘心where i =the group of product class
W p,i =the remaining capacity assigned for each industry, t/a p i =the employment population percentage of the basin for each industry, %
G i =the GDP percentage of the basin for each industry, % s i =the pollution emission amount percentage of the basin for each industry, %
IV. R ESULTS AND DISCUSSION
A. River Self-purification Capacity
The monthly lf-purification capacity of COD Cr , TN and TP estimated with Input-Output balance principle has relevance with the predictive value of equation (4), (5), (6), of which the correlation coefficient is, respectively, r 0.9601 (n =12), r =0.9894 (n =12), r =0.9961 (n =12). Seen from Figure 1, 2, 3, the regression equation established can be well predicted on lf-purification capacity of COD Cr , TN and TP in the basin.
Fig.1 Monthly capability of COD Cr decontamination compare to results of
prediction
Fig.2 Monthly capability of TN decontamination compare to results of
prediction
Fig.3 Monthly capability of TP decontamination compare to results of
二胡的指法prediction
According to the established model, the water environmental capacity of COD Cr , TN and TP in the basin is, respectively, 50939t/a, 5771t/a, 1495t/a. And the monthly distribution is COD Cr : 851t/m~10345t/m; TN:95t/m~1101t/m; TP:32t/m~271t/m.
The month maximum capacity of the basin for COD Cr appears in Jun, Jul and Sept, which is 27643t totally and accounts for 54.27% of the whole year. The month minimum capacity for COD Cr appears from Oct to Mar, which is 3445t totally and accounted for 6.76% of the whole year.
month
C O
D C r (t )
month
month
T N (t )
T P (t )
:actual value :predictive value
:predictive value
:predictive value
:actual value :actual value
The month maximum capacity of the basin for TN and TP appears in Jun, Jul and Aug, which is totally respectively 2933t and 723t and accounted for 50.82% and 48.39% of the whole year. The month minimum capacity for TN and TP appears from Jan to Mar, which is 259t and 93t totally and accounts for 4.49% and 6.23% of the whole year.
B. Allocation of Remaining Capacity
According to calculations, the remaining capacity of water environment COD Cr , TN and TP is 49524t/a, 5191t/a, 1449t/a, respectively. The monthly distribution is COD Cr : 851t/m~10345t/m; TN: 95t/m~1101t/m; TP: 32t/m~271t/m.
Various pollution indicators of lifestyle sources assigned to the remaining capacity of water environment is respectively
COD Cr 3053t/a, TN 602t/a, TP 126t/a, and production class assigned to remaining capacity is COD Cr 46417t/a, TN 4589t /a,
TP 1323t/a. Each remaining capacity of lifestyle sources is shown in Table 1. T ABLE 1 R ESULTS OF ASSIGNED POLLUTION REMAINING CAPACITY OF THE
WATER ENVIRONMENT TO TRADES OF THE LIFESTYLE OF THE VARIOUS
SOURCES OF DRAINAGE AREA
裁字组词语pollutant source type COD Cr /(t/a) TN/(t/a) TP/(t/a) fertilizer 0.00 282.26 37.00 livestock and poultry 856.84 197.42 7.23
urban life 1104.42 72.26 38.30 rural life 1091.70 50.32 43.80 V. C ONCLUSIONS
In this paper, through the calculation and distribution results of the water environmental capacity, conclusions can be drawn as followed:
1) The measurement results of water environmental capacity showed that water environment capacity and
remaining available capacity of COD Cr , TN and TP is larger,
but is unevenly distributed in a year, the principle of which is
large capacity in the high-flow period and small capacity in dry ason. The reason is mainly due to the big difference of the allocation of basin water flow for the year as well as the low proportion of non-point source pollution load in the total input into the river basin pollution load. 2) Seen from the capacity distribution results of lifestyle pollution sources, the order of size gotten from distribution for COD Cr is urban life ＞rural life ＞livestock and poultry ＞agricultural fertilizers; agricultural fertilizers ＞livestock and poultry ＞urban life ＞rural life for TN; livestock and poultry ＞agricultural fertilizers ＞urban life ＞rural life for TP.
Bad on the achievements existed on the water environmental capacity, the statistical lf-purification models of pollutants established in this article, which is better pertinence through practical application. At the same time, becau of differences between basins and data matched with a specific basin when models built, the models in this paper are only applicable to the Dadu River of Luding Segment.
A CKNOWLEDGMENT
This study was funded by Talent Introduction Foundation of Sichuan Agricultural University (No. 01402000).
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