CN104345131A - Rice field nitrogen and phosphorus runoff loss load field scale estimation and calculation method - Google Patents

Abstract

The invention relates to a distributed rice field runoff loss load field scale estimation and calculation method, which comprises the following steps of (1) different soil type rice field surface water contaminant dynamic change rule measurement and calculation: the dynamic change of the concentration of contaminants in the field surface water is mainly monitored, and then, an equation showing the dynamic change of the contaminant concentration along with the time is subjected to fitting; and (2) target rice field runoff contaminant loss load estimation and calculation: basic information such as target rice field area, fertilization level, fertilization time and showed height from rice field water discharging opening to rice field are manly determined, in addition, information such as contamination concentration and rainfall in rainwater during rainfall is measured, and then, the runoff loss load is calculated according to the calculation equation. The estimation and calculation method can be applied to rice field nitrogen and phosphorus runoff loss load estimation and calculation in field scales, the building of large-scale civil engineering facilities such as runoff pools is not needed during the measurement and calculation, and the estimation and calculation method has the advantages that the required parameters are few, the measurement method is simple, and the application range is wide.

Description

The maturity in field evaluation method of a kind of rice field nitrogen phosphorus runoff loss load

Technical field

The present invention relates to a kind of non-point source pollution load evaluation method, particularly relate to a kind of rice field nitrogen phosphorus runoff loss load evaluation method.

Background technology

In recent years, along with point-source pollution is governed gradually, non-point pollution problem highlights.And farmland nitrogen and phosphorus loss is the main ingredient of non-point pollution, paying attention to agricultural nonpoint source pollution is international megatrend.On June 5th, 2013, " 2012 China Environmental State Bulletin " that national environmental protection portion announces claims, and the river of the whole nation more than 30% is not up to standard with the underground water more than 50%, and wherein widespread pollution from the overuse of fertilizers and pesticides in rural area is one of arch-criminal that cannot ignore.The contradiction of having a large population and a few land in China's agro based economic development impels the dependence of agricultural production to chemical fertilizer application extremely strong.Chemical fertilizer agricultural supplie excessive is used and be result in a large amount of nitrogen, phosphorus nutrition material enters surrounding body along with storm runoff or farming draining, causes body eutrophication.Chinese Academy of Sciences academician Zhu Zhaoliang thinks: " in the years to come; industry and city domestic sewage will reduce gradually on the impact of water pollution; if do not adopted an effective measure, the pollution of area source caused by crop-planting and livestock and poultry breeding industry, will highlight day by day to water quality and air-polluting contribution rate ".Therefore, control the Basin Pollution Control of agricultural nonpoint source pollution to China to be extremely important.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, provide a kind of rice field Loss in Runoff load estimate method, evaluation method of the present invention comprises the steps:

1. a maturity in field evaluation method for rice field nitrogen phosphorus runoff loss load, comprises the steps:

1) rice field Soil surface water pollutant dynamic rule measuring and calculating under soil type:

Pollutant levels Monitoring on Dynamic Change in 1.1 Soil surface water: the test soil selecting soil species that in this area each rice soil subclass, proportion is maximum representatively this subclass rice soil, set up experimental plot respectively, according to the scheme preset, carry out the dynamic monitoring of pollutant levels in the Soil surface water under Different Fertilization level;

1.2 pollutant levels dynamic change equation models: respectively for different soils subclass take pollutant levels as dependent variable, and carry out matching apart from the number of days of fertilising for independent variable with Fertilization Level and monitoring date, fit equation is wherein n is the number of days after the distance fertilising of monitoring date, and unit is d; for pollutant levels in rainfall Soil surface water on the same day, unit is mg/L; P is Fertilization Level, and unit is kg/hm ²; A, b, k, c are constant;

2) pollutant loss load estimate in the runoff of target rice field

The height that 2.1 areas determining target rice field, Fertilization Level, fertilization time, affiliated subtype of soil and paddy field drainage mouth show apart from rice field;

2.2 measure Soil surface water height before rainfall, and after rainfall terminates, collect the same day rainfall product data and rainwater in pollutant levels;

Rainfall is worked as the number of days of solar distance fertilization time as parameter n by 2.3, using Fertilization Level as parameter P, substitutes into the fit equation obtained in step 1.2, calculates pollutant levels C in rainfall Soil surface water on the same day _s;

According to pollutant loss load in the runoff of following formulae discovery rice field:

$Q=A[C_R(H_R+H-H_{\max })+H(C_s-C_R)(1-e^{-\frac{H_R+H-H_{\max }}{H_{\max }}})]$

In formula: Q is pollutant loss load in the runoff of rice field, and unit is g; A is rice field area, and unit is m ²; C _sfor pollutant levels in Soil surface water before rainfall, unit is mg/L; H is Soil surface water height before rainfall, and unit is m; H _rfor rainfall amount, unit is m; C _rfor pollutant levels in rainwater, unit is mg/l; H _maxfor freeing port is apart from the height on surface, rice field, unit is m.

The present invention is compared with prior art beneficial effect: the method is studied by the Transport And Transformation of pollutant in Soil surface water after applying rice field to chemical fertilizer, draw its dynamic rule, and this rule is coupled with rainfall-Runoff Model, for calculating the rice field nitrogen and phosphorus loss load in rainfall.Compared with traditional single output Y-factor method Y, the method more can reflect that non-point source produces the change in time and space of discharge coefficient, and does not need to set up runoff testing field; In addition, compared with mechanistic model, the required basic data of this method is relative with parameter less, and estimated work is little.

Embodiment

The invention will be further described by the following examples.

Embodiment 1:

Choose Hangjiahu Plain as application region.

1) rice field Soil surface water pollutant dynamic rule measuring and calculating under soil type:

Pollutant levels Monitoring on Dynamic Change in 1.1 Soil surface water

The four class rice soil that the present embodiment is chosen in Hangjiahu Plain are studied, and are respectively submerged paddy, ooze and educate type rice soil, Waterlogged paddy soil and de-Waterlogged paddy soil of diving, the maximum soil species information of its accounting example as table 1 so.

Table 1 soil essential information

Often kind of different soils all selects one piece of rice field to test in locality, every block rice field ridge is divided into 18 area 2m ²unit.Ridge all carries out coating process, and each unit independently carries out irrigation and drainage, prevents from influencing each other.Six Fertilization Level are set, are respectively 0,90,180,270,360,450kg N/hm ², each Fertilization Level designs 3 parallel experiments simultaneously; The fertilizer of each unit divides to be used for three times, seed manure: tillering fertilizer: ear manuer=20%: 40%: 40%, three fertilization times be respectively 2013 ?06 ?25,2013 ?07 ?13,2013 ?09 ?02, in process of the test, Soil surface water height remains on about 3.5cm according to local farming operating habit.In latter 1st, 2,3,5,7,9,18,27 day of fertilising, sample each test unit respectively, sample was taken back laboratory and is analyzed, and analysis indexes is TN, and analytical approach is see " water and waste water method for monitoring and analyzing the 4th edition ";

1.2 pollutant levels dynamic change equation models

After obtaining above-mentioned data, utilize SPSS 20.0 statistical analysis software to carry out matching to soil type and the data obtained in Different Fertilization stage, fit equation is wherein n is number of days after fertilising, and unit is d; for fertilising pollutant levels in Soil surface water after n days, unit is mg/L; P is rate of fertilizer application, and unit is kg/hm ²; A, b, k, c are constant.The variation rule curve of three fertilising TN, as following table:

Table 2 TN dynamic change matched curve parameter list

2) pollutant loss load estimate in the runoff of target rice field

Choose each one piece of the representative rice field of doube bridge farm, Jiaxing City Wang Jiang river rising in Ningxia and flowing into central Shaanxi (testing site 1) and Yuhang District, Hangzhou Liang Zhu (testing site 2), set up runoff hand gathering barrel and carry out result verification.

2.1 determine rice field essential information

The essential information in field survey record two pieces of rice fields, as shown in table 3:

Table 3 rice field essential information

2.2, during the fertilising on July 26th, 2013 spraying fertilizer of first time on July 11st, 2013, there is 2 obvious rainfalls altogether, before twice rainfall in Soil surface water height, rainfall amount and rainwater TN concentration in table 4.

Table 4 Soil surface water altitude gauge rainfall data

2.3 twice rainfall are respectively 9 days and 10 days apart from the number of days n of fertilization time, and the horizontal P of this Paddy fields is 72kg/hm ², this fertilising is base manure, therefore adopts the fitting formula in table 2 calculate, obtain TN concentration in the Soil surface water of the 9th day and the 10th day with be respectively 33.3 and 27.3mg/L;

Respectively will with pollutant loss load in the runoff of following formulae discovery rice field is substituted into other parameters in table 3, table 4,

$Q=A[C_R(H_R+H-H_{\max })+H(C_s-C_R)(1-e^{-\frac{H_R+H-H_{\max }}{H_{\max }}})]$

Result of calculation is that the rice field TN Loss in Runoff amount of the 9th day and the 10th day is respectively 10.5 and 25.2g, as shown in table 5 with actual runoff monitoring Comparative result:

Table 5 estimates result and actual monitoring Comparative result

As can be seen here, complicated relative to influence factor, the rice field Loss in Runoff load of estimation difficulty, evaluation method of the present invention reaches higher estimation accuracy, has actual application value widely.

Claims (1)

1. a maturity in field evaluation method for rice field nitrogen phosphorus runoff loss load, is characterized in that comprising the steps:

1) rice field Soil surface water pollutant dynamic rule measuring and calculating under soil type:

Pollutant levels Monitoring on Dynamic Change in 1.1 Soil surface water: the test soil selecting soil species that in this area each rice soil subclass, proportion is maximum representatively this subclass rice soil, set up experimental plot respectively, according to the scheme preset, carry out the dynamic monitoring of pollutant levels in the Soil surface water under Different Fertilization level;

1.2 pollutant levels dynamic change equation models: respectively for different soils subclass take pollutant levels as dependent variable, and carry out matching apart from the number of days of fertilising for independent variable with Fertilization Level and monitoring date, fit equation is wherein n is the number of days after the distance fertilising of monitoring date, and unit is d; for pollutant levels in rainfall Soil surface water on the same day, unit is mg/L; P is Fertilization Level, and unit is kg/hm ²; A, b, k, c are constant;

2) pollutant loss load estimate in the runoff of target rice field

The height that 2.1 areas determining target rice field, Fertilization Level, fertilization time, affiliated subtype of soil and paddy field drainage mouth show apart from rice field;

2.2 measure Soil surface water height before rainfall, and after rainfall terminates, collect the same day rainfall product data and rainwater in pollutant levels;

Rainfall is worked as the number of days of solar distance fertilization time as parameter n by 2.3, using Fertilization Level as parameter P, substitutes into the fit equation obtained in step 1.2, calculates pollutant levels C in rainfall Soil surface water on the same day _s;

According to pollutant loss load in the runoff of following formulae discovery rice field:

$Q=A[C_R(H_R+H-H_{\max })+H(C_s-C_R)(1-e^{-\frac{H_R+H-H_{\max }}{H_{\max }}})]$

In formula: Q is pollutant loss load in the runoff of rice field, and unit is g; A is rice field area, and unit is m ²; C _sfor pollutant levels in Soil surface water before rainfall, unit is mg/L; H is Soil surface water height before rainfall, and unit is m; H _rfor rainfall amount, unit is m; C _rfor pollutant levels in rainwater, unit is mg/l; H _maxfor freeing port is apart from the height on surface, rice field, unit is m.