A method for estimating river sediment content in areas with insufficient data

Abstract

The present invention belongs to the technical field of hydrological data processing, and relates to a method for estimating the sediment content of rivers in areas with insufficient data. First, according to the dynamic conditions and material source conditions of the study area, the estimation index is screened from the factors affecting the sediment content; secondly, the quantitative value method of each index is given; finally, a sediment content estimation formula is established based on the collected river data, so as to obtain the sediment content change process. The method described in the present invention comprehensively considers the precipitation intensity, terrain conditions, rock and soil anti-scourability and vegetation coverage in the study area, estimates the impact of river sediment content, and considers all factors. Traditional sediment content calculation methods can often only estimate the average sediment content of the river, but cannot give the change process of the sediment content. The method described in this application can be used to estimate the change process of the sediment content of the water flow in the study section over time.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrological data processing, and in particular relates to a method for estimating the sediment content of a river in a data-deficient area. Background Art

[0002] Sediment content refers to the proportion of solid sediment particles in a unit volume of turbid water. The sediment content of water flow is an important parameter in river dynamics and numerical simulation of water and sediment. Due to the limitations of actual conditions, some rivers have no monitoring data on sediment content or only a small amount of data. The lack of sediment content data will directly affect scientific research or production work in river dynamics and numerical simulation of water and sediment processes. Therefore, the proposed sediment content estimation method is of great significance for the dynamics research of rivers in areas with insufficient data and numerical simulation of water and sediment.

[0003] At present, the estimation of river sediment content in areas with insufficient data mainly adopts regional analogy or empirical methods. For example, based on the Lopkin diagram method, Chinese scholar Dou Guoren used mathematical indicators to represent the influence of soil anti-scouring strength, ground inclination and vegetation on soil erosion, and proposed an empirical estimation formula for the average sediment content of rivers (Sediment Handbook, Sediment Professional Committee of Chinese Hydraulic Engineering Society, Beijing: China Environmental Science Press, 1992).

[0004] However, traditional sediment content calculation methods can often only estimate the average sediment content of a river, but cannot give the changing process of the sediment content. However, the sediment content process is sometimes indispensable in the numerical simulation and dynamic analysis of river water and sediment.

[0005] Therefore, how to obtain the changing process of sediment content within a certain period of time in areas with scarce data is a problem that needs to be solved. Summary of the invention

[0006] In order to overcome the problems of the prior art, the present invention proposes a method for estimating river sediment content in data-deficient areas. This method can estimate the change process of water sediment content in the study river section over time, and provide basic data support for river dynamics analysis, numerical simulation of river water and sediment movement, etc.

[0007] The object of the present invention is achieved in that:

[0008] A method for estimating river sediment content in areas with insufficient data includes the following steps:

[0009] Step 1, screening of estimation indicators:

[0010] The estimation indicators are screened based on the influencing factors of river sediment content. The estimation indicators obtained by screening include precipitation intensity R, terrain conditions J, rock and soil anti-scourability K and vegetation coverage P;

[0011] Step 2, estimate the classification of indicators:

[0012] Classify the estimated indicators obtained from step 1 according to standards and classifications including industry specifications and geological / geomorphological characteristics;

[0013] Step 3, establish the sediment content estimation formula:

[0014] Based on the existing river data, a sediment content estimation formula is established, which is:

[0015]

[0016] In the formula, S is the sediment content of the river; R, J, K, and P are respectively precipitation intensity, topography, rock and soil anti-scourability, and vegetation coverage; t is time; b1, b2, and b3 are all coefficients;

[0017] Step 4: Obtaining the change process of sediment content:

[0018] According to the calculation results of the sediment content estimation formula in step 3, the average sediment content of the river or the sediment content change process is obtained.

[0019] The advantages and beneficial effects of the present invention are:

[0020] (1) In the method for estimating river sediment content in data-deficient areas described in the present invention, a comprehensive estimation method is proposed that considers the influence of precipitation intensity, topography, rock and soil anti-scourability and vegetation coverage in the study area on river sediment content from the perspective of dynamic conditions and material source conditions, and considers all factors;

[0021] (2) Traditional sediment content calculation methods can often only estimate the average sediment content of a river, but cannot provide the changing process of the sediment content. The method described in this application can be used to estimate the changing process of the sediment content of the study river section over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 It is a flow chart of the device method described in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Embodiment 1:

[0025] like Figure 1 As shown, this embodiment provides a method for estimating the sediment content of rivers in areas with insufficient data. First, according to the dynamic conditions and material source conditions of the study area, the estimation index is selected from the influencing factors of the sediment content; secondly, the quantitative value method of each index is given; finally, the sediment content estimation formula is established based on the collected river data.

[0026] The specific method includes the following steps:

[0027] Step 1, screening of estimation indicators:

[0028] The estimation indicators are screened according to the influencing factors of river sediment content, and the estimation indicators obtained by screening include precipitation intensity R, terrain conditions J, rock and soil anti-scourability K and vegetation coverage P.

[0029] The precipitation intensity R reflects the impact of runoff dynamic conditions at different time periods on river sediment content. For example, the river sediment content in the flood season with more precipitation is usually higher than that in the non-flood season.

[0030] The topographic conditions J reflect the dynamic conditions of river sediment transport;

[0031] The rock and soil anti-scourability K and vegetation coverage P reflect the sand supply situation of the river section.

[0032] Step 2, estimate the classification of indicators:

[0033] According to standards and classifications including industry norms and geological / geomorphological characteristics, the estimation indicators screened in step 1 are classified. Specifically, the specific classification and quantitative values ​​of each estimation indicator are:

[0034] (1) Classification of precipitation intensity R

[0035] According to the national meteorological industry standards, precipitation intensity R is divided into ten levels according to the amount of daily precipitation, namely "none, light rain, light to moderate rain, moderate rain, moderate to heavy rain, heavy rain, heavy to torrential rain, torrential rain, heavy rainstorm and extremely heavy rainstorm".

[0036] (2) Classification of terrain conditions J

[0037] According to the landform characteristics, the terrain conditions are divided into eight levels, namely "very flat, relatively flat, flat, not too flat, steep, relatively steep, very steep and extremely steep".

[0038] (3) Classification of rock and soil impact resistance K

[0039] According to Dou Guoren's soil impact strength quantification method (Sediment Manual, Sediment Professional Committee of China Hydraulic Engineering Society, Beijing: China Environmental Science Press, 1992) and rock and soil characteristics and classification method (Geotechnical Engineering Investigation Code, Ministry of Construction of the People's Republic of China, Beijing: China Building Industry Press, 2009), the rock and soil impact resistance K is divided into ten levels, namely "very hard, relatively hard, hard, not too hard, soft, relatively loose, very loose, relatively easy to be impacted, easy to be impacted and extremely easy to be impacted".

[0040] (4) Classification of vegetation coverage P

[0041] According to the vegetation characteristics, the vegetation coverage P is divided into ten levels, namely "very dense, relatively dense, dense, not too dense, sparse, relatively sparse, very sparse, semi-bare, bare and aurora".

[0042] The characteristics of each factor and the quantitative values ​​of the corresponding indicators are shown in Table 1.

[0043] Table 1 Characteristics of each factor and the quantitative values ​​of the corresponding indicators

[0044]

[0045] Step 3, establish the sediment content estimation formula:

[0046] Based on the existing data of more than 100 rivers including the Yangtze River, Yellow River, Heilongjiang River and Yarlung Zangbo River, the sediment content estimation formula is calculated by nonlinear fitting of the data:

[0047]

[0048] Where S is the sediment content of the river (kg / m 3 ); R, J, K, and P are respectively precipitation intensity, topography, rock and soil anti-scourability, and vegetation coverage; t is time, which can be in hours or days. Usually, the precipitation intensity in the study area changes with time (hours, days), and the vegetation coverage changes with the seasons. Therefore, the sediment content will also change with the two, so the change process of the sediment content of the river section can be obtained. The first term on the right side of formula (1) reflects the influence of the dynamic conditions in the study area on the sediment content, the second term reflects the influence of the sediment source conditions in the study area on the sediment content, and the third term is the correction number.

[0049] b1, b2, and b3 are all coefficients, with values ​​of 0.02, 0.18, and -0.77, respectively. The final fitted sediment content estimation formula is:

[0050]

[0051] Step 4: Obtaining the change process of sediment content:

[0052] According to the calculation results of the sediment content estimation formula (2) in step 3, the average sediment content of the river or the sediment content change process is obtained.

[0053] When the precipitation data is hourly (or daily) data, the hourly (or daily) change process of the sediment content can be estimated. When the precipitation, rock and soil quality, landform and vegetation conditions in the study area are uneven, the calculation can be divided into different areas and the weighted average can be taken according to the area ratio.

[0054] Application examples:

[0055] Taking a river in a data-deficient area as an example, through data collection and field investigation, the precipitation, topography and other data of the river section are obtained, and the sediment content of the river is estimated using the method described in this application. The specific steps include:

[0056] ① Collect data on precipitation processes and changes in vegetation coverage in the area where the study river section is located, and investigate the rock and soil characteristics and topography of the study area.

[0057] ②Use the quantitative value selection method of each indicator given in Table 1 and determine the values ​​of R, J, K, and P based on the collected data.

[0058] ③ Calculate the river sediment content according to the above formula (2) to obtain the change process of river sediment content.

[0059] In order to illustrate the operation process and reliability of this method, several river data with high and low sediment content were selected to estimate the sediment content of a river section on a certain day. This method was used to estimate the sediment content of the river, and the measured and estimated values ​​of the sediment content were compared. The situation of each river section and the comparison results are shown in Table 2.

[0060] Table 2 Method validation

[0061]

[0062] From the verification results in Table 2, it can be seen that the average error of the estimated sediment content obtained by this method is 8.68%. In comparison, the estimated results for high sediment content are more reliable, and the estimated results for low sediment content have a slightly larger error. This may be related to the fact that this method cannot take into account the changes in river sediment content in the absence of precipitation. However, it is still feasible as an estimation method for river sediment content in areas with insufficient data.

[0063] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred arrangement scheme, a person skilled in the art should understand that the technical solution of the present invention (such as the use of various formulas, the sequence of steps, etc.) can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for estimating river sediment content in areas with insufficient data, characterized in that: The method comprises the following steps: Step 1, screening of estimation indicators: According to the influencing factors of river sediment content, the estimation indicators obtained by screening include precipitation intensity R , terrain conditions J , rock and soil erosion resistance K and vegetation coverage P ; The precipitation intensity R The influence of runoff dynamic conditions at different time periods on the sediment content of the river is reflected in the terrain conditions. J The dynamic conditions of river sediment transport are reflected in the rock and soil anti-scour properties. K and vegetation coverage P Reflect the sediment supply situation in the river section; Step 2, estimate the classification of indicators: Classify the estimated indicators obtained from step 1 according to standards and classifications including industry specifications and geological / geomorphological characteristics; The specific classification and quantitative values ​​of each estimation indicator are: (1) Precipitation intensity R Classification According to the national meteorological industry standards, the precipitation intensity R It is divided into ten levels according to the daily precipitation, namely "none, light rain, light to moderate rain, moderate rain, moderate to heavy rain, heavy rain, heavy to torrential rain, torrential rain, heavy rainstorm and extremely heavy rainstorm"; (2) Topography J Classification According to the topographic characteristics, the terrain J It is divided into eight levels, namely "very gentle, relatively gentle, gentle, not too gentle, steep, relatively steep, very steep and extremely steep"; (3) Rock and soil anti-scourability K Classification According to Dou Guoren's soil impact strength quantification method and rock and soil characteristics and classification method, rock and soil impact strength K It is divided into ten levels, namely "very hard, relatively hard, hard, not too hard, soft, relatively loose, very loose, relatively flushable, flushable and extremely flushable"; (4) Vegetation coverage P Classification According to the vegetation characteristics, the vegetation coverage P It is divided into ten levels, namely "very dense, relatively dense, dense, not too dense, sparse, relatively sparse, very sparse, semi-bald, bald and aurora"; Step 3, establish the sediment content estimation formula: Based on the existing river data, a sediment content estimation formula is established, which is: In the formula, is the sediment content of the river, in kg / m³; They are precipitation intensity, topographic conditions, rock and soil erosion resistance, and vegetation coverage; is the time, in hours or days; the precipitation intensity in the study area changes with time, and the vegetation coverage changes with the seasons. Therefore, the sediment content will also change with the two, thus obtaining the change process of the sediment content of the river section; the first term on the right side of formula (1) reflects the influence of the dynamic conditions in the study area on the sediment content, the second term reflects the influence of the sediment source conditions in the study area on the sediment content, and the third term is the correction number; are coefficients, with values ​​of 0.02, 0.18 and -0.77 respectively. The final fitted sediment content estimation formula is: Step 4: Obtaining the change process of sediment content: According to the calculation results of the sediment content estimation formula (2) in step 3, the average sediment content of the river or the sediment content change process is obtained, specifically: When the precipitation data is hourly or daily data, estimate the hourly or daily change of sediment content; when the precipitation, rock and soil quality, landform and vegetation conditions in the study area are uneven, calculate them by zone and take the weighted average according to the area ratio.

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