6. ESTIMACIÓN DE LA CANTIDAD DE RESIDUOS GENERADOS
6.1. TIPOLOGÍA DE RESIDUOS
4 0 0 0 0 3.7 3.7 -3.7 -3.7 0 0 19.519.5
5
5 1.5 1.5 0 0 3.7 3.7 -3.7 -3.7 0 0 15.8 15.8 (1.5 (1.5 x x 0.8)0.8) less than 1.85 less than 1.85 6
6 5.8 5.8 4.6 4.6 3.7 3.7 +0.9 +0.9 0 0 16.716.7 7
7 0 0 0 0 3.7 3.7 -3.7 -3.7 0 0 13.013.0
8
8 0 0 0 0 3.7 3.7 -3.7 -3.7 0 0 9.39.3
9
9 53.2 53.2 20.7 20.7 3.7 3.7 +17.0 +17.0 0 0 26.3 26.3 (53.2 (53.2 x x 0.8) 0.8) ++ 9.3 greater 9.3 greater than 30.0 than 30.0 10
10 2.5 2.5 2.0 2.0 3.7 3.7 -1.7 -1.7 0 0 24.624.6 11
11 20.3 20.3 5.4 5.4 3.7 3.7 +1.7 +1.7 0 0 26.3 26.3 (30.0 (30.0 - - 24.6)- 24.6)-5.4
5.4 12
12 35.0 35.0 3.7 3.7 3.7 3.7 0.0 0.0 0 0 26.3 26.3 (30.0 (30.0 - - 26.3)- 26.3)-3.7
3.7 The method must be modified in respect of rainfall ef
The method must be modified in respect of rainfall efficiency, the moisture storage capacitficiency, the moisture storage capacity of they of the soil, and evapotranspiration, before it can be used for other situations.
soil, and evapotranspiration, before it can be used for other situations.
Vietnam Vietnam
The water holding capacity of rice soils is assumed to be 50 mm. Daily rainfall below 5 mm and The water holding capacity of rice soils is assumed to be 50 mm. Daily rainfall below 5 mm and above 50 mm is disregarded. If daily evapotranspiration is 10 mm, a two
above 50 mm is disregarded. If daily evapotranspiration is 10 mm, a two -days' successive rainfall of -days' successive rainfall of up to 60 mm is taken as effective and excess over this limit is disregarded. Similarly, three days' up to 60 mm is taken as effective and excess over this limit is disregarded. Similarly, three days' successive rainfall of up to 70 mm is taken as effective and the excess is disregarded. The same successive rainfall of up to 70 mm is taken as effective and the excess is disregarded. The same procedure is followed for more rainy days.
procedure is followed for more rainy days.
In different months different percentages are considered to be effective out of the total rainfall In different months different percentages are considered to be effective out of the total rainfall received.
received.
Period
Period % % taken taken as as effectiveeffective RemarksRemarks April
April - - September September 75 75 Wet Wet seasonseason October
October 65 65 High High rainfall rainfall intensityintensity November
November 80 80 Dry seasonDry season December
December - - March March 90 90 Dry Dry and and cool cool seasonseason Burma
Burma
Rainfall below 0.5 in is considered as ineffe
Rainfall below 0.5 in is considered as ineffective. Above 0.5 in, 80 percent of the amount in excess isctive. Above 0.5 in, 80 percent of the amount in excess is considered as effective.
considered as effective.
4. Evaluation of methods
4. Evaluation of methods
A method must account satisfactorily for surface run-off, water storage changes in the soil, A method must account satisfactorily for surface run-off, water storage changes in the soil, evapotranspiration and crop characteristics. For fiel
evapotranspiration and crop characteristics. For field use, the method should be simple, inexpensive,d use, the method should be simple, inexpensive, rapid and accurate. It should be useful for broad regional planning or precise irrigation scheduling rapid and accurate. It should be useful for broad regional planning or precise irrigation scheduling under a given set of conditions. For each method measurement of total r
under a given set of conditions. For each method measurement of total r ainfall using & rain gauge or ainfall using & rain gauge or rain recorder is essential. Relative merits and limitations of the different methods discussed are
rain recorder is essential. Relative merits and limitations of the different methods discussed are
shown in Table 9. Of the field methods, the first method (No.2.1) involving periodic measurement of shown in Table 9. Of the field methods, the first method (No.2.1) involving periodic measurement of soil water changed is accurate only when a sufficient number of replications are made; it is very soil water changed is accurate only when a sufficient number of replications are made; it is very laborious and cumbersome for field application. The method can be used to verify the applicability laborious and cumbersome for field application. The method can be used to verify the applicability of empirical methods developed elsewhere. The soil water balance sheet method (No.2.2) involving of empirical methods developed elsewhere. The soil water balance sheet method (No.2.2) involving the use of meteorological data and estimation of ETa will provide data on estimating effective
the use of meteorological data and estimation of ETa will provide data on estimating effective rainfall if relevant input data ar
rainfall if relevant input data are available. The estimation of ETa, however, is more complicated e available. The estimation of ETa, however, is more complicated andand less accurate than the
less accurate than the estimation of ETp. In the integrating gauge method (No.2.3), ceramic platesestimation of ETp. In the integrating gauge method (No.2.3), ceramic plates are used; the relation between evaporation from the
are used; the relation between evaporation from the plate and the evapotranspiration from the cropplate and the evapotranspiration from the crop must be known but is difficult to establish. Errors
must be known but is difficult to establish. Errors are due to dust and salt accumulation on theare due to dust and salt accumulation on the evaporating surface, The Ramdas method (No.2.4) is simple bat may not be accurate
evaporating surface, The Ramdas method (No.2.4) is simple bat may not be accurate unless a largeunless a large number of replications are made. This may make the method cumbersome for
number of replications are made. This may make the method cumbersome for field use. The use of field use. The use of lysimeters of large diameters (No.2.5) is the best and the most reliable method in assessment of lysimeters of large diameters (No.2.5) is the best and the most reliable method in assessment of effective rainfall. It i
effective rainfall. It is, however, expensive for field use. It should be installed in ress, however, expensive for field use. It should be installed in res earch stations.earch stations.
The method can be used to check the accuracy of
The method can be used to check the accuracy of the other methods. The drum technique for ricethe other methods. The drum technique for rice (No.2.6) has given promising results. The method requires replications to give accurate data (No.2.6) has given promising results. The method requires replications to give accurate data ..
Of the empirical formulae the Renfro equation method (No. 3.1) is too empirical. The U.S. Bureau of Of the empirical formulae the Renfro equation method (No. 3.1) is too empirical. The U.S. Bureau of Reclamation method (NO. 3.2) neglects many essential parameters. The method based on the ratio of Reclamation method (NO. 3.2) neglects many essential parameters. The method based on the ratio of potential evapotranspiration to precipitation (No.3.3) will provide the
potential evapotranspiration to precipitation (No.3.3) will provide the best results. It can be used for best results. It can be used for broad estimation of effective rainfall in irrigation planning. The USDA, S
broad estimation of effective rainfall in irrigation planning. The USDA, SCS method (NO. 3.4) hCS method (NO. 3.4) hasas been based on data representing a wide range of conditions. Th
been based on data representing a wide range of conditions. The method is satisfactory and can bee method is satisfactory and can be applied for field use after verification in a given situation. The empirical methods for crops other applied for field use after verification in a given situation. The empirical methods for crops other than rice (No.3.5.1) and for rice (No.3.5.2), are based on long experience. They may be satisfactory than rice (No.3.5.1) and for rice (No.3.5.2), are based on long experience. They may be satisfactory under local conditions but need verification when applied in conditions very different from those under local conditions but need verification when applied in conditions very different from those under which they were developed.
under which they were developed.
Methods described under 2.2, 3.3, 3.4, and 3.5.1 when used
Methods described under 2.2, 3.3, 3.4, and 3.5.1 when used in planning should first be in planning should first be checked for checked for accuracy using methods 2.1 or 2.5. The choice of method to be used depends upon the funds,
accuracy using methods 2.1 or 2.5. The choice of method to be used depends upon the funds, facilities and basic data that are locally available.
facilities and basic data that are locally available.
Table 9: RELATIVE
Table 9: RELATIVE MERITS OF DIFFERENT METHODS FOR DETERMININGMERITS OF DIFFERENT METHODS FOR DETERMINING EFFECTIVE RAINFALL
EFFECTIVE RAINFALL Methods
Methods Factors taken intoFactors taken into account
Soil AridityAridity CropCrop 2.1 Field
apparatus apparatus 2.3
2.3 Lysimeters Lysimeters - - + + + + + + + + Very Very high high Very Very high high Practicability Practicability medium,medium, good as a check on good as a check on other methods other methods 2.6 Drum
2.6 Drum
technique (rice) technique (rice)
+
+ + + + + + + + + Very Very high high Low Low Practicability Practicability highhigh 3.1 Renfro
3.1 Renfro equation equation
-
- B B + + - - + + Low Low Negligible Negligible Too Too empiricalempirical 3.2 U.S. Bureau
3.2 U.S. Bureau of Reclamation of Reclamation method
method
+
+ - - - - - - - - Low Low Negligible Negligible Not Not suitable suitable for for widewide use
use 3.3 Ratio of
3.3 Ratio of ETp to
ETp to
precipitation precipitation
B
B B B + + - - - - Medium Medium Low Low Satisfactory Satisfactory for for veryvery preliminary planning preliminary planning purposes
purposes 3.4 USDA, SCS
3.4 USDA, SCS method
method
-
- B B + + B B - - Medium Medium Low Low Good Good for for areas areas withwith low intensity of low intensity of rainfall and high soil rainfall and high soil infiltration rate
infiltration rate 3.5.1 Empirical
3.5.1 Empirical methods (other methods (other than rice)
than rice)
B
B B B B B B B - - Low Low toto high high
Negligible
Negligible Practicability veryPracticability very high
high 3.5.2 Empirical
3.5.2 Empirical methods (rice) methods (rice)
B
B B B B B B B - - Medium Medium Negligible Negligible Needs Needs verification;verification;
practicability high practicability high + = positive; - = negative; B = first approximation
+ = positive; - = negative; B = first approximation