Curve number tables

MODIPE is based on the Soil Conservation Service Curve Number method.

To choose the curve number of a zone we must use tables that appear in most of the Hydrology books. The question is to choose from the table the more similar description to the studied zone.

The resulting curve number is inside the interval 0-100.

High curve numbers imply high run-off (=poor infiltration; =degraded slopes). On the other hand, low curve numbers guarantee high infiltration rates, low surface run-off and low hydric erosion.

In this spot of the web site we reproduce the main curve number table, so it's at hand for the user. We have also developed a Visual basic application that let you choose curve numbers automatically. This is the program NUMCUR 10 IE, in bilingual version (English-Spanish) and with a number of help windows that appear when pressing F1 key.

We also offer a PDF file (Pequeña guía de uso de MODIPÉ 465 KB , in Spanish), where we have included notes, comments and indications that are needed to use and interprete the tables correctly.

Figure: Input data for MODIPE

GENERAL TABLE

Land use	Treatment	Hyidrologic condition	Soil type
Land use	Treatment	Hyidrologic condition	A	B	C	D
Fallow land	Naked	-	77	86	91	94
	CR	Poor	76	85	90	93
	CR	Good	74	83	88	90
Row crops (aligned cultivated soils)	R	Poor	72	81	88	91
	R	Good	67	78	85	89
	R + CR	Poor	71	80	87	90
	R + CR	Good	64	75	82	85
	C	Poor	70	79	84	88
	C	Good	65	75	82	86
	C + CR	Poor	69	78	83	87
	C + CR	Good	64	74	81	85
	C + T	Poor	66	74	80	82
	C + T	Good	62	71	78	81
	C + T + CR	Poor	65	73	79	81
	C + T + CR	Good	61	70	77	80
Small grain (non aligned cultivated soils)	R	Poor	65	76	84	88
	R	Good	63	75	83	87
	R + CR	Poor	64	75	83	86
	R + CR	Good	60	72	80	84
	C	Poor	63	74	82	85
	C	Good	61	73	81	84
	C + CR	Poor	62	73	81	84
	C + CR	Good	60	72	80	83
	C + T	Poor	61	72	79	82
	C + T	Good	59	70	78	81
	C + T + CR	Poor	60	71	78	81
	C + T + CR	Poor	58	69	77	80
Dense leguminous crops or meadows in rotation	R	Poor	66	77	85	89
	R	Good	58	72	81	85
	C	Poor	64	75	83	85
	C	Good	55	69	78	83
	C + T	Poor	63	73	80	83
	C + T	Good	51	67	76	80
Natural pastures	-	Poor	68	79	86	89
	-	Fair	49	69	79	84
	-	Good	39	61	74	80
Pastures	C	Poor	47	67	81	88
	C	Fair	25	59	75	83
	C	Good	6	35	70	79
Permanent meadows (protected from grazing)	-	-	30	58	71	78
Brush-grassland, with brush dominating	-	Poor	48	67	77	83
	-	Fair	35	56	70	77
	-	Good	≤30	48	65	73
Mixture of woods and grassland, woody agriculture crops	-	Poor	57	73	82	86
	-	Fair	43	65	76	82
	-	Good	32	58	72	79
Woods with pastures (silvopastoral use)	-	Poor	45	66	77	83
	-	Fair	36	60	73	79
	-	Good	25	55	70	77
Woods	-	I Very poor	56	75	86	91
	-	II Poor	46	68	78	84
	-	III Fair	36	60	70	76
	-	IV Good	26	52	63	69
	-	V Very good	15	44	54	61
Country houses	-	-	59	74	82	86
Gravel roads	-	-	72	82	87	89
Asphalt roads	-	-	74	84	90	92

Abbreviations meaning:

CR=with vegetal residue cover that extends for at least 5% of the soil surface all over the year

R=when soil labours (ploughing, sowing,etc) are made in straight line, without considering the slope

C=when cultivation is made according to contour lines

T=in terraces cultivations (open terraces with drainage for soil conservation)