Documentation

Soil Types – Infiltration Properties

Horton parameters

We use the Horton infiltration equation for modeling infiltration in various parts of the Scalgo Live system, including the Flash Flood Map with infiltration and drainage and Core+ DynamicFlood. Each soil type in our topsoil map can have both a "High compaction" and "Low compaction" state. The compaction state of the topsoil in a given cell is determined based on the land cover, see further below. We have a set of horton parameters for each of the soil typologies we use.

JB-based soil types

The table below lists the Horton parameters for the soil types in the Scalgo Live topsoil map using our JB-based soil types:

	High compaction			Low compaction			Porosity
Soil type	fc [mm/h]	f0 [mm/h]	k	fc [mm/h]	f0 [mm/h]	k	[fraction]
Rocks and boulders	500	1000	5	500	1000	5	0.4
Gravel	500	1000	5	500	1000	5	0.4
Coarse sand	30	120	5	300	500	5	0.4
Fine sand	25	100	5	200	400	5	0.3
Coarse sand with clay	21	85	5	85	150	5	0.3
Fine sand with clay	20	80	5	50	130	5	0.3
Coarse clay with sand	12	50	5	30	120	5	0.25
Fine clay with sand	9	47	6	25	100	4	0.25
Clay	5	20	5	20	50	5	0.2
Fine clay	0.5	2	5	2	20	5	0.2
Very fine clay	0.01	0.1	5	0.1	1	5	0.2
Silt	20	80	5	50	130	5	0.25
Gyttja/peat	21	85	5	85	150	5	0.4
Bedrock	0	0	5	0	0	5	0
Glacier	0	0	5	0	0	5	0
Water	0	0	5	0	0	5	0

Table: Horton parameters for the JB-based soil types used in Scalgo Live; infiltration rates given in mm/hr. The values were chosen based an evaluation including the sources listed at the bottom of this page.

Horton parameters - USDA-based soil types

The table below lists the Horton parameters for the soil types in the Scalgo Live topsoil map using our USDA-based soil types:

	High compaction			Low compaction			Porosity
Soil type	fc [mm/h]	f0 [mm/h]	k	fc [mm/h]	f0 [mm/h]	k	[fraction]
Rocks and boulders	500	1000	5	500	1000	5	0.4
Gravel	500	1000	5	500	1000	5	0.4
Sand	70	200	5	300	500	5	0.4
Loamy sand	30	100	5	200	300	5	0.3
Sandy loam	12	60	5	120	200	5	0.3
Loam	5	50	5	50	100	5	0.3
Silt loam	5	50	5	50	100	5	0.2
Silt	2	20	5	40	80	5	0.2
Sandy clay loam	2	20	5	40	80	5	0.2
Clay loam	1	10	5	30	60	5	0.2
Silty clay loam	1	10	5	30	60	5	0.2
Sandy clay	1	10	5	30	60	5	0.2
Silty clay	0.5	5	5	20	40	5	0.2
Clay	0.3	3	5	10	20	5	0.2
Gyttja/peat	21	85	5	85	150	5	0.3
Bedrock	0	0	5	0	0	5	0
Glacier	0	0	5	0	0	5	0
Water	0	0	5	0	0	5	0

Table: Horton parameters for the USDA-based soil types used in Scalgo Live; infiltration rates given in mm/hr. The values were chosen based an evaluation including the sources listed at the bottom of this page.

Grouping into high/low compaction

The land cover type of a given location decides whether we use the high or low compaction Horton parameters for that location, the table below details how we map each land cover type to a compaction degree.

Land cover type	Compaction degree	Note
Bare land	High
Shallow vegetation	High
Dense vegetation	Low
Fields	High
Unpaved roads	High
Bare rock	N/A	All rainfall is turned to runoff, zero infiltration
Snow/ice	N/A	All rainfall is turned to runoff, zero infiltration

Table: Soil compaction degrees assigned to different land cover types.

References for Horton parameters

Dyhr, A. S., & Lindbæk, K. W. (2021). Sammenligning af kurvenummermetoden og Hortons model. Bachelor’s thesis, DTU.

Etana, A. (2020). Undersökning av markpackning. Swedish University of Agricultural Sciences.

Gregory, J.H., Dukes, M. D., Jones, P. H., & Miller, G. L. (2006). Effect of urban soil compaction on infiltration rate. Journal of Soil and Water Conservation, 61 (3) 117-124.

Ministère de l’Écologie, du Développement durable et de l’Énergie, Wikhydro.

Kotlar, A. M., de Jong van Lier, Q., Andersen, H. E., Nørgaard, T., & Iversen, B. v. (2020). Quantification of macropore flow in Danish soils using near-saturated hydraulic properties. Geoderma, 375.

Parnas, F. E. Å., Abdalla, E. M. H., & Muthanna, T. M. (2021). Evaluating three commonly used infiltration methods for permeable surfaces in urban areas using the SWMM and STORM. Hydrology Research, 52(1), 160–175.

Rahmati, S. et. al (2018). Development and analysis of the Soil Water Infiltration Global database. Earth Syst. Sci. Data, 10, 1237–1263.

Rossman, L. A., & Simon, M. A. (2022). Storm Water Management Model User’s Manual Version 5.2.

van der Molen, W. H., Martínez Beltrán, J., Ochs, W.J. (2007). Guidelines and computer programs for the planning and design of land drainage systems. FAO Irrigation and Drainage Paper 62.