Equation for Calculating Evapotranspiration of Technical Soils for Urban Planting

Oliver Weiss,Ulrike Pitha,Bernhard Scharf,Pia Minixhofer

doi:10.3390/land10060622

Abstract

Equations for calculating evapotranspiration in technical soils show great differences regarding their results. Causes are the different climatic conditions and vegetation specifics during their development. Every equation of evapotranspiration only delivers 100% correct results if it is used under the same climatic condition as it was developed in. To determine the evapotranspiration, the loss of weight of different technical soils and plants was measured in a test series on load cells in a climate chamber. The result of these test series is the development of an easy-to-use equation. An equation for calculating evapotranspiration at any temperature is possible while using a polynomial correlation. To determine the evapotranspiration rate (in mm/m² per 24 h), only temperature, vegetation type, and technical soil have to be defined to obtain an output of evapotranspiration in mm/day. Using the well-known equation by Makkink, evapotranspiration in technical soils is 0.12 mm/day, whereas the newly developed equation calculates (1) 2.59–5.58 mm/day for the variant with no vegetation, (2) 3.15–4.00 mm/day for Sedum floriferum, (3) 4.40–4.55 mm/day for Geranium x cantabrigiense. The application of this equation will help to determine the evapotranspiration in chosen technical soils (used in the sector of rainwater management) with or without vegetation.

Highlights

The on-going climate crisis leads to an increase of heavy rainfall events and a higher risk of longer dry periods [1,2,3]
Evapotranspiration can be described as the sum of water loss by soil surface and the water loss by plants [8]
Equations are presented for calculating evapotranspiration in different chosen substrates with or without any type of planting

Summary

Introduction

The on-going climate crisis leads to an increase of heavy rainfall events and a higher risk of longer dry periods [1,2,3]. Green infrastructure could cope with the intensified stormwater events, urban development has been practiced for years without including them [4]. Green infrastructures, such as bioswales or raingardens, are permeable and have a high impact on evapotranspiration, which influences the urban climate enormously [5,6,7]. The urban water cycle is heavily influenced by the high sealing rate and the decreasing infiltration capacity of the remaining open surfaces [9]. The decreasing infiltration rate and higher surface water runoff [10] impacts further on the overall evapotranspiration rate

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Results

Discussion

Conclusion