1) Norway Case Study - Preventing floods and landslides
The researchers in Norway tested flood retention and the impact of vegetation on river bank stability in the Morsa Catchment. They modelled the effect of different sized retention dams in forest areas (upstream agricultural fields) and the root strength of river bank vegetation.
|Preventing floods and landslides
Water retention ponds
- The flood peak is most likely lowered by the inclusion of a retention area in the catchment. The retention area has a large impact on decreasing soil erosion on the down-slope agricultural fields. It captures and diverts surface runoff, resulting in less sheet and especially gully erosion on the agricultural land.
- Although the number of floods was not quantified during the experiment, according to the statements of the farmers, the flooding over
the agricultural land is reduced from 2-3 times a year to once every second year (reduction in local flooding).
|Example of the modelling results for the area without and with implemented retention pond
- The grass and shrub plots showed similar dynamics both in groundwater level and soil water content fluctuation, while clear differences were observed in hydrological responses within the plot containing trees. The trends observed in soil water content variation corresponded to the groundwater level fluctuations. The differences can be explained by different root depths and subsequent root water uptake.
- Soil-root strength changes with time. In all three plots, higher values of shear strength were observed during late spring and summer. This trend stems from two factors: intensity of the vegetation growth (higher root density) and lower soil moisture content. Variation in modelled slope stability corresponds to variation in groundwater levels and stream water levels. The probability of riverbank failure was higher during spring and early autumn, and lower during the summer. The tree plot was the most stable and shows the highest capacity to accommodate potential shear stress.
|Changes in average shear strength with time and with
depth, for the three plots
|Frequency of Fs for all simulated scenarios, for min and max slope angles. Stability classes: red – unstable slope; yellow – conditional stability; green – stable slope
2) Slovakia Case Study - Mitigating muddy floods and soil erosion
The researchers in Slovakia conducted three eperiments 1) tested the effect of rainfall intensity, soil moisture and vegetation cover on generation of overland flow and sediment transport; 2) measurements of gully erosion; and 3) measurements of sediment loads and bed sediments in a small water reservoir.
|Mitigating muddy floods and gully erosion
|1. Generation of surface runoff
|2. Changes in erosion gully
|3. Changes in sediment loads
Further details about the experiment on the generation of runoff can be found in the fact sheet HERE(SK), changes in erosion gully fact sheet HERE (SK) and changes in sediment loads HERE (SK) and in the project report HERE.
Michaela Danáčová, Radovan Nosko, Roman Výleta, Beata Randusová, Ján Szolgay (2015) Possibilities of estimating the gully erosion changes on the Myjava Basin Published in: ACTA HYDROLOGICA SLOVACA Ročník 16, Tematické číslo 1, 2015, 167 - 175
Korbeľová, Lenka, and Silvia Kohnová (2017) Methods for Improvement of the Ecosystem Services of Soil by Sustainable Land Management in the Myjava River Basin Published in: Slovak Journal of Civil Engineering 25, no. 1, 2017, 29-36 https://doi.org/10.1515/sjce-2017-0005
Čistý, M., Čelár, Ľ., Minarič, P. (2015) Conversion Between Soil Texture Classification Systems Using the Random Forest Algorithm, Air, Soil and Water Research. Published in: Air, Soil and Water Research. Volume 8, Pages 67-75, ISSN 1178-6221 http://www.la-press.com/conversion-between-soil-texture-classification-systems-using-the-rando-article-a5217