Anomaly in the rainfall-runoff behaviour of the Meuse catchment. Climate, land-use, or land-use management?

Abstract

Abstract. The objective of this paper is to investigate the time variability of catchment characteristics in the Meuse basin through its effect on catchment response. The approach uses a conceptual model to represent rainfall-runoff behaviour of this catchment, and evaluates possible timedependence of model parameters. The main hypothesis is that conceptual model parameters, although not measurable quantities, are representative of specific catchment attributes (e.g. geology, land-use, land management, topography). Hence, we assume that eventual trends in model parameters are representative of catchment attributes that may have changed over time. The available hydrological record involves ninety years of data, starting in 1911. During this period the Meuse catchment has undergone significant modifications. The catchment structural modifications, although documented, are not available as "hard-data". Hence, our results should be considered as "plausible hypotheses". The main motivation of this work is the "anomaly" found in the rainfall runoff behaviour of the Meuse basin, where ninety years of rainfall-runoff simulations show a consistent overestimation of the runoff in the period between 1930 and 1965. Different authors have debated possible causes for the "anomaly", including climatic variability, land-use change and data errors. None of the authors considered the way in which the land is used by for instance agricultural and forestry practises. This aspect influenced the model design, which has been configured to account for different evaporation demand of growing forest. As a result of our analysis, we conclude that the lag time of the catchment has decreased significantly over time, which we attribute to more Correspondence to: F. Fenicia (f.fenicia@tudelft.nl) intensive drainage and river training works. Furthermore, we hypothesise that forest rotation has had a significant impact on the evaporation of the catchment. These results contrast with previous studies, where the effect of land-use change on the hydrological behaviour of the Meuse catchment was considered negligible, mainly because there was not sufficient change in land cover to account for it. Here we hypothesise that in the Meuse it was not the change of land cover that was responsible for hydrological change, but rather the way the land was managed.

On the lack of robustness of hydrologic models regarding water balance simulation: a diagnostic approach applied to three models of increasing complexity on 20 mountainous catchments

“…Working on an (until then) unexplained overestimation of the Meuse River runoff between 1930and 1965, Fenicia et al (2009 showed the major impact of changes in land use management and forest age on the catchment's functioning. Such temporary or permanent changes of a catchment functioning result in significant model robustness problems if not included in the modelling framework.…”

How are flood risk estimates affected by the choice of return-periods?

“…Although there are differences in the results, most studies suggest that the frequency of floods will increase in the future due to climate change. Several studies of the Meuse have looked specifically at the effects of changes in land use on the hydrology of the Meuse, finding: (a) a relatively small influence of changes in land cover during the 20th century (Ashagrie et al, 2006;Tu et al, 2005 et Ward et al, 2008Ward et al, , 2011; (b) a larger influence of the way the land was managed during the 20th century (Fenicia et al, 2009); and (c) a large influence of land use change over the last 4000 yr (Ward et al, 2008(Ward et al, , 2011 ; and Attention to Safety . Other recent publications that investigated flood risk in those large downstream dike rings are De , who examined how flood exposure has changed in the Netherlands since 1900 and Bouwer et al (2009Bouwer et al ( , 2010, who estimated future potential damage from river flooding in dike-ring 36 (Land van Heusden/De Maaskant).…”

“…In reality, the damage that would actually occur is highly dependent on the season in which a flood occurs (e.g. Förster et al, 2008). Since most floods of the Meuse River occur during the winter season, this means that the standard SDFs will overestimate damage to agriculture.…”

“…Since most floods of the Meuse River occur during the winter season, this means that the standard SDFs will overestimate damage to agriculture. Damagescanner could be improved by integrating information on the seasonal distribution of agricultural losses; examples of studies that use a seasonal approach can be found in Förster et al (2008). The second major cause of discrepancy between the modelled damages and those reported by Wind et al (1999) is caused by damage from the category "Private" in 1995 (the majority of which is damage to residential properties).…”

Spatial and temporal variability of canopy and forest floor interception in a beech forest

“…At best a distinction is made between leaf‐on and leaf‐off periods (e.g. Rutter et al , 1975; Rowe, 1983; Hörmann et al , 1996; Zhang et al , 2006; Fenicia et al , 2008b; Herbst et al , 2008), but the transition between these states is rarely described. The spatial variability of the canopy coverage also causes large variations in the storage capacity and differs per season (Staelens et al , 2006).…”