[1] Groundwater can have a profound effect on water availability to vegetation in temperate climate regions. Here we attempt to model groundwater, soil water, and vegetation dynamics in groundwater controlled ecosystems and to assess how these depend on climate and topography. We focus on the possible location of a boundary between two vegetation types on a slope. One vegetation type is adapted to wetter soil moisture conditions, and one is adapted to drier conditions. We hypothesized that the vegetation type boundary along the slope in climax state is located where the slopeaverage evapotranspiration is highest and/or where vegetation stress is minimal. Vegetation stress is a combination of occurring water stress as defined by and a newly defined oxygen stress, which results from anaerobic conditions. To study this system, we built a two-dimensional model of saturated-unsaturated flow along a slope in which the abundance of two vegetation types varied along the slope. The results show that boundary between the vegetation types based on maximum evapotranspiration occurs at approximately the same location as that is predicted based on minimum plant stress. When precipitation increases, the boundary between the two vegetation types moves up slope. Sensitivity of the location of the vegetation boundary to changes in precipitation decreases with increasing slope angle.Citation: Brolsma, R. J., and M. F. P. Bierkens (2007), Groundwater -soil water -vegetation dynamics in a temperate forest ecosystem along a slope, Water Resour.
Despite the recognized potential of nature-based solutions (NBSs) to support climate adaptation, there are still wide barriers for a wider uptake of such NBS in urban areas. While tailored NBS tools could facilitate and accelerate this process, a comprehensive mapping of their availability and capacity to respond to cities’ challenges is missing. This research aims to provide an overview of tools that intend to facilitate the uptake of NBS for urban climate adaptation supporting cities in overcoming their challenges. To do so, this paper (i) presents the results of interviews and workshops with municipal officers and decision-makers from different European cities that identified the challenges they experience with NBS uptake; (ii) selects and reviews NBS tools and (iii) analyzes them on their capacity to address these implementation challenges. Our research revealed four key challenges that municipal officers experience: resources availability; level of expertise, know-how or competence; the institutional setting, and collaborative governance and planning. The results from the tools’ review show that existing tools can support overcoming a lack of expertise (31), but, to a smaller extent, can also be of use when experiencing the institutional setting (13), availability of resources (11), and collaborative governance and planning (10) as a challenge. This work provides researchers and tool developers with insights into potential market saturation as well as scarcity of certain types of tools that would match cities’ challenges, highlighting needs and opportunities for new tool development.
Vegetation growth models often concentrate on the interaction of vegetation with soil moisture but usually omit the influence of groundwater. However the proximity of groundwater can have a profound effect on vegetation growth, because it strongly influences the spatial and temporal distribution of soil moisture and therefore water and oxygen stress of vegetation. In two papers we describe the behavior of a coupled vegetation-groundwater-soil water model including the competition for water and light. In this first paper we describe the vegetation model, compare the model to measured flux data and show the influence of water and light competition in one dimension. In the second paper we focus on the influence of lateral groundwater flow and spatial patterns along a hillslope. The vegetation model is based on a biophysical representation of the soil-plant-atmosphere continuum. Transpiration and stomatal conductance depend both on atmospheric forcing and soil moisture content. Carbon assimilation depends on environmental conditions, stomatal conductance and biochemical processes. Light competition is driven by tree height and water competition is driven by root water uptake and its water and oxygen stress reaction. The modeled and measured H 2 O and CO 2 fluxes compare well to observations on both a diurnal and a yearly timescale. Using an upscaling procedure long simulation runs were performed. These show the importance of light competition in temperate forests: once a tree is established under slightly unfavorable soil moisture conditions it can not be outcompeted by smaller trees with better soil moisture uptake capabilities, both in dry as in wet conditions. Performing the long simulation runs with a background mortality rate reproduces realistic densities of wet and dry adapted tree species along a wet to dry gradient. These simulations show that the influence of groundwater is apparent for a large range of groundwater depths, by both capillary rise and water logging. They also show that species composition and biomass have a larger influence on the water balance in eco-hydrological systems than soil and groundwater alone.
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