From spatial models to spatial evaluation in the analysis of wetland restoration in the Vecht river basin

Water tables are strictly controlled throughout much of the Netherlands. Higher water tables could permit the restoration of wetland ecosystems. Deriving benefits from this requires the spatial matching of physical planning, eco-hydrological processes, and economic activities. This paper reports on a study combining spatial analysis and disciplinary integration to assess management strategies for the Vecht river basin in the Netherlands. The paper addresses two research questions. How can the information generated by spatial models be condensed into performance indicators for the evaluation of strategies? How can spatial information be retained in the evaluation, and does this lead to different rankings and/or insights? Procedures for the construction of performance indicators for three criteria – net present value, environmental quality and spatial equity – are presented. The evaluation concludes that recreation and higher water tables provide a means for restoration, recouping of costs, and stimulating regional incomes. Maintenance of spatial detail led to different insights, and in particular indicated uncertainty about this conclusion.     

The occurrence of PCH3-containing compounds in surface waters

The concentration of PCH₃-containing compounds was determined in several surface water samples obtained from a number of countries in Western Europe and North-America. A correlation was found between this concentration and the grade of water pollution which suggests that the presence of PCH₃-containing compounds is due to industrial sources.     

The occurrence and determination of PCH3-containing compounds in surface water

A procedure has been developed in which the presence of PCH₃-containing compounds in surface waters can be detected in a sensitive and specific way. The compounds of interest are hydrolysed, yielding methylphosphonic acid as a common breakdown product. This acid is concentrated using an anion-exchange column and subsequently transformed into its dimethyl ester by diazomethane. After a clean-up on a microsilica gel column the ester is analysed by means of gas chromatography using a thermionic detector as a specific phosphorus detector. The lowest detectable concentration is approximately 1 nmol of a PCH₃-containing compound per litre of water.Samples from the rivers Rhine and Meuse and from two lakes in the Netherlands were analysed. Concentration levels of 0.1 – 1 μg/l of PCH₃-containing compounds expressed as methylphosphonic acid were found. The origin of the compounds and their possible accumulation in the environment are discussed.     

Mediated Modeling in Water Resource Dialogues Connecting Multiple Scales

We observe a paradigm shift toward collaborative, multi‐level (from local to global) water management and suggestions for scale‐related design principles in the literature. Decision‐support tools are needed that can help achieve scale design principles. Mediated modeling (MM) refers to model building with people, rather than for people. This tool belongs to a family of participatory, systems oriented tools. This article explores their suitability for addressing challenges and principles that arise at multiple‐scales. MM can promote the understanding of cross‐level and cross‐scale links, creating salient, credible, and legitimate knowledge and encouraging boundary functions. Prerequisites for successful MM processes include an openness and willingness to collaborative learning. As new “meso‐level” institutions emerge to address complex challenges in water management collaboratively, tools like MM may play an important role in structuring dialogues, developing adaptive management capacity and advance an ecosystem services approach.     

Flood Protection: Highlighting an Investment Trap Between Built and Natural Capital

We present a simulation model developed to communicate a potential investment trap associated with using man‐made river engineering to protect built infrastructure. A small system dynamics model in STELLA? was constructed following a collaborative model‐building process to increase understanding among stakeholders of the role natural capital plays in wealth creation. We set out to explore the dynamic relationship between investing tax revenue in natural capital (specifically forested headwaters and low land wetlands) rather than built capital (specifically stopbanks) for flood protection in the Manawatū watershed, New Zealand. Significant investment is currently required to maintain and enhance river engineering infrastructure and keep pace with changes in the river's geomorphology. Viewed from a systems perspective, we suggest diversion of a proportion of existing funding into restoration of forested headwaters on steep slopes and restoration of functioning wetlands on floodplains could in the longer term provide an effective approach to flood protection. Co‐benefits of increased natural capital include the ecosystem services nutrient cycling, sediment capture, water purification, biodiversity, pollination, and cultural and recreational values. Overcoming an investment trap requires a longer term perspective. This simple model consisting of two feedback loops and two delays aims to contribute to an ongoing stakeholder dialogue concerning the Manawatū River watershed in New Zealand.     

Flood protection and endogenous sorting of households: the role of credit constraints

Human migration is increasingly seen as a promising climate change adaptation and flood risk reduction strategy. The purpose of this paper is to investigate how spatial differences in flood risk, due to differences in flood protection, reduce the mobility of vulnerable households through a credit constraint mechanism. Using an equilibrium model with two households types and endogenous sorting, we show how spatial differences in flood protection lead to clustering of vulnerable households in a risky region, in a real-world setting of common United States (US) flood zones. We find clustering effects of some size for flood zones with return periods of less than 30 years.