Purpose

Wetland areas are under heavy pressure and require the attention of both natural and social scientists. In order to arrive at useful policy and management suggestions to ameliorate problems related to the human use of, and impacts on, wetlands, the integration of theories, models and indicators of relevant natural and social sciences is necessary. For this purpose, the present study as developed an integrated research method that combines hydrology, ecology and economics, using spatial modelling and evaluation techniques. This method was applied to the Vecht wetlands area (De Vechtstreek) in the centre of the Netherlands, an area of about 160km2 in size that includes natural and artificial lakes, reedbeds, fens, peatlands, marshes, forests and wet pasturelands. The area's land cover, land use and landscape are the product of an interaction between human activities and natural processes over centuries. The main activities are agriculture and recreation, while the main conflicts are between agriculture, on the one hand, and nature conservation and outdoor recreation, on the other hand. Much information is available for the area, via natural science studies performed in the past, as well as through local, regional and national policy documents.

Method of integrated research

The method of integrated study entailed the heuristic integration of hydrological quality and quantity modelling, vegetation response modelling and economic modelling and accounting.

Problems, policy and management of wetlands

It is now widely recognised that wetlands provide many important goods and services to human societies. Examples include drinking water, flood mitigation, water quality control, fish products and recreational and residential opportunities. The non-use values that society attributes to wetland species and ecosystems can also be significant (Turner et al., 1998a). Wetland ecosystems are, however, under stress from human activities, in particular changes in land use with concomitant habitat loss and fragmentation, resource extraction, drainage and reclamation, and pollution. Not surprisingly, wetlands are currently receiving considerable attention in environmental science and policy.

Wetlands all over the world are threatened, in spite of various international agreements and national policies to protect them. There are a number of fundamental reasons for this (see also Turner et al., 2000). Market failures exist because of the public good aspects of many wetlands and consequent lack of property rights for certain wetland goods and services. In addition, economic activities such as agriculture, industry and water abstraction trigger externalities for other stakeholders. These stakeholders include direct, indirect and even non-users of wetland goods and services. Next, there is a failure of information and a lack of understanding of the multitude of values associated with wetlands as a result of the complexity and ‘invisibility’ of spatial relationships between groundwater, surface water and wetland vegetation.

Introduction

This chapter provides a concise introduction to the elements – concepts, theories, methods and models for empirical analysis – contributed by the natural and social sciences to studies of wetlands. The case study discussed in Chapters 5 to 10 of the book will draw upon some of these elements. Section 2.2 presents the natural science perspective, focusing on hydrology and ecology, while Section 2.3 presents the social science perspective, focusing on environmental and ecological economics. Section 2.4 examines approaches to, and problems associated with, integrating the two perspectives.

Hydrology and ecology

According to the Ramsar definition, a wetland is an area where wet conditions predominate (see Section 1.2). Abiotic – chemical and hydrological – conditions of waters and soil together influence biological processes in a wetland, which in turn affect its environmental and economic functions. This section will provide information about these various connections, illustrated by examples taken from the Netherlands.

Processes and characteristics of hydrological systems

Each wetland is part of the hydrological cycle. The latter refers to the process of water evaporating from the surface of the earth and returning through precipitation: rain, snow, etc. The volume of precipitation is the major force in the cycle. Since gravity drives water flows, surface water ends up in rivers and oceans, where it can evaporate again (Chow, 1964; Manning, 1997; Ward and Robinson, 2000).

Introduction

This chapter looks at the changes in costs, benefits and nutrient flows under the three scenarios, as formulated in Chapter 6. The goals of this chapter are (a) to present the economic indicators, calculate these under each scenario and perform a financial cost–benefit analysis (CBA), and (b) to calculate the changes in the run-off of nutrient flows under each scenario. The economic cost and benefit indicators will be entered, along with the ecological and spatial equity indicators (Ch. 9), into the scenario evaluation (Ch. 10). Additional economic indicators, to be calculated, are the changes in net present value (NPV) and employment, and the effects of changes in the spatial and economic structure on nutrient flows. The last leads to the calculation of environmental indicators for run-off and surplus of nitrogen and phosphate, which serve as inputs to the ecosystem model discussed in Chapter 7.

There are several types of CBA. In this chapter, financial CBA indicators are generated, which means that only financial transactions are considered. Another approach is economic CBA, which also includes (social) costs and benefits for non-market goods and services, such as those related to changes in nature (Zerbe and Dively, 1994). As no prices are available for these non-market valuations, values must be estimated.

Description of the area

The Vecht area is a plain with wetlands, located between the river Vecht in the west (Fig. 5.1) and the sandy ice-pushed hill ridge ‘Het Gooi’ approximately 8km to the east. To the north, a former sea (‘Zuiderzee’), now reclaimed, bounds the area; 20km to the south near the city of Utrecht, the hill ridge and the river almost meet (Fig. 5.2). The area is a wetland region with many shallow lakes. Even where a solid soil is present, the groundwater table is close to the surface. The soil diversity is represented by the presence of three types of soil: close to the river and the former sea, there are deposits of clay soils; the centre of the plain is covered by a peat layer some metres in depth; and in the eastern direction this peat layer gets thinner until it reaches the sandy soil of the hill ridge. The area straddles two provinces (North-Holland and Utrecht) and includes 10 municipalities. The number of inhabitants in these areas is restricted. The centres with significant population sizes are mostly at the border of, or just outside, the area (see Table 5.1).

Agriculture and nature dominate land use; industry is almost absent (Fig. 5.3). Agriculture is primarily dairy farming.

Introduction

This chapter describes the hydrological and ecological modelling that underlies the integrated modelling approach in this study. In addition, some general characteristics of the intermediate results are discussed. Aggregation of the latter will be pursued in later chapters. Modelling the interaction of hydrology and vegetation of a wetland has three main elements.

1. A water quantity model, describing amounts of groundwater and surface water expected at specified locations in the present hydrological conditions;

2. A water quality model, describing the chemistry of groundwater and surface water at specified locations; and

3. An ecological model describing the presence of wetland plant species at specified locations, depending on local environmental conditions.

These three models interact, as summarised in Table 7.1. The water quantity model provided inputs to the water quality model, while both these models predict the abiotic conditions that serve as input for the ecological model.

A set of boundary conditions is needed to define the domains of the models. These boundary conditions can then be manipulated in scenarios. However, some input variables of the model are assumed to be static in the time domain adopted here, e.g. soil texture.

The modelling has a spatial dimension. Therefore, each of the models requires spatially differentiated input.

Introduction

This chapter presents development scenarios for the Vecht area that will be used in the integrated modelling exercise reported in later chapters. These scenarios reflect choices made in physical planning, nature policy, agricultural policy and the regulation of recreation and drinking water production, which are the main political and economic interests in the area. The scenarios have a spatial disaggregation and are formulated at polder level. The hydrological parameters are defined at grid level (500 m × 500 m) and the economic parameters at polder level. This is because the hydrological model assumes homogeneity and is formulated at grid level, while the economic model is formulated at the polder level. Any information at grid level can be aggregated up to polder level.

As the static model approach is used, static scenarios are formulated. Each scenario will provide information about land use and water levels at polder level for 72 polders (Fig. 6.1). The procedure for such a spatially disaggregated approach is complicated. Land use depends on the type of activity and the type of soil. The first includes historical conditions, classified into agricultural land (grassland, cropland), nature and forestry, urban settlements and open water. The soil type is classified into sand, clay and peat.

Objective and approach

The Vecht area study is intended to contribute to the development of an integrated framework and method for multidisciplinary analysis of policy and management scenarios for areas dominated by wetland ecosystems. The nature of wetlands, characterised by transitions from land to water, is such that several disciplines need to provide information and insights to allow evaluation of the impacts of proposed changes in wetlands areas. These changes include, for example, land reallocation, management of water tables, regulation of economic activities and construction of infrastructure. As discussed in Chapter 2, the core disciplines in wetlands research are hydrology, ecology and economics. Hydrology studies qualitative and quantitative aspects of stocks and flows of groundwater and surface water. Ecology studies the relationship of living organisms with their environment. Economics studies the behaviour of households and companies in the context of market interactions between the demand and supply of goods and services. As discussed in Chapter 3, these disciplines can be integrated for the purpose of case studies through the use of integrated economic–environmental modelling. The approach adopted in the Vecht area study is consistent with the very basic and general drivers–pressured–state–impact–response (DPSIR) framework that was discussed in Section 2.4. Chapter 5 will present each of the elements of this framework in the context of the case study.

In all parts of the world, wetlands are endangered by human activities and development. Areas with wetlands often provide locations for housing and recreation. Consequently, threats to wetlands rapidly lead to the loss of the valuable services they provide to humans. Wetlands have been studied in many disciplines, both in the natural and the social sciences. Integration between disciplines has been tried, though often without much success. This study approaches the analysis of wetlands' development and policy by using integrated ecosystem modelling that builds upon a combination of insights from hydrology, ecology and economics. It devotes particular attention to the spatial dimension, the development of a set of complementary indicators and the aggregation and evaluation of information.

The first part of the book provides a short introduction to the relevant building blocks of the approach, which include discussions of wetlands, the natural sciences, economics, integrated modelling and evaluation. The second part of the book presents a case study in which the integrated modelling approach is applied to a wetlands area in the centre of the Netherlands: the Vecht area.

The case study was part of an EU project entitled Ecological–Economic Analysis of Wetlands: Functions, Values and Dynamics, sponsored by the EU's Environment and Climate R&D programme (ECOWET, contract no. ENV4-CT96-0273).

Introduction

The performance indicators developed in Chapter 9 reflect three objectives (net present value (NPV), environmental quality and spatial equity), which will be used to evaluate the scenarios. This section presents the results of this evaluation. Its aim is to rank the scenarios, to identify where trade-offs among objectives may be needed, to identify spatial features within the ranking, and to identify elements within the scenarios that bear further consideration in regional planning. A distinction is made between point evaluation (the subject of Section 10.2) and spatial evaluation (the subject of Section 10.3). This distinction is illustrated below in Fig. 10.5.

Point evaluation

The point evaluation stems from the performance indicators calculated for the region as a whole. Table 10.1 presents the results of calculating performance indicators, as outlined in the previous section. This table forms the basis for the evaluation.

The objective function for this evaluation is some mathematical combination of the three objectives appearing in Table 10.1. The form of this function is unknown, and it is further complicated by the use of different measurement units for each objective. Taken individually, each objective yields a different ranking of the scenarios, where > indicates ‘preferred to’: